Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P30044 (antioxidant enzyme)
 8,037 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Scavenging mechanisms for persistent free radicals were investigated using nitroxide-type radicals as model compounds. The free radical reducing activity of a) isolated thioredoxin reductase, a flavin containing oxidoreductase, b) skin homogenates, and c) the epidermis of hairless mice was studied by electron spin resonance spectroscopy. In all three systems, reduction rates of different classes of nitroxide free radicals exhibited the following order: oxazolidinoxy greater than piperidinoxy greater than dihydropyrroloxy. The main reductant for piperidinoxy radicals in mouse skin homogenate is ascorbic acid. Other reducing activities were stimulated by NAD(P)H and could be inhibited by N-ethyl maleimide, suggesting involvement of thiol-dependent processes. Mammalian thioredoxin, a competitive inhibitor of nitroxide reduction by thioredoxin reductase, significantly stimulates nitroxide scavenging in skin homogenate. Thioredoxin reductase did not significantly participate in nitroxide reduction in skin homogenates. At the surface of mouse epidermis a cationic dihydropyrroloxy nitroxide, which was stable in the presence of mammalian thioredoxin reductase was readily reduced. The epidermal reduction was inhibited by zinc, N-ethyl maleimide, and by heat (70 degrees C, 5 min). At least for mouse epidermis, reduction of a variety of nitroxides is a complex phenomenon involving enzymatic and nonenzymatic mechanisms and cannot be used as a specific assay for an enzyme, e.g., thioredoxin reductase. The study indicates the epidermis contains an effective antioxidant system that scavenges ascorbate-sensitive piperidinoxy nitroxides as well as more reducing radicals exemplified by dihydropyrroloxy nitroxides.
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PMID:Free radical reduction mechanisms in mouse epidermis skin homogenates. 238 May 82

NAD(P)H:quinone reductase, or DT-diaphorase, has been studied primarily in the liver where it appears to function as an antioxidant-like enzyme in the 2-electron reduction of some quinones to less toxic hydroquinones. This property together with new molecular biology evidence that oxidants such as H2O2 can induce gene transcription of DT-diaphorase provide especially intriguing reasons to examine the possibility that lung DT-diaphorase could have an important antioxidant enzyme role versus pulmonary O2 toxicity during exposure to hyperoxia. We found that similar to the 'classical' lung antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) DT-diaphorase activity increased significantly in the late gestational fetal lung; also its activity was altered in the same way as the antioxidant enzymes by prenatal hormonal treatment. Another similarity is that DT-diaphorase activity was induced in the neonatal animal lung during hyperoxia, but not in the adult animal lung. However, using various drug treatments which markedly increased lung DT-diaphorase activity (e.g., 3-methylcholanthrene, butylated hydroxyanisole, methimazole) we found no improved hyperoxic survival in the treated adult rats. Also, dicumarol treatment, which markedly depressed DT-diaphorase activity, did not diminish the hyperoxic survival rate in an O2-tolerant adult rat model. Thus, we conclude that unlike the classical antioxidant enzymes, increased pulmonary DT-diaphorase activity is probably neither necessary nor sufficient to protect against pulmonary O2 toxicity during hyperoxia.
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PMID:Does lung NAD(P)H:quinone reductase (DT-diaphorase) play an antioxidant enzyme role in protection from hyperoxia? 846 17

The effects of primaquine treatment on antioxidant enzyme activities were investigated in rat liver and kidney. Male Sprague-Dawley rats were treated with 0.21 mg/kg daily for two weeks (chronic treatment) or a single dose at 0.21 or 0.63 mg/kg. Antioxidant enzyme activities were determined in liver and kidney cytosolic fractions whereas glutathione (GSH) and malondialdehyde (MDA) levels were determined in tissue samples. Results for the liver showed increases in cytosolic superoxide dismutase (SOD) and glutathione peroxidase (GPX) enzymatic activities after chronic primaquine treatment. Levels of MDA, a marker for lipid peroxidation, were also increased by more than 50% indicating enhanced oxidative damage in the liver. In the single dose study, 0.63 mg/kg primaquine caused a more than 100% increase in liver SOD and a 36% increase in NAD (P) H: quinone oxidoreductase (NQOR) activities. Results for the kidney, however, showed fewer primaquine-induced changes in antioxidant enzyme activities when compared to the liver in both the chronic and single dose studies. Overall, our results indicate that primaquine treatment causes an oxidative stress in the two rat organs. These results are consistent with the known pro-oxidant effects of primaquine in vivo, and supplement current knowledge on the effects of antimalarial drugs on various enzyme systems.
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PMID:Primaquine alters antioxidant enzyme profiles in rat liver and kidney. 935 Apr 21

