Efficacy of Topically Applied Tocopherols and Tocotrienols in Protection of Murine Skin From Oxidative Damage Induced by UV-Irradiation

To assess the efficacy of various forms of vitamin E in protection of skin from UV-light-induced oxidative stress, vitamin E (tocotrienol-rich fraction of palm oil, TRF) was applied to mouse skin and the contents of antioxidants before and after exposure to UV-light were measured. Four polypropylene plastic rings (1 cm2) were glued onto the animalsʹ backs, and 20 image 5% TRF in polyethylene glycol-400 (PEG) was applied to the skin circumscribed by two rings and 20 image PEG to the other two rings. After 2 h, the skin was washed and half of the sites were exposed to UV-irradiation (2.8 mW/cm2 for 29 mi: 3 MED). TRF treatment (n = 19 mice) increased mouse skin image-tocopherol 28 ± 16-fold, image-tocotrienol 80 ± 50-fold, image-tocopherol 130 ± 108-fold, and image-tocotrienol 51 ± 36-fold. A significantly higher percentage of image-tocopherol was present in the skin as compared with that in the applied TRF. After UV-irradiation, all vitamin E forms decreased significantly (p < .01), while a larger proportion of the vitamin E remained in PEG-treated (≈80%) compared with TRF-treated (≈40%) skin. Nonetheless, vitamin E concentrations in irradiated TRF-treated skin were significantly higher than in the nonirradiated PEG-treated (control) skin (p < .01). Thus, UV-irradiation of skin destroys its antioxidants; however, prior application of TRF to mouse skin results in preservation of vitamin E. Copyright © 1997 Elsevier Science Inc.