148 JOURNAL OF COSMETIC SCIENCE to those used in cosmetics, improving their photostability. The addition of perfumed compositions to the microemulsion, in order to obtain suitable cosmetic lotions, gen­ erally did not dramatically influence the photostability of either active ingredient. Moreover, some perfumed compositions exerted some protective effect against photo­ degradation, especially in the case of kojic acid, probably thanks to the presence of linalool. In contrast, the photostability of other odorous molecules, such as vanillin, underwent a sharp decrease in the presence of kojic acid. It is of fundamental importance for the formulator of a cosmetic microemulsion with whitening activity to make a correct choice of ingredients in order to obtain a pleasantly smelling product with sufficient activity and stability over time. REFERENCES (1) J. K. Salmon and I. J. Frieden, in Pigmentation and Pigmentary Disorders, N. Levine, Ed. (CRC Press, Boca Raton, FL, 1993), pp. 149-208. (2) 0. Lee and E. Kim, Skin lightening, Cosmet. Toiletr., 110, 51-56 (1995). (3) J. L. Bolognia, S. A. Sodi, M. P. Osber, and J.M.Pawelek, Enhancement of the depigmentry effect of hydroquinone by cystamine and butionine sulfoximine, Br. J. Dermatol., 133, 349-357 (1995). (4) DM 17 agosto 2000-Aggiornamento degli elenchi allegati alla legge 11 ottobre 1986, n. 713, sulla produzione e la vendita dei cosmetici, in attuazione delle direttive della Commissione dell'Unione Europea 2000/6/CE e 2000/11 CE. (5) J. Cabanes, S. Chazarra, and F. Garcia-Carmona, Kojic acid, a cosmetic skin whitening agent, is a slow-binding inhibitor of catecholase activity of tyrosinase,J. Pharm. Pharmacol., 46, 982-985 (1993). (6) Y. Shih and Z. Jyh-Myng, Voltammetric determination of kojic acid in cosmetic bleaching products using a disposable screen-printed carbon electrode, Electroanalysis, 11, 229-233 (1998). (7) K. Maeda and M. Fukuda, Arbutin: Mechanism of its depigmenting action in human melanocyte culture, Exp. Ther., 276, 765-769 (1996). (8) S. Akiu, T. Suzuk, T. Asahara, Y. Fujinuma, and M. Fukuda, Inhibitory effect of arbutin on mela­ nogenesis-Biochemical study using cultured B16 melanoma cells,Jpn. J. Dermatol., 101, 609-613 (1991). (9) C. Coiffard, L. J.M. Coiffard, and Y. De Roeck-Holtzhauer, Degradation kinetics of arbutin in solution, Pharm. Ind, 61, 574-576 (1999). (10) M. Gallarate, M. E. Carlotti, I. Cagliani, and D. Negri, Formulation and characterization of disperse systems as topical vehicles for odorous molecules, J. Cosmet. Sci., 51, 209-226 (2000). (11) M. Gallarate, M. E. Carlotti, M. Trotta, and A. E. Grande, Cosmetic microemulsions containing naturally occurring whitening agents, Proceedings of the 4th World Meeting on Pharmaceutics, Biopharma­ ceutics, Pharmaceutical Technology, Florence, April 2002. (12) M. Trotta, M. R. Gasco, and S. Morel, Behaviour of oil/water microemulsions upon dilution with water,]. Dispersion Sci. Tech., 12, 239-255 (1991). (13) M. E. Carlotti, V. Rossatto, and M. Gallarate, Vitamin A and vitamin A palmitate stability over time and under UVA and UVB radiation, Int. J. Pharm., 240, 85-94 (2002). (14) C. Couteau and L. J.M. Coiffard, Photostability determination of arbutin, a vegetable whitening agent, Il Farmaco, 55, 410-413 (2000). (15) J.M. Blakeway, M. L. Frey, S. Lacroix, and M. S. Salerno, Chemical reactions in perfume aging, Int. j. Cosmet. Sci., 9, 203-214 (1987). (16) K. Kimura, H. Nishimura, I. Iwata, and J. Mizutani, Deterioration mechanism of lemon flavor. 2. Formation mechanism of off-odor substances arising from citral, J. Agric. Food Chem., 31, 801-804 (1983).

J. Cosmet. Sci., 55, 149-155 (March/April 2004) Normal human epidermal keratinocytes treated with 7-dehydrocholesterol express increased levels of heat shock protein THOMAS MAMMONE, NEELAM MUIZZUDDIN, EARL GOYARTS, DAVID GAN, PAOLO GIACOMONI, KEN MARENUS, and DANIEL MAES, Estee Lauder Laboratories, 125 Pinelawn Road, Melville, NY 11747. Accepted for publication January 26, 2004. Synopsis Human skin, and its isolated cells, respond to insults with a variety of repair and protective mechanisms. One such mechanism is the production of heat shock proteins (HSPs). Heat shock proteins help the other cellular proteins fold correctly into their active three-dimensional structures. Therefore, they can enhance the survival of cells under harsh, denaturing conditions. In order to develop a means of promoting the heat shock response to prepare the skin to withstand insult, we are investigating materials that appear to protect the skin biologically. One such material is vitamin D3 and its precursors. We have observed that keratinocytes treated with 7-dehydrocholesterol (7-DHC), a precursor of vitamin D3, have increased levels of protein and mRNA for heat shock proteins. In addition, we observed that topically applied 7-DHC increases the minimal dose of UVB required to induce erythema. These data suggest that 7-DHC can induce heat shock proteins in skin keratinocytes and that they will be more resistant to UVB insult. INTRODUCTION Mammalian cells have a variety of protection and repair systems that enhance the survival of their cells under stressful environments. These include DNA repair, antioxi­ dants, and heat shock proteins. Heat shock proteins (HSPs) are a family of conserved proteins that can be induced in all organisms upon exposure to stress conditions such as high temperatures, UVA irradiation, and oxidative insult. Experimental evidence has shown that HSP proteins can protect cells from a variety of stress-induced damage (1-7), including UVB. Repeated heat shock and heat shock protein induction has even been shown to delay aging of skin fibroblasts (8). In addition to environmental insults, a number of chemical agents have been shown to induce cellular expression of heat shock proteins. This list includes sodium arsenite, cadmium salts, sodium salicylate, and alcohols (9-11). 1,25-Dihydroxyvitamin D3 has 149