Evidence from a number of studies suggests that the mechanism by which tumor necrosis factor (TNF) kills transformed cells involves oxidative stress. NAD(P)H:(quinone acceptor) oxidoreductase (NQO1) is an antioxidant enzyme with particular relevance to cancer. The MCF-7 breast cancer cell line was stably transfected with rat NQO1 cDNA to determine whether increased NQO1 activity alters sensitivity to TNF-induced apoptosis. Five clones, with a range of NQO1 enzyme activities from 5- to 50-fold greater than the MCF-7 line, and two control transfectants were examined. Northern blot hybridization analyses and reverse transcription-PCR demonstrated that the increase in NQO1 activity in the transfectants was attributable to expression from the transfected rat sequence. Based on sulforhodamine B assays for the number of viable cells, the NQO1 clones showed increased sensitivity to EO9, an indoloquinone that undergoes bioactive reduction by NQO1. Viability studies also demonstrated that the NQO1 transfectants were significantly more sensitive to TNF than the control transfectants or MCF-7 parent. This increased sensitivity could not be explained by changes in superoxide dismutase or catalase activity or to increased sensitivity to oxidative stress in general, as assessed by response to hydrogen peroxide and paraquat treatment. Using dichlorodihydrofluorescein diacetate as a probe, we found that the NQO1 transfectants had no difference in baseline level of oxidative stress compared to the control cells but did exhibit greater intracellular oxidative stress after TNF treatment. We conclude that NQO1 can affect the TNF-mediated pathway to apoptosis.
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PMID:Increased tumor necrosis factor-alpha sensitivity of MCF-7 cells transfected with NAD(P)H:quinone reductase. 1091 79

Wistar rats were fed with different diets with or without supplement coenzyme Q(10) (CoQ(10)) and with oil of different sources (sunflower or virgin olive oil) for six or twelve months. Ubiquinone contents (CoQ(9) and CoQ(10)) were quantified in homogenates of livers and brains from rats fed with the four diets. In the brain, younger rats showed a 3-fold higher amount of ubiquinone than older ones for all diets. In the liver, however, CoQ(10) supplementation increased the amount of CoQ(9) and CoQ(10) in both total homogenates and plasma membranes. Rats fed with sunflower oil as fat source showed higher amounts of ubiquinone content than those fed with olive oil, in total liver homogenates, but the total ubiquinone content in plasma membranes was similar with both fat sources. Older rats showed a higher amount of ubiquinone after diets supplemented with CoQ(10). Two ubiquinone-dependent antioxidant enzyme activities were measured. NADH-ferricyanide reductase activity in hepatocyte plasma membranes was unaltered by ubiquinone accumulation, but this activity increased slightly with age. Both cytosolic and membrane-bound dicumarol-sensitive NAD(P)H:(quinone acceptor) oxidoreductase (DT-diaphorase, EC 1.6.99.2) activities were decreased by diets supplemented with CoQ(10). Animals fed with olive oil presented lower DT-diaphorase activity than those fed with sunflower oil, suggesting that the CoQ(10) antioxidant protection is strengthened by olive oil as fat source.
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PMID:Effect of dietary coenzyme Q and fatty acids on the antioxidant status of rat tissues. 1276 37

