title: Involvement of cytochrome P450-mediated metabolism in tienilic acid hepatotoxicity in rats.
abstract: 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.
authors.affiliation: Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 16-13 Kita-Kasai 1-Chome, Edogawa-ku, Tokyo 134-8630, Japan. nishiya.takayoshi.dv@daiichisankyo.co.jp
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nishiya
authors.forename: Michiyuki
authors.initials: M
authors.lastname: Kato
authors.forename: Takami
authors.initials: T
authors.lastname: Suzuki
authors.forename: Chikako
authors.initials: C
authors.lastname: Maru
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kataoka
authors.forename: Chiharu
authors.initials: C
authors.lastname: Hattori
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Mori
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Jindo
authors.forename: Yorihisa
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Sunao
authors.initials: S
authors.lastname: Manabe
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000737:chemistry / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects; D001646:Bile / Q000737:chemistry / Q000378:metabolism; D056486:Chemical and Drug Induced Liver Injury; D002853:Chromatography, Liquid / Q000379:methods; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D020869:Gene Expression Profiling; D005721:Glutamate-Cysteine Ligase / Q000235:genetics; D005978:Glutathione / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000235:genetics; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008107:Liver Diseases / Q000235:genetics / Q000378:metabolism*; D008297:Male; D015394:Molecular Structure; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053719:Tandem Mass Spectrometry / Q000379:methods; D013989:Ticrynafen / Q000008:administration & dosage / Q000737:chemistry / Q000633:toxicity*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D000959:Antihypertensive Agents; D012333:RNA, Messenger; D003577:Cytochrome P-450 Enzyme System; D051547:Heme Oxygenase-1; D016660:NAD(P)H Dehydrogenase (Quinone); D005721:Glutamate-Cysteine Ligase; D005978:Glutathione; D013989:Ticrynafen