RESUMEN
In the present study, the effect of a melanin-containing phytosorbent, "Victoria," on mercury accumulation in rabbits' tissues was studied. This phytosorbent is derived from black sunflower seed husks. Domestic rabbits were administered either one single nontoxic low-level dose of mercuric chloride (i.e., 50 microg/1 kg body weight [control group]) or combinations of mercury and the phytosorbent "Victoria" (i.e., experimental group). Mercury and phytosorbent were administered per os daily for 12 d. Mercury in tissues was determined by cold-vapor atomic absorption spectroscopy. Mercury in kidney and muscle of the experiment group was, on average, 25.8 and 4.7 times less, respectively, than in the control group. The authors concluded that the phytosorbent prevented accumulation of mercury in the kidney and muscle tissues and exerted a protective effect against mercury toxicity.
Asunto(s)
Quelantes/farmacología , Helianthus , Riñón/metabolismo , Cloruro de Mercurio/farmacocinética , Músculos/metabolismo , Semillas , Absorción/efectos de los fármacos , Administración Oral , Animales , Hígado/metabolismo , Conejos , Distribución Tisular/efectos de los fármacosRESUMEN
Interaction between Fe2+ ions and melanoproteid granules (MPG) of bovine eye pigment epithelium was studied by gammaresonance spectroscopy. MPG was found to form complexes with bi- and three-valent ferrum ions. MPG can both directly bind Fe2+ ions and oxidize them Fe3+ inactive in prooxidant state and bind the latter. The activity of ferrum ion binding increases when suspension is illuminated with visible light and pH of the incubation solution increases. The protein part of MPG does not participate in the complex formation with ferrum ions. The complex formation proceeds mainly by carboxyl, amino- and imino-groups of melanin polymer.
Asunto(s)
Gránulos Citoplasmáticos/metabolismo , Proteínas del Ojo/metabolismo , Hierro/metabolismo , Melaninas/metabolismo , Epitelio Pigmentado Ocular/metabolismo , Proteínas/metabolismo , Animales , Bovinos , Técnicas In Vitro , Espectrometría gammaAsunto(s)
Ojo/metabolismo , Melaninas/metabolismo , Fenotiazinas/metabolismo , Pigmentos Biológicos/metabolismo , Superóxidos/metabolismo , Animales , Bovinos , Decápodos , Dihidroxifenilalanina/análogos & derivados , Dihidroxifenilalanina/metabolismo , Interacciones Farmacológicas , Técnicas In Vitro , Cinética , Peróxidos Lipídicos/metabolismo , Masculino , Melanocitos/metabolismo , Oxidación-Reducción , RanidaeRESUMEN
Melanosomas of eye pigment epithelium tissue of vertebrates, synthetic DOPA-melanin and ommochromas from eye of invertebrates bind effectively bivalent iron ions. Constants of the binding process are calculated. Endogenic iron concentration in melanosomas of the frog eye pigment epithelium is determined. A conclusion is drawn that mechanism of antioxidation action of shielding eye pigments may include Fe2+ ion binding into inactive components.
Asunto(s)
Compuestos Ferrosos/metabolismo , Hierro/metabolismo , Melanocitos/metabolismo , Fenotiazinas/metabolismo , Epitelio Pigmentado Ocular/metabolismo , Animales , Técnicas In Vitro , Invertebrados , Cinética , Oxidación-Reducción , Rana temporariaRESUMEN
The rate of nitroblue tetrazolium (NBT) reduction by dihydroxyphenylalanine-melanin, pheomelanin and retinal pigment epithelium melanosomes under aerobic conditions (pH 7.4) is low both in the dark and upon illumination, but increases drastically in the presence of cetyltrimethylammonium bromide (CTAB). Under these conditions, the light insignificantly stimulates NBT reduction (1.3-fold). The reaction is effectively inhibited by superoxide dismutase. This suggests that superoxide anions (O2-. are formed as intermediate reaction products in the course of NBT reduction by melanins. At alkaline values of pH (greater than or equal to 9.0), the O2-.-dependent reduction of NBT can also take place in the absence of CTAB. In contrast with oxidation of photoreduced riboflavin, the melanin oxidation by O2 cannot induce lipid peroxidation. It is concluded that O2-. generation via melanin oxidation of melanosomes occurs only under non-physiological conditions and can hardly take place in vivo.