title: Identification of human UDP-glucuronosyltransferase isoforms involved in the isofraxidin glucuronidation and assessment of the species differences of the reaction.
abstract: Isofraxidin, 7-Hydroxy-6.8-dimethoxy-2H-1-benzopyran-2-one, is a major active component of Acanthopanax senticosus, which has been used as Acanthopanax (Ciwujia) injection to treat cardiovascular and cerebrovascular diseases in China for more than thirty years. The purpose of this study was to identify the roles of human UDP-glucuronosyltransferases (UGTs) in isofraxidin glucuronidation in the liver and intestinal microsomes and to reveal the potential species differences by comparing the liver microsomal glucuronidation from different experimental animals. One metabolite was biosynthesized and characterized as isofraxidin-7-O-glucuronide by liquid chromatography tandem mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (NMR). The intrinsic clearances in human liver and intestinal microsomes were 63.8 and 16.4μL/min/mg, respectively. Human liver microsomes displays higher potential for isofraxidin elimination than human intestinal microsomes. The reaction phenotyping analysis was conducted using cDNA-expressed human UGTs and chemical inhibitors. The results indicated that UGT1A1 and UGT1A9 were the main isoforms involved in the formation of isofraxidin-7-O-glucuronide. The isofraxidin glucuronidation in liver microsomes from human (HLM), rat (RLM), mouse (MLM), dog (DLM), monkey (CyLM), minipig (PLM), and guinea pig (GpLM) followed the Michealis-Menten model. The isofraxidin glucuronidation displays species differences in terms of catalytic activities. GpLM had the highest clearance with the CLintvalue of 152μL/min/mg. CyLM, RLM and MLM exhibit similar catalytic activities in isofraxidin glucuronidation with the intrinsic clearance values of 54.6, 58.0 and 50.2μL/min/mg, respectively, which are higher than those of PLM and DLM (23.9 and 37.7μL/min/mg, respectively). Rat exhibits the most similar intrinsic metabolic clearance (CLint) to human.
authors.affiliation: Chinese Medicine Toxicological Laboratory, Institute of Traditional Chinese Medicine, Drug Safety Evaluation Center, Heilongjiang University of Chinese Medicine, Harbin 150040, China.
authors.forename: Fanxing
authors.initials: F
authors.lastname: Meng
authors.affiliation: Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors.forename: Guiyuan
authors.initials: G
authors.lastname: He
authors.affiliation: Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors.forename: Guangbo
authors.initials: G
authors.lastname: Ge
authors.affiliation: Chinese Medicine Toxicological Laboratory, Institute of Traditional Chinese Medicine, Drug Safety Evaluation Center, Heilongjiang University of Chinese Medicine, Harbin 150040, China. Electronic address: keji-liu@163.com.
authors.forename: Shumin
authors.initials: S
authors.lastname: Liu
mesh_terms: D000818:Animals; D003374:Coumarins / Q000737:chemistry*; D004285:Dogs; D004365:Drugs, Chinese Herbal / Q000737:chemistry; D028001:Eleutherococcus / Q000737:chemistry; D014453:Glucuronosyltransferase / Q000737:chemistry*; D006168:Guinea Pigs; D007527:Isoenzymes / Q000737:chemistry; D007700:Kinetics; D008252:Macaca fascicularis; D051379:Mice; D008861:Microsomes / Q000187:drug effects*; D008862:Microsomes, Liver / Q000187:drug effects; D015394:Molecular Structure; D051381:Rats; D013045:Species Specificity; D013552:Swine; D013556:Swine, Miniature; D000090264:UDP-Glucuronosyltransferase 1A9; D000099148:UGT1A1 Enzyme
chemical_list: D003374:Coumarins; D004365:Drugs, Chinese Herbal; D014453:Glucuronosyltransferase; D007527:Isoenzymes; D000090264:UDP-Glucuronosyltransferase 1A9; D000099148:UGT1A1 Enzyme; C000715591:UGT1A9 protein, human; C000715592:Ugt1a9 protein, mouse; C008182:isofraxidin
keywords: Human intestinal microsomes (HIM); Human liver microsomes (HLM); Isofraxidin; Species differences; UDP-glucuronosyltransferases (UGTs)