title: Assessment of UDP-glucuronosyltransferase catalyzed formation of Picroside II glucuronide in microsomes of different species and recombinant UGTs.
abstract: This study compared the hepatic glucuronidation of Picroside II in different species and characterized the glucuronidation activities of human intestinal microsomes (HIMs) and recombinant human UDP-glucuronosyltransferases (UGTs) for Picroside II. The rank order of hepatic microsomal glucuronidation activity of Picroside II was rat > mouse > human > dog. The intrinsic clearance of Picroside II hepatