Anhydrous formulations contain no intentionally added water and are generally based on oils, esters, waxes, butters, silicones or other non-aqueous materials.

Examples include lip balms, lipsticks, facial oils, cleansing oils, body balms, petroleum-based products and certain solid sticks.

The absence of water can provide formulation advantages. Ingredients that are unstable in aqueous environments may be easier to formulate in anhydrous systems, and many microorganisms require available water for growth.

However, anhydrous does not mean automatically microbiologically safe. Water can be introduced during consumer use, particularly in products used with wet hands or in the shower.

Stability

Oxidative stability is often an important concern. Oils rich in unsaturated fatty acids can oxidize during storage, producing changes in odor, color and potentially the sensory characteristics of the product.

Antioxidants, oxygen-limiting packaging and appropriate storage conditions may therefore be important.

Texture

In balms and sticks, wax selection and crystallization behavior strongly influence hardness, payoff, melting point and sensory characteristics.

Cooling rate can affect crystal formation and therefore the final texture of the product.

References

Barel, A. O., Paye, M. and Maibach, H. I. Handbook of Cosmetic Science and Technology. CRC Press.

European Commission. CosIng – Cosmetic Ingredients Database.

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The aqueous phase is the water-rich part of a cosmetic formulation. In conventional emulsions, it is combined with an oil phase to produce the final emulsion.

Purified water is usually the major component, but the aqueous phase may also contain glycerin, propanediol, glycols, water-soluble polymers, acids, bases, buffers, chelating agents, preservatives and water-soluble active ingredients.

The composition of the aqueous phase has a major influence on the final properties of the formulation. pH, conductivity, ionic strength and dissolved solids can affect viscosity, emulsification, preservation and ingredient stability.

Processing

The order of addition can be particularly important. Some polymers need to be fully hydrated before electrolytes are introduced, while certain active ingredients should only be added during the cooling phase because they are heat sensitive.

Water quality is also critical. Variations in mineral content, microbial quality and conductivity can contribute to differences between batches.

Formulation Considerations

The aqueous phase should be evaluated for pH, clarity, viscosity and compatibility before and after incorporation into the complete formulation.

Changes in the aqueous phase can influence the performance of emulsifiers, preservatives and rheology modifiers, meaning that an ingredient that behaves well in water alone may behave differently in the finished product.

References

Barel, A. O., Paye, M. and Maibach, H. I. Handbook of Cosmetic Science and Technology. CRC Press.

European Commission. CosIng – Cosmetic Ingredients Database.

Lachman, L., Lieberman, H. A. and Kanig, J. L. The Theory and Practice of Industrial Pharmacy.

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An active ingredient is an ingredient selected because it is intended to provide a defined cosmetic effect in the finished product. Examples include ingredients used to moisturize the skin, reduce the appearance of wrinkles, improve skin texture, provide antioxidant protection, condition hair or support an even-looking complexion.

The term "active ingredient" is widely used in cosmetic formulation and marketing, but its precise regulatory meaning depends on the market. An ingredient described as an active in cosmetic development should not automatically be considered a medicinal active ingredient.

The concentration of an active ingredient is an important consideration. The concentration required for formulation performance may be different from the concentration used to support a particular cosmetic claim.

Formulation Considerations

An active ingredient should be evaluated for solubility, stability, compatibility, pH sensitivity, temperature sensitivity and interaction with other formulation components.

Some actives are sensitive to oxygen, light or heat and may therefore require specific processing conditions or protective packaging. Others may require encapsulation or a particular delivery system.

The supplier specification should be reviewed carefully because the same INCI ingredient can be supplied in different grades, concentrations or delivery systems.

Claims and Efficacy

Where an active ingredient is used to support a cosmetic claim, the evidence should be appropriate to the claim being made.

Ingredient literature can provide useful background information, but evidence relating to an isolated ingredient does not automatically demonstrate the efficacy of the finished cosmetic product. Where appropriate, finished-product testing can provide stronger support.

References

Barel, A. O., Paye, M. and Maibach, H. I. Handbook of Cosmetic Science and Technology. CRC Press.

European Commission. CosIng – Cosmetic Ingredients Database.

European Commission. Commission Regulation (EU) No 655/2013.

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Phenethyl alcohol, also known as phenylethyl alcohol or 2-phenylethanol, is an aromatic alcohol consisting of a benzene ring attached to a two-carbon alcohol chain. It is a colorless, transparent and slightly viscous liquid with a characteristic rose-like odor.

The ingredient occurs naturally in plants, microorganisms and animals and has been identified in numerous essential oils, foods, spices, tobacco, beer, wine and other fermented products. Although it can be obtained from natural sources, commercial phenethyl alcohol is most commonly produced synthetically because natural extraction, particularly from rose oil, is economically inefficient.

INCI Name: Phenethyl Alcohol
Other Names: Phenylethyl Alcohol, 2-Phenylethanol
CAS Number: 60-12-8
EINECS Number: 200-456-2
Molecular Formula: C8H10O
Molecular Weight: 122.17 g/mol
Chemical Class: Aromatic Alcohol
Function: Fragrance Ingredient, Preservative-supporting Ingredient, Masking Agent

Fragrance Properties

Phenethyl alcohol has a characteristic soft, sweet and rose-like floral odor and is an important material in perfumery.

It can be used to impart a floral character to a formulation or to modify and mask undesirable odors originating from other ingredients. Because of its relatively mild and pleasant odor, it is frequently used in fragrances for personal care and cosmetic products.

Phenethyl alcohol is also naturally present in rose oil and contributes to the characteristic aroma of roses.

Preservative and Antimicrobial Properties

Phenethyl alcohol has antimicrobial activity and can inhibit the growth of certain microorganisms. For this reason, it is frequently used in cosmetic formulations as part of a preservation system.

Its antimicrobial effect can help prevent or retard bacterial growth and therefore contribute to the protection of a cosmetic product against microbial spoilage.

However, phenethyl alcohol should not automatically be considered a complete broad-spectrum preservative when used alone. Its effectiveness depends on the concentration, formulation pH, water activity, packaging and the other components of the preservation system.

In practice, it may be combined with other antimicrobial or preservative ingredients to provide more comprehensive protection against bacteria, yeasts and molds.

Cosmetic Applications

Phenethyl alcohol is used in a wide variety of cosmetic and personal care products.

It can be found in skincare products, haircare products, cleansers, creams, lotions, fragrances, deodorants and other fragranced formulations. It can function simultaneously as a fragrance component, odor-masking ingredient and antimicrobial component of the preservation system.

Its dual fragrance and antimicrobial properties make it particularly useful in formulations where both functions are desirable.

Formulation Considerations

Phenethyl alcohol is a liquid ingredient that can be incorporated into a variety of cosmetic formulation systems.

Because it is both a fragrance material and an antimicrobial ingredient, its concentration should be selected according to the intended purpose. A concentration chosen primarily for fragrance may not provide sufficient preservation, while a concentration chosen for antimicrobial activity may have a significant effect on the sensory profile of the finished product.

The ingredient should therefore be evaluated as part of the complete preservation strategy rather than considered in isolation.

Compatibility with the other fragrance components, preservatives, emulsifiers and active ingredients should be evaluated during formulation development.

Stability

Phenethyl alcohol is relatively stable under normal formulation and storage conditions. Nevertheless, the stability of the ingredient and the finished product can be influenced by temperature, light, oxygen and interactions with other formulation components.

Finished products containing phenethyl alcohol should undergo appropriate stability testing to evaluate changes in odor, appearance, color, pH, viscosity and microbiological quality throughout the intended shelf life.

Skin Compatibility

Phenethyl alcohol is generally well tolerated at the concentrations commonly used in cosmetic products. However, as with many fragrance materials, individual sensitivity can occur.

The potential for irritation or sensitization should be considered according to the concentration and the intended application. Products intended for sensitive skin or prolonged leave-on exposure should be evaluated particularly carefully.

The safety of a finished formulation depends on the total exposure to phenethyl alcohol and other fragrance and preservative ingredients present in the product.

Natural Occurrence

Phenethyl alcohol occurs naturally in a wide range of biological materials. It has been identified in rose oil and other essential oils, as well as in various foods, spices, tobacco and fermented alcoholic beverages.

It is also produced naturally by microorganisms, plants and animals and has been detected as a metabolite in humans, including in urine.

Despite its natural occurrence, the phenethyl alcohol used commercially in cosmetics is frequently produced synthetically because this provides a more consistent and economically practical source of the ingredient.

Safety

The safety of phenethyl alcohol in cosmetic products has been evaluated by the Cosmetic Ingredient Review Expert Panel.

The CIR Expert Panel concluded that phenethyl alcohol is safe for use in cosmetics and personal care products at concentrations of up to 1%. The conclusion was subsequently reaffirmed during the CIR's scheduled re-evaluation in 2006 after consideration of additional available data.

The appropriate concentration in a finished cosmetic product should nevertheless be determined according to the product type, exposure conditions, intended use and applicable regulations.

Toxicological Information

Historical acute oral toxicity data report an LD50 of approximately 1,790 mg/kg body weight in rats.

This is an acute oral animal toxicity value and should not be interpreted as a safe cosmetic concentration or directly extrapolated to topical exposure.

A reliable ingredient-specific NOAEL for topical cosmetic exposure is not provided in the supplied source and should not be inferred from the oral LD50 value.

Regulatory Information

The U.S. Food and Drug Administration includes phenethyl alcohol among direct food additives permitted for use as a synthetic flavoring substance under applicable conditions.

For cosmetic use, the CIR Expert Panel has concluded that phenethyl alcohol is safe at concentrations up to 1% based on its assessment of the available safety data.

Regulatory requirements may differ between markets and product categories. The final concentration and intended function should therefore be assessed against the applicable cosmetic and fragrance regulations in the target market.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

Cosmetic Ingredient Review Expert Panel. Final Report on the Safety Assessment of Phenethyl Alcohol.

Cosmetic Ingredient Review Expert Panel. Annual Review of Cosmetic Ingredient Safety Assessments, 2006.

U.S. Food and Drug Administration. Food Additive Status List – Phenethyl Alcohol.

European Commission. CosIng – Cosmetic Ingredients Database.

National Center for Biotechnology Information. PubChem – Phenethyl Alcohol.

National Center for Biotechnology Information. PubMed – Phenethyl Alcohol safety and toxicology.

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Glutamic acid is a naturally occurring acidic amino acid that forms part of proteins and peptides. It is also an important component of the amino acid pool present in the skin's Natural Moisturizing Factor (NMF).

Glutamic acid contains two carboxylic acid groups and one amino group. In aqueous systems, it can exist in different ionic forms depending on the pH.

INCI Name: Glutamic Acid
CAS Number: 56-86-0
EINECS Number: 200-293-7
Molecular Formula: C5H9NO4
Molecular Weight: 147.13 g/mol
Chemical Class: Amino Acid
Function: Humectant, Antistatic, Skin Conditioning Agent

Role in the Skin

Glutamic acid is one of the amino acids naturally present in the skin and contributes to the skin's Natural Moisturizing Factor. NMF is a mixture of water-soluble substances, including free amino acids, amino acid derivatives, lactate, urea and other components that help the stratum corneum retain water.

Because of this physiological relationship, glutamic acid and other amino acids are of interest in moisturizing and skin-conditioning formulations.

Topically applied glutamic acid can contribute to the water-binding properties of a formulation, although the performance of a finished cosmetic product depends on the complete formulation rather than on the presence of a single NMF-related ingredient.

Cosmetic Applications

Glutamic acid and glutamate-derived ingredients are used in a wide range of cosmetic and personal care products.

Applications include skincare products, haircare products, bath products, eye makeup and tanning products.

