Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.17.3.2 (xanthine oxidase)
 8,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of protoporphyrin (PP) administration on the activities of enzymes related to and/or involved in lipid peroxidation and on the content of reduced glutathione (GSH) was investigated in rat liver. PP, at an intravenous dose of 20 mg/kg, increased GSH content, caused a weak suppression of NADPH-cytochrome c reductase activity and a slight increase of gamma-glutamyl transpeptidase activity 24 h after dosing, but had no effect on the activities of other enzymes such as xanthine oxidase, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, gamma-glutamylcysteine synthetase or glutathione synthetase. Treatment of rats with diethyl maleate following PP injection resulted in the disappearance of antioxidative action of PP. Furthermore, sinusoidal, but not canalicular, efflux of hepatic GSH was decreased by the PP treatment. The increase of liver GSH content by PP treatment due to the decrease of sinusoidal efflux of GSH from the liver, thus would be involved in the exertion of antioxidative action of PP.
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PMID:Antioxidative effect of protoporphyrin and increase of glutathione in protoporphyrin-administered rat liver. 810 76

To clarify the mechanism of oxidative stress in skeletal muscle atrophied by immobilization, we measured the activities of antioxidant enzymes and xanthine oxidase (XOD) and carried out the cytochemical study of hydrogen peroxide in a typical slow red muscle, the soleus. Male Wistar rats (15 wk old), of which ankle joints of one hindlimb were immobilized in the fully extended position, were killed after 4, 8, or 12 days. The activities of Mn-containing superoxide dismutase (Mn-SOD), Cu-Zn-containing superoxide dismutase (Cu-Zn-SOD), Se-dependent glutathione peroxidase (Se-GSHPx), glutathione S-transferase, catalase, and glutathione reductase were measured spectrophotometrically. The XOD activity and the concentrations of hypoxanthine, xanthine, and urate were measured using a high-performance liquid chromatography. The cytochemical study of hydrogen peroxide in short-term organ culture was performed using an electron microscope. Increased Cu-Zn-SOD and decreased Mn-SOD in atrophy might reflect increased generation of superoxide anions in the cytoplasm rather than in the mitochondria. The source of superoxide anions in the cytoplasm might be the increased superoxide-producing XOD. Enhanced generation of superoxide anions and increased Cu-Zn-SOD activity in atrophy suggested the enhanced generation of hydrogen peroxide in the cytoplasm. Due to the unchanged activity of Se-GSHPx and the unchanged or slightly increased activity of catalase in atrophy, the ability to degrade hydrogen peroxide might not increase so much. Hence, hydrogen peroxide is expected to be increased in atrophy. The cytochemical study supported this expectation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanism of oxidative stress in skeletal muscle atrophied by immobilization. 827 38

The susceptibility of mitochondria from liver and kidney of diabetic and normal rats to in vitro oxidative damage was assessed. Mitochondria were isolated from diabetic rats 4 weeks after streptozotocin injection and from age-matched, normal rats. Liver mitochondria from diabetic rats were less susceptible to oxidative damage (induced by Fe3+/adenosine 5'-diphosphate (ADP) xanthine/xanthine oxidase), as assessed by the formation of thiobarbituric acid reacting substances (TBARS) and sulfhydryl loss, than were mitochondria from normal rats. The decreased susceptibility of liver mitochondria from diabetic rats to oxidative damage correlated with a sevenfold increase in mitochondrial alpha-tocopherol levels. Activities of the antioxidant enzymes, glutathione reductase, glutathione peroxidase, and superoxide dismutase, were lower in liver mitochondria from diabetic compared to normal rats. Manipulation of dietary alpha-tocopherol, to counteract the increased intake of alpha-tocopherol due to diabetes-associated polyphagia, failed to lower liver mitochondrial alpha-tocopherol to the levels found in normal rats. Mitochondria from kidney of diabetic rats were equally as susceptible to in vitro oxidative damage as kidney mitochondria from normal rats. They had increased levels of superoxide dismutase and glutathione peroxidase but identical levels of alpha-tocopherol compared to mitochondria from normal rats. Dietary manipulation of alpha-tocopherol had no effect on kidney mitochondrial levels of the nutrient.
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PMID:Decreased susceptibility of liver mitochondria from diabetic rats to oxidative damage and associated increase in alpha-tocopherol. 845 24

