Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Abstract: Carboplatin, a second-generation platinum-containing anticancer drug, is currently being used against a variety of cancers. High-dose carboplatin chemotherapy can cause renal tubular injury in cancer patients. However, the biochemical mechanism of carboplatin-induced renal injury has not been well studied. This study investigated the dose response of carboplatin-induced changes in endogenous antioxidants, lipid peroxidation and platinum content in rat kidney. Male Wistar rats (250-300 g) were divided into five groups and treated as follows: (1) control (saline, intraperitoneally); (2) carboplatin (64 mg/kg, intraperitoneally); (3) carboplatin (128 mg/kg, intraperitoneally); (4) carboplatin (192 mg/kg, intraperitoneally); and (5) carboplatin (256 mg/kg, intraperitoneally). The animals were sacrificed four days after treatment. The blood and kidneys were isolated and analyzed. Plasma creatinine and blood urea nitrogen levels were increased significantly in response to carboplatin in a dose-dependent manner. Renal superoxide dismutase and catalase activities were decreased significantly due to carboplatin at dosages of 128 mg/kg and above. The protein expressions of renal copper/zinc-superoxide dismutase and manganese-superoxide dismutase significantly depleted after carboplatin. Carboplatin (192 and 256 mg/kg) significantly increased lipid peroxidation (malondialdehyde concentration) in rat kidneys. Carboplatin dose-dependently increased the renal platinum concentration, with significance at dosages of 128 mg/kg and above. Carboplatin (256 mg/kg) significantly increased renal xanthine oxidase activity, while ratio of reduced to oxidized glutathione depleted significantly. The data suggested that carboplatin caused dose-dependent oxidative renal injury, as evidenced by renal antioxidant depletion, enhanced lipid peroxidation, platinum content, plasma creatinine and blood urea nitrogen levels in rats.
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PMID:Dose response of carboplatin-induced nephrotoxicity in rats. 1242 Jul 97

Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is a master regulator to sense decreased oxygen partial pressure. HIF-1 alpha stability regulation initiates a complex biological response that allows cells to act appropriately to meet patho-physiological situations of decreased oxygen availability. Recently, nitric oxide emerged as a messenger with the ability to stabilize HIF-1 alpha and to transactivate HIF-1 under normoxia. Considering that reactive nitrogen species are recognized for post-translation protein modifications, among others S-nitrosation, we asked whether HIF-1 alpha is a target for S-nitrosation. In vitro NO+ donating NO donors such as GSNO and SNAP provoked massive S-nitrosation of purified HIF-1 alpha. All 15 free thiol groups found in human HIF-1 alpha are subjected to S-nitrosation. Thiol modification is not shared by spermine-NONOate, a NO radical donating compound. However, spermine-NONOate in the presence of O(2)(-), generated by xanthine/xanthine oxidase, regained S-nitrosation, most likely via formation of a N(2)O(3)-like species. In vitro, S-nitrosation of HIF-1 alpha was attenuated by the addition of GSH or ascorbate. In RCC4 and HEK293 cells GSNO or SNAP reproduced S-nitrosation of HIF-1 alpha, however with a significantly reduced potency that amounted to modification of three to four thiols, only. Importantly, endogenous formation of NO in RCC4 cells via inducible NO synthase elicited S-nitrosation of HIF-1 alpha that was sensitive to inhibition of inducible NO synthase activity with N-monomethyl-L-arginine. NO-stabilized HIF-1 alpha was susceptible to the addition of N-acetyl-cysteine that destabilized HIF-1 alpha in close correlation to the disappearance of S-nitrosated HIF-1 alpha. In conclusion, HIF-1 alpha is a target for S-nitrosation by exogenously and endogenously produced NO.
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PMID:HIF-1 alpha protein as a target for S-nitrosation. 1256 87

