Phytosphingosine for Skin Differentiation and Other Topics: Literature Findings

This month’s survey of recent patent and research literature describes money-making ideas for personal care product development, including silicone resin waxes to modify texture and rheology, imidazoline for hair conditioning, gallnut and Eclipta prostrata to minimize hair dye damage, renewable propanediol, and an in vitro measurement for SPF, among others.

Skin and Skin Care
Phytosphingosine for keratinocyte differentiation: Schiemann et al. published on polar emollients in cosmetic formulations to enhance the penetration and biological effects of phytosphingosine on skin.1 Recent cosmetic and dermatological work has focused on actives to support the biological functions of the skin, such as protecting against physical and chemical stress, UV irradiation and microbes.

As is well-known, keratinocytes represent key elements of the skin barrier since they form the outermost, water-impermeable layers of skin. To reduce the amount of water that evaporates from skin, keratinocytes undergo a unique differentiation process from the stratum basale to the stratum corneum (SC). The SC is then formed from end-differentiated keratinocytes called corneocytes.

The other main constituents of the water-impermeable barrier are barrier lipids such as ceramides, cholesterol and free fatty acids. Ceramides are formed by keratinocytes by amidation of sphingoid bases such as phytosphingosine with fatty acids. Furthermore, phytosphingosine is a natural antimicrobial compound that is involved in several cellular processes including cell differentiation and anti-inflammation.

The present study aimed to evaluate the effects of phytosphingosine as an active ingredient in cosmetic formulations to determine whether the type of formula influences its biological activity. Cultured keratinocytes were incubated with phytosphingosine and gene expression profiling was performed using DNA micro arrays, which revealed that phytosphingosine significantly promoted cell differentiation.

Additional penetration studies of phytosphingosine formulated with cosmetic oils of different polarity were conducted using dermatomed pig skin in Franz cells. Penetration experiments clearly showed that the biological skin delivery of phytosphingosine depends on the polarity of the emollient, with polar oils providing the greatest penetration.

Further evaluation of the biological effects of phytosphingosine was accomplished in vitro by applying the test formulations to reconstructed human epidermis, followed by RT-qPCR analysis of selected genes relating to keratinocyte differentiation. Using this approach, the study further demonstrated that the biological effect of phytosphingosine on keratinocyte differentiation in reconstructed human epidermis is clearly dependent on its bioavailability, which is determined by the polarity of the cosmetic oil.

In conclusion, the researchers demonstrated that phytosphingosine promotes keratinocyte differentiation and is therefore a viable active ingredient for cosmetic applications whose biological activity can be enhanced by the use of an appropriate formulation.

Artificial dermis wrinkle model: Shiseido Co. has patented an artificial dermis wrinkle model, its manufacture and an antiwrinkle ingredient evaluation method.2 The artificial dermis wrinkle model is made with contraction collagen gel-containing fibroblasts and can be used for the validation of antiwrinkle ingredients.

Hair and Hair Care
Minimizing dye damage to hair with gallnut and Eclipta prostrata: Amorepacific Corp. disclosed a hair dye containing gallnut and/or Eclipta prostrata extract in the first agent, along with an oxidative dye precursor, a coupler and alkaline chemicals, while the second agent contained an oxidant.3Gallnut and Eclipta prostrata are natural antioxidants and were combined with water-soluble antioxidants and reducing agents in the first agent to prevent oxidation, thus maintaining the stability of the ingredients and dyes. This in turn improved the dyeability of hair and minimized damage.

Cationic polymer hair coloring: Boston Cosmetics LLC disclosed pigment-functionalized, cationic polymer compositions for hair coloring.4 A plurality of treatment formulations applied one after the other was used to improve the characteristics of hair coloring. Additional formulations or treatments, such as sealing compositions and final coating formulations, were then used to impart durability. Other formulations/compositions were discussed as well, including the processes for using such compositions.

Furthering the compositions, kits were assembled where the various compositions were compartmentalized for storage until the time of application. Thus, a dispersion was prepared comprising 3.75 g carbon black and 250 mg of a 50% aqueous solution of poly(ethyleneimine) in 67.5 mL water. Blonde hair was dyed black with the 50% diluted carbon black slurry and coated with maleic anhydride polymer. The black color did not rinse out with washing and was resistant to removal with mild abrasion.

Identifying actives for keratin fiber modification: L’Oréal has patented a method to select actives for modifying the shape of hair and the cosmetic use of such actives; no specific active was identified in the research.5 Steps to modify the shape of keratin fibers involve: culturing mammalian cells; adding the test substance to the culture; assaying the amount of glycosaminoglycan (GAG) in the mammalian cells or in the cell culture medium after incubation; comparing the amount of GAG measured with a control culture obtained under the same conditions but in the absence of the test substance; and selecting the substances for which the amount of GAG is modified by a factor of ≥ 0.5 relative to the control. An example hair straightening composition is shown in Formula 1.