Glutamic acid can be used in moisturizing formulations where its humectant properties are desirable. It can also be incorporated into amino-acid-based moisturizing systems designed to mimic or complement components of the skin's Natural Moisturizing Factor.

Humectant Properties

Glutamic acid can contribute to the hydration of the skin through its ability to interact with water. As an amino acid naturally associated with the NMF, it is particularly relevant to formulations designed to support skin hydration and improve the sensation of dryness.

Its use can be especially relevant in moisturizing products intended for daily use, where amino acids are combined with other water-binding substances such as urea, sugars and other NMF-related components.

Hair Care

Glutamic acid and glutamate-derived ingredients can also be used in haircare formulations.

Amino acids can contribute to hair conditioning and may help improve the feel, flexibility and manageability of the hair. Glutamic acid can be incorporated into moisturizing systems intended to increase the water content and improve the conditioning characteristics of hair.

The performance of the ingredient depends on the formulation and on the interaction between the amino acid and the hair fiber.

Glutamate Derivatives

Glutamic acid is chemically related to several other ingredients used in cosmetics.

Sodium Glutamate is the sodium salt of glutamic acid. Zinc Glutamate is a zinc salt of glutamic acid. Polyglutamic Acid is a polymer composed of glutamic acid units, while Sodium Polyglutamate is the corresponding sodium salt.

These materials should not be considered interchangeable with Glutamic Acid. Their molecular structures, physicochemical properties, formulation behavior and cosmetic functions can differ substantially.

This distinction is particularly important when selecting an ingredient for a formulation because a specification for Glutamic Acid does not describe the properties or performance of Polyglutamic Acid or its salts.

Natural Moisturizing Factor

Glutamic acid is particularly relevant to cosmetic formulations because amino acids are naturally present in the skin's Natural Moisturizing Factor.

The NMF is not a single substance but a complex mixture of low-molecular-weight, water-soluble compounds located primarily within the stratum corneum. These substances help maintain hydration and support the physical properties of the skin barrier.

Formulations containing glutamic acid alongside other amino acids, urea and carbohydrates can therefore be designed to provide an NMF-inspired moisturizing system.

Formulation Example

Commercial moisturizing complexes may combine glutamic acid with other amino acids, urea and mono- and disaccharides to create an NMF-inspired moisturizing system.

One example described in the supplied source is Hygroplex™ HHG, which contains urea, dextrin, fructose, glucose, sucrose, alanine, glutamic acid and aspartic acid. The system is designed to support moisturization and smoothing of the skin and to increase the water content and elasticity of hair.

The finished formulation should be evaluated according to the specific supplier's recommended use level, compatibility requirements and technical documentation.

Formulation Considerations

Glutamic acid is water soluble and is therefore generally suitable for incorporation into the aqueous phase of cosmetic formulations.

Because glutamic acid is an ionizable molecule, formulation pH can influence its ionic state and its behavior within the formulation. The final pH should therefore be considered when combining glutamic acid with other ingredients.

Compatibility with preservatives, electrolytes, active ingredients and other components should be evaluated during formulation development.

When using a commercial glutamate-based moisturizing complex rather than pure Glutamic Acid, the supplier's technical documentation should be followed because the formulation characteristics and recommended use levels may differ.

Stability

The stability of glutamic acid in a finished formulation depends on factors including pH, temperature, water content and interactions with other ingredients.

Amino acid-containing formulations should undergo appropriate stability testing to monitor changes in appearance, odor, pH, viscosity and other relevant quality parameters throughout the intended shelf life.

Safety

Glutamic acid is a naturally occurring amino acid and is also present in many proteins and foods.

The U.S. Food and Drug Administration considers glutamic acid a multiple-purpose substance Generally Recognized as Safe (GRAS) for appropriate food uses. Monosodium glutamate, the sodium salt of glutamic acid, is also recognized by the FDA as a GRAS food ingredient when used in accordance with applicable requirements.

Food-use safety status should not automatically be interpreted as a complete safety assessment for a particular cosmetic formulation. The safety of the finished cosmetic product depends on concentration, exposure, formulation type and intended use.

Toxicological Information

Historical acute oral toxicity data report an LD50 of approximately 15,800 mg/kg body weight in rats and 16,400 mg/kg in mice.

These values indicate relatively low acute oral toxicity in the tested animal models. They should not, however, be interpreted as cosmetic use levels or as a direct measure of the safety of topical exposure.

A specific NOAEL for topical cosmetic exposure is not provided in the supplied source and should not be inferred from the LD50 values.

Regulatory Considerations

Glutamic acid has established uses in both food and cosmetic applications. Regulatory requirements for its use in cosmetics depend on the target market and the intended product.

The U.S. FDA lists glutamic acid as a multiple-purpose GRAS food substance and recognizes sodium glutamate as a GRAS food ingredient under applicable conditions.

For cosmetic product development, the regulatory status, ingredient specification and intended claims should be verified for the target market.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

U.S. Food and Drug Administration. Substances Generally Recognized as Safe (GRAS).

European Commission. CosIng – Cosmetic Ingredients Database.

National Center for Biotechnology Information. PubChem – Glutamic Acid.

National Center for Biotechnology Information. PubMed – Glutamic Acid, Natural Moisturizing Factor and skin hydration.

Ashland. Hygroplex™ HHG – Technical Information.

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Citrus paradisi, commonly known as grapefruit, is a citrus species belonging to the Rutaceae family. Grapefruit peel oil is obtained from the outer peel of the fruit and is primarily produced by cold expression or cold pressing of the fresh peel.

The typical oil yield from fresh grapefruit peel is approximately 0.5–1%, although the yield can vary depending on the fruit variety, growing conditions and extraction process.

Grapefruit peel oil is an aromatic volatile oil and should be distinguished from grapefruit seed oil, grapefruit seed extract and non-volatile grapefruit-derived oils, which have substantially different compositions and properties.

INCI Name

Citrus Paradisi Peel Oil

CAS Number

8016-20-4

Function

Fragrance Ingredient, Masking Agent

Composition

Grapefruit peel oil contains a complex mixture of volatile terpenes and oxygenated compounds. The major constituents generally include limonene, α-pinene, sabinene and myrcene, together with smaller quantities of compounds such as geraniol, linalool, citronellal, decyl acetate, neryl acetate and terpinen-4-ol.

Limonene is typically the predominant constituent and is responsible for much of the characteristic fresh, sweet and citrus-like aroma of grapefruit peel oil.

The precise chemical profile can vary according to grapefruit cultivar, geographical origin, fruit maturity, extraction method and storage conditions.

Fragrance Properties

Grapefruit peel oil is valued for its fresh, bright and characteristic citrus aroma. It provides a naturally derived citrus note and is frequently used in fragrances, soaps, shower products, shampoos and other personal care products.

Its fresh sensory character makes it particularly useful when a formulation requires a refreshing or uplifting fragrance profile. It can also be combined with floral, woody, herbal, green and other citrus essential oils.

Cosmetic Applications

Grapefruit peel oil is primarily used as a fragrance ingredient and masking agent.

It can be incorporated into a broad range of personal care products, including creams, lotions, cleansers, shampoos, conditioners, body washes, soaps, deodorants and other fragranced formulations.

It may also be used in fragrances and other products where a natural citrus character is desired.

The appropriate concentration depends on the intended product, exposure conditions, regulatory requirements and the composition of the specific grapefruit oil used.

Phototoxicity and Sun Exposure

Grapefruit peel oil requires particular consideration in products intended for application to areas of skin that may subsequently be exposed to sunlight.

The phototoxic potential of citrus oils depends strongly on the extraction method and the concentration of naturally occurring furanocoumarins and other photoreactive constituents. Cold-expressed citrus oils may contain these compounds, whereas appropriately processed or distilled materials may have substantially different phototoxic profiles.

For this reason, grapefruit peel oil should not be considered automatically non-phototoxic simply because a particular supplier specification or historical reference describes it as such.

The use level and product category should be assessed according to the applicable IFRA standards and current regulatory requirements, particularly for leave-on products applied to sun-exposed skin.

IFRA and Fragrance Restrictions

Grapefruit peel oil may contain naturally occurring fragrance allergens and other restricted constituents.

Historically reported restricted constituents include citral, farnesol and geraniol. The maximum permitted concentration depends on the specific product category and the current IFRA Standards.

The concentration limits cited in older technical references should therefore not be treated as universally applicable current limits. Formulators should always obtain the latest IFRA certificate and allergen declaration for the specific grapefruit oil supplied.

This is particularly important for leave-on products and products intended for application to areas that may be exposed to sunlight.

Formulation Considerations

Grapefruit peel oil is an oil-soluble volatile ingredient and can generally be incorporated into the oil phase of emulsions or directly into anhydrous formulations.

Because it is a highly aromatic essential oil, it should be added at a concentration appropriate for the desired fragrance intensity and within the applicable safety limits.

The composition of grapefruit oil can vary between suppliers, so the raw material specification, chromatographic profile, allergen declaration and IFRA documentation should be reviewed before formulation.

When used in leave-on products, the potential for fragrance-related irritation, sensitization and photoreactivity should be considered.

Stability

Grapefruit peel oil contains a high proportion of volatile and unsaturated terpene compounds and can be susceptible to oxidation during storage.

Exposure to oxygen, heat and light can cause changes in the chemical composition and odor profile of the oil. Oxidation products of citrus terpenes may also have a greater potential for skin sensitization than the freshly distilled or expressed oil.

The oil should therefore be stored in appropriate containers with limited exposure to heat, light and oxygen. Antioxidant protection may be considered where appropriate.

Finished cosmetic products containing grapefruit peel oil should undergo stability testing to monitor changes in odor, color, appearance and other relevant characteristics.

Skin Compatibility

Grapefruit peel oil is generally used at relatively low concentrations in cosmetic products because of its strong fragrance and the presence of biologically active volatile constituents.

The original source describes grapefruit oil as non-toxic, non-irritant and non-sensitizing at appropriate exposure levels. However, modern safety assessment should take into account the possibility of irritation or sensitization, particularly with oxidized essential oils or higher concentrations.

Individual sensitivity to fragrance ingredients can occur, and the safety of the finished formulation should be assessed according to its intended use.

Toxicological Information

Historical toxicological data report an oral LD50 of approximately 5,000 mg/kg body weight in rats and a dermal LD50 of approximately 5,000 mg/kg body weight in rabbits.

These values represent acute toxicity endpoints from animal studies and should not be interpreted as safe cosmetic concentrations for human topical use.

A reliable ingredient-specific NOAEL should only be reported where the underlying study clearly identifies the test material, exposure route, dose and relevant endpoint. The available information supplied for grapefruit peel oil does not provide a sufficiently robust ingredient-specific NOAEL for inclusion as a definitive value.

Regulatory Considerations

Grapefruit peel oil is widely used as a fragrance ingredient in cosmetic and personal care products. Its regulatory assessment is influenced by its chemical composition, extraction method, product category and intended area of application.

For cosmetic development, the supplier's current specification, allergen declaration, IFRA certificate and information concerning phototoxic constituents should be obtained.

Particular attention should be paid to the distinction between expressed grapefruit oil and oils obtained through alternative processing methods, because their furanocoumarin and phototoxic constituent profiles may differ.

Other Uses

Grapefruit peel oil is also used as a flavoring and fragrance material in food, beverages and other consumer products, subject to the applicable regulations.

The characteristic citrus aroma has made grapefruit oil a popular ingredient in perfumes, household products and personal care formulations.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

International Fragrance Association (IFRA). IFRA Standards and Guidance for Fragrance Ingredients.

European Commission. CosIng – Cosmetic Ingredients Database.

National Center for Biotechnology Information. PubChem – Citrus paradisi and grapefruit peel oil constituents.

