title: In vitro glucuronidation of Armillarisin A: UDP-glucuronosyltransferase 1A9 acts as a major contributor and significant species differences.
abstract: 1. This study is performed to investigate liver microsomal glucuronidation of Armillarisin A (A.A), an effective cholagogue drug, aiming at characterizing the involved UDP-glucuronosyltranferases (UGT) and revealing potential species differences. 2. A.A glucuronidation in human liver microsomes (HLM) generates one metabolite (M2) glucuronidated at the phenol hydroxyl group, obeying Michaelis-Menten kinetic model. Multiple isoforms including UGT1A1, 1A7, 1A9 and 2B15 can catalyze A.A glucuronidation. Kinetic assays and chemical inhibition studies both demonstrate that UGT1A9 is responsible for A.A glucuronidation in HLM. A.A glucuronidation in Cynomolgus monkey microsomes (CyLM) also follows Michaelis-Menten model, but can additionally catalyze the traced glucuronosyl substitution at the alcohol hydroxyl group (M1). The reactions in liver microsomes from Sprague-Dawley rats (RLM), ICR/CD-1 mouse (MLM), Beagle dog (DLM) all display biphasic kinetics and only M2 is detected. HLM, RLM and CyLM exhibit very similar catalytic activities towards A.A glucuronidation, with the intrinsic clearance values of respective 38, 37 and 37 μL/min/mg, which are much higher than MLM and DLM. 3. This in vitro study indicates that UGT1A9 acts as a major contributor to A.A glucuronidation in human liver, and the reaction displays large species differences.
authors.affiliation: Department of Traditional Chinese Medicine Resources, School of Traditional Chinese Medicine, Shenyang Pharmaceutical University , Shenyang , China .
authors.forename: Dongxue
authors.initials: D
authors.lastname: Sun
authors.forename: Liangliang
authors.initials: L
authors.lastname: Zhu
authors.forename: Ling
authors.initials: L
authors.lastname: Xiao
authors.forename: Yangliu
authors.initials: Y
authors.lastname: Xia
authors.forename: Guangbo
authors.initials: G
authors.lastname: Ge
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Cao
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.forename: Jun
authors.initials: J
authors.lastname: Yin
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
mesh_terms: D000818:Animals; D001578:Benzopyrans / Q000378:metabolism*; D004285:Dogs; D020719:Glucuronides / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008252:Macaca fascicularis; D008813:Mice, Inbred ICR; D008862:Microsomes, Liver / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D000090264:UDP-Glucuronosyltransferase 1A9
chemical_list: D001578:Benzopyrans; D020719:Glucuronides; D007527:Isoenzymes; C000715591:UGT1A9 protein, human; C000715592:Ugt1a9 protein, mouse; D014453:Glucuronosyltransferase; D000090264:UDP-Glucuronosyltransferase 1A9; C023435:armillarisin A
keywords: Armillarisin A; UDP-glucuronosyltranferases; liver microsomal glucuronidation; species difference