236 JOURNAL OF COSMETIC SCIENCE and protective properties on the stratum corneum functions. This combination was found to be more effective than either 10% urea and slightly more effective than 10% glycerin. It is possible that urea enhances the penetration of glycerin into deeper layers of the stratum corneum and thus improves the function of glycerin. In a study by Sagiv et aL (20) entitled "The efficacy of humectants as skin moisturizers in the presence of oil," the researchers found that treatments with glycerol (1 M) in water reversed skin dryness as measured by a corneometer and mexameter (measurement of erythema). When glycerol dissolved in medium-chain triglycerides was tested, no mois- turizing effect was found. This study confirms previous findings that glycerol requires an optimum concentration of water to function effectively. CONCLUSION As indicated above, the selection of emulsifying agents and the choice of vehicle addi- tives have the potential to influence the functionality of glycerol. Much remains to be studied systematically in these areas. I expect that future studies with glycerol formu- lations will include the use of liquid crystal, polymeric, and dimethicone copolyol emulsifier systems. The inclusion of appropriate skin barrier agents, such as petrolatum and or polymeric agents, is anticipated to further augment skin hydration and the protective properties of formulations containing glycerin. Glycerol presents a wonderful example of how recent basic scientific advances, combined with diverse bioengineering technology and sophisticated clinical testing methodolo- gies, have enabled us to gain a new appreciation for a classical cosmetic raw material with recently discovered multiple mechanisms of action. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) Glycerine, a Key Cosmetic Ingredient (Marcel Dekker, New York, 1991), p. 1. Skin protectant drug products for over-the-counter human use, Federal Register (tentative), February 15, 1983. Ajinomoto Bulletin PRD-8101. V. Deshpande, Cosmet. Technol., September 1980. D. R. Highley,•l. Soc. Cosmet. Chem., 27, 351-363 (August 1976). D. L. Bissett, J, Soc. Cosmetic Chem., 35,345-350 (November 1984). M.D. Batt, J. Soc. Cosmetic Chem., 39, 367-381 (November/December 1988). C. L. Froebe, J. Soc. Cosmetic Chem., 41, 51-65 (January/February 1990). S. E. Friberg,J. Disp. Sci. TechnoL, 6, 485-495 (1985). S. E. Friberg,J. Soc. Cosmet. Chem., 41, 155-171 (May/June 1990). A. Rawlings, Arch Dermatol. Res., 287, 457-464 (1995). W. R. Shapiro, Cosmet. Dermatol. (November 1996) (Supplement: Proc. First Int. Symp. Cosmet. Efficacy, April 1996, 26-30). J. W. Fluhr et al., Acta Derre. Venereol., 418-421 (1999). M. Denda et al., JID, III, 5 (November 1998). Dry-Flo, technical literature, National Starch. U.S. Patent 6,017,548, assigned to the Andrew Jergens Company. Curel Extreme Care Body Lotion, technical literature, the Andrew Jergens Company. Croda Formula SC-192-1-Low Solids Cationic Lotion, technical literature. J. W. Fluhr, G. Vrzak, M. Gloor, Z. Hautkr., 73, 210-214, 1998. A. E. Sagiv et al., Skin Res, Technol., 7, 32-35 (2001).

j. Cosmet. Sci., 53, 237-240 (July/August 2002) A test for antioxidant activity in cosmetic formulations E. PELLE, T. MAMMONE, K. MARENUS, D. DICANIO, and D. MAES, Estee Lauder Research Laboratories, 125 Pindawn Road, Me/ville, NY l 1747. Accepted for publication March 15, 2002. Synopsis The aim of this study was to develop a technique to assay for the activity of antioxidants in a finished cosmetic product. This was accomplished by adapting the Randox Assay for Total Antioxidant Status kit so that diluted samples could be evaluated by kinetic as well as end-point determinations. Using this technique, we found that a finished product had an IC5o of 0.07 gm of product and a relative antioxidant activity concentration of 52.7 nmoles/mg. INTRODUCTION Environmental insult to human skin by ultraviolet (UV) radiation, as well as by cigarette smoke and air pollution, generates reactive oxygen intermediates that contribute to both acute and chronic skin damage (1,2). For example, immediately after overexposure to sunlight, an erythemal response is induced that is associated with epidermal inflamma- tory oxidative reactions. Moreover, in terms of chronic exposure, the involvement of oxygen free radicals has also been implicated in actinic skin damage that manifests itself in elastosis, collagen disorganization, and most notably in the appearance of wrinkles (3). Due to increased outdoor leisure activities, these visible signs of photodamage and premature aging have become widespread in our society. To address this problem, the cosmetics industry has devoted much research toward the development of various skin care products. Although protective sunscreen products that absorb UV and diffuse photonic energy are widely used, cosmetic products that contain antioxidants, which scavenge deleterious reactive oxygen species produced in skin after environmental trauma, have also become standard for a healthy skin care regimen. Although analytical techniques are available to measure the level of antioxidants in cosmetic products, in general, they do not provide any information regarding their potential activity. Further, due to the complex nature of cosmetic formulations, extract- ing and determining biochemical activity in a finished product can be a challenging task. Previously, we evaluated the antioxidant potential of certain cosmetic ingredients (4) and also the antioxidant efficacy of finished products on skin (5). In this study, we 237