The inhibiting effect of catecholamine-melanins on UV-induced lecithin peroxidation

It was found that the yield of thiobarbituric acid reactive substances in UV-irradiated liposome membranes was significantly suppressed in the presence of catecholamine-melanins, indicating their ability to inhibit lipid peroxidation. The extent of inhibition depended on the type and concentration of melanin polymers. Melanin-copper complexes inhibited lecithin photooxidation less effectively than copper-free melanins derived from the same precursor. The antioxidant efficiency of melanins appears to be related to the levels of intrinsic and photo-induced free radical centers in the melanin polymer, as well as to accessibility of these centers for active species formed during irradiation of liposomes.