RESUMO
The effect of phenolic antioxidants on the rat liver microsomal glutathione S-transferase (MGST1) was investigated in vitro. When microsomes were incubated with various polyphenolic antioxidants, gallic acid (3,4,5-trihydroxybenzoic acid) markedly increased MGST1 activity and the increase was prevented in the presence of superoxide dismutase (SOD) or catalase. The MGST1 activity increased by gallic acid was decreased by further incubation with sodium arsenite, a sulfenic acid reducing agent, but was not with dithiothreitol, a disulfide bond reducing agent. The incubation of microsomes with gallic acid in the presence of the NADPH generating system which generates reactive oxygen species (ROS) through cytochrome P-450 system increased the MGST1activity in spite of scavenging the ROS and the increase was also depressed by SOD/catalase. The increase of MGST1 activity by gallic acid was prevented by co-incubation with a stable radical, 1,1-diphenyl-2-picrylhydrazyl or ferric chloride. These results suggest that the gallic acid acts as a pro-oxidant and activates MGST1 through oxidative modification of the enzyme.
Assuntos
Ativadores de Enzimas/farmacologia , Ácido Gálico/farmacologia , Glutationa Transferase/metabolismo , Microssomos Hepáticos/enzimologia , Animais , Antioxidantes/farmacologia , Catalase/metabolismo , Relação Dose-Resposta a Droga , Sequestradores de Radicais Livres/farmacologia , Radicais Livres/química , Técnicas In Vitro , Cinética , Medições Luminescentes , Masculino , Microssomos Hepáticos/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase/farmacologiaRESUMO
To determine the genotypes of Giardia intestinalis from domestic and wild animals in Japan, Giardia isolates obtained from feces of 24 dogs kept in households and breeding kennels, three companion cats, five dairy calves and three wild monkeys, Macaca fuscata, were genotyped using the 177 bp sequence of the glutamete dehydrogenase gene (gdh). The genotypes were assemblages A, C, D or A/D for dog isolates, Assemblage F for cat isolates, assemblages A or E for calf isolates and assemblage B for monkey isolates. This is the first report on the genotypes of Giardia isolates from cats, calves and wild monkeys in Japan.
Assuntos
Doenças do Gato/parasitologia , Doenças dos Bovinos/parasitologia , Doenças do Cão/parasitologia , Giardia lamblia/genética , Giardíase/veterinária , Glutamato Desidrogenase/genética , Doenças dos Macacos/parasitologia , Animais , Gatos , Bovinos , Análise por Conglomerados , DNA de Protozoário/química , DNA de Protozoário/genética , Cães , Genótipo , Giardia lamblia/classificação , Giardia lamblia/enzimologia , Giardíase/genética , Giardíase/parasitologia , Glutamato Desidrogenase/química , Haplorrinos , Reação em Cadeia da Polimerase/veterinária , Análise de Sequência de DNARESUMO
Free radical scavenging and protective actions against chemically induced hepatotoxicity of Crassocephalum crepidioides were investigated. A water extract of C. crepidioides strongly scavenged superoxide anion, hydroxyl radical and also stable radical 1,1-diphenyl-2-picrylhydrazyl. Galactosamine (GalN, 400 mg/kg) and lipopolysaccharide (LPS, 0.5 microg/kg) induced hepatotoxicity of rats as seen by an elevation of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and of lipid peroxidation in liver homogenates was significantly depressed when the herbal extract was given intraperitoneally 1 and 15 h before GalN and LPS treatment. Similarly, carbon tetrachloride (CCl4) induced liver injury as evidenced by an increase in AST and ALT activities in serum was also inhibited by the extract pretreatment. Isochlorogenic acids, quercetin and kaempferol glycosides were identified as active components of C. crepidioides with strong free radical scavenging action. These results demonstrate that C. crepidioides is a potent antioxidant and protective against GalN plus LPS- or CCl4-induced hepatotoxicity.