Melanins: Skin Pigments and Much More—Types, Structural Models, Biological Functions, and Formation Routes

Figure 1

Structure of melanin precursors for the different types of melanin (in brackets). Only the most representative for every type is shown. (a) L-tyr and L-Dopa (eumelanin); (b) 5-cys-dopa (pheomelanin); (c) dopamine and 5-S-cys-dopamine (neuromelanin); (d) N-acetyl-dopamine (insect-melanin); (e) catechol (catechol-melanin, plants); (f) DHN, 1,8-dihydroxynaphthalene (DHN-melanin, fungi); (g) GHB, 4-glutaminyhydroxylbenzene (GHB-melanin, mushroom); (h) HGA, homogentisic acid (pyomelanin).