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Technically Speaking: From Enzymes to Fragrance Ingredient Testing: A Literature Overview

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Skin and Skin Care

Exfoliative proteolytic enzymes: Smith et al report on how topical proteolytic enzymes affect epidermal and dermal properties.1 Although proteolytic enzymes have a history of use in skin care products, it is not known whether they simply induce superficial exfoliation or if, with continued use, they can alter epidermal and dermal skin properties. The authors examined whether enhanced exfoliation resulting from treatment with an aspartyl-dependent acid protease improved appearance and, over time, changes in the epidermis and dermis. Test participants applied a serum containing 15% enzymes and a simple moisturizer twice daily for three months. A matched control group applied the same serum without enzyme and moisturizer.

Changes in skin smoothness and texture, the depth and number of lines and wrinkles, and epidermal and dermal firmness and thickness were examined in a double-blind fashion. Treatment with the enzyme product resulted in significant improvement in epidermal properties after one month and both epidermal and dermal properties after three months. The control group showed modest improvements in surface properties only. These results demonstrate that significant appearance benefits can be derived from use of exfoliative proteolytic enzymes. Such improvements are the result of changes to the epidermis and dermis and are strikingly similar to results observed with higher concentrations of alpha hydroxy acids. 

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Flavanone derivatives: Pola Chemical Industries discloses an external preparation for skin containing a flavanone derivative.2 To increase the tissue regeneration of a living body such as the collagen production ability of fibroblasts in the dermis in a skin defect area typified by a large wrinkle or wound, a flavanone derivative such as farrerol is used as an active ingredient in an external preparation for the skin. Furthermore, to efficiently screen a substance having an excellent effect on promoting wound healing, the remodeling action of a collagen fiber bundle is tested by using a skin wound model. 

Skin barrier cosmetics: Pola Chemical Industries also discloses skin barrier cosmetics containing N-acylglutamic acid diesters and pyrrolidonecarboxylic acid-modified dimethylpolysiloxanes.3 The described cosmetics, which complement skin barrier function damaged by UV radiation and are especially useful as cosmetics for summer, contain N-acylglutamic acid diesters, pyrrolidonecarboxylic acid-modified dimethylpolysiloxanes, and optional hyaluronic acid salt. Thus, a one-week application of a makeup base containing the above ingredients to UV-induced rough skin of volunteers significantly decreased transepidermal water loss. 

Skin moisturizing compositions: Shiseido Co., Ltd. discloses skin-moisturizing compositions containing quince seed extracts, polysaccharides, lower alcohols and alkyl-modified carboxyvinyl polymers.4 The skin-moisturizing compositions contain quince seed extracts; cellulose and its derivatives, and/or polysaccharide thickeners except quince seed extracts; lower alcohols; alkyl-modified carboxyvinyl polymers; and humectants. An example is shown in Formula 1.

The product showed a beneficial skin-moisturizing effect and refreshing feeling, without  a sticky afterfeel or viscosity changes after 30-day storage at room temperature (RT).

Compositions for oily skin: Kosei Co., Ltd. discloses oily skin cleansing compositions containing higher alcohols, nonionic surfactants, polyglyceryl isostearate and hydrocarbon oils.5 The compositions are intended to wash out water-resistant cosmetics with rinsing, and they contain minimal amounts of surfactants that can cause skin/eye irritation. Disclosed is a composition characterized by: containing a liquid higher alcohol, e.g. octyl dodecanol, jojoba oil, oleyl alcohol, isostearyl alcohol; a polyoxyethylene chain-containing nonionic surfactant with an HLB value 5–16, e.g. polyoxyethylene sorbitol tetraoleate and polyoxyethylene glyceryl triisostearate, 1–3%; polyglyceryl diisostearate and/or polyglyceryl triisostearate; and a liquid hydrocarbon oil. An example of an oily skin cleansing composition is shown in Formula 2.

Hair and Hair Care

Malodor reduction in permed hair: Savaides et al. disclose a method and composition for reducing malodor in permanently waved hair.6 A method and composition treatment are used to reduce post-permanent malodor by applying a leave-in aqueous treatment of pH 2.5–4.5 containing hydrolyzed vegetable protein, polyquaternium-7, dimethicone and fragrance with a water/octanol partition coefficient of log P of 3–4.5. The post-permanent odor in hair is reduced by minimizing any reactions of hair with residual chemical compounds in hair after the perming process or after the oxidation step, lessening or suppressing any odoriferous compounds by decreasing their vapor pressure and depositing long-lasting fragrance components in hair to mask the malodor or make the malodor more pleasant. An example of an odor-reducing post-treatment composition is shown in Formula 3.

