Biomelanin antioxidants in cosmetics: Assessment based on inhibition of lipid peroxidation

Acute adverse effects of ultraviolet (UV) radiation in humans include sunbu rn, photosensitivity reactions and immunological suppression. Chronic expos ure to UV light, particularly the UVB (290-320 nm) component of the UV radi ation, and certain environmental chemicals increase the risk of nonmelanoma skin cancer and play a major role in cutaneous aging. The lipid peroxidati on (LPO) of biomembranes, mediated by reactive oxy gen species and free rad icals, is one of the major causes of cellular damage induced by UV radiatio n and toxins. Antioxidants, such as vitamin E, vitamin C and melanins, are reactive oxygen and radical scavengers, thereby minimizing the light- and t oxin-induced tissue destruction. We examined the influence of 8 biotechnica lly produced polyphenolic melanins on the LPO of microsomal membranes in co mparison with alpha-tocopherol, ascorbate and synthetic melanin. All biomel anins showed better inhibition of peroxidative damage than synthetic melani n. Th ree of the 8 tested drugs inhibited the LPO at least as effectively a s vitamin C and vitamin E. The combination of the most effective biomelanin with both vitamin C and vitamin E resulted in greater LPO inhibition than caused by each agent alone. Our data show that biomelanins are potent inhib itors of the peroxidative destruction of biomembranes, indicating that thes e compounds may be useful antioxidative agents in cosmetic preparations. Co pyright (C) 2000 S. Karger AG, Basel.