The effect of Wen-Pi-Tang extract on renal injury induced by peroxynitrite (ONOO-) production was investigated using rats subjected to intravenous lipopolysaccharide (LPS) injection and then renal ischemia followed by reperfusion. The plasma level of 3-nitrotyrosine, a marker of cytotoxic ONOO formation in vivo, was enhanced markedly in control rats subjected to LPS plus ischemia-reperfusion, but was significantly reduced by the oral administration of Wen-Pi-Tang extract, at doses of 62.5 and 125 mg/kg body weight/day, for 30 days prior to LPS plus ischemia-reperfusion. The activities of inducible nitric oxide synthase (iNOS) and xanthine oxidase (XOD) in renal tissue of control and Wen-Pi-Tang extract-treated rats did not change significantly, while those of the antioxidant enzymes, superoxide dismutase, catalase and glutathione peroxidase, were significantly increased by the administration of Wen-Pi-Tang extract, indicating that Wen-Pi-Tang improved the defense system by scavenging free radicals, not by directly inhibiting nitric oxide and superoxide production by iNOS and XOD. In addition, the levels of the hydroxylated products, m- and p-tyrosine, declined, whereas that of phenylalanine increased, after oral administration of Wen-Pi-Tang extract. Furthermore, the elevated plasma urea nitrogen and creatinine levels resulting from LPS plus ischemia-reperfusion process were significantly reduced by Wen-Pi-Tang extract, implying amelioration of renal impairment. The present study indicates that Wen-Pi-Tang extract contributes to the regulation of ONOO- formation and plays a beneficial role against ONOO(-) -induced oxidative injury and renal dysfunction in vivo.
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PMID:Prevention of peroxynitrite-induced renal injury through modulation of peroxynitrite production by the Chinese prescription Wen-Pi-Tang. 1260 16

The effects of the BuOH fraction from mustard leaf in rats subjected to renal ischemia-reperfusion were examined. The elevated serum superoxide anion (O2-) level and renal xanthine oxidase (XOD) activity in rats subjected to 6-h reperfusion following 1-h ischemia significantly and dose-dependently declined after oral administration of the BuOH fraction at doses of 50 and 200 mg/kg body weight/d for 10 d prior to ischemia-reperfusion. These findings indicate that this fraction might scavenge O2- or inhibit the generation of O2- through XOD activated by the ischemia-reperfusion process. In addition, the thiobarbituric acid-reactive substance level of the renal mitochondrial fraction of rats given the BuOH fraction orally was significantly lower than that of control rats given physiological saline (vehicle), implying that this fraction exerted protective action against lipid peroxidation caused by ischemia-reperfusion. Furthermore, oral administration of the BuOH fraction reduced the serum urea nitrogen and creatinine levels, indicators of renal function. These results suggest that the BuOH fraction has protective effects against ischemia-reperfusion injury, acting as an antioxidant by scavenging O2-, inhibiting O2- generation through XOD, protecting against lipid peroxidation and ameliorating renal functional impairment.
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PMID:Protective effects of the BuOH fraction from mustard leaf in a renal ischemia-reperfusion model. 1265 12

Potassium bromate (KBrO3) is a potent nephrotoxic agent. In this paper, we report the chemopreventive effect of Nigella sativa (black cumin) on KBrO3-mediated renal oxidative stress, toxicity and tumor promotion response in rats. KBrO3 (125 mg/kg body weight, intraperitoneally) enhances lipid peroxidation, gamma-glutamyl transpeptidase, hydrogen peroxide and xanthine oxidase with reduction in the activities of renal antioxidant enzymes and renal glutathione content. A marked increase in blood urea nitrogen and serum creatinine has also been observed. KBrO3 treatment also enhances ornithine decarboxylase (ODC) activity and [3H] thymidine incorporation into renal DNA. Prophylaxis of rats orally with Nigella sativa extract (50 mg/kg body weight and 100 mg/kg body weight) resulted in a significant decrease in renal microsomal lipid peroxidation (P < 0.001), gamma-glutamyl transpeptidase (P < 0.001), H2O2 (P < 0.001) and xanthine oxidase (P < 0.05). There was significant recovery of renal glutathione content (P < 0.01) and antioxidant enzymes (P < 0.001). There was also reversal in the enhancement of blood urea nitrogen, serum creatinine, renal ODC activity and DNA synthesis (P < 0.001). Data suggest that Nigella sativa is a potent chemopreventive agent and may suppress KBrO3-mediated renal oxidative stress, toxicity and tumour promotion response in rats.
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PMID:Nigella sativa (black cumin) ameliorates potassium bromate-induced early events of carcinogenesis: diminution of oxidative stress. 1275 70