NAD(P)H: quinone oxidoreductase 1 (NQO1) is an antioxidant enzyme, important in the detoxification of environmental carcinogens. A single base substitution (C --> T) polymorphism at nucleotide 609 (null-allele) of NQO1 gene impairs stability and function of the NQO1 protein. To investigate the association of this NQO1 polymorphism with susceptibility to esophageal squamous cell carcinoma (ESCC), the NQO1 C609T genotypes were determined by PCR-RFLP analysis in 450 patients with ESCC (257 German Caucasians and 193 northern Chinese) and 393 unrelated healthy controls (252 German Caucasians and 141 northern Chinese). Additionally, NQO1 protein expression was determined by immunohistochemistry in a subset of 74 ESCC (50 German, 24 Chinese). A significant difference in NQO1 C609T genotype distribution was observed between Caucasian healthy controls (C/C, 73.4%; C/T, 25.0%; T/T, 1.6%) and Chinese healthy controls (C/C, 34.0%; C/T, 49.7%; T/T, 16.3%) (chi(2) = 68.40, P < 0.001). The NQO1 T/T genotype significantly increased the risk for developing ESCC in both Caucasian subjects (OR = 4.62, 95% CI = 1.54-13.86) and Chinese subjects (OR = 1.81, 95% CI = 1.04-3.15), compared with the combined C/C and C/T genotypes. In Chinese subjects, this increased susceptibility was pronounced in patients with family history of upper gastrointestinal cancers (OR = 2.18, 95% CI = 1.14-4.17). Immunohistochemical analysis showed NQO1 protein expression in 53 carcinomas, whereas 21 carcinomas were negative. Negativity for NQO1 expression correlated strongly with the NQO1 genotype, being present in 8.6% of cases with C/C, 22.2% of cases with C/T and 100% of cases with T/T genotype (chi(2) = 16.60, P < 0.001). In summary, the association of the NQO1 C609T polymorphism with ESCC in genetically distinct populations makes a strong argument for its importance in carcinogenesis of ESCC in the German Caucasian and the northern Chinese population.
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PMID:Association of NAD(P)H: quinone oxidoreductase 1 (NQO1) C609T polymorphism with esophageal squamous cell carcinoma in a German Caucasian and a northern Chinese population. 1277 Oct 35

Concentration of lipid peroxidation products and antioxidant enzyme activities in rat brain and erythrocytes and the effects of nicotinamide and nicotinoyl-GABA administration on these parameters were estimated on 21st day of streptozotocin-induced diabetes. It was demonstrated more then two-fold diabetes-induced accumulation of conjugated dienes and malondialdehyde in tissues studied. Superoxide dismutase and glutathione reductase activities of both brain homogenate and erythrocytes as well as catalase and glutathione peroxidase activities of brain homogenate were shown to decrease significantly in diabetic rats, meanwhile, catalase activity of erythrocytes was increased and glutathione peroxidase unchanged. So the correlation between changes in enzymatic antioxidant system in brain and erythocytes failed to be found. Alterations observed were virtually prevented by the course of nicotinamide and nicotinoyl-GABA treatment. The results suggested that the suppression of antioxidant system could be primary biochemical disturbance in diabetic neuropathy progression. It was shown that the antioxidant efficacy of nicotinoyl-GABA is lower than that of nicotinamide. It was suggested that the mechanism of antioxidant action of nicotinamide and its structural analogue consists of both scavenging of lipid peroxides and NAD biosynthesis that leads to activation and normalization of altered energy and lipid metabolism.
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PMID:[Oxidative stress correction by nicotinamide and nicotynol-GABA in diabetic neuropathy]. 1291 62

Glyoxals are reactive alpha-oxoaldehydes that are formed endogenously from sugars, the levels of which are increased in various pathological conditions associated with hyperglycaemia and thiamine deficiency. However, the molecular cytotoxic mechanisms of glyoxal are not known. Results presented here and in the other studies cited provide a glimpse into the cytotoxicity mechanisms involved and their pathological implications. We found that glyoxal (10 microM) markedly increased the susceptibility of hepatocyte glutathione (GSH) to oxidation by hydrogen peroxide (H(2)O(2)) and markedly increased cytotoxicity by compromising the cellular antioxidant enzyme system. At higher concentrations, glyoxal was cytotoxic towards hepatocytes, which can be attributed to GSH depletion, oxidative stress and mitochondrial toxicity. Aminoguanidine or penicillamine protected the hepatocytes. Glyoxal cytotoxicity was prevented by increasing glyoxal metabolism with thiamine or NAD(P)H generators, and was increased in GSH- or thiamine-deficient hepatocytes. It was also found that feeding rats reduced thiamine levels in a diet high in simple sugars increased the number of aberrant crypt foci/colon in the absence of clinical evidence of beriberi. This was associated with decreased plasma thiamine and low erythrocyte transketolase activity. Western diets, which are frequently poor in thiamine and high in sugars, could result in increased levels of endogenous glyoxals, which in turn may lead to a predisposition to AGE (advanced glycation end-product)-related pathologies and neoplastic conditions.
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PMID:Toxicity of glyoxals--role of oxidative stress, metabolic detoxification and thiamine deficiency. 1464 Oct 70

