title: Lipofuscin component A2E does not reduce antioxidant activity of DOPA-melanin.
abstract: 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.
authors: N. M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia.
authors: A E
authors: AE
authors: Dontsov
authors: A D
authors: AD
authors: Koromyslova
authors: N L
authors: NL
authors: Sakina
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D004847:Epithelial Cells / Q000737:chemistry / Q000378:metabolism; D008062:Lipofuscin / Q000737:chemistry; D008543:Melanins / Q000378:metabolism; D020460:Melanosomes / Q000378:metabolism; D010084:Oxidation-Reduction; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D011726:Pyridinium Compounds / Q000378:metabolism*; D012160:Retina / Q000166:cytology; D012176:Retinoids / Q000378:metabolism*
chemical_list: C112040:A2-E (N-retinylidene-N-retinylethanolamine); D000975:Antioxidants; D008062:Lipofuscin; D008543:Melanins; D011726:Pyridinium Compounds; D012176:Retinoids; D004295:Dihydroxyphenylalanine; C040616:DOPA melanin