National Center for Biotechnology Information. PubMed – Citrus essential oils, phototoxicity and safety.

Food and Drug Administration. 21 CFR – Flavoring substances and related regulatory information.

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Juniperus communis fruit extract is obtained from the ripe fruits of Juniperus communis L., commonly known as common juniper, a member of the Cupressaceae family.

The ripe fruits, commonly referred to as juniper berries, are used as a traditional botanical ingredient and have a long history of use in food, beverages and herbal preparations. The fruits can be processed using different extraction methods, including water and ethanol extraction, resulting in extracts with different chemical compositions and biological properties.

The botanical source should be clearly specified because several Juniperus species are used as sources of cosmetic and personal care ingredients.

INCI Name

Juniperus Communis Fruit Extract

Botanical Name

Juniperus communis L.

Plant Part Used

Ripe fruit

Family

Cupressaceae

Function

Juniperus communis fruit extract is primarily used as a skin-conditioning and antioxidant botanical ingredient. Depending on the extraction method and composition, juniper fruit preparations may also contribute antimicrobial, astringent and sensory properties to cosmetic formulations.

Antioxidant Properties

In-vitro studies have investigated the antioxidant activity of both water and ethanol extracts prepared from Juniperus communis fruits.

Both extraction types demonstrated significant total antioxidant activity in laboratory testing. The results suggest that compounds present in juniper fruit may have the ability to inhibit oxidative processes, including lipid peroxidation.

The antioxidant activity of the extract is likely associated with its phenolic and other naturally occurring phytochemical constituents. However, the antioxidant capacity of an extract measured in vitro should not automatically be interpreted as a clinically demonstrated antioxidant effect on human skin.

The antioxidant properties may nevertheless make juniper fruit extract useful in formulations positioned around skin protection and botanical antioxidant activity.

Phytochemical Composition

Juniperus communis fruits contain a complex mixture of naturally occurring compounds, including flavonoids, phenolic compounds, terpenoids, organic acids and other secondary metabolites.

The composition of an extract depends strongly on the extraction solvent, extraction conditions, geographical origin, maturity of the fruit and processing method.

Water-based and ethanol-based extracts should therefore not be assumed to have identical chemical profiles or biological activity.

Cosmetic Applications

Juniperus communis fruit extract can be incorporated into a variety of cosmetic and personal care formulations.

Juniper-derived ingredients have been used in makeup products including lipsticks, foundations, mascaras, blushers and face powders. They are also used in certain skincare formulations where botanical extracts are desired for their conditioning and antioxidant properties.

The extract may be incorporated into creams, lotions, gels, serums and other formulations depending on its solvent system and supplier specification.

Skin Conditioning

As a botanical extract, Juniperus communis fruit extract can contribute to the conditioning properties of cosmetic formulations.

Its suitability for a particular product depends on the extraction medium and the concentration of active constituents present in the finished raw material. Water-based extracts can be particularly suitable for aqueous and emulsion-based formulations.

Claims concerning specific effects on the skin should be supported by appropriate evidence relating to the actual extract used in the finished cosmetic product.

Traditional Uses

Juniper berries have been used traditionally for centuries as a culinary condiment and flavoring ingredient.

The fruits are particularly well known for their role in the production of gin and have also been used to flavor bitter preparations and other foods and beverages.

Juniper has also been used historically in traditional herbal practices. These traditional applications should be distinguished from scientifically established cosmetic or therapeutic effects.

Extract and Essential Oil

Juniperus communis fruit extract should be distinguished from Juniperus communis fruit oil and juniper essential oil.

The essential oil is a volatile aromatic fraction containing primarily terpene constituents and is chemically different from a non-volatile botanical extract.

The extraction solvent also has a major influence on the resulting ingredient. A water-based extract will generally contain a different spectrum of constituents from an ethanol extract and should therefore be evaluated independently for safety, stability and cosmetic performance.

Formulation Considerations

The formulation strategy should take into account the extraction medium and supplier specification.

Water-based Juniperus communis fruit extracts can generally be incorporated into the aqueous phase of emulsions, gels, lotions and other water-containing formulations. Ethanol-based extracts may require different handling depending on their residual solvent content and intended application.

The color, odor and composition of botanical extracts can vary between batches and suppliers. These characteristics should be considered during formulation development, particularly in color cosmetics and products with a light or fragrance-sensitive base.

Compatibility with preservatives, pH, electrolytes and other formulation components should also be evaluated.

Stability

The stability of Juniperus communis fruit extract depends on the extraction method, phytochemical composition and formulation environment.

Factors including light, oxygen, temperature, pH and interactions with other ingredients may influence the stability of botanical constituents.

Finished formulations should undergo appropriate stability testing to evaluate changes in appearance, color, odor, pH, viscosity, microbial quality and other relevant characteristics throughout the intended shelf life.

Safety

The safety assessment of juniper-derived ingredients should distinguish between different plant parts, extraction methods and ingredient types.

The Cosmetic Ingredient Review Expert Panel has reviewed Juniperus-derived ingredients and reported that the available data were insufficient to determine whether Juniperus communis fruit extract was safe or unsafe for use in cosmetics and personal care products at the time of the assessment.

This historical conclusion should not be interpreted as evidence that the ingredient is inherently unsafe. Rather, it indicates that sufficient ingredient-specific safety data were not available for a definitive conclusion under the CIR assessment.

Water-based extracts may have a substantially different composition and exposure profile from juniper essential oils or concentrated solvent extracts. Consequently, safety information concerning juniper essential oil should not automatically be applied to a water-based Juniperus communis fruit extract.

Toxicological Information

Ingredient-specific NOAEL and LD50 values should be interpreted according to the exact Juniperus material tested.

Toxicological data obtained from juniper essential oil, concentrated extracts or other Juniperus species should not automatically be presented as representative of Juniperus communis fruit extract.

Where a specific extract is used commercially, the supplier's toxicological and safety documentation should be consulted together with the extraction method, concentration and intended cosmetic exposure.

Regulatory Information

Juniper-derived ingredients have a history of use in both cosmetic and food applications.

The U.S. Food and Drug Administration includes juniper berry oil among essential oils considered Generally Recognized As Safe (GRAS) for intended food use. This food-use status should not be interpreted as a blanket safety determination for every juniper-derived cosmetic ingredient.

Juniper tar has also been used in certain OTC pharmaceutical applications in the United States, but this is a different material from Juniperus communis fruit extract and its regulatory status should not be applied to the extract.

For cosmetic development, the botanical species, plant part, extraction method and exact INCI designation should be confirmed through supplier documentation and the regulations applicable in the target market.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

Cosmetic Ingredient Review Expert Panel. Safety Assessment of Juniper-Derived Ingredients as Used in Cosmetics.

European Commission. CosIng – Cosmetic Ingredients Database.

National Center for Biotechnology Information. PubChem – Juniperus communis.

National Center for Biotechnology Information. PubMed – Juniperus communis fruit antioxidant activity.

U.S. Food and Drug Administration. GRAS Substances Database – Juniper Berry Oil.

Kováts, E. and others. Research concerning the phytochemical composition and biological activity of Juniperus communis fruit extracts.

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Resveratrol is a naturally occurring stilbene polyphenol. The biologically and cosmetically relevant form is generally trans-resveratrol, also known as trans-3,5,4'-trihydroxystilbene.

Resveratrol is produced by plants as a phytoalexin, meaning that its production can increase in response to environmental stress and attack by microorganisms such as fungi and bacteria.

INCI Name: Resveratrol
Chemical Name: trans-3,5,4'-Trihydroxystilbene
CAS Number: 501-36-0
Molecular Formula: C14H12O3
Molecular Weight: 228.24 g/mol
Chemical Class: Stilbene Polyphenol
Function: Antioxidant, Skin Protectant

Natural Sources

Resveratrol occurs naturally in a number of plants. It is particularly associated with the skins of red grapes and products derived from grapes, including red wine.

It is also found in Japanese knotweed (Fallopia japonica), which is one of the important commercial botanical sources of resveratrol. The compound has also been identified in other plant species.

In plants, resveratrol is synthesized as part of a defense response to environmental stress and microbial attack. Fungal infection, particularly by Botrytis species, can stimulate its production.

History

Resveratrol was originally isolated from the roots of white hellebore by the Japanese researcher Michio Takaoka in 1940. It was subsequently identified in the roots of Japanese knotweed in 1963.

Interest in resveratrol increased substantially following research into the so-called "French Paradox", the epidemiological observation that some populations consuming diets containing relatively high levels of saturated fat appeared to have lower rates of cardiovascular disease while also consuming red wine.

Although resveratrol has demonstrated antioxidant and biological activity, the amount of resveratrol present in red wine is generally considered too low to conclusively explain the entire phenomenon. The relationship between dietary resveratrol, red wine consumption and cardiovascular health remains more complex than the original hypothesis suggested.

Antioxidant Properties

Resveratrol is a potent polyphenolic antioxidant that can interact with reactive oxygen species and influence several cellular pathways associated with oxidative stress.

Oxidative stress is an important contributor to skin aging and can be increased by environmental factors such as ultraviolet radiation and pollution. Because of this, resveratrol has attracted significant interest as a cosmetic active for products designed to support the skin's defense against oxidative damage.

Its antioxidant activity has also been investigated in comparison with other cosmetic antioxidants. Some supplier-sponsored studies have reported very high antioxidant activity for specific resveratrol-based formulations compared with other antioxidant systems. Such comparisons should be interpreted in relation to the test method and formulation rather than treated as a universal ranking of antioxidant efficacy.

Anti-Aging and Photoaging

Resveratrol has been extensively investigated as a potential anti-aging cosmetic active.

Research suggests that resveratrol can influence several pathways involved in cellular aging, oxidative stress, inflammation and extracellular matrix degradation. It has also been studied in relation to the prevention of photoaging caused by chronic exposure to ultraviolet radiation.

One area of particular interest is the relationship between resveratrol and Sirtuin 1 (SIRT1), a protein involved in cellular stress responses, metabolism and longevity-associated signaling. Resveratrol has been reported to activate or influence SIRT1-dependent pathways under certain experimental conditions.

However, the biological mechanisms of resveratrol are complex and the extent to which SIRT1 activation contributes to topical cosmetic effects in humans remains an area of continuing research.

Skin Protection

Resveratrol may help protect skin cells against oxidative stress generated by environmental factors, including UV exposure.

Laboratory and experimental studies have investigated its effects on oxidative stress, inflammatory signaling and cellular responses to UV radiation. These findings provide a scientific rationale for including resveratrol in products designed to support skin protection and anti-aging routines.

Resveratrol should not, however, be considered a replacement for sunscreen. A cosmetic product containing resveratrol does not automatically provide a validated level of UV protection unless the finished product has been appropriately tested and complies with the applicable sunscreen regulations.

Collagen and Skin Structure

Resveratrol has been investigated for its potential effects on processes associated with collagen degradation and extracellular matrix remodeling.

UV exposure can increase oxidative stress and stimulate enzymes involved in the breakdown of collagen and other extracellular matrix components. Experimental research suggests that resveratrol may influence some of these pathways.

These findings have contributed to interest in resveratrol as an ingredient for products targeting the visible signs of skin aging, although the magnitude of the effect in topical cosmetic use depends on the formulation, concentration, delivery system and skin exposure.

Formulation Considerations

Resveratrol presents formulation challenges because it has low water solubility. Appropriate formulation strategies may therefore be required to achieve adequate dispersion, solubilization and delivery.

Resveratrol can be incorporated into oil-containing systems or formulated using suitable solubilizers, emulsions, encapsulation systems or other delivery technologies depending on the intended product.

Because the compound is sensitive to environmental conditions and its stability can depend on the formulation matrix, the choice of solvent system, pH, packaging and antioxidant system should be considered during product development.

