SCAVENGER EFFECT OF VITAMIN-E AND DERIVATIVES ON FREE-RADICALS GENERATED BY PHOTOIRRADIATED PHEOMELANIN

The free radical scavenger properties of vitamin E (DL-alpha-tocopherol), a natural antioxidant, and derivatives were studied using an original in vitro method consisting of free radical production by photoirradiation of pheomelanin and direct detection of the free radicals by a physical, specific technique, electron spin resonance. Validation of this method has been realized using well-known biological free radical scavengers, superoxide dismutase and reduced glutathione. DL-alpha-Tocopherol, tocopheryl acetate, tocopheryl linoleate, and tocopheryl polyoxyethylene (POE) succinate induced a significant diminution of the free radical production. In order of efficiency, tocopheryl POE succinate was the best scavenger (37.6% inhibition at 0.25%) followed by tocopheryl linoleate (25.6% inhibition at 1%) and tocopheryl acetate (23.9% inhibition at 0.5%) and finally DL-alpha-tocapherol (16.2% inhibition at 0.05%). The results reported a decrease of the inhibitory effect for high concentrations of DL-cr-tocopherol (0.1%) and tocopheryl acetate (1%), showing a tendency of this compound to act as a prooxidant. Used in optimal concentrations in cosmetologic or dermatologic formulations, Vitamin E and these derivatives should prevent or reduce the harmful activity of free radicals in the skin.