RESUMO
Bilirubin, biliverdin and their serum albumin complexes were tested as oxyradical scavengers (superoxide generated by the xanthine/xanthine oxidase system and peroxyl radical-trapping antioxidant ability). As superoxide scavengers the free bile pigments showed activities near to that of serum albumin, higher than the water soluble vitamin E analog Trolox and lower than ascorbic acid. The peroxyl radical-trapping antioxidant abilities of the tested bile pigments were much higher than those of the serum albumin and of the same order as their serum albumin complexes. This interaction with peroxyl radicals showed different stoichiometric factors for bilirubin (approximately 2) and biliverdin (approximately 4).
Assuntos
Antioxidantes/farmacologia , Pigmentos Biliares/farmacologia , Animais , Antioxidantes/química , Pigmentos Biliares/química , Bilirrubina/química , Bilirrubina/farmacologia , Biliverdina/química , Biliverdina/farmacologia , Bovinos , Sequestradores de Radicais Livres , Humanos , Técnicas In Vitro , Oxirredução , Albumina Sérica/química , Superóxidos/químicaRESUMO
Under light excitation transmembrane electron transfer is observed when a stacked Zn-Cu-Zn triporphyrin is incorporated in a bilayer between aqueous redox phases. The electric polarization of the membrane due to the photoinduced transmembrane charge flux drives ion transport. This effect increases the net charge transfer across the system, giving rise to an amplification similar to a field effect transistor. Thus this system can be considered an organic phototransistor.
Assuntos
Bicamadas Lipídicas , Metaloporfirinas/química , Radiossensibilizantes/química , Transporte de Elétrons , Potenciais da Membrana , Modelos Biológicos , Oxirredução , FotoquímicaRESUMO
The use of bimolecular lipid membranes (BLM) as model membrane allows the analysis of the transport of mercury compounds across the lipidic barriers of biological membranes. The results of flux measurements show that two mercury compounds--HgCl2 and CH3HgCl--cross the BLM but the overall permeabilities are dependent on the pH of the aqueous media, and are not apparently influenced by the different phospholipid constituents of the bilayers. On the other hand, electrical measurements show that, function of the chemical speciation, the transport of this metal is done essentially in the neutral form.