Stability

Resveratrol is sensitive to factors including light, oxygen and environmental conditions. The trans form can undergo isomerization under certain conditions, potentially affecting the chemical profile and performance of the formulation.

Appropriate protection from light and oxygen can therefore be beneficial. Packaging selection should take into account the sensitivity of the active ingredient as well as the composition of the finished product.

Finished formulations should undergo appropriate stability testing to monitor changes in appearance, color, odor, pH, viscosity and active ingredient content throughout the intended shelf life.

Skin Compatibility

Resveratrol is generally considered suitable for topical cosmetic applications and has been investigated in a range of skincare formulations.

Available research suggests that topical resveratrol is generally well tolerated, although individual sensitivity or irritation can occur with any active cosmetic ingredient. The overall tolerability of a product depends on the concentration, formulation vehicle, delivery system and combination with other active ingredients.

Safety

A small human study reported that single oral doses of trans-resveratrol of up to 5 g produced no serious adverse effects in healthy volunteers, although gastrointestinal symptoms and other mild effects have been reported in studies using higher oral doses.

These oral safety data should not be directly extrapolated to topical cosmetic use. Topical exposure produces a substantially different pharmacokinetic profile, and the safety of a finished cosmetic product must be evaluated according to its concentration, application area, frequency of use and intended population.

Available evidence does not suggest that serious adverse effects should generally be expected from appropriately formulated topical resveratrol, although the safety assessment of the finished cosmetic product remains essential.

Toxicological Information

Historical toxicological sources have reported an estimated acute oral LD50 of approximately 2,000 mg/kg body weight for resveratrol.

This value should be treated as toxicological background information rather than as a direct measure of the safety of topical cosmetic use. LD50 values obtained from animal studies cannot be directly converted into a safe cosmetic concentration for human topical application.

A reliable ingredient-specific NOAEL should only be reported when the underlying toxicological study clearly identifies the test material, exposure route and relevant endpoint. Where such data are not sufficiently established for the intended cosmetic application, a NOAEL should not be inferred from the LD50 value.

Bioavailability

Resveratrol has relatively low systemic bioavailability following oral administration because of rapid metabolism and elimination.

Studies have demonstrated that resveratrol can be detected in plasma following oral exposure, although the majority of circulating material may occur as metabolites rather than unchanged resveratrol.

These pharmacokinetic characteristics have contributed to significant research into alternative delivery systems, including topical formulations and encapsulation technologies designed to improve local availability.

Cosmetic Applications

Resveratrol is used primarily in skincare products positioned around antioxidant protection and the visible signs of skin aging.

It may be incorporated into serums, creams, lotions, masks and other leave-on formulations. It is particularly suitable for formulations targeting mature skin, environmental stress and uneven or dull-looking skin.

Resveratrol is also frequently combined with other antioxidants and skin-conditioning ingredients to create multifunctional anti-aging formulations.

Regulatory Considerations

Resveratrol is a naturally occurring cosmetic ingredient and is used in cosmetic formulations in a number of markets. However, the regulatory status of a specific product depends on the ingredient specification, concentration, intended use and claims.

Cosmetic claims relating to antioxidant activity, skin conditioning or the appearance of signs of aging should be supported by appropriate evidence. Claims suggesting treatment or prevention of a disease or medical condition may cause a product to fall under medicinal regulations depending on the jurisdiction.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

Baur, J. A. and Sinclair, D. A. “Therapeutic potential of resveratrol: the in vivo evidence.” Nature Reviews Drug Discovery, 2006, 5, 493–506.

Berman, A. Y., Motechin, R. A., Wiesenfeld, M. Y. B. and Holz, M. K. “The therapeutic potential of resveratrol: a review of clinical trials.” NPJ Precision Oncology, 2017, 1, 35.

Ratz-Łyko, A. and Arct, J. “Resveratrol as an active ingredient for cosmetic formulations.” Journal of Cosmetic and Laser Therapy.

National Center for Biotechnology Information. PubChem – Resveratrol.

National Center for Biotechnology Information. PubMed – Resveratrol and skin health.

European Commission. CosIng – Cosmetic Ingredients Database.

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Lawsone is the principal coloring molecule found in the leaves of henna, primarily Lawsonia inermis L., a flowering shrub belonging to the Lythraceae family. The plant has historically also been referred to as Lawsonia alba and Lawsonia spinosa.

The leaves are dried and commonly powdered to produce henna preparations. Lawsone, chemically known as 2-hydroxy-1,4-naphthoquinone, is responsible for the characteristic orange-red to reddish-brown coloration produced by henna.

Chemical Information

Lawsone is a naturally occurring naphthoquinone derivative. Its chemical structure contains a hydroxyl group and a quinone system, which are important for its characteristic color and its ability to interact with proteins.

INCI Name: Lawsonia Inermis Leaf Extract
Chemical Name: 2-Hydroxy-1,4-naphthoquinone
CAS Number: 83-72-7
Chemical Class: Naphthoquinone
Molecular Formula: C10H6O3
Molecular Weight: 174.15 g/mol

The exact INCI designation depends on whether the cosmetic raw material is the whole plant material, a leaf extract or isolated lawsone. The specification supplied by the raw material manufacturer should therefore always be checked.

Function

Lawsone functions primarily as a natural colorant and hair-coloring agent. It is particularly notable for its ability to interact with keratin, allowing the pigment to become substantively associated with hair and skin.

Experimental research has also investigated antimicrobial and antioxidant properties associated with lawsone and henna extracts.

Hair Coloring

Henna has been used as a natural hair colorant for thousands of years. The coloring effect is primarily attributed to lawsone present in the leaves of Lawsonia inermis.

Unlike some synthetic or metallic hair dyes, lawsone does not simply form a superficial colored coating over the hair. The molecule has an affinity for keratin and can bind to keratin proteins, producing a durable orange-red to auburn coloration.

The final color depends on the natural hair color, hair structure, amount and quality of lawsone, application conditions, processing time and whether henna is combined with other botanical colorants.

Henna can also be used as a hair-conditioning and color-enhancing treatment, particularly where warm chestnut, copper or auburn tones are desired.

Interaction with Keratin

One of the most important characteristics of lawsone is its substantivity toward keratin.

Lawsone can react with amino groups present in keratin proteins, forming covalent or strongly associated colored products. This interaction allows the pigment to become incorporated into the outer structure of the hair rather than behaving solely as a surface coating.

The same general chemical affinity explains the traditional use of henna for temporary skin decoration. When applied to the skin, lawsone interacts with keratin in the outer layers of the epidermis and produces an orange-red to brown stain.

Skin Applications

Henna has traditionally been used for decorative body art and skin staining in many cultures. The practice has a history extending back thousands of years and has been documented in ancient Egypt and throughout parts of North Africa, the Middle East and South Asia.

The coloration results from the interaction of lawsone with keratin in the superficial layers of the skin. The resulting stain gradually disappears as the stained keratinized cells are shed.

Henna and lawsone-containing preparations have also been used traditionally on the skin in connection with minor wounds and various skin complaints. These historical uses should be distinguished from clinically established therapeutic applications.

Color Characteristics

Pure henna generally produces a warm orange, copper, auburn or reddish-brown coloration rather than a black color.

The final shade is influenced by the concentration of lawsone and the characteristics of the substrate. In hair, the resulting color is strongly influenced by the underlying hair color. On skin, the stain generally develops from orange to deeper reddish-brown over several hours following application.

The addition of other botanical materials can alter the final color of a henna preparation.

Formulation Considerations

Lawsone is naturally present in henna leaves and can be delivered through aqueous or other suitable extraction systems depending on the desired application.

Both water-soluble and oil-associated henna extracts have been described for cosmetic applications, although the chemical composition and coloring performance can differ substantially between extracts.

For hair-coloring products, the quality and concentration of lawsone are important parameters. Botanical source, harvesting conditions, processing, storage and extraction method can all influence the amount of available pigment.

The pH of the formulation and the conditions under which the product is applied can also influence the release and interaction of lawsone with keratin.

Stability

Lawsone and henna preparations can be affected by processing and storage conditions. Exposure to oxygen, light, heat and moisture can influence the stability and coloring performance of botanical preparations.

The stability of an isolated lawsone preparation may differ from that of a whole-leaf henna extract because the plant matrix contains numerous other compounds that can influence the behavior of the pigment.

Finished cosmetic products containing henna or lawsone should therefore undergo appropriate stability testing to evaluate changes in color, odor, appearance, viscosity, microbial quality and coloring performance.

Antimicrobial Properties

Lawsone and extracts of Lawsonia inermis have demonstrated antimicrobial activity in laboratory studies. Research has investigated activity against various bacterial and fungal microorganisms.

These findings may help explain some traditional uses of henna, but in-vitro antimicrobial activity should not be interpreted as evidence that a cosmetic product containing henna or lawsone can treat or cure a skin infection.

UV and Photoprotective Properties

Henna and other botanical extracts containing reactive naphthoquinones have been investigated for their interactions with keratin and their potential influence on UV absorption.

The interaction of lawsone with keratin produces colored compounds that can contribute to optical absorption. However, the presence of lawsone or a henna extract in a cosmetic formulation should not be interpreted as providing a validated sunscreen effect.

A product intended to provide UV protection must comply with the applicable regulatory requirements and be appropriately tested for its claimed level of protection.

Safety and Allergic Reactions

Pure, unadulterated henna has historically been considered relatively well tolerated, and adverse reactions to traditional henna preparations are uncommon.

However, allergic contact dermatitis has been reported following exposure to henna. The risk is particularly important with products marketed as “black henna.” These products may contain para-phenylenediamine (PPD) or other added colorants that are not naturally present in pure henna and can cause significant allergic sensitization.

The safety of a henna cosmetic ingredient therefore depends on the identity and purity of the raw material. Formulators should use appropriately specified, uncontaminated cosmetic-grade material and verify the absence of undeclared additives or adulterants.

Toxicological Information

Toxicological data for isolated lawsone should be distinguished from data relating to whole henna preparations or Lawsonia inermis extracts. The toxicological profile can vary depending on the test material, concentration and exposure route.

A specific NOAEL or LD50 value should only be reported when the underlying study clearly identifies lawsone or the relevant Lawsonia preparation as the tested material. Values from unrelated henna preparations or from adulterated “black henna” products should not be presented as representative of purified lawsone.

Traditional and Historical Use

Henna has been used as a natural dye for approximately 5,000 years. Historical evidence indicates that it was used in ancient Egypt for coloring hair, nails and skin.

Henna has also played an important cultural role in wedding and ceremonial traditions across North Africa, the Middle East and South Asia. Its use in decorative body art remains widespread.

Traditional accounts have also described the use of henna for hair conditioning, tired feet, minor wounds and various skin complaints. These historical uses form part of the ethnobotanical history of Lawsonia inermis but do not necessarily represent scientifically validated medical indications.

Regulatory Considerations

The regulatory status of henna and lawsone depends on the specific product, concentration, intended use and target market.

For cosmetic development, the botanical identity, plant part, extraction method and exact composition of the raw material should be documented. Particular attention should be paid to the distinction between pure henna and products marketed as black henna, which may contain additional chemical colorants.

Where lawsone or henna is used for hair coloring or skin coloration, the applicable cosmetic colorant and hair-dye regulations of the target market should be reviewed before commercialization.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

European Commission. CosIng – Cosmetic Ingredients Database.

National Center for Biotechnology Information. PubChem – Lawsone.

National Center for Biotechnology Information. PubMed – Lawsonia inermis and lawsone.

World Health Organization. WHO Monographs on Selected Medicinal Plants – Lawsonia inermis.