Enzyme catalyzed biotransformation of the energetic chemical octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is not known. The present study describes a xanthine oxidase (XO) catalyzed biotransformation of HMX to provide insight into the biodegradation pathway of this energetic chemical. The rates of biotransformation under aerobic and anaerobic conditions were 1.6+/-0.2 and 10.5+/-0.9 nmolh(-1)mgprotein(-1), respectively, indicating that anaerobic conditions favored the reaction. The biotransformation rate was about 6-fold higher using NADH as an electron-donor compared to xanthine. During the course of reaction, the products obtained were nitrite (NO(2)(-)), methylenedinitramine (MDNA), 4-nitro-2,4-diazabutanal (NDAB), formaldehyde (HCHO), nitrous oxide (N(2)O), formic acid (HCOOH), and ammonium (NH(4)(+)). The product distribution gave carbon and nitrogen mass-balances of 91% and 88%, respectively. A comparative study with native-, deflavo-, and desulfo-XO and the site-specific inhibition studies showed that HMX biotransformation occurred at the FAD-site of XO. Nitrite stoichiometry revealed that an initial single N-denitration step was sufficient for the spontaneous decomposition of HMX.
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PMID:Mechanism of xanthine oxidase catalyzed biotransformation of HMX under anaerobic conditions. 1280 94

Intestinal inflammation is accompanied by excessive production of reactive oxygen and nitrogen metabolites. In order to counteract their harmful effects, the intestinal mucosa contains an extensive system of antioxidants. It has previously been shown that the levels of and the balance between the most important antioxidants are seriously impaired within the intestinal mucosa from inflammatory bowel disease (IBD) patients compared with normal mucosa. The present study investigated the consequences of this antioxidative imbalance by evaluating parameters of oxidative stress-related mucosal damage in the same tissue samples. The extent of apoptosis, peroxynitrite-mediated protein nitration (3-NT), and lipid peroxidation were assessed in relation to the expression of nitric oxide synthase (NOS) and the superoxide-producing enzyme xanthine oxidase (XO). In addition, bi- and multi-variate regression analyses were performed to associate these parameters with the levels of the antioxidants assessed previously. Apoptotic cell death was visualized by TUNEL staining in luminal epithelium of normal controls, and in IBD additionally in the inflammatory infiltrate and in deeper parts of the crypts, but its frequency was unrelated to the severity of inflammation. In Crohn's disease (CD), epithelial apoptosis levels were strongly associated with the expression of XO, implying a role for this enzyme in the regulation of epithelial cell homeostasis, although its levels were unaffected by intestinal inflammation and were comparable to those in normal control mucosa. 3-NT immunoreactivity was substantially increased in luminal crypt cells, neutrophils, and mononuclear cells in the inflamed mucosa of ulcerative colitis (UC) patients. The inflamed IBD luminal epithelium, but not the inflammatory cells, also contained increased amounts of NOS. The immunoreactivity of both 3-NT and NOS was significantly higher in UC than in CD. Unexpectedly, the increased 3-NT expression in UC was associated with neutrophilic myeloperoxidase and not with NOS, which suggests that 3-NT is formed in areas with a dense neutrophilic infiltrate via a peroxynitrite-independent oxidation pathway. Lipid peroxidation, as estimated by the malondialdehyde (MDA) concentration, was elevated in both the inflamed CD and the inflamed UC mucosa, and was identified in the luminal epithelium using a histochemical technique. In CD, lipid peroxidation was independently associated with the concentration of metallothionein and with Mn-superoxide dismutase activity, suggesting the involvement of hydroxyl radicals and superoxide anions. In UC, however, the amount of MDA was associated with epithelial catalase expression and neutrophilic myeloperoxidase activity, suggesting a hydrogen peroxide- and/or hypochlorous acid-mediated mechanism. The present study underlines the importance of oxidative stress in the pathogenesis of IBD and provides clues regarding the (anti)oxidants involved which indicate that this process evolves through diverging pathways in CD and UC.
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PMID:Intestinal oxidative damage in inflammatory bowel disease: semi-quantification, localization, and association with mucosal antioxidants. 1295 14

