title: Identification of novel glutathione adducts of benzbromarone in human liver microsomes.
abstract: Benzbromarone (BBR) is a potent uricosuric drug that can cause serious liver injury. Our recent study suggested that 1'-hydroxy BBR, one of major metabolites of BBR, is metabolized to a cytotoxic metabolite that could be detoxified by glutathione (GSH). The aim of this study was to clarify whether GSH adducts are formed from 1'-hydroxy BBR in human liver microsomes (HLM). Incubation of 1'-hydroxy BBR with GSH in HLM did not result in the formation of GSH adducts, but 1',6-dihydroxy BBR was formed. In addition, incubation of 1',6-dihydroxy BBR with GSH in HLM resulted in the formation of three novel GSH adducts (M1, M2 and M3). The structures of M1 and M2 were estimated to be GSH adducts in which the 1-hydroxyethyl group at the C-2 position and the hydroxyl group at the C-1' position of 1',6-dihydroxy BBR were substituted by GSH, respectively. We also found that the 6-hydroxylation of 1'-hydroxy BBR is mainly catalyzed by CYP2C9 and that several CYPs and/or non-enzymatic reaction are involved in the formation of GSH adducts from 1',6-dihydroxy BBR. The results indicate that 1'-hydroxy BBR is metabolized to reactive metabolites via 1',6-dihydroxy BBR formation, suggesting that these reactive metabolites are responsible for BBR-induced liver injury.
authors.affiliation: Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Cho
authors.affiliation: Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan. Electronic address: kaoruk@faculty.chiba-u.jp.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Mina
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Bio-functional Molecular Chemistry, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kogure
authors.affiliation: Department of Bio-functional Molecular Chemistry, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Takayama
authors.affiliation: Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, 260-8675, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Chiba
mesh_terms: D001553:Benzbromarone / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D005978:Glutathione / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008658:Inactivation, Metabolic; D008862:Microsomes, Liver / Q000378:metabolism*; D015394:Molecular Structure
chemical_list: D001553:Benzbromarone; D005978:Glutathione
keywords: Benzbromarone; CYP; Drug-induced liver injury; Glutathione adduct; Reactive metabolite