Reducing damage in oxidative hair care: Henkel discloses reduced damage oxidative hair care.7 Cream is suitable in oxidative hair care for reducing damage to hair as well as irritation on the scalp. The company describes a procedure for an oxidative hair treatment in which an oxidative cosmetic agent in a carrier is applied onto the hair, and after an induction period, is rinsed out. In addition, the oxidative cosmetic agent contains a cream that reduces hair damage caused by oxidative processes and improves scalp sensitivity. An example of such a formulation is shown in Formula 4

Skin Pigmentation

PFPE phosphate and DHA in sunless tanners: G. Pantini et al. report on sunless tanning products containing dihydroxyacetone (DHA) in combination with a perfluoropolyether phosphate (PFPE phosphate).8 The shelf-life of products containing DHA is unsatisfactory, thus the adjustment to an acidic pH is often recommended to improve DHA stability. Changing to an acidic pH, however, is a challenge for cosmetic chemists not only because of the risks of skin irritation, but also because of the strong limitations in the choice of the acidic agent. The use of hydroxy acids and phosphoric acid/phosphate buffers has undesired effects. 

Recently, a PFPE phosphate was introduced as a new acidic agent to lower pH without increasing skin irritation. The authors investigated sunless tanners containing PFPE phosphate and DHA, monitoring the aging of sunless tanners with and without PFPE phosphate by visual observation and instrumentation such as pH measures and 1H-NMR spectroscopy. Furthermore, to evaluate whether the substances produced from the DHA degradation were potential irritants, patch tests on volunteers were used to confirm the safety and, indirectly, the stability of the compositions. Their investigations of formulating DHA-containing sunless tanners confirmed that pH is a key parameter in formulating these compositions. They also established that PFPE phosphate is a safe and compatible ingredient that can be used to lower pH levels. The research also gave some evidence of the critical importance of thickeners thus suggesting a strategy based on multifunctional agents to minimize the number of ingredients. 

Slimming and firming self-tanner: Toma’s LLC discloses self-tanning emulsions having slimming, firming and toning properties.9 The compositions are emulsions containing safe, effective amounts of sunless tanning agents and slimming, firming and toning constituents. A method for preparing such compositions is also disclosed. An example is shown in Formula 5.


Homosalate effect on SPF: Barbier et al. have studied the effect of homosalate concentration and vehicle on SPF.10 In order to understand the influence of vehicle and filter concentration on SPF, the researchers calculated the 

in vitro determination of SPF from an o/w emulsion vs. mineral oil containing homosalate at various concentrations. The in vitro determination of SPF is based on the physical reduction of energy in the UV range through a film of product previously spread on an adequate substrate. Approximately 30 mg was applied on roughened polymethylmethacrylate plates, and the transmission measurements were carried out using a spectrophotometer equipped with an integrating sphere. Regardless of homosalate concentration, the SPF was higher with the mineral oil emulsion, with a mean of 49%. The SPF can be optimized by adequate filter concentration and suitable vehicle. 

ODABs and sunscreen photo-stability: Tursilli et al. report on solid lipid microparticles containing the sunscreen agent octyl-dimethylaminobenzoate (ODAB) and the effects of the vehicle.11 Solid lipid microparticles (SLMs) loaded with the sunscreen agent ODAB were prepared to enhance sunscreen photostability. The microparticles were produced by melt dispersion technique using glyceryl behenate as lipidic material and poloxamer 188 as the emulsifier. The obtained SLMs showed proper features in terms of size distribution (1.67–15.81 μm) and ODAB loading (16.15 ± 0.11% w/w). 

The sunscreen released from the SLMs was slower than its dissolution rate, and the photodecomposition of ODAB was markedly decreased (>51.3%) by encapsulation into the lipid microparticles. The efficacy of the SLM carrier system was also evaluated after its introduction in model topical formulations such as hydrogel and o/w emulsions. Further in vitro release measurements were performed using Franz diffusion cells with polycarbonate membranes, indicating that the retention capacity of the microparticles was lost after their incorporation into the emulsion, whereas it was retained in the hydrogel. 

Moreover, the SLMs achieved a reduction of the sunscreen photodegradation in the hydrogel vehicle—the ODAB loss decreased from 87.4% to 59.1%—whereas no significant photoprotective effect was observed in the emulsion. Therefore, the efficacy of the ODAB-loaded SLMs was markedly affected by the vehicle. 

Organic and inorganic filters and SPF: El-Boury et al. report the effects of combined organic and inorganic filters on SPF, determined by an in vitro method.14 O/W emulsions containing inorganic filters, such as titanium dioxide and zinc oxide, combined with 18 EU-authorized UVB organic filters were tested. SPF measurements were carried out using a spectrophotometer equipped with an integrating sphere. This study observed a synergistic effect when titanium dioxide was combined with either anisotriazine or octyldimethyl PABA. The combination of zinc oxide with 11 UVB organic filters also exhibited a similar synergy; however, the measured SPF was systematically lower than the protection factor achieved with titanium dioxide. 


