Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Administration of the antihypertensive drug ticrynafen [2,3-dichloro-4-(2-thienylcarbonyl)-phenoxyacetic acid] has been reported to potentiate the effects of coumarin anticoagulants and to have caused hemorrhagic incidents in some patients. This drug interaction has now been reproduced in the rat. Ticrynafen administration enhanced the degree of hypoprothrombinemia and altered plasma and hepatic vitamin K epoxide concentrations in warfarin-treated rats. Ticrynafen did not affect vitamin K-dependent carboxylase or vitamin K epoxide reductase activities in vitro. Cytosolic DT-diaphorase was very sensitive to ticrynafen inhibition in vitro, and inhibition of vitamin K reduction via this enzyme is a possible mechanism by which ticrynafen potentiates coumarin anticoagulant action. Inhibition of this enzyme may also contribute to the reported hepatotoxicity of ticrynafen.
 ...
PMID:Mechanism of ticrynafen potentiation of coumarin anticoagulant action. 661 42

Tienilic acid is reported to be converted into electrophilic metabolites by cytochrome P450 (CYP) in vitro. In vivo, however, the metabolites have not been detected and their effect on liver function is unknown. We previously demonstrated that tienilic acid decreased the GSH level and upregulated genes responsive to oxidative/electrophilic stresses, such as heme oxygenase-1 (Ho-1), glutamate-cysteine ligase modifier subunit (Gclm) and NAD(P)H dehydrogenase quinone 1 (Nqo1), in rat liver, as well as inducing hepatotoxicity by co-treatment with the glutathione biosynthesis inhibitor l-buthionine-(S,R)-sulfoximine (BSO). In this study, for the first time, we identified a glutathione-tienilic acid adduct, a stable conjugate of putative electrophilic metabolites with glutathione (GSH), in the bile of rats given a single oral dose of tienilic acid (300mg/kg). Furthermore, a tienilic acid-induced decrease in the GSH level and upregulation of Ho-1, Gclm and Nqo1 were completely blocked by pretreatment with the CYP inhibitor 1-aminobenzotriazole (ABT, 66mg/kg, i.p.). The increase in the serum ALT level and hepatocyte necrosis resulting from the combined dosing of BSO and tienilic acid was prevented by ABT, despite a low hepatic GSH level. These findings suggest that the electrophilic metabolites of tienilic acid produced by CYP induce electrophilic/oxidative stresses in the rat liver and this contributes to the hepatotoxicity of tienilic acid under impaired GSH biosynthesis.
 ...
PMID:Involvement of cytochrome P450-mediated metabolism in tienilic acid hepatotoxicity in rats. 1899 96