When the subject is sun protection it seems that several of the basic rules of photochemistry are not being considered. If one wants to avoid a photochemical-induced reaction, the first question should be if there are and what are the absorbing molecules. This simple consideration would make clear that visible light should be considered in photo-protection strategies, since there are several photoactive molecules that are present in our skin and hair and that absorb in this wavelength region. This review will focus on the antagonist roles of melanin, which is a fundamental molecule that protect against UV-B exposure, but as any photoactive molecule, generates reactive agents, including singlet oxygen (1O2), upon photoexcitation. We aim to provide a generic overview of the reactivity of 1O2 against different types of biomolecules and a critical evaluation of the recent literature dealing with the photochemistry of melanin, with emphasis on the generation of 1O2 and its consequences to the health of skin and hair.
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