The biochemical basis for the cancer chemopreventive and anti-cancer activities of glucarate, retinoids (13-cis-retinoic acid, hydroxyphenyl retinamide) and their synergistic combination, has been evaluated. Neither alone nor in combination did these agents affect the level in the rat, of enzymes which are (a) known to correlate with reduced risk of carcinogenesis (detoxification enzyme, catalase, glutathione reductase) nor (b) enzymes which correlate with increased risk of carcinogenesis (beta-glucuronidase, xanthine oxidase, glucose-6-phosphate dehydrogenase). Retinoids, but neither glucarate nor its lactone inhibited free radical-induced lipid peroxidation. Both agents alone and synergistically in combination, raise cellular cAMP levels, repress protein kinase C and more generally inhibited DNA synthesis.
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PMID:Basis for the anti-tumor and chemopreventive activities of glucarate and the glucarate:retinoid combination. 851 53

The small intestine can metabolize a variety of substances and can play a role in the presystemic clearance of ingested compounds. Relatively little is known about the ability of small intestine to catalyze the presystemic reductive metabolism of xenobiotics. 1,3-Dinitrobenzene (1,3-DNB), which is known to undergo reductive biotransformation in an intact, oxygenated isolated perfused intestinal preparation, was used as a model substrate for reductive enzymes of the small intestine of the rat. Subcellular fractions from duodenal, jejunal, and ileal regions of rat small intestinal mucosa were used to characterize the enzyme source(s) of those reductive reactions of 1,3-DNB that are relevant in the oxygenated intestinal tissue. 1,3-DNB was reduced to 3-nitroaniline (3-NA) by cytosol from duodenum and jejunum. The rate of reduction was 2 times faster when incubations contained duodenal rather than jejunal cytosol. Jejunal cytosol-catalyzed reduction of 1,3-DNB was supported by hypoxanthine, NADPH, or NADH. Duodenal microsomes catalyzed the reduction of 1,3-DNB to 3-NA in the presence of supplemental NADPH or NADH; however, the reaction was very slow. Jejunal microsomes, ileal microsomes, and ileal cytosol failed to catalyze the reduction of 1,3-DNB. Studies with chemical inhibitors suggested possible roles for DT diaphorase, glutathione reductase, or xanthine oxidase in the jejunal cytosol-catalyzed reaction. Purified, commercially available xanthine oxidase (from buttermilk) catalyzed the reduction of 1,3-DNB to 3-NA when supplemented with NADH or hypoxanthine.
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PMID:Metabolism of [14C]1,3-dinitrobenzene by rat small intestinal mucosa in vitro. 856 89

Nitroreductase enzymes generally catalyze the reduction of nitroaromatic compounds to the corresponding amines. In contrast, ferredoxin NADP oxidoreductase (FNR), glutathione reductase, xanthine oxidase, and cytochrome c reductase catalyze the NADPH dependent elimination of the nitramine nitro group from 2,4,6-trinitrophenylmethylnitramine to form N-methylpicramide (NMP). Nitrite elimination was inhibited under aerobic conditions. Our results suggest that under aerobic conditions, tetryl is enzymatically reduced to the nitroanion radical which is then involved in the reduction of molecular oxygen. Under anaerobic conditions, the radical is reduced to NMP and nitrite is eliminated.
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PMID:Elimination of nitrite from the explosive 2,4,6-trinitrophenylmethylnitramine (tetryl) catalyzed by ferredoxin NADP oxidoreductase from spinach. 860 4

Pregnant Quackenbush Special mice were exposed to ethanol under semiacute (3.0 g/kg body weight intragastrically, days 7 to 12 of pregnancy), and chronic conditions (15% ethanol in drinking water for 5 weeks before and during pregnancy) to assess whether embryo-fetotoxic actions of the drug involve oxidative stress effects. Effects were monitored both in the maternal system and embryo. Alcohol compromised the maternal system by increasing the generation of lipid peroxides in the liver. It also decreased glutathione and vitamin E levels, and glutathione peroxidase and superoxide dismutase activities in this organ. Glutathione peroxidase activity in the maternal blood decreased. Only minor alcohol-induced changes occurred in the uterine endometrium, including decreased xanthine oxidase and increased gamma-glutamyl transpeptidase. Similarly, only few changes were induced in day-12 embryos by alcohol. In this case, glutathione content and xanthine oxidase activity decreased while glutathione reductase activity increased following exposure to the chronic regime. With the possible exception of the maternal liver where evidence of oxidative damage was detected, these results do not reflect substantial changes in the antioxidant defences of either the pregnant mouse or embryo. However, the changes may contribute to the growth retarding and other fetotoxic effects of alcohol when they are totalled into the multifactorial actions of the drug.
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PMID:Oxidative stress and the fetotoxicity of alcohol consumption during pregnancy. 885 47