Semwal, R. B., Semwal, D. K., Combrinck, S., and Viljoen, A. M. “Lawsonia inermis L. (henna): Ethnobotanical, phytochemical and pharmacological aspects.” Journal of Ethnopharmacology.

Al-Snafi, A. E. “A review on Lawsonia inermis: A potential medicinal plant.” International Journal of Current Pharmaceutical Research.

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Juglans nigra L., commonly known as black walnut, is a deciduous tree belonging to the Juglandaceae family. It is native to eastern and central North America and has been used historically by Native American communities and later by European settlers for medicinal, household and practical applications.

Different parts of the plant have traditionally been used for different purposes, including the bark, leaves, green fruit hulls and mature seeds. The chemical composition and biological activity of these plant parts can differ substantially, and therefore information relating to one part of the plant should not automatically be applied to another.

Traditional Uses

Black walnut has an extensive history of traditional use. Native Americans and settlers used preparations of the plant as laxatives and tonics. Traditional applications included the use of bark preparations for constipation and fruit-derived preparations for intestinal worms.

The bark, leaves and fruit hulls were also traditionally used in preparations associated with skin complaints, wounds, inflammation, eczema, herpes and fungal infections such as ringworm. Infusions and washes made from the leaves or bark were used externally as cleansing or astringent preparations.

The oil obtained from mature seeds was traditionally applied externally to wounds and various skin conditions.

These uses represent traditional and ethnobotanical applications and should not be interpreted as evidence that black walnut preparations are clinically proven to treat these conditions.

Cosmetic Applications

Juglans nigra-derived ingredients may be relevant to cosmetic formulations depending on the specific plant part and extraction method used. Black walnut extracts, hull-derived ingredients and seed oil can provide different functional properties and should therefore be treated as distinct cosmetic raw materials.

Black walnut seed oil can function as a plant-derived emollient and skin-conditioning ingredient. Extracts from the leaves, bark or hulls may contain tannins, phenolic compounds and other constituents that can contribute to their astringent or antioxidant characteristics.

Green walnut hulls are particularly rich in tannins and have traditionally been used in preparations associated with skin cleansing and coloring.

Seed Oil

The oil obtained from mature Juglans nigra seeds is a lipid-rich plant oil that can be used externally as an emollient and skin-conditioning material.

As with other botanical oils, its fatty acid composition can vary according to cultivar, geographical origin, growing conditions, maturity and extraction method. The specific technical specification of the raw material should therefore be consulted when developing a cosmetic formulation.

Black walnut seed oil may be incorporated into creams, lotions, balms, facial oils and other oil-based formulations where a botanical emollient is desired.

Skin-Related Traditional Use

Black walnut has historically been associated with topical preparations for various skin complaints. Traditional preparations of the bark, leaves and green hulls were used for conditions described historically as eczema, herpes, ringworm, wounds and inflammation.

The green hull and bark contain significant amounts of tannins and other phenolic compounds. These compounds may contribute to astringent and antimicrobial activity observed in experimental research.

Modern cosmetic formulations should distinguish between traditional use and scientifically demonstrated cosmetic benefits. A traditional application does not by itself substantiate a therapeutic claim for a finished cosmetic product.

Antimicrobial and Antifungal Properties

Black walnut has been investigated for antimicrobial and antifungal activity, particularly in relation to extracts of the hull, bark and other non-oil plant parts.

The naphthoquinone juglone is one of the characteristic constituents associated with Juglans species and has demonstrated antimicrobial and biological activity in experimental studies. Tannins and other phenolic constituents may also contribute to the biological activity of black walnut preparations.

However, the concentration and composition of these compounds vary considerably between plant parts and extraction methods. Results obtained using concentrated extracts should therefore not automatically be attributed to black walnut seed oil.

Antioxidant Properties

Black walnut plant materials contain phenolic compounds and other constituents with antioxidant activity in laboratory studies. Green hulls, bark and leaves may contain particularly significant levels of phenolic compounds and tannins.

The antioxidant properties of a finished cosmetic ingredient depend on the specific extraction process, standardization, concentration and stability of the resulting raw material.

Formulation Considerations

The appropriate formulation approach depends on whether the raw material is black walnut seed oil, a leaf extract, bark extract or hull extract. These materials have substantially different compositions and should not be treated as interchangeable.

Black walnut seed oil can be incorporated into the oil phase of emulsions or used in anhydrous formulations. Extracts may require different solvent systems and may have a significant influence on the color, odor and stability of the finished formulation.

Hull and bark extracts can contain tannins and other strongly colored constituents, which may affect the appearance of the finished product. Their compatibility with other formulation components and packaging should therefore be evaluated during product development.

Stability

The stability of Juglans nigra-derived ingredients depends on the specific plant part, extraction method and formulation system.

For seed oil, oxidation should be considered because the unsaturated fatty acids present in the oil can undergo oxidative degradation when exposed to oxygen, heat and light. Appropriate antioxidant protection and packaging may be considered according to the raw material specification.

Extracts containing phenolic compounds and tannins may also be sensitive to environmental conditions and interactions with other formulation components.

Finished formulations should undergo appropriate stability testing to evaluate changes in color, odor, appearance, pH, viscosity, microbial quality and other relevant parameters.

Safety

Black walnut contains biologically active compounds, and safety considerations depend strongly on the plant part and preparation used.

Juglone, tannins and other constituents found particularly in the hulls, bark and leaves contribute to the biological activity of the plant. These compounds also mean that concentrated extracts should not automatically be considered equivalent to the relatively mild traditional use of the whole plant.

Topical products containing black walnut-derived ingredients should be evaluated according to the concentration, extraction method, purity and intended exposure. Particular care should be taken when using concentrated extracts in leave-on products.

The safety profile of black walnut seed oil should not be inferred from toxicological data relating to bark, hull or leaf extracts.

Traditional and Other Uses

Black walnut has historically been used for numerous non-cosmetic purposes. The green hulls, bark and leaves have been used as sources of natural dyes, particularly brown and yellow pigments. The high tannin content of the hulls makes them particularly suitable for dyeing.

The shells have also been used for practical and decorative applications, including jewelry and charcoal. Ground walnut shell material has historically been used as an abrasive and filtration material.

Black walnut is also well known for its allelopathic properties. Roots, leaves and other plant parts produce compounds, particularly juglone, that can inhibit the growth of certain neighboring plants. This natural chemical defense is one of the characteristic biological properties of Juglans species.

Regulatory Considerations

The regulatory status of Juglans nigra-derived ingredients depends on the specific plant part, extraction method, intended use and target market.

When developing a cosmetic product, the exact botanical identity and plant part should be confirmed together with the supplier's INCI designation, extraction method, specification and safety documentation.

Traditional medicinal claims such as treatment of fungal infections, wounds, inflammation or other diseases should not be used for a cosmetic product unless permitted under the applicable regulatory framework.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

European Medicines Agency. Juglans regia L., folium – European Union herbal monograph.

National Center for Biotechnology Information. PubChem – Juglone.

National Center for Biotechnology Information. PubMed – Juglans nigra and juglone.

European Commission. CosIng – Cosmetic Ingredients Database.

U.S. Department of Agriculture. Juglans nigra L. – Black Walnut.

Bhatia, K. et al. Research on the phytochemistry and biological activities of Juglans nigra and its constituent juglone.

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Coriander seed oil is obtained from the seeds of Coriandrum sativum L., an annual aromatic plant belonging to the Apiaceae family. The plant is commonly known as coriander or cilantro, although the term cilantro generally refers to the fresh leaves, while the seeds are commonly referred to as coriander.

The supplied material is sourced from Ukraine and uses the seed as the plant part.

Coriander has been cultivated and used by humans for thousands of years as both a culinary ingredient and traditional medicinal plant. Archaeological evidence indicates that coriander seeds were known in ancient Egypt, and historical records describe their use as a flavoring and medicinal herb. Coriander subsequently became widely distributed throughout Europe and other regions.

INCI Name

Coriandrum Sativum Seed Oil

Plant Part Used

Seed

Country of Origin

Ukraine

Function

Coriander seed oil functions primarily as a skin-conditioning and emollient ingredient in cosmetic formulations. Depending on its composition and processing, it may also contribute antioxidant and other biological properties to a formulation.

Composition

Coriander seed oil is unusual among vegetable oils because its major fatty acid is often petroselinic acid, a positional isomer of oleic acid.

Studies of coriander seed oil commonly report approximately 60–75% petroselinic acid, although the exact composition can vary substantially depending on cultivar, geographical origin, growing conditions and extraction method. Linoleic acid is generally present as another important fatty acid, together with smaller amounts of oleic, palmitic and stearic acids.

The fatty acid composition reported for coriander seed oil therefore differs from that of many common cosmetic plant oils and is an important characteristic of the ingredient.

Cosmetic Applications

Coriander seed oil can be incorporated into cosmetic formulations where a plant-derived emollient is desired. It may be used in skincare products such as creams, lotions, balms, facial oils and cleansing products, as well as in haircare formulations.

Its lipid composition can provide a conditioning and lubricating effect on the skin. The presence of linoleic acid may also be relevant to formulations intended to support the skin barrier, as linoleic acid is an important component of epidermal lipids.

Coriander seed oil should be distinguished from coriander essential oil. The fixed seed oil is predominantly composed of triglycerides and fatty acids, whereas coriander essential oil is a volatile aromatic fraction in which compounds such as linalool are major constituents.

Skin Conditioning Properties

As a vegetable oil rich in unsaturated fatty acids, coriander seed oil can provide emollient properties and contribute to the softness and smoothness of the skin.

Its high proportion of monounsaturated fatty acids gives the oil a distinctive lipid profile. The presence of linoleic acid is also of interest in skin formulations because linoleic acid plays an important structural role in the stratum corneum and is involved in maintaining epidermal barrier function.

Antioxidant and Biological Activity

Research has investigated antioxidant and antimicrobial activities associated with coriander seed oil and its constituents. The activity observed can depend strongly on the extraction method and the chemical composition of the resulting oil.

It is therefore important to distinguish between the biological properties demonstrated in laboratory studies and proven effects of a finished cosmetic formulation. The presence of antioxidant activity in an isolated oil does not automatically mean that a finished product will provide a measurable antioxidant effect on the skin.

Anti-Inflammatory Research

Coriander seed oil has also been investigated for potential anti-inflammatory effects.

Research has identified petroselinic acid as a major constituent of coriander seed oil and has investigated its possible influence on inflammatory pathways. A pilot clinical study involving virgin coriander seed oil reported reductions in experimentally induced redness and itching in healthy women with sensitive skin following oral supplementation. These findings are interesting from a biological perspective, but they should not be directly interpreted as evidence that topical cosmetic coriander seed oil treats inflammatory skin conditions.

Formulation Considerations

Coriander seed oil is an oil-soluble ingredient and can be incorporated into the oil phase of emulsions or used directly in anhydrous formulations.

It may be combined with other vegetable oils, esters, butters and synthetic emollients to adjust the sensory characteristics and overall fatty acid profile of a formulation.

The sensory properties of coriander seed oil can vary according to its processing, refining level and fatty acid composition. Formulators should therefore evaluate the specific raw material rather than assuming that all coriander seed oils will have identical performance.

Stability

The relatively high proportion of monounsaturated fatty acids contributes to the oxidative characteristics of coriander seed oil, although the presence of polyunsaturated fatty acids means that oxidation remains an important consideration.

Storage conditions, extraction method, refining, exposure to oxygen and light, and the presence of naturally occurring or added antioxidants can all influence the stability of the oil.

Finished formulations containing coriander seed oil should undergo appropriate stability testing. Packaging that limits exposure to oxygen and light may be beneficial depending on the formulation and expected shelf life.

Traditional Uses

Coriander has been used as a culinary and medicinal herb since antiquity. Historical sources describe its use as a flavoring, while traditional practices have associated coriander preparations with digestive, soothing and other applications.

