Elucidation of ultraviolet radiation-induced physiological degradation pathway of eumelanin and pheomelanin

黑色素分为黑色真黑色素和微红色真黑色素。我们的研究旨在阐明紫外线诱导的这两种黑色素的生理降解。利用人的黑发和红发，我们发现真黑素被降解成PTCA(吡咯-2，3，5-三羧酸)，而真黑素则从苯并噻嗪转变为苯并噻唑结构。接下来，用小鼠的头发和人的头发以及合成的真黑素和褐黑素，我们发现在UVA辐射下黑色素的结构发生了类似的变化。最后，利用培养的黑素细胞和视网膜色素上皮细胞，我们发现真黑素在UVA或可见光照射下会产生交联结构。

Melanin is classified into black eumelanin and reddish pheomelanin. Our study aimed at elucidating UV-induced physiological degradation of both melanins. Using human black hair and red hair, we found that eumelanin is degraded to give PTCA (pyrrole-2,3,5-tricarboxylic acid) while pheomelanin is changed from benzothiazine to benzothiazole structure. Next, using mouse hair and human hair and synthetic eumelanin and pheomelanin, we found similar changes in structure of melanin upon UVA irradiation. Finally, using cultured melanocytes and retinal pigment epithelial cells, we showed that eumelanin gives rise to cross-linking structure upon UVA or visible light irradiation.