Permanent hair waving with metal salts and sericin hydrolyzates: Seiren Co., Ltd. has disclosed hair treatment agents containing monovalent or divalent metal salts and sericin hydrolyzates and their use between reduction and oxidation processes.6 The title agents optionally contained keratin hydrolyzates to impart elasticity, shape-retaining properties, volume and smoothness to hair damaged by brushing, drying, bleaching, perming, etc.

Thus, a hair bundle damaged by repeated bleaching was wound around a rod and treated with the first agent containing a reducing agent at 45°C for 15 min. The bundle then was rinsed and treated with an aqueous solution of sericin hydrolyzates, magnesium chloride and citric acid for 10 min. Again, the hair bundle was rinsed and treated with a second agent containing an oxidizing agent at 45°C for 10 min. The bundle was rinsed and the rod removed. The hair bundle was dried at RT for 24 h and showed long-lasting curl retention, elasticity and a smooth texture.

Hair conditioning with imidazoline: Henkel AG and Co. disclosed hair conditioning products containing imidazolines and selected silicones and/or cosmetic oils.7,8 The preparations described contained at least one imidazoline derivative with at least two long fatty groups and at least one silicone and/or one cosmetic oil. The weight ratio of the imidazoline derivative to silicones and/or cosmetic oils was 20:1 to 1:20. An example conditioning shampoo is shown in Formula 2.

Gentle shampoo for dyed hair: Henkel AG and Co., KGaA also has patented shampoos combining surfactants with hair care benefits.9 The shampoos disclosed gently cleansed hair and were found especially beneficial for dyed hair since the dye was washed out to a significantly lesser extent, in spite of high cleansing performance. The shampoos contained: 0.1–15% w/w cryptoanionic surfactant; 0.1–10% w/w of at least one amphoteric surfactant; 0.1–10%% w/w of at least one nonionic surfactant; and 0.001–10% w/w of at least one cationic guar derivative, cationic cellulose derivative or silicone in a cosmetically acceptable carrier.

Hair dye paste: Mario et al. disclose an anhydrous composition in a paste or pulverulent form for the coloring of human keratinous fibers comprising at least: one oxidation dye, one alkaline agent and one complex of hydrogen peroxide, and a polymer comprised of at least one vinyl heterocylic polymer.10 A method for coloring keratinous fibers is also described where the above mentioned anhydrous composition is mixed with an aqueous composition, advantageously devoid of hydrogen peroxide, and the resulting composition is applied to the keratinous fibers. The composition is left to stand, and the fibers are rinsed.

A paste containing sodium metasilicate, ammonium chloride, EDTA, sodium carboxymethylcellulose, diethylhexyl sodium sulfosuccinate/sodium benzoate, sodium lauryl sulfate, ascorbic acid, p-phenylenediamine, m-aminophenol, 2-methyl-5-hydroxyethylaminophenol, glycol distearate, polyvinylpyrrolidone/H2O2a, liquid paraffin and lanolin was mixed with water and applied to a lock of natural hair comprised of 90% white hairs for 30 min, resulting in a purplish color.

Bleaching keratin fibers: L’Oréal has published a process for bleaching human keratin fibers using an anhydrous composition and a particulate organic amine. The company also disclosed a suitable device for the bleaching composition.11 The composition was created with one or more fatty substances and surfactants; one or more organic amines whose pH was less than 12 at 25°C; and one or more oxidative agents.

Composition A contained 21.67 g polyoxyethylene sorbitan monolaurate, 11 g silica and a balance to 100 g of a mineral oil. Composition B contained an aqueous solution of 40% w/w monoethanolamine. Thus, nine parts of A was mixed with one part of B and 10 parts of an aqueous solution of 6% hydrogen peroxide. The resulting composition, which had a pH of 10, was applied to the hair. Air-oxidative hair dye agent: Kao Corp. has disclosed air-oxidative hair dye agents to improve the coloring of gray hair as well as dye storage stability.12

The air-oxidative agent is characterized by containing: 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid or a salt thereof; an alkanolamine; L-ascorbic acid or its salt; a sulfite; and water, and could further contain a water-soluble or water-dispersible synthetic polymer. The agent had a pH between 10–11 at 25°C. An aerosol-type, air-oxidative hair dye agent filled in a pressure-resistant container with a propellant and a method for producing the hair dye agent are also disclosed. An example is shown in Formula 3.

Sunscreen Testing
Measurement of SPF in vitro: Miura et al. have published an algorithm for the in vitro determination of sun protection factors (SPF) based on a transmission spectrum measurement with the concomitant evaluation of photostability.13 During in vitro evaluations for SPF, the photostability of UV filters can have a major impact, especially for high SPF formulations; however, this is generally not taken into consideration. The described study presents a UV transmission spectrum measurement system utilizing a high-sensitivity UV photomultiplier tube with concomitant evaluation of photostability.