Traditional external use has included preparations applied to the skin for various purposes, including rheumatic discomfort. Historical and folkloric accounts also attribute a variety of properties to coriander, including its use in traditional Chinese medicine and medieval European folklore.

These historical uses are part of the cultural history of the plant and should not be interpreted as evidence of clinically established effects of coriander seed oil.

Other Uses

Coriander seeds and their oils have applications beyond cosmetics. The seeds are widely used as a culinary spice, while coriander seed oil has been investigated and utilized in food, soap, detergent and other industrial applications.

Coriander seed oil should not be confused with coriander essential oil, which has a substantially different chemical composition and is primarily used for its characteristic aromatic properties.

Safety

Coriander seed oil has a long history of use as a food and botanical ingredient. However, safety should be assessed according to the specific type of oil, extraction process, purity and intended route of exposure.

Available safety information is more extensive for coriander essential oil and the spice than for every specific cosmetic-grade fixed seed oil. Essential oil data should therefore not automatically be applied to the fixed seed oil.

As with other botanical oils, the quality and identity of the raw material should be verified, and the finished cosmetic formulation should undergo appropriate safety assessment.

Regulatory Considerations

The regulatory status of coriander seed oil depends on the market, product category, raw material specification and intended use.

For cosmetic development, the botanical identity, plant part, extraction method and corresponding INCI designation should be confirmed using the supplier's technical and regulatory documentation.

Particular attention should be paid to distinguishing the fixed seed oil from coriander essential oil because they represent different fractions of the plant and have substantially different compositions and cosmetic functions.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

Senrayan, J. and Venkatachalam, S. “Optimization of ultrasound-assisted solvent extraction (UASE) based on oil yield, antioxidant activity and evaluation of fatty acid composition and thermal stability of Coriandrum sativum L. seed oil.” Journal of Food Science and Technology, 2019. DOI: 10.1007/s10068-018-0467-1.

“Effect of the supplementation of virgin coriander seed oil on reducing reactivity in healthy women with sensitive skin: a randomized double-blind placebo-controlled pilot clinical study.” Clinical, Cosmetic and Investigational Dermatology, 2022.

“Coriandrum sativum L.: A Review on Ethnopharmacology, Phytochemistry, and Cardiovascular Benefits.” Molecules, 2021.

“Essential Oil from Coriandrum sativum: A review on Its Phytochemistry and Biological Activity.” Molecules, 2023.

Burdock, G. A. and Carabin, I. G. “Safety assessment of coriander (Coriandrum sativum L.) essential oil as a food ingredient.” Food and Chemical Toxicology, 2009, 47(1), 22–34. DOI: 10.1016/j.fct.2008.11.006.

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Camellia japonica seed oil is the fixed oil expressed from the seeds of Camellia japonica L., a flowering plant belonging to the Theaceae family. The plant is commonly known as Japanese camellia and is sometimes referred to as the Christmas camellia because of its winter flowering period.

The oil is traditionally known as Tsubaki oil and is widely used in Japanese cosmetic and personal care applications. It should not be confused with tea seed oil derived from Camellia sinensis, the plant used to produce tea leaves.

Camellia japonica seed oil is sometimes referred to as Japanese tea oil, Japanese camellia seed oil, Tsubaki oil or white camellia seed oil.

Composition

Camellia japonica seed oil is predominantly composed of triglycerides containing monounsaturated and saturated fatty acids. Oleic acid is its principal fatty acid and typically represents around 80% of the total fatty acid composition.

A representative fatty acid profile includes approximately 9% palmitic acid (C16:0), 2% stearic acid (C18:0), 81% oleic acid (C18:1), 8% linoleic acid (C18:2) and approximately 0.5% linolenic acid (C18:3).

The reported average carbon number is approximately 17.91 and the average molecular weight is approximately 280.04. The exact composition can vary depending on cultivar, geographical origin, cultivation conditions and oil extraction and processing methods.

Function

Camellia japonica seed oil functions primarily as an emollient and skin-conditioning ingredient. Its high oleic acid content contributes to a smooth, lubricating skin feel and makes the oil suitable for formulations intended to soften and condition the skin.

In hair care formulations, the oil can provide conditioning and lubricating properties while helping to improve the sensory characteristics and manageability of the hair.

Cosmetic Applications

Camellia japonica seed oil is widely used in skincare and haircare formulations. It can be incorporated into facial oils, cleansing oils, creams, lotions, balms, hair oils, conditioners and other products where an emollient plant oil is desired.

Its relatively high oleic acid content gives it a substantive and protective sensory character. Compared with lighter oils containing higher proportions of polyunsaturated fatty acids, Camellia japonica seed oil may provide a somewhat richer and more substantial skin feel.

The oil is particularly associated with traditional Japanese hair and skin care and has been used historically to condition and maintain the appearance of hair.

Skin Benefits

Camellia japonica seed oil provides emollient properties that can help improve the softness and smoothness of the skin. Its lipid composition allows it to form part of the oil phase of cosmetic formulations and contribute to the replenishment of the skin's surface lipids.

The oil is also valued for its protective and conditioning sensory characteristics. Its high oleic acid content contributes to its relatively rich and substantive skin feel.

Research has investigated the biological activity of Camellia japonica seed oil, including potential anti-inflammatory effects. However, the biological activity demonstrated in experimental studies should not automatically be interpreted as a clinically established benefit of a cosmetic product containing the oil.

Anti-Inflammatory Activity

Experimental research has investigated the effects of Camellia japonica seed oil on inflammatory signaling pathways.

In an in-vitro study using lipopolysaccharide-induced inflammatory responses, Camellia japonica seed oil reduced activation of AP-1 and NF-κB promoters. It also attenuated LPS-induced phosphorylation of IκBα, ERK, p38 and JNK.

The study suggested that Camellia japonica seed oil may exert anti-inflammatory effects through downregulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, associated with inhibition of NF-κB and AP-1 signaling.

These findings provide a mechanistic basis for further investigation but should be distinguished from clinical evidence demonstrating an anti-inflammatory effect in humans.

Hair Care Applications

Camellia japonica seed oil has a long history of use in traditional Japanese hair care. It is used as a conditioning oil to improve the appearance, softness and manageability of hair.

The oil is particularly associated with traditional Japanese hairstyles, where Tsubaki oil has historically been applied to the hair. It can also be incorporated into modern hair oils, conditioners, masks and leave-in treatments.

Its lubricating properties can contribute to improved hair feel and reduce the dry or rough sensation associated with damaged or dehydrated hair.

Formulation Considerations

Camellia japonica seed oil is an oil-soluble ingredient and can be incorporated directly into the oil phase of anhydrous formulations or into the oil phase of emulsions.

It can be used in creams, lotions, balms, facial oils, cleansing oils, hair oils and other oil-based formulations. The final sensory profile will depend on the concentration of Camellia japonica seed oil and its combination with other emollients.

Because the oil contains a high proportion of oleic acid and smaller amounts of polyunsaturated fatty acids, its oxidative stability should still be considered during formulation development. Antioxidant systems and suitable packaging may be used where appropriate to help protect the oil from oxidation.

Stability

The stability of Camellia japonica seed oil depends on its fatty acid composition, processing history, storage conditions and exposure to oxygen, heat and light.

Although its high oleic acid content generally provides greater oxidative stability than oils dominated by polyunsaturated fatty acids, the presence of linoleic and linolenic acids means that oxidation can still occur.

Finished formulations containing Camellia japonica seed oil should therefore be evaluated under appropriate stability conditions. Packaging with suitable protection against oxygen and light can be considered where necessary.

Traditional and Other Uses

Camellia oils have a long history of use in Japan and other parts of East Asia. Tsubaki oil has traditionally been used for hair care and skin conditioning.

Camellia seed oils have also been used outside cosmetics for culinary purposes, including frying and food preparation, as well as in applications such as lubricants and soaps.

Camellia japonica seed oil has traditionally been associated with Japanese hair care, including its use for maintaining traditional hairstyles.

Safety

Camellia japonica seed oil is widely used as a cosmetic emollient and has a long history of topical application. As with other plant-derived oils, the safety of a finished cosmetic product depends on the purity and quality of the raw material, concentration, formulation, exposure conditions and intended population.

The possibility of individual sensitivity or irritation should be considered when developing finished products containing botanical oils. Appropriate safety and stability assessment should be conducted on the finished cosmetic formulation.

Regulatory Considerations

The regulatory status and permitted use of Camellia japonica seed oil may vary between markets and should be assessed according to the applicable cosmetic regulations of the target market.

Particular attention should be paid to the botanical identity of the raw material because Camellia japonica and Camellia sinensis are different species. The correct botanical source and corresponding INCI designation should therefore be confirmed with the raw material supplier and regulatory documentation.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

National Center for Biotechnology Information. PubChem – Camellia japonica and related constituents.

European Commission. CosIng – Cosmetic Ingredients Database.

Lee, et al. Research investigating the anti-inflammatory activity of Camellia japonica oil through NF-κB and AP-1 signaling pathways.

Matsui, et al. Research on the fatty acid composition and physicochemical properties of Camellia seed oils.

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Tranexamic acid is a synthetic derivative of the amino acid lysine and is classified pharmacologically as an antifibrinolytic agent. It is a white crystalline compound that is readily soluble in water. Its primary pharmaceutical function is to inhibit fibrinolysis, but research has also identified mechanisms that make it relevant to dermatological and cosmetic applications, particularly pigmentation disorders.

INCI Name: Tranexamic Acid
CAS Number: 1197-18-8
EC Number: 214-818-2
Molecular Formula: C8H15NO2
Molecular Weight: 157.21 g/mol
Chemical Class: Amino Acid Derivative
Function: Skin Conditioning Agent, Skin Brightening Agent

Cosmetic Applications

Tranexamic acid is increasingly used in skincare formulations designed to improve the appearance of uneven skin tone and hyperpigmentation. It is particularly associated with products targeting melasma and post-inflammatory hyperpigmentation.

It may be incorporated into serums, creams, lotions and other leave-on skincare products. Topical tranexamic acid has been investigated both as a standalone active and in combination with other cosmetic ingredients used for pigmentation concerns.

Clinical research has evaluated topical tranexamic acid in concentrations including 2% and 5%, although the appropriate concentration for a cosmetic formulation depends on the intended product, formulation system, target market and applicable regulatory requirements.

How Tranexamic Acid Works

Tranexamic acid primarily acts by inhibiting the interaction of plasminogen and plasmin with fibrin. This antifibrinolytic activity is well established in its pharmaceutical use.

In skin, the mechanism is more complex. Ultraviolet radiation and inflammatory processes can increase plasmin activity in keratinocytes. Increased plasmin activity may contribute to the release of inflammatory and melanogenic mediators that influence melanocyte activity and melanin production.

By inhibiting plasminogen activation and plasmin-related pathways, tranexamic acid may reduce several processes associated with melanogenesis. Research has also investigated anti-inflammatory and anti-angiogenic effects that may contribute to its activity in melasma and other pigmentation disorders.

The exact mechanism by which topical tranexamic acid improves pigmentation is not completely understood, and several biological pathways are likely involved.

Formulation Considerations

Tranexamic acid is water soluble, which makes it suitable for incorporation into aqueous cosmetic systems such as serums, gels and emulsions.

When developing a formulation containing tranexamic acid, the compatibility of the ingredient with the complete formulation system should be considered. pH, solvent system, preservatives, other active ingredients and packaging can all influence the stability and performance of the finished product.

Because tranexamic acid is often combined with other ingredients targeting uneven pigmentation, the overall formulation should be assessed for compatibility and skin tolerability. Combinations with ingredients such as niacinamide, vitamin C derivatives, azelaic acid and exfoliating acids may require particular attention to formulation pH and irritation potential.