Tissue-specific changes in antioxidant defenses and lipid peroxidation damage were analyzed in spadefoot toads, Scaphiopus couchii, to determine how these responded during estivation, a state of suppressed oxygen consumption. Maximal activities of glutathione-S-transferase, glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase were measured in six organs from 2-month-estivated toads and compared with activities in animals awakened for 10 days after estivation. Activities of many enzymes, particularly the glutathione-linked enzymes, were significantly lower in tissues of estivating toads than in awake toads. This indicates that enzymatic antioxidant defenses are probably modulated in response to the rate of reactive oxygen species generation in tissues, which is proportional to oxygen consumption. Antioxidant enzyme activities were largely insensitive to high urea, which accumulates during estivation, but were inhibited by elevated KCl. Levels of reduced glutathione were also significantly lower in three organs during estivation and all organs, except skeletal muscle, exhibited a higher oxidized/reduced glutathione ratio, indicating a more oxidized state during estivation. Products of lipid peroxidation (conjugated dienes, lipid hydroperoxides) were higher in tissues of estivated than control toads, suggesting accumulated oxidative damage to lipids during dormancy. One enzymatic source of free radical generation, xanthine oxidase, appeared to have little impact because its activity was detectable only in liver and was significantly lower in estivated toads. The data indicate that both enzymatic and metabolite antioxidant defenses in toads are adaptable systems that are modulated in estivating versus awake states.
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PMID:Antioxidant defenses and lipid peroxidation damage in estivating toads, Scaphiopus couchii. 954 48

It has been suggested that reactive oxygen intermediates (ROIs) may have a role in the genotoxic effects of lead (Pb2+) and mercury (Hg2+), but there have not been any definitive studies demonstrating a causal relationship between the induction of ROIs by these metals and mutagenesis. We previously demonstrated, using the transgenic Chinese hamster ovary cell line AS52, that low concentrations (0.1-1 microM) of Pb2+ and Hg2+ are mutagenic. In the present study, using a novel histochemical computer-enhanced image analysis technique, we demonstrate that Pb2+ and Hg2+ induce the formation of H2O2 in AS52 cells by at least two distinct mechanisms. One is characterized by the rapid induction of H2O2 following treatment of cells with concentrations of Pb2+ or Hg2+ below 0.8 and 1 microM, respectively, while the second occurs in AS52 cells treated with concentrations of Pb2+ or Hg2+ greater than 0.8 and 1 microM, respectively. Pb2+ and Hg2+ (0.1-1 microM) had no effect on the activities of partially purified catalase, glutathione peroxidase, or glutathione reductase, important enzymes involved with antioxidant defense, but these metals stimulated the activities of copper-zinc superoxide dismutase (CuZn-SOD) and xanthine oxidase (XO). Allopurinol (50 microM), a specific inhibitor of xanthine oxidase, inhibited the induction of H2O2 by Pb2+ (0.8-1 microM) and Hg2+ (1 microM) and also inhibited Pb2+- and Hg2+-induced mutagenesis. These results demonstrate that Pb2+ and Hg2+ disrupt the redox status of AS52 cells by enhancing the activities of CuZn-SOD and XO. Furthermore, the results of these studies also demonstrate that there is a causal relationship between the induction of H2O2 by these metals and mutagenesis.
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PMID:Lead and mercury mutagenesis: role of H2O2, superoxide dismutase, and xanthine oxidase. 965 45

Reactive oxygen species are important mediators of tissue injury during malaria infection. The status of hepatic oxidative stress and antioxidant defence indices were studied during Plasmodium yoelii nigeriensis (P. y. nigeriensis) infection and chloroquine/ polyinosinic-polycytidylic acid stabilized with polylysine and carboxymethylcellulose (poly ICLC) treatment of infected mice. P. y. nigeriensis infection resulted in a significant increase in oxidative stress indices viz., xanthine oxidase and rate of lipid peroxidation (LPO). This was accompanied by a highly significant increase in antioxidant defence indices viz., reduced glutathione (GSH) and glutathione reductase while superoxide dismutase (SOD) and catalase showed a highly significant decrease with respect to normal mice. Chloroquine treatment of infected mice caused a decrease in parasitaemia which was associated with restoration of indices altered during infection towards normalization. Poly ICLC treatment of infected mice caused no change in blood parasitaemia but resulted in a significant increase in GSH, glutathione reductase, SOD and catalase with respect to infected mice. Combination therapy of chloroquine and poly ICLC resulted in clearance of parasitaemia and restoration of all oxidative stress and antioxidant defence indices to normal levels.
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PMID:Studies on hepatic oxidative stress and antioxidant defence system during chloroquine/poly ICLC treatment of Plasmodium yoelii nigeriensis infected mice. 1039 Nov 38


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