-
Melanin
Sun worshippers may have more to worry about than the DNA damage that occurs while they’re relaxing on the beach. It seems that the DNA photoproducts responsible for cancer-causing mutations in skin cells continue to be generated for hours after sunlight exposure. Premi et al. find that a key mediator of this delayed damage is melanin, a pigment thought to protect against cancer (see the Perspective by Taylor). They propose a “chemiexcitation” model in which reactive oxygen and nitrogen species induced by ultraviolet light excite an electron in melanin fragments. This energy is then transferred to DNA, inducing the same damage as ultraviolet light, but in the dark. Conceivably, this energy could be dissipated by adding quenchers to sunscreens. -
1 Reply
-
I don’t have direct access to the full paper, but I can tell you that something like this was suspected 20 yrs. ago when I was a researcher in the field. That is, melanin was suspected simultaneously of being UV-protective & UV damage-mediating. Every molecular species that can hold such an excited state is a candidate both to quench and to propagate damage from free radicals.
Log in to reply.