Stability

Tranexamic acid is considered a relatively stable water-soluble ingredient, although the stability of a finished formulation depends on the complete formulation system.

Factors including pH, temperature, concentration, water quality, interactions with other ingredients and packaging should be considered during formulation development.

Finished products should undergo appropriate stability testing to evaluate changes in appearance, color, odor, pH, viscosity, microbial quality and other relevant quality characteristics throughout the intended shelf life.

Skin Compatibility

Topical tranexamic acid has generally demonstrated good tolerability in clinical studies. Compared with some traditional depigmenting ingredients, topical tranexamic acid has been reported to cause relatively few local adverse effects.

However, irritation, dryness, redness, itching or a transient burning or stinging sensation may occur, particularly when tranexamic acid is combined with other active ingredients that can affect skin tolerance.

The tolerability of the finished product depends on the concentration, formulation vehicle, pH, frequency of application and combination with other ingredients.

Safety

The safety profile of topical tranexamic acid differs from that of systemic administration. Oral tranexamic acid is a pharmaceutical medicine with systemic antifibrinolytic effects and requires medical consideration because of its potential effects on blood clotting.

Topical cosmetic use results in a different exposure profile, and clinical studies of topical tranexamic acid have generally reported good local tolerability. Nevertheless, the safety of a finished cosmetic formulation must be assessed based on its actual concentration, exposure, application area, frequency of use and intended consumer population.

Claims or formulations involving systemic treatment should not be extrapolated from cosmetic topical use.

Evidence in Hyperpigmentation

Tranexamic acid has been investigated extensively for melasma and other pigmentation disorders. A 2023 focused review covering 46 studies concluded that oral, topical and intralesional tranexamic acid had demonstrated improvements in melasma outcomes, while also noting that topical administration was generally better tolerated than systemic administration.

A randomized controlled study investigating topical 5% tranexamic acid in women with melasma reported improvement over a 12-week treatment period.

More recent literature has continued to investigate topical tranexamic acid for melasma and post-inflammatory hyperpigmentation. A 2026 review concluded that topical and intradermal tranexamic acid show promising results for hyperpigmentation disorders, while emphasizing that evidence and regulatory status vary depending on the condition and route of administration.

Regulatory Considerations

Tranexamic acid is primarily recognized as a pharmaceutical active ingredient rather than a conventional cosmetic ingredient. Its regulatory status and permitted use in cosmetic products therefore need to be assessed carefully in the target market.

In particular, the distinction between a cosmetic product and a medicinal product is important when determining product claims. Claims that a product treats, prevents or cures a medical condition may cause the product to fall under medicinal product regulations rather than cosmetic regulations.

The applicable regulatory framework, ingredient status, concentration and intended claims should therefore be evaluated before commercializing a product containing tranexamic acid.

References

AlJabr, A., AlAnazi, A. M. I., and AlEtebi, R. A. A. “Tranexamic Acid for Hyperpigmentation Disorders: A Literature Review on Efficacy and Safety in Melasma and PIH.” Journal of Cosmetic Dermatology, 2026, 25(2), e70692. DOI: 10.1111/jocd.70692.

Maeda, K. “Mechanism of Action of Topical Tranexamic Acid in the Treatment of Melasma and Sun-Induced Skin Hyperpigmentation.” Cosmetics, 2022, 9(5), 108. DOI: 10.3390/cosmetics9050108.

Konisky, H., Balazic, E., Jaller, J. A., Khanna, U., and Kobets, K. “Tranexamic acid in melasma: A focused review on drug administration routes.” Journal of Cosmetic Dermatology, 2023, 22(4), 1197–1206. DOI: 10.1111/jocd.15589.

Na Ayuthaya, K. P., Niumphradit, N., Manosroi, A., and Nakakes, A. “Topical 5% tranexamic acid for the treatment of melasma in Asians: a double-blind randomized controlled clinical trial.” Journal of Cosmetic and Laser Therapy, 2012, 14(3), 150–154. DOI: 10.3109/14764172.2012.685478.

Kim, K. M. and Lim, H. W. “The uses of tranexamic acid in dermatology: a review.” International Journal of Dermatology, 2023, 62(5), 589–598. DOI: 10.1111/ijd.16160.

National Center for Biotechnology Information. PubChem – Tranexamic Acid.

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Azelaic acid is also known as nonanedioic acid. It is a naturally occurring saturated dicarboxylic acid found in small amounts in grains such as wheat, rye and barley. Azelaic acid is widely used in dermatological and cosmetic formulations, particularly in products intended for blemish-prone, redness-prone and uneven-toned skin.

Chemical Information

Azelaic acid is a straight-chain, saturated dicarboxylic acid containing nine carbon atoms. Its molecular formula is C9H16O4 and its molecular weight is 188.22 g/mol. It contains two carboxylic acid groups and behaves as a weak acid in aqueous systems.

INCI Name: Azelaic Acid
Other Name: Nonanedioic Acid
CAS Number: 123-99-9
Chemical Class: Dicarboxylic Acid
Molecular Formula: C9H16O4
Molecular Weight: 188.22 g/mol

Function

Azelaic acid is associated with antimicrobial, anti-inflammatory, keratinization-modulating, antimelanogenic and antioxidant activities. In cosmetic formulations, it is primarily used in products targeting blemish-prone skin, uneven skin tone, redness and the appearance of post-inflammatory hyperpigmentation.

Cosmetic Applications

Azelaic acid can be incorporated into skincare formulations intended for blemish-prone skin, uneven skin tone, redness-prone skin and products targeting the appearance of post-inflammatory hyperpigmentation. It may be used in creams, gels, lotions and other topical formulations.

Azelaic acid is particularly well known for its use in dermatological products for acne vulgaris and papulopustular rosacea. Research has also investigated its application in hyperpigmentation and melasma.

How Azelaic Acid Works

Azelaic acid has several biological activities that are relevant to skin care and dermatological applications.

It has antimicrobial activity against microorganisms associated with acne, including Cutibacterium acnes and Staphylococcus epidermidis. Its antimicrobial effects are considered one of the mechanisms contributing to its use in acne treatment.

Azelaic acid also influences keratinization within the follicle. By modulating abnormal keratinization, it can help reduce processes associated with the formation of comedones and clogged pores.

The ingredient also demonstrates anti-inflammatory activity. Research suggests that azelaic acid can influence inflammatory pathways and reduce oxidative stress, including the production of reactive oxygen species by neutrophils.

Azelaic acid has also been studied for its effects on melanogenesis. It can inhibit tyrosinase activity and preferentially affect abnormal or highly active melanocytes, which contributes to its use in formulations and dermatological treatments targeting hyperpigmentation.

The mechanisms responsible for the effects of azelaic acid in rosacea are complex and are not completely understood.

Formulation Considerations

Azelaic acid has relatively low solubility in water, which can present formulation challenges. Depending on the formulation system, it may be incorporated through appropriate dispersion, solvent or solubilization strategies.

Particle size and dispersion quality are important considerations when formulating products containing azelaic acid. Poor dispersion can result in an uneven texture, grittiness or reduced sensory quality in the finished product.

The choice of vehicle and supporting formulation components can significantly affect the performance and sensory characteristics of an azelaic acid product. Rheology modifiers, emollients, emulsifiers and solvents should therefore be selected according to the intended dosage form and formulation requirements.

Because azelaic acid is commonly used at relatively high concentrations in some dermatological preparations, achieving a homogeneous and cosmetically elegant formulation can require careful development and optimization.

Recommended Use

The appropriate concentration of azelaic acid depends on the intended product type, regulatory classification, target market, formulation system and intended claims.

Dermatological products commonly contain concentrations such as 15% or 20%, while cosmetic formulations may use different concentrations depending on the intended application and applicable regulations.

The concentration and claims of a cosmetic product should always be assessed in accordance with the regulatory requirements of the target market.

Skin Compatibility

Azelaic acid is generally well tolerated when appropriately formulated. However, topical application may cause temporary sensations such as stinging, burning, itching, dryness or irritation, particularly when higher concentrations are used or when the ingredient is first introduced.

The tolerability of azelaic acid can be influenced by concentration, formulation vehicle, pH and the presence of other potentially irritating active ingredients.

Stability

Azelaic acid itself is considered a relatively stable molecule, although the stability of a finished formulation depends on the complete formulation system.

Important factors include pH, temperature, particle size, dispersion quality, solvent system, packaging and interactions with other ingredients.

Finished products containing azelaic acid should undergo appropriate stability testing to evaluate changes in appearance, color, odor, pH, viscosity, texture, physical integrity and other relevant quality characteristics throughout the intended shelf life.

Safety

Azelaic acid has been extensively evaluated in dermatological applications and is generally considered to have a favorable topical safety profile.

Clinical studies of topical azelaic acid commonly report local adverse effects such as mild and transient stinging, burning, itching, dryness or irritation. These effects are generally localized and tend to decrease with continued use.

Historical toxicological data report an acute oral LD50 greater than 5,000 mg/kg in rats. Older experimental studies have also reported mild irritation in certain rabbit skin and eye tests.

Animal toxicology data should be interpreted in the context of the specific experimental conditions and should not be directly equated with the safety of a finished cosmetic product. The safety of a finished formulation depends on factors including concentration, exposure route, frequency of use, formulation matrix, intended application and target population.

Regulatory Considerations

Azelaic acid is used in both cosmetic and medicinal products, and its regulatory status may differ between jurisdictions depending on the product category, concentration and claims.

When developing a cosmetic product containing azelaic acid, the applicable legislation in the target market should be reviewed before determining the formulation, concentration and product claims.

The regulatory assessment should distinguish between cosmetic and medicinal use, particularly where claims relate to the treatment or prevention of a disease or medical condition.

Scientific Background

Azelaic acid has been extensively studied in dermatology. Research has demonstrated antimicrobial, anti-inflammatory, keratinization-modulating and antimelanogenic activities.

A 2024 review described azelaic acid as a saturated dicarboxylic acid with antibacterial, anti-keratinizing, antimelanogenic, antioxidant and anti-inflammatory properties. The review also discussed mechanisms involving inflammatory signaling, microbial activity, keratinization and melanogenesis.

Clinical research and systematic reviews have reported evidence supporting the topical use of azelaic acid for acne and rosacea, while additional research has investigated its potential role in the management of hyperpigmentation and melasma.

References

Dweck, Anthony. Handbook of Natural Ingredients. Dweck Books.

Feng, X., Shang, J., Gu, Z., Gong, J., Chen, Y., and Liu, Y. “Azelaic Acid: Mechanisms of Action and Clinical Applications.” Clinical, Cosmetic and Investigational Dermatology, 2024. DOI: 10.2147/CCID.S485237.

King, S., Campbell, J., Rowe, R., Daly, M.-L., Moncrieff, G., and Maybury, C. “A systematic review to evaluate the efficacy of azelaic acid in the management of acne, rosacea, melasma and skin aging.” Journal of Cosmetic Dermatology, 2023. DOI: 10.1111/jocd.15923.

U.S. Food and Drug Administration. Azelex (azelaic acid) Cream 20% Prescribing Information.

National Center for Biotechnology Information. PubChem – Azelaic Acid.

National Center for Biotechnology Information. PubMed – Azelaic Acid.

Jones, D. A. “Rosacea, Reactive Oxygen Species, and Azelaic Acid.” The Journal of Clinical and Aesthetic Dermatology, 2009.