The researchers developed an algorithm to establish SPF in vitro by converting the amount of UV light transmission through the sunscreen layer into cumulative relative erythema effectiveness to obtain one minimal erythema dose. Thus, the algorithm uses the same endpoint as in vivo SPF methods but with a photomultiplier tube as the detector instead of skin. The values obtained showed excellent correlation with in vivo SPF values, even for high SPF sunscreens exceeding SPF 50. This method should be suitable as an in vitro SPF testing method.

Interesting Raw Materials and Vehicles
Silicone resin waxes: Shoji has published a review on a family of high performance silicone resin waxes.14 These materials are based on a linear model similar to polydimethylsiloxane; however, longer chain alkyl groups replace some of the methyl groups. Specifically, in this work, new molecules were synthesized by replacing the linear silicone chain in the alkyl siloxane with a propyl silsesquioxane resin. This resin is a branched structure end-capped with longer chain alkyl groups.

The new resin wax was easily incorporated into personal care formulations based on w/o and o/w systems and showed improved compatibility with standard ingredients over conventional silicone waxes, including dual compatibility with both volatile silicone oils and organic oils such as castor oil. When used in skin creams, the resin wax acted as a rheology and texture modifier. In solid and liquid lip color and blushes the resin wax improved non-transfer properties and color intensity. Additional benefits such as improved eyelash coating and curve-holding were found with use of the resin wax in a mascara.

Renewable propanediol: Managi et al. reviewed the moisturizing characteristics and cosmetic applications of renewably sourced propanediol for skin and hair care.15 Glycols are key ingredients used in cosmetics as solvents, moisturizing agents and formulation-adjustment agents; however, most glycols are petroleum-based. With the growing trend among cosmetic customers for safe and naturally derived ingredients, petroleum-free glycols are in high demand.

In the decribed research, 1,3-propanediol, a transparent, bio-sourced glycol from corn sugar, is introduced.b The material is renewably sourced and ECOCERT certified for the personal care market. Patch testing showed the ingredient does not stimulate the skin, and it is safe for cosmetic use. In addition, 1,3-propanediol imparts longer-lasting moisturization on skin than 1,3-butylene glycol and propylene glycol, and can be applied with glycerin to maintain the effect longer.

In hair care, 1,3-propanediol increases water content in hair and imparts moisture to hair via shampoos and leave-in products. According to the authors, renewably sourced propanediol is expected to apply to various formulations since it satisfies a natural need.

Starch-based thickening agents: Lehmann et al. have published on starch-based thickening agents for personal care and surfactant systems.16 The described work was aimed at synthesizing and characterizing a starch-based thickener for use in nonionic C14-C18 alkyl polyglycosides (APG). A new starch derivative was applied in an aqueous formula of 14% w/w APG with 0.5–2% w/w of different 2-hydroxyalkyl carboxymethyl starches as thickeners to obtain a formula registering a shear viscosity of approximately 6,000 mPas.

Earlier research of carboxymethyl starch as a thickener for this surfactant system indicated that the starch, with a different degree of substitution, could be used as a thickener for APG formulations—a surfactant class that is difficult to thicken without use of PEG derivatives.17 The disadvantage of carboxymethyl starch as a thickener for APG formulations is its low transparency.

Here, the researchers characterized a modified starch by 13C NMR spectroscopy. For detergent formulations, analysis of the starch-based thickener was conducted with static light scattering and viscosity measurements. The carboxymethyl starch was further modified with 2-hydroxyalkyl substituents to create a better interaction between the surfactant and modified starch; to improve this interaction, varying 1,2-epoxyalkanes were used.

Waxy maize starch was first hydrophobically modified through homogeneous reaction conditions using 1,2-epoxyalkanes. Then, it was hydrophilically modified under heterogeneous reaction conditions using monochloro acetic acid. Use of the modified starch at 0.5% w/w as a thickener in aqueous APG formulations showed, by a similar degree of substitution of the hydrophobic and hydrophilic substituents, that the transparency could be increased with the increasing alkyl chain length of the 2-hydroxyalkyl substituents, up to 75%. At the same time, the formula viscosity stayed in the range of 6,000 mPas. The viscosity and the transparency of the surfactant systems could thus be controlled by varying the ratio of hydrophobic and hydrophilic functional groups.

Liquid crystal-silica composite dispersions with improved stability: Shiseido Co. disclosed liquid crystal-silica composite dispersions with improved stability, in addition to their production.18 The dispersions contained an amphipathic substance, water and a fine-particle dispersant. The inverse bicontinuous cubic liquid crystal phase was formed when the amphipathic substance, i.e., tetramethyltrihydroxyhexadecane, and a portion of the water are dispersed in the remainder of water and the dispersant. The silica is formed inside the inverse bicontinuous cubic liquid crystal phase.

