Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Benzimidazole derivatives possessing a leaving group in the 2 alpha-position and either 4,7-dione, 4,7-diol, or 4,7-dimethoxy substituents were examined as inhibitors of buttermilk xanthine oxidase. The quinone and hydroquinone derivatives are not inhibitors of xanthine-oxygen reductase activity, even though the latter is a powerful alkylating agent. The methoxylated hydroquinones are linear noncompetitive inhibitors, the best of which is the 2 alpha-bromo analogue (Ki = 46 microM). During xanthine-oxygen reductase activity, the 2 alpha-bromo analogue irreversibly traps the reduced enzyme. Formation of a C(4a) adduct of the reduced functional FAD cofactor is postulated on the basis of UV-visible spectral evidence and reconstitution of the enzyme after removal of the altered FAD. A probable sequence of events is reversible binding at or near the reduced cofactor followed by adduct formation. It is concluded that potent tight binding inhibitors could be designed that act at the FAD cofactor rather than the purine active site.
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PMID:Noncompetitive and irreversible inhibition of xanthine oxidase by benzimidazole analogues acting at the functional flavin adenine dinucleotide cofactor. 375 35

Angiotensin II is known to potentiate vasoconstriction induced by electrical field stimulation (EFS), but the underlying mechanisms for this potentiation are not fully understood. This study was designed to investigate the role of superoxide anion in the potentiation effects of angiotensin II. Contraction of rat mesenteric arterial segments was induced by perivascular nerve stimulation with EFS, and superoxide production was measured with lucigenin-enhanced chemiluminescence. Extracellular signal-regulated kinase (ERK) phosphorylation was determined in cultured smooth muscle cells with Western blot. Angiotensin II concentration dependently potentiated the contraction of rat mesenteric arteries to EFS, which is frequency-dependent. This potentiation was blunted by an angiotensin AT(1) receptor antagonist (2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimidazole-7-carboxylic acid, CV-11974), NAD(P)H oxidase inhibitor (apocynin), superoxide dismutase (SOD) and its mimetic tiron, but not affected by angiotensin AT(2) receptor antagonist and inhibitors of xanthine oxidase, cytochrome P450, and cyclooxygenase. Angiotensin II increased superoxide production by mesenteric arteries, which was blunted by angiotensin AT(1) receptor antagonist CV-11974, and NAD(P)H oxidase inhibitor apocynin. Superoxide generating compound pyrogallol mimicked the effects of angiotensin II. Tyrosine kinase inhibitor (tyrphostin A25) and mitogen-activated protein kinase (MAPK)/ERK inhibitors (1,4-diamino-2,3-dicyano-1,4-bis [2-aminophenylthio]butadiene (U 0126)) inhibited angiotensin II- and pyrogallol-induced potentiation of EFS-induced contraction, while inactive forms of these inhibitors did not show any inhibitory effects. In cultured smooth muscle cells from mesenteric arteries, angiotensin II and superoxide similarly induced ERK phosphorylation. These results showed that superoxide mediated angiotensin II-induced potentiation of contractile response to EFS and tyrosine kinase-MAPK/ERK activation was involved.
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PMID:Superoxide anion mediates angiotensin II-induced potentiation of contractile response to sympathetic stimulation. 1853 62

2-Aryl-1-arylmethyl-1H-benzimidazole derivatives having different side chains on the structure were examined in vitro for their antioxidant abilities by 2,2-diphenyl-1-picryl hydrazine radical scavenging activity, reducing ability, OH radical scavenging activity, inhibition of polyphenol oxidase and xanthine oxidase. Overall, with few exceptions, all the 2-aryl-1-arylmethyl-1H-benzimidazoles showed moderate biological activity with all parameters examined. The 2-aryl-1-arylmethyl-1H-benzimidazoles were found to be reactive toward 2,2-diphenyl-1-picryl hydrazine radical and had considerable reducing ability, with significant xanthine oxidase inhibition. With few exceptions, all the compounds under study were found to possess moderate-to-poor OH radical scavenging activity and inhibited polyphenol oxidase significantly. These findings suggest that these 2-aryl-1-arylmethyl-1H-benzimidazoles can be considered as potential antioxidant and xanthine oxidase inhibitory agents, those might be further, explored for the design of lead antioxidant and antigout drug candidates using in vivo trials.
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PMID:In vitro evaluation of selected benzimidazole derivatives as an antioxidant and xanthine oxidase inhibitors. 2358 8