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The Food and Drug Administration (FDA) has approved the use of Benzophenone-3 and Benzophenone-4 as safe and effective, over-the-counter (OTC) sunscreen ingredients. When used as a sunscreen ingredient in the United States, Benzophenone-3 is called Oxybenzone, and may be used at concentrations up to 6%, and Benzophenone-4 is called Sulisobenzone, and may be used at concentrations up to 10%. The safety of Benzophenone-3 and related ingredients has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that Benzophenone-1, -3, -4, -5, -9 and -11 were safe for use in cosmetics and personal care products.

CAS: 131-56-6

Function: UV absorber.

Source: Dweck, Anthony. Handbook of Cosmetic Ingredients: - their use, safety and toxicology (Dweck Books 5) . Dweck Data. Kindle Edition.

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CoQ10 is an antioxidant that protects the skin from free radical damage.

CAS: 303-98-0

Function: Skin conditioning/antioxidant. 

Source: Dweck, Anthony. Handbook of Cosmetic Ingredients: - their use, safety and toxicology (Dweck Books 5) . Dweck Data. Kindle Edition.

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The Food and Drug Administration (FDA) conducted an OTC drug review of Ethylhexyl Methoxycinnamate (also called Octyl Methoxycinnamate) and approved the use of this ingredient as an active ingredient in sunscreen products up to a concentration of 7.5%. When used as an active ingredient in an OTC sunscreen product, this ingredient will be listed on the label as Octinoxate. 

CAS: 5466-77-3

Function: UV filter/UV absorber.

Source: Dweck, Anthony. Handbook of Cosmetic Ingredients: - their use, safety and toxicology (Dweck Books 5) . Dweck Data. Kindle Edition.

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Nigella Sativa Seed Oil is the fixed oil expressed from the seeds of Black Caraway, Nigella sativa. It  is an important medicinal herb. In many Arabian, Asian and African countries, black seed oil is used as a natural remedy for a wide range of diseases, including various allergies. The plant’s mechanism of action is still largely unknown. N. sativa seed oil possesses antimicrobial activity against several multidrug-resistant pathogenic bacteria and may be used topically in susceptible cases.

‍CAS: 90064-32-7

Function: Emollient/ perfuming/ skin conditioning.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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The Food and Drug Administration (FDA) lists Licorice (the dried and ground rhizome and root portions of Glycyrrhiza glabra or other species of Glycyrrhiza) as a direct food substance Generally Recognized as Safe (GRAS). The safety of the Licorice-derived ingredients has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that all of the Licorice-derived ingredients were safe for use as cosmetic ingredients.

CAS: 84775-66-6

Function: Soothing/ smoothing/ emollient/ moisturising.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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Sesamum indicum (Sesame) Seed Oil is a very lubricious and oil that leaves a soft film of protective oil on the skin to protect against moisture loss.

Also known as gingilli oil, this oil has been known since earliest antiquity, from ancient Egypt to the Indian continent, as a soothing, gentle emollient. It is an extremely good substitute for olive oil and has excellent longevity in massage preparations. Mixed with lime water, the oil is used externally to treat burns, boils and ulcers. A new antioxidant sesamol and tocopherol were obtained from seeds. The seeds and seed oil are used for medicinal purposes. As the seed oil (sesame oil) has various properties, it is the most widely used oil, by ayurvedic practitioners and pharmacy. Externally, the massage with tila oil reduces the dryness of the skin and alleviates the vata dosha. The oil can also be used in barrier creams to protect the skin from harmful UV light radiation. Because of the presence of sesamin and sesamolin, sesame oil has a strong antioxidant power; it increases the elasticity of the skin and prevents aging. It prevents thickening of the epidermis and dehydration.

The safety of Sesamum Indicum (Sesame) Seed Oil has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that Sesamum Indicum (Sesame) Seed Oil was safe as a cosmetic ingredient in the present practices of use.

CAS: 8008-74-0

Function: Emollient/ hair conditioning/ skin conditioning.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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Centella Asiatica is one of the most exciting new materials to come under scientific scrutiny and is probably better known as Gotu Kola or Indian Pennywort. It is not related to kola and contains no caffeine. The plant is used for the treatment of abscesses, ulcers, skin eruptions, and has been shown to promote wound healing. It contains an active principle called asiaticoside, which is reported to help remedy skin lesions and improve the blood supply to connective tissue. It is also cited for eczema, psoriasis and chapped or scaly skin. The uses are supported by clinical data. Treatment of wounds, burns, and ulcerous skin ailments, and prevention of keloid and hypertrophic scars. Extracts of the plant have been employed to treat second- and third-degree burns. Extracts have been used topically to accelerate healing, particularly in cases of chronic postsurgical and post-trauma wounds. Extracts have been administered orally to treat stress-induced stomach and duodenal ulcers. The safety in topical use is rated safe

CAS: 84696-21-9

Function: Cleansing/ skin conditioning/ smoothing/ soothing/ tonic.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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Castor oil is one of the richest oils known to nature and certainly one of the glossiest when applied to the skin. This oil, which is listed in both the British Pharmacopoeia and British Herbal Pharmacopoeia, is one of the most protective to the skin and is a major component of zinc and castor oil cream, which is used to prevent nappy rash. In man, castor oil has been used as a laxative, but the ingestion of high doses has resulted in vomiting, nausea, colic and, in one individual, coma. It is applied to the skin for its emollient effect, but has provoked allergic reactions in some subjects. The oil is reputed to have a soothing effect on the human eye. Variable results have been obtained in animal studies of skin irritation potential.

Traditional use: A very glossy oil on the skin. Used in lipsticks, lip balms and lip salves. Also used in transparent soaps and hair grooming products. Also cleans and softens the hair. The oil is an effective rub for inflammed skin, bruises, to prevent falling hair and to grow new hair (where hair follicles are not totally withered). Used externally for ringworm, itch, piles, sores, abscesses; hairwash for dandruff.

CAS: 8001-79-4

Function: Emollient/ skin conditioning/ moisturising/ smoothing/ solvent.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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Vitamin E is found widely throughout nature, particularly in wheatgerm oil. It is one of the oil soluble vitamins and it has been used therapeutically for the treatment of numerous conditions such as sunburn, acne, rheumatic conditions, wound healing and pruritic (itching) skin conditions. It has also been shown to reduce scar forming tissue, helps prevent premature skin ageing by blocking the lipid peroxidation responsible for cell membrane damage and also inhibit erythema (skin redness) induced by UV light. It is a potent free radical scavenger (antioxidant) and excellent skin protectant.

The Food and Drug Administration (FDA) includes Tocopherol on its list of nutrients considered Generally Recognized As Safe (GRAS). Tocopherol is also on FDA's list of GRAS food preservatives. The safety of Tocopherol and related ingredients (Dioleyl Tocopheryl Methylsilanol, Potassium Ascorbyl Tocopheryl Phosphate, Tocophersolan, Tocopheryl Acetate, Tocopheryl Linoleate, Tocopheryl Linoleate/ Oleate, Tocopheryl Nicotinate, Tocopheryl Succinate) has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that Tocopherol and the related ingredients were safe as used in cosmetics and personal care products.

CAS: 59-02-9

Function: Antioxidant/ skin conditioning.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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Montmorillonite is a type of refined clay, composed of hydrated aluminium silicate. It often has a natural color that is caused by the presence of trace amounts of minerals such as iron in the structure of the clay. It has similar properties to kaolin. The Food and Drug Administration (FDA) has approved Pyrophyllite as a color additive exempt from certification. Pyrophyllite is allowed to be used as a color in externally applied cosmetics and personal care products and drugs if it conforms to FDA specifications. It is not allowed to be used in products intended for the lips or the eye area. The Food and Drug Administration (FDA) has reviewed the safety of Calcium Silicate and Bentonite and determined that they are Generally Recognized as Safe (GRAS) for use as direct food additives (Calcium Silicate at up to 2% of weight of food). Aluminum Silicate is approved for use in polymers with incidental contact with food. The safety of Aluminum Silicate and Montmorillonite has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that the ingredients were safe as used in cosmetics and personal care products.

CAS: 1318-93-0

Function: Absorbent/ bulking/ emulsion stabilising/ stabilising/ viscosity controlling.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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Kaolin or China Clay is mainly hydrated aluminium silicate and is a mined mineral. It has been used in pharmaceuticals, cosmetics and skin care for many generations. It is used for its absorbent properties and for its emollient feel on the skin. Kaolin is used in face powders, eye shadows and masks. It is also used as a bulking agent in scrubs and masks.

CAS: 1332-58-7

Function: Absorbant/ anticaking/ abrasive/ bulking/ opacifying.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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In the traditional medicine of India, green tea is recorded as a mild excitant, stimulant, diuretic and astringent, and the leaf-infusion (tea) was formerly used to remedy fungal infections caused by insects. It has antioxidant and firming properties.

CAS: 84650-60-2

Function: Skin conditioning/ astringent/ tonic.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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Bakuchiol has been reported to exhibit strong antibacterial effects. In relation, a comparative DNA microarray study using bakuchiol and retinol, and bakuchiol’s anti-aging potential were recently reported by Chaudhuri. Interestingly, the authors reported that Tazarotene-inducible gene 1 (TIG1) is significantly up-regulated by both bakuchiol and retinol, and the expression of TIG1 is found to be down-regulated in a variety of human cancers as well as acne, rosacea and psoriasis. Thus, it is quite conceivable to assume that the up-regulation of TIG1 gene by bakuchiol may provide a solution to problem skin. This led the authors to further examine that material’s anti-acne activity in the described study, where a specific natural 95% pure meroterpene obtained from the edible seeds of Psoralea corylifolia, Bakuchiol was evaluated to determine if it could effectively treat acne-affected skin. In addition, the authors sought to determine if bakuchiol could be used in combination with salicylic acid. Assessments were made by evaluating the material’s effects on 5-α-reductase expression, antibacterial and antifungal inhibition, collagenase and elastase inhibition, and inflammation. Its clinical efficacy also was evaluated. Based on the results, formulations containing 1% bakuchiol (and) 2% salicylic acid showed a nearly 70% reduction in acne lesions and inflammation, as judged by the acne grading system. The next best results were with 1% bakuchiol, which reduced acne by a score of about 57%, whereas 2% salicylic acid only reduced acne by about 48%. As expected, the control group provided practically no improvement in the reduction of acne.None of the subjects observed or reported any adverse reaction using these formulated products. These results clearly show that bakuchiol is an effective ingredient, especially when combined with an exfoliating agent like salicylic acid, for the treatment of acne.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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AHAs (Alpha Hydroxy Acids) are fruit acids that produce a mild exfoliating effect on the skin. In ordinary over-the-counter beauty products, they are extremely diluted (usually between 2% and 10%) in order to gently slough off superficial dead skin cells and reveal brighter, newer, more refined skin underneath. This has the added effect of increasing cell turnover for a slightly rejuvenating effect. The acids used are usually glycolic acid (from sugar cane); lactic acid (from sour milk and tomato juice); citric acid (from citrus fruits such as lemon and orange); malic acid (from apples) or tartaric acid (from grapes). Used moderately in, say, one product per day, they help refresh the skin surface, improve hydration, reduce fine lines and discolouration, and even improve dermal thickness for a plumper, younger appearance. However, when used in too many products at once (for example, in cleanser, toner, day cream and night cream), their concentrated effects can cause irritation and redness. Qualified beauty therapists and salons also use these fruit acids in stronger concentrations (typically 20%-30%) in anti-ageing peeling treatments, but they are used in the highest concentrations (of 50%-70%) by dermatologists and plastic surgeons. The medical version of the chemical peel produces a controlled burn that peels away the outer skin layers, revealing newer, smoother, tighter skin underneath and thereby reducing lines, wrinkles, crepiness, roughness, discolouration and acne scarring. However, healing may take up to two to three weeks.

Source: Dweck, Anthony. Handbook of Natural Ingredients (Dweck Books 4) . Dweck Data. Kindle Edition.

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