Synthetic melanin and ferric ions promote superoxide anion-mediated lipid peroxidation.

In this study, we demonstrate that synthetic dopa-melanin produced superoxide anions and promoted the peroxidative cleavage of phospholipids in the presence of Fe(3+)-ADP complexes. SOD significantly suppressed this lipid peroxidation, while catalase or sodium benzoate did not. During the reaction, MCLA-dependent chemiluminescence was detected, and this was suppressed to the control level by the addition of SOD. Melanin has been postulated to be toxic to tissues because of its interaction with redox-active paramagnetic metal ions, and these findings suggest that superoxide anion-mediated lipid peroxidation is induced by melanin in the presence of iron.