A method for producing the composite dispersion is also disclosed. For example, 75 parts tetramethyltrihydroxyhexadecane (phytantriol), 5 parts glycerin-substituted silane derivative, and 20 parts water were mixed to make a transparent gel composition having inverse bicontinuous cubic liquid crystal phase (V2 phase). The gel composition was added in a solution of 0.1% polyoxyethylene lauryl ether acetic acid sodium salt to obtain a liquid crystal-silica composite spherical fine particle dispersion. In addition, a lotion containing the dispersion was formulated.

Gemini amphiphiles: Yamamoto et al. have reviewed oil gelation using a novel Gemini-type peptide amphiphile.19 Gemini amphiphiles, having novel properties not found in other surfactants, have become the subject of recent research. The described study developed a process for the synthesis of sodium dilauramidoglutamide lysine (DLGL) that consisted of two lauroylglutamates linked by glutamic acid-lysine-glutamic acid as a spacer. The company investigated its properties and characteristics, confirming that DLGL exhibits high affinity to hair and skin as well as penetration and repair capabilities. Moreover, DLGL showed oil gelation properties. A variety of oil gels were formed with 0.3% DLGL and the material was found to improve: sensory attributes, the water content in the SC, and makeup removal capabilities. Researchers suggest DLGL gel for use in makeup removers, skin care oil gels, massage oil gels and hair treatment gels.

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1. Y Schiemann et al, Polar emollients in cosmetic formulations enhance the penetration and biological effects of phytosphingosine on skin, Colloids and Surfaces, A: Physicochemical and Engineering Aspects 331(1-2) 103–107 (2008) (in English)
2. JP 2009 139,335, Cultured skin wrinkle model, its manufacture, and antiwrinkles drugs evaluation method, Shiseido Co, Ltd, Japan (Jun 25, 2009)
3. KR 2009 56,200, Hair dyes containing gallnut and/or Eclipta prostrata extracts, Amorepacific Corp, S. Korea (Jun 3, 2009)
4. WO 2009 73,759, Pigment-functionalized cationic polymer compositions for hair coloring, Boston Cosmetics, LLC, USA (Jun 11, 2009)
5. FR 2,924,722, Method of selecting agents for modifying the shape of the hair and cosmetic use of the active agents, L’Oréal, France (Jun 12, 2009)
6. JP 2009 132,648, Hair treatment agents containing monovalent or divalent metal salts and sericin hydrolyzates and their use between reduction and oxidation processes, Seiren Co, Ltd, Japan (Jun 18, 2009)
7. WO 2009 74,463, Hair-conditioning products containing imidazolines and selected silicones and/or cosmetic oils, Henkel AG & Co KGaA, Germany (Jun 18, 2009)
8. DE 102,007,060,528, Hair-conditioning products containing imidazolines and selected silicones and/or cosmetic oils, Henkel AG & Co KGaA, Germany (Jun 18, 2009)
9. WO 2009 74,366, Shampoos with a surfactant and hair care combination, Henkel AG & Co KGaA, Germany (2009)
10. US 2009 151,087, Anhydrous composition comprising at least one oxidation dye, at least one complex of hydrogen peroxide, and a specific polymer, and a coloring process using the same, M Mario et al, France (Jun 18, 2009)
11. EP 2,072,035, Process for bleaching human keratin fibers using an anhydrous composition and a particulate organic amine, and device suitable therefore, L’Oréal, France (Jun 24, 2009)
12. JP 2009 137,877, Air-oxidative hair dye agents and production, Kao Corp, Japan (Jun 25, 2009)
13. Miura Y et al, Algorithm for in vitro sun protection factor based on transmission spectrum measurement with concomitant evaluation of photostability, Photochemistry and Photobiology 84(6) 1569–1575 (2008) (in English)
14. H Shoji, Silicone resin waxes: A new family of high performance materials, Fragrance J 37(5) 35–38 (2009) (in Japanese)
15. H Managi et al, Characteristics and cosmetic applications of renewably sourced propanediol, Fragrance J 37(5) 61–64 (2009) (in Japanese)
16. A Lehmann et al, Starch based thickening agents for personal care and surfactant systems, Colloids and Surfaces, A: Physicochemical and Engineering Aspects 331(1-2) 150–154 (2008) (in English)
17. US Patent 6,464,966, P Simon, Stable w/o/w emulsion and its use as cosmetic and/or dermatologic composition (2002)
18. JP 2009 57,332, Liquid crystal-silica composite dispersions, and production thereof, Shiseido Co, Ltd (Mar 19, 2009)
19. M Yamamoto et al, Oil gelation utilizing a novel Gemini-type peptide amphiphile, Fragrance J 37(5) 42–45 (2009) (in Japanese)

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