A re-evaluation of the tissue distribution and physiology of xanthine oxidoreductase

Kooij, A.

doi:10.1007/bf00174006

Cited by 40 publications

(33 citation statements)

References 306 publications

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“…Therefore, in the reperfusion phase, high proportions of XO and its substrate hypoxanthine coincide with the other substrate, oxygen, thus producing ROS and tissue injury. This mechanism, accepted by many authors, has been studied mainly in warm experimental ischemia of the liver, and has shown contradictory results (7,8). In addition, injurious effects produced by circulating XO have also been reported, caused by production of ROS in organs other than those where the enzyme is released (9).…”

Section: Markers Was Higher In the Ce Of Patients With Moderate Primmentioning

confidence: 93%

Xanthine Oxidoreductase and Preservation Injury in Human Liver Transplantation

et al. 2004

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Section: Markers Was Higher In the Ce Of Patients With Moderate Primmentioning

confidence: 93%

Xanthine Oxidoreductase and Preservation Injury in Human Liver Transplantation

et al. 2004

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“…Consequently, XO uses molecular oxygen instead of NAD + during reperfusion and leads to formation of the free radical superoxide anion (O 2 .-) [15][16][17]. Superoxide anion can form hydrogen peroxide through superoxide dismutase activity and, in presence of iron, the extremely reactive hydroxyl radical by Fenton-type reactions [18,19].…”

mentioning

confidence: 99%

Uric Acid and Oxidative Stress

Glantzounis

Tsimoyiannis²,

Kappas³

et al. 2005

CPD

849

591

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Uric acid is the final product of purine metabolism in humans. The final two reactions of its production catalyzing the conversion of hypoxanthine to xanthine and the latter to uric acid are catalysed by the enzyme xanthine oxidoreductase, which may attain two inter-convertible forms, namely xanthine dehydrogenase or xanthine oxidase. The latter uses molecular oxygen as electron acceptor and generates superoxide anion and other reactive oxygen products. The role of uric acid in conditions associated with oxidative stress is not entirely clear. Evidence mainly based on epidemiological studies suggests that increased serum levels of uric acid are a risk factor for cardiovascular disease where oxidative stress plays an important pathophysiological role. Also, allopurinol, a xanthine oxidoreductase inhibitor that lowers serum levels of uric acid exerts protective effects in situations associated with oxidative stress (e.g. ischaemia-reperfusion injury, cardiovascular disease). However, there is increasing experimental and clinical evidence showing that uric acid has an important role in vivo as an antioxidant. This review presents the current evidence regarding the antioxidant role of uric acid and suggests that it has an important role as an oxidative stress marker and a potential therapeutic role as an antioxidant. Further well designed clinical studies are needed to clarify the potential use of uric acid (or uric acid precursors) in diseases associated with oxidative stress.

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“…• -), which initiate reactions that produce a variety of free radical species including • OH and H 2 O 2 (Kooij 1994). These oxygen-derived radical species are hypothesized to oxidize DBAN and release CN -.…”

Section: Discussionmentioning

confidence: 98%

In vitro activation of dibromoacetonitrile to cyanide: role of xanthine oxidase

Mohamadin

Abdel-Naim

2003

Arch Toxicol

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Dibromoacetonitrile (DBAN) is a disinfection byproduct of chlorination of drinking water. Epidemiological studies indicate that it might present a potential hazard to human health. The present work provides evidence for DBAN activation to cyanide (CN(-)) by the hypoxanthine (HX)/xanthine oxidase (XO)/iron (Fe) system in vitro. Optimum conditions for the oxidation of DBAN to CN(-)were characterized. Addition of the sulfhydryl compounds glutathione, N-acetyl- L-cysteine or dithiothreitol significantly enhanced the rate of CN(-)release. A high positive correlation existed between hydroxyl free radical ((*)OH) generation and CN(-) formation. Addition of the (*)OH scavengers mannitol or dimethylthiourea to the reaction mixtures resulted in a significant decrease in the rate of DBAN oxidation. Addition of the antioxidant enzymes catalase or superoxide dismutase resulted in a significant decrease in the rate of DBAN oxidation. The iron chelator desferrioxamine significantly decreased CN(-) formation. The maximum velocity (V(max)) and Michaelis-Menten constant (K(m)) of the reaction were assessed. Allopurinol competitively inhibited the reaction, while folic acid uncompetitively inhibited the reaction. In conclusion, (*)OH generated by the HX/XO/Fe system are implicated in DBAN oxidation. The present results represent a novel pathway for DBAN activation and might be important in explaining DBAN-induced toxicity.

show abstract

A re-evaluation of the tissue distribution and physiology of xanthine oxidoreductase

Cited by 40 publications

References 306 publications

Xanthine Oxidoreductase and Preservation Injury in Human Liver Transplantation

Xanthine Oxidoreductase and Preservation Injury in Human Liver Transplantation

Uric Acid and Oxidative Stress

In vitro activation of dibromoacetonitrile to cyanide: role of xanthine oxidase

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