Oxidant pollutants such as diesel exhaust particles (DEPs) can initiate and exacerbate airway allergic responses through enhanced IgE production. These effects are especially pronounced in individuals in whom phase II antioxidant enzyme responses are impaired. We confirmed that DEPs and DEP extracts (DEPX) can act directly on B lymphocytes and showed that DEPX could enhance IgH epsilon germline transcription in a B cell line and in PBMCs. We therefore studied the regulation in B cells of NAD(P)H: quinone oxidoreductase (NQO1) as a typical model phase II enzyme and its role in modulating DEPX-enhanced IgE responses. DEPX increased NQO1 mRNA expression in a dose-dependent manner. NQO1 protein induction by DEPX was confirmed by Western blot. DEPs induced activity of the antioxidant response element located in the NQO1 gene promoter. Induction of both NQO1 mRNA and protein expression could be blocked by coculture with an antioxidant and partly repressed by inhibitors of PI3K and p38 MAPK, but not by inhibitors of MAPK/ERK kinase (MEK/ERK) or protein kinase C. The ability of DEPX to enhance IgE production was blocked by the induction of phase II enzymes, including NQO1 in B cells by the chemical sulforaphane. These findings suggest that a natural protective mechanism in B cells from oxidant pollutants such as diesel particles is the expression of phase II enzymes through induction of antioxidant response elements and support the approach of overexpression of these enzymes as a potential future chemopreventative strategy.
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PMID:Phase II enzymes induction blocks the enhanced IgE production in B cells by diesel exhaust particles. 1692 Sep 90

In rat liver, in addition to their intrinsic transferase activity, alpha-class GSTs have Se-independent glutathione peroxidase activity toward fatty acid hydroperoxides, cumene hydroperoxide and phospholipids hydroperoxides but not toward H(2)O(2.) We have previously shown that hepatic GST activity by these isoenzymes is significantly increased 24h after cadmium or manganese administration (Casalino et al., 2004). Here it is reported that Se-independent glutathione peroxidase activity by alpha-class GSTs is also stimulated in the liver of intoxicated rats. The stimulation is associated with a higher level of alpha-class GST proteins, whose induction is blocked by actinomycin D co-administration. The observed Se-independent glutathione peroxidase activity is due to alpha-class GST isoenzymes, as indicated by the studies with diethyldithiocarbamate which, at any concentration, equally inhibits both GST and Se-independent glutathione peroxidase and is an uncompetitive inhibitor of both enzymes. As for liver Se-GSPx, it is not at all affected under these toxic conditions. For comparison, we have evaluated the status of another important antioxidant enzyme, NAD(P)H:quinone reductase, 24h after cadmium or manganese administration. NQO1 too results strongly stimulated in the liver of the intoxicated rats. In these animals, a higher expression of Nrf2 protein is observed, actively translocated from the cytoplasm to the nucleus. The results with the transcription inhibitor, actinomycin D, and the effects on Nrf2 protein are the first clear indication that acute manganese intoxication, similarly to that of cadmium and other heavy metals, increases both the hepatic level of Nrf2 and its transfer from the cytoplasm to the nucleus where it actively regulates the induction of phase II enzymes.
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PMID:The Nrf2 transcription factor contributes to the induction of alpha-class GST isoenzymes in liver of acute cadmium or manganese intoxicated rats: comparison with the toxic effect on NAD(P)H:quinone reductase. 1757 73


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