The xanthine oxidase activity of mouse regenerating liver has been shown to be elevated during the period of rapid liver growth and proliferation. This increase is evident when the enzyme activity is expressed per unit wet tissue weight, per unit nitrogen, or per cell. The adrenal cortex probably plays only a minor role in implementing this phenomenon. Further augmentation of the xanthine oxidase level of regenerating liver is not induced by the administration of large quantities of the substrate, xanthine, to the animal.
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PMID:Xanthine oxidase activity in regenerating liver. 1347 88

Reactive nitrogen and oxygen species are implicated in the damage of ischemic tissue that is reperfused. One important pathway may involve xanthine oxidase. Xanthine oxidase uses xanthine, a product of ATP degradation in ischemic tissue, to produce superoxide and hydrogen peroxide. Superoxide reacts rapidly with nitric oxide to form peroxynitrite, a powerful oxidant. Another potential source of reactive nitrogen species is the myeloperoxidase-hydrogen peroxide-nitrite system of activated phagocytes. We demonstrate that peroxynitrite and myeloperoxidase nitrate xanthine in vitro. Through 13C NMR spectroscopy, UV/visible spectroscopy, and mass spectrometry, the major product was identified as 8-nitroxanthine. Xanthine nitration by peroxynitrite was optimal at neutral pH and was markedly stimulated by physiological concentrations of bicarbonate. Xanthine nitration by myeloperoxidase required hydrogen peroxide and nitrite. However, it was independent of chloride ion and little affected by scavengers of hypochlorous acid, suggesting that the reactive agent is a nitrogen dioxide-like species. 8-Nitroxanthine was generated by a low, steady flux of peroxynitrite, and also by the myeloperoxidase-hydrogen peroxide-nitrite system of activated human neutrophils, suggesting that the reactions may be physiologically relevant. 8-Nitroxanthine may exert biological effects because it markedly increased the production of superoxide by the xanthine oxidase-xanthine system. Our observations suggest a mechanism for the enhanced formation of superoxide in reperfused tissue, which might increase the production of peroxynitrite and 8-nitroxanthine. Generation of 8-nitroxanthine by peroxynitrite and myeloperoxidase could represent a positive feedback mechanism that enhances further the production of both reactive oxygen and nitrogen species in ischemic tissue that is reperfused.
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PMID:8-Nitroxanthine, a product of myeloperoxidase, peroxynitrite, and activated human neutrophils, enhances generation of superoxide by xanthine oxidase. 1367 77

Reactive nitrogen species (RNS) have been reported to be involved in the inflammatory process in chronic obstructive pulmonary disease (COPD). However, there are no studies on the modulation of RNS in COPD. It was hypothesised that inhibition of xanthine oxidase (XO) might decrease RNS production in COPD airways through the suppression of superoxide anion production. Ten COPD and six healthy subjects participated in the study. The XO inhibitor allopurinol (300 mg x day(-1) p.o. for 4 weeks) was administered to COPD patients. RNS production in the airway was assessed by 3-nitrotyrosine immunoreactivity and enzymic activity of XO in induced sputum as well as by exhaled nitric oxide (eNO) concentration. XO activity in the airway was significantly elevated in COPD compared with healthy subjects. Allopurinol administration to COPD subjects significantly decreased XO activity and nitrotyrosine formation. In contrast, eNO concentration was significantly increased by allopurinol administration. These results suggest that oral administration of the xanthine oxidase inhibitor allopurinol reduces airway reactive nitrogen species production in chronic obstructive pulmonary disease subjects. This intervention may be useful in the future management of chronic obstructive pulmonary disease.
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PMID:Xanthine oxidase inhibition reduces reactive nitrogen species production in COPD airways. 1451 25


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