Evidence for the occurrence of selenium-independent glutathione peroxidase activity in rat liver microsomes
ABSTRACT Rat liver microsomes exhibit selenium-independent glutathione peroxidase activity which is associated with glutathione S-transferase activity. The peroxidase activity is not due to contamination with either soluble selenium-dependent or selenium-independent glutathione peroxidase activities of the cytosol. N-Ethylmaleimide treatment which stimulates rat liver microsomal glutathione transferase activity concomitantly stimulates the glutathione peroxidase activity. In contrast, N-ethylmaleimide depresses both enzyme activities of the cytosol. A protein exhibiting both glutathione peroxidase and glutathione transferase activity was isolated from the microsomes and purified to homogeneity by DEAE cellulose ion-exchange and S-hexylglutathione Sepharose 6B affinity chromatography.
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ABSTRACT: This study is investigated the effect of selenium against neurotoxicity induced by MPTP(1-methy-4-phenyl-propion-oxypiperidine) in mice. In order to demonstrate neuroprotective activity of selenium, mice were administrated orally with selenium(25, 50, 100 , once/day) for 10 days, and MPTP(10 mg/kg) was injected subcutaneously into the mice for 6 days from the beginning 1hr before selenium treatment. Test of rota road activity was inhibited by treatment with selenium in MPTP-induced neurotoxicity group when compared to MPTP treatment group in normal mice. Monoamine oxidase(MAO)-B activity and cerebral lipid peroxide content were significantly decreased in the treatment of selenium in MPTP-induced neurotoxicity group when compared to MPTP treatment group in normal mice and MAO-A was not affected. Activities of cerebral superoxide dismutase, catalase and glutathione peroxidase were significantly increased in the treatment of selenium in MPTP-induced neurotoxicity group when compared to MPTP treatment group in normal mice. These results suggest that selenium might be estimated the result from the cooperative action of its inhibitory effect on monoamine oxidase-B with that of the enhancement of antioxidant(SOD, catalase, GSH-Px) defence ability.01/2006; 16(2). DOI:10.5352/JLS.2006.16.2.266
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ABSTRACT: Andrographolide, a bioactive diterpenoid, is identified in Andrographis paniculata. In this study, we investigated the pharmacokinetics and bioavailability of andrographolide in rats and studied whether andrographolide enhances antioxidant defense in a variety of tissues and protects against carbon tetrachloride-induced oxidative damage. After a single 50-mg/kg administration, the maximum plasma concentration of andrographolide was 1μM which peaked at 30min. The bioavailability of andrographolide was 1.19%. In a hepatoprotection study, rats were intragastrically dosed with 30 or 50mg/kg andrographolide for 5 consecutive days. The results showed that andrographolide up-regulated glutamate cysteine ligase (GCL) catalytic and modifier subunits, superoxide dismutase (SOD)-1, heme oxygenase (HO)-1, and glutathione (GSH) S-transferase (GST) Ya/Yb protein and mRNA expression in the liver, heart, and kidneys. The activity of SOD, GST, and GSH reductase was also increased in rats dosed with andrographolide (p<0.05). Immunoblot analysis and EMSA revealed that andrographolide increased nuclear Nrf2 contents and Nrf2 binding to DNA, respectively. After the 5-day andrographolide treatment, one group of animals was intraperitoneally injected with carbon tetrachloride (CCl4) at day 6. Andrographolide pretreatment suppressed CCl4-induced plasma aminotransferase activity and hepatic lipid peroxidation (p<0.05). These results suggest that andrographolide is quickly absorbed in the intestinal tract in rats with a bioavailability of 1.19%. Andrographolide protects against chemical-induced oxidative damage by up-regulating the gene transcription and activity of antioxidant enzymes in various tissues.Toxicology and Applied Pharmacology 08/2014; 280(1). DOI:10.1016/j.taap.2014.07.024 · 3.63 Impact Factor
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ABSTRACT: Phototoxins are compounds capable of absorbing light to form an excited state molecule, which can itself react with macromolecules to cause toxicity or react with molecular oxygen to form toxic oxygen species such as singlet oxygen, superoxide anion, and other oxyradicals. Aerobic organisms possess a suite of antioxidant enzymes to protect against reactive oxygen damage. Significant differences in activities of antioxidant enzymes as well as were found in larvae of three species of Papilio (Lepidoptera: Papilionidae). Levels of catalase, glutathione reductase, glutathione peroxidase, and glutathione transferase were high in P. polyxenes, intermediate in P. cresphontes, and low in P. glaucus glaucus. Levels of superoxide dismutase were similar in P. polyxenes and P. cresphontes and significantly higher than in P. glaucus glaucus. The overall hierarchy of antioxidant enzyme activity level in these species is consistent with the phytochemical composition of their host plants: P. polyxenes and P. cresphontes feed almost exclusively on plants (in the Apiaceae and Rutaceae, respectively) that contain phototoxic compounds; P. glaucus glaucus feeds almost exclusively on plants that lack phototoxins. The presence of considerable antioxidant enyme activity in the integument of P. polyxenes and P. cresphontes suggests that these enzymes may protect cuticle, which is not only exposed to sunlight but also to toxic oxyradicals generated from phototoxins at the leaf surface.Biochemical Systematics and Ecology 04/1992; 20(3):197–207. DOI:10.1016/0305-1978(92)90054-H · 1.17 Impact Factor