ALL-TRANS-RETINOL IN CREAM 197 20 '10 0 0 i i 5 ]0 Time(days) Figure 5. Percent remaining ofall-trans-retinol in 500 ppm ofretinol in 100% ethanolic solution. I, 75% ethanolic solution [•, 50% ethanolic solution O, 50% ethanolic solution with 2% polyoxyethylene glycerol monoisostearate (60 tool) ¸, after 10 days storage at 50øC (with argon gas blanket). 100,00• • ReI.AtJ 0,• ....................................................... : 300 34O 3•0 Wavelength (rim) Figure 6. UV spectra of products in 500 ppm retinol 50%-ethanolic solution with 2% polyoxyethylene glycerol monoisostearate (60 mol) after ten days storage at 50øC (with argon gas blanket).

198 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS H, OH L.• all- trans-retinol 13- cis-retinol anhydro-vitamin A. Figure 7. The structural formulas of all-tram-retinol, 13-cis-retinol, and anhydrovitamin A. Table II Percent Remaining of All-Trans-Retinol in Retinol (500 ppm)-Ethanolic Solution With and Without Antioxidants During Five Days Storage at 50øC (without argon gas blanket) Antioxidants After 3 days storage After 5 days storage Without 500 ppm BHT 500 ppm BHA 500 ppm Vitamin E 500 ppm Vitamin C (pH 7.0) 1.6% 94.4% (or = 0.71) 99.9% (or = 1.32) 96.4% (or = 2.67) 97.6% (or = 0.02) 92.0% (or = 0.46) 97.4% (or = 1.73) 89.6% (or = 0.30) 93.1% (or = 0.24) Standard deviation. In prescribing the formula of retinol-cream we have a dilemma because the increase of oil phase can cause thermal isomerization and the increase of water can cause decom- position. Therefore, a balance of oils and water in cream is considered to be very important. ACKNOWLEDGEMENTS We are grateful to Y. Yamada, H. Terai, and T. Yanagida for their assistance in preparing creams. REFERENCES (1) Y. Koizumi, Effect of retinoids on the skin diseases, FragranceJ. Jpn., 20, 26-31 (1992). (2) C. Kwasaki and M. Hida, Tests for vitamin A antioxidants, Vitamins, 15, 383-386 (1958). (3) T. Tabata, A study on the isomerization of vitamin A in drugs, Vitamins, 18, 164-167 (1961). (4) S. Hayashi and Y. Nishii, Stability of vitamin A in micellar solution, Vitamins, 28, 269-273 (1971). (5) L. Zechmeister, Cis-trans isomeric carotenoids vitamins A and arylpolyenes, 131 (1962). (6) L. Zechmeister, Cis-trans isomeric carotenoids vitamins A and arylpolyenes, 251 (1962). (7) K. Tsukida, M. Ito, and F. Ikeda, Vitamin A degradation products encountered on vitamin A analysis. Internat. J. Vit. Nutr. Res., 41, 158-170 (1971). (8) T. Anmo, M. Washitake, Y. Takashima, M. Isohata, M. Furuya, and K. Koike, Studies on the stability of vitamin A, Vitamins, 46, 193-203 (1972). (9) T. Tsunoda and K. Takabayashi, Behavior of the stability of retinol in oil, J.A.O.C.S. (in press).