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 animals' backs, and 20 microliters 5% TRF in polyethylene glycol-400 (PEG) was applied to the skin circumscribed by two rings and 20 microliters 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 alpha-tocopherol 28 +/- 16-fold, alpha-tocotrienol 80 +/- 50-fold, gamma-tocopherol 130 +/- 108-fold, and gamma-tocotrienol 51 +/- 36-fold. A significantly higher percentage of alpha-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 (approximately 80%) compared with TRF-treated (approximately 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.
Weber
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Department of Molecular and Cell Biology, University of California-Berkeley 94720-3200, USA.
Podda
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Rallis
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Thiele
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Traber
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Packer
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D000042:Absorption; D000287:Administration, Topical; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D005260:Female; D008054:Lipid Peroxides / Q000378:metabolism; D051379:Mice; D008812:Mice, Hairless; D018384:Oxidative Stress / Q000187:drug effects* / Q000528:radiation effects*; D011817:Rabbits; D012867:Skin / Q000187:drug effects* / Q000293:injuries / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014810:Vitamin E / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000737:chemistry
D000975:Antioxidants; D008054:Lipid Peroxides; D014810:Vitamin E