The important role of melanin as protector against free radicals in skin

Abstract

hroughout the body, melanin is a homogenous biological polymer containing a population of intrinsic, semiquinone - like radicals. Additional extrinsic free radicals are reversibly photo-generated by UV and visible light. Melanin is the only known biopolymer containing stable free radicals. Melanin photochemistry, particularly the formation and decay of extrinsic radicals, has been the subject of numerous electron spin resonance (ESR) spectroscopy studies. Several melanin monomers exist, and the predominant monomer in a melanin polymer depends on its location within an organism. In skin melanin differs in eumelanin or pheomelanin. Its bio-radical character and its susceptibility to UV irradiation makes mela- nin an excellent indicator for UV-related processes in skin. The existence of melanin in skin is strongly correlated with the prevention of free radicals/ROS generated by UV radiation. Especially in the skin mela- nin (mainly eumelanin) ensures the only natural UV protection by elimi- nating the generated free radicals. The aim of this study was to investigate the suitability of melanin as protector of skin against UV generated free radicals. Abstract