What are melanins?
Melanins compose a class of compounds that serve predominantly as a pigment. These pigments are derivatives of the amino acid tyrosine. There are at least three types of naturally occurring melanins: eumelanin, pheomelanin and neuromelanin. Both the chemical composition and the physical properties differ for the various types of melanin, suggesting that their chemical and biological responses may behave differently when exposed to light. Although melanins are ubiquitous in humankind, our understanding of their chemistry is surprisingly limited. Melanin pigments have a complex natural structure that has defied detailed analysis. Once separated from living tissue, they form an amorphous mass and lose their inherent structure, making them very difficult to analyze.
