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Bull Exp Biol Med. 2013 Mar;154(5):624-7.

Lipofuscin component A2E does not reduce antioxidant activity of DOPA-melanin.

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N. M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia.


We studied the capacity of DOPA-melanin (natural eumelanin analog) to bind chromophore A2E of retinal pigmented epithelial cell lipofuscin granule into complexes. DOPA-melanin bound up to 200 nm A2E per 1 mg polymer; antioxidant activity of the resultant complexes was evaluated. Luminol chemiluminescence quenching in the presence of hydrogen peroxide showed that the chemiluminescence latency/concentration constants were virtually the same for DOPA-melanin and its A2E complexes. Comparison of the inhibitory effects of DOPA-melanin and DOPA-A2E complexes by rate of UV-induced peroxidation of the outer segments of photoreceptor cells showed higher inhibitory activity of the complexes in comparison with pure DOPA-melanin. Antioxidant activity of DOPA-A2E complexes towards Fe(2+)-ascorbate-induced peroxidation of the outer segments of photoreceptor cells was also higher than that of DOPA-melanin. The results indicated that chromophore A2E of lipofuscin granules in the studied concentrations did not attenuate the antioxidant effects of DOPA-melanin and even potentiated it. This suggested that A2E excess in retinal pigmented epithelium cells could be bound by melanosome melanin and lose its toxicity.

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