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Figure 3. The melatoninergic antioxidative system (MAS) of the skin. Parallel to scavenging UVB-induced reactive oxygen species (ROS) namely hydroxyl radicals, melatonin is also transformed to 2-hydroxymelatonin, 4-hydroxymelatonin, and consecutively to AFMK. AFMK is a potent free radical scavenger and, therefore, by itself capable of protecting the skin against lipid peroxidation, protein oxidation, and oxidative DNA damage. The endogenous melatoninergic system can be supported by exogenous application of melatonin, which penetrates easily through the stratum corneum into deeper layers of the skin. SC, stratum corneum; SG, stratum granulosum; SS, stratum spinosum; SB, stratum basale; BM, basement membrane.