Preventing and reducing perspiration: Mackles et al. disclose antiperspirants with water soluble esters as detackifying agents.12 This invention discloses antiperspirants comprising a water-soluble ester to combat auxillary body odor by preventing or reducing perspiration. The invention also discloses a new class of detackifying agents are readily water-soluble and provide clear, cosmetically elegant products without the stickiness and tackiness normally associated with aqueous-based products. An example of a roll-on antiperspirant composition is shown in Formula 6.


Preservative system with reduced irritation potential: Playtex Products Inc. discloses synergistic preservative systems formulated with organic and inorganic acids and their derivatives and oil-miscible glycols, and their use in cosmetic compositions.13 The invention provides a preservative system having at least one preservative component, one oil-miscible glycol component and cosmetic compositions formulated with the system. According to the authors, the preservative system has unexpectedly resulted in a synergistic effect, allowing for the use of reduced amount of preservative in cosmetic compositions, in turn resulting in a composition with reduced irritation potential and reduced material costs. An example of a sunscreen utilizing this combination is shown in Formula 7. Tests performed with various bacteria and fungi for in vitro effectiveness indicated that caprylyl glycol alone at a 3.5% concentration failed to provide adequate preservative properties, where its addition to glucono-delta-lactone and sodium benzoate provided proficient preservative properties. 


Cosmetic composition: L’Oréal discloses cosmetic compositions comprising an ester of polyol(s), a fatty diacid dimer and a polyamide.15 The invention relates to a cosmetic composition for making up or caring for keratin materials and includes at least one ester of polyol(s) and of fatty diacid dimer, or an ester thereof, with at least one polyamide with an average molecular mass of less than 100,000. This composition is formulated with a polymer backbone of hydrocarbon-based repeating units containing at least one amide function, optionally a pendent fatty chain or at least one terminal fatty chain, that is optionally functionalized, containing 6–120 carbon atoms, and linked to these hydrocarbon-based units. The composition of a lip gloss using this system is shown in Formula 8.

Nail Lacquer

Custom-colored nail lacquer: L’Oréal also discloses custom-colored nail lacquer compositions comprising colorants, gelling agent and a film-former.16 The process for making a custom-colored cosmetic nail composition involves providing a first and second gelled nail polish composition, each having a viscosity of at least 20 P.  The compositions must contain: at least one gelling agent, one film-former, one solvent, and one colorant present in at least one gelled nail polish composition; at least one viscosity-reducing agent; and the first and second gelled nail polish compositions and viscosity reducing agent must be combined to form a custom-colored nail polish varnish having a viscosity of at most 30 P. The composition of a gold-pearlescent shade gelled nail polish composition having a viscosity of 4000 P is shown in Formula 9.

Raw Materials

Alcohol-based hand sanitizers: H. Loffler et al. have published a study on alcohol as an irritant.17 Alcohol-based hand sanitizers are used worldwide to prevent transmission of nosocomial pathogens. The authors investigated skin irritation caused by alcohols alone and in combination with detergent washing. 

Single and repetitive patch testing with 60–100% alcoholsethanol, 1-propanol, 2-propanol (synonyms: isopropyl alcohol, isopropanol), a positive control, 0.5% sodium lauryl sulfate (SLS), and negative controls, i.e., an empty chamber and water, were performed. Wash tests were performed where 80% ethanol and 0.5% SLS were applied to the forearms of 15 volunteers with each agent alone and with both agents in a tandem design. 

Skin hydration, erythema and barrier disruption, measured as transepidermal water loss (TEWL), were evaluated. They researchers found no significant change in skin barrier or erythema induced by the alcohols in the patch tests, whereas skin hydration decreased significantly. Application of alcohols to previously irritated skin did not show a stronger skin barrier disruption than application of SLS alone. Wash tests demonstrated that alcohol application caused significantly less skin irritation than washing with a detergent. Even on previously irritated skin, ethanol did not enhance irritation. 

By contrast, a protective effect of ethanol used after skin washing was observed. The investigators concluded that alcohol-based hand sanitizers cause less skin irritation than hand washing, and are therefore preferred for hand hygiene from the dermatological point of view. An alcohol-based hand sanitizer may even decrease rather than increase skin irritation due to partial elimination of the detergent. 

Fragrance ingredient testing: Schnuch et al. review the sensitization to 26 fragrances that will be labeled according to current European regulation as a result of the Information Network of Departments of Dermatology (IVDK) and review the literature.18 During four periods of six months from Jan. 1, 2003–Dec. 31, 2004, 26 fragrances were patch tested for a total of 21,325 patients. The number of patients tested with each of the fragrances ranged from 1,658–4,238. Hydroxymethylpentylcyclohexene carboxaldehyde (HMPCC) was tested throughout all periods. The following frequencies of sensitization, standardized for sex and age, were noted, with rates in percent: tree moss, 2.4; HMPCC 2.3; oak moss, 2.0; hydroxycitronellal, 1.3; isoeugenol, 1.1; cinnamic aldehyde, 1.0; farnesol, 0.9;  cinnamic alcohol, 0.6; citral, 0.6; citronellol, 0.5; geraniol, 0.4; eugenol, 0.4; coumarin, 0.4; lilial, 0.3;  amyl-cinnamic alcohol, 0.3; benzyl cinnamate, 0.3; benzyl alcohol, 0.3; linalool, 0.2; methylheptin carbonate, 0.2; amyl-cinnamic aldehyde, 0.1; hexyl-cinnamic aldehyde, 0.1; limonene, 0.1; benzyl salicylate, 0.1; gamma-methylionon, 0.1; benzyl benzoate, 0.0; and anisyl alcohol, 0.0. Substances with higher sensitization frequencies were characterized by a considerable number of “++/+++” reactions. Substances with low sensitization frequencies were characterized by a high number of doubtful irritant, and a low number of stronger “++/+++” reactions. Also, there were fragrances among the 26 which were, in regard to contact allergy, of great importance, others of minor importance, and some of no importance at all. 


1. WP Smith et al, Topical proteolytic enzymes affect epidermal and dermal properties, Intl J Cosm Sci 29(1) 15–21 (2007) 

2. WO 2007 94,384, External preparation for skin containing flavanone derivative, assigned to Pola Chemical Industries Inc. (Aug 23, 2007)

3. JP 2007 210,892, Skin barrier cosmetics containing N-acylglutamic acid diesters and pyrrolidonecarboxylic acid-modified dimethylpolysiloxanes, assigned to Pola Chemical Industries Inc. (Aug 23, 2007)

4. JP 2007 210,959, Skin-moisturizing compositions containing quince seed extracts, polysaccharides, lower alcohols, and alkyl-modified carboxyvinyl polymers, assigned to Shiseido Co. Ltd. (Aug 23, 2007)

5. JP 2007 217,302, Oily skin cleansing compositions containing higher alcohol, nonionic surfactants, polyglyceryl isostearate, and hydrocarbon oils, assigned to Kosei Co. Ltd.(Aug 30, 2007)

6. US 2007 190,007, Method and composition for reducing malodor in permanently waved hair comprising hydrolyzed vegetable protein, polyquaternium-7, dimethicone and fragrance, A Savaides et al, (Aug 16, 2007)

7. DE 102,006,053,692, Oxidative hair care with reduced hair damage, Henkel K.G.a.A., (Aug 23, 2007)

8. G Pantini et al, Sunless tanning products containing dihydroxyacetone in combination with a perfluoropolyether phosphate, Intl J Cosm Sci 29(3) 201–209 (2007)

9. US 2007 183,994, Self-tanning emulsion having slimming, firming and toning properties associated therewith, assigned to Toma’s LLC. (Aug 9, 2007)

10. M Barbier et al, Sun protection factor (SPF): effect of homosalate concentration and vehicle, J de Pharmacie de Belgique 62(2) 61–63 (2007) (in French)

11. R Tursilli et al, Solid lipid microparticles containing the sunscreen agent, octyl-dimethylaminobenzoate: Effect of the vehicle, Eur J Pharmaceutics and Biopharmaceutics 66(3) 483–487 (2007) 

12. WO 2007 92,890, Antiperspirants with water soluble esters as detackifying agents, L Mackles and W Bess, (Aug 16, 2007)

13. US 2007 190,005, Synergistic preservative systems comprising organic/inorganic acids and derivatives and oil-miscible glycols, and their use in cosmetic compositions, Playtex Products Inc., (Aug 16, 2007)

14. S El-Boury et al, Effect of the combination of organic and inorganic filters on the Sun Protection Factor (SPF) determined by in vitro method, Intl J Pharmaceutics 340(1–2) 1–5 (2007)

15. US 2007 190,001, Cosmetic composition comprising an ester of polyol(s) and of fatty diacid dimer and a polyamide, L’Oréal, (Aug 16, 2007)

16. US 2007 189,995, Custom-colored nail lacquer compositions comprising colorants, gelling agent and film former, L’Oréal, (Aug 16, 2007)

17. H Loffler et al, How irritant is alcohol? , Brit J Dermatol, 157(1) 74–81 (2007)

18. A Schnuch et al, Sensitization to 26 fragrances to be labeled according to current European regulation: result of the IVDK and review of the literature, Contact Dermatitis  57(1) 1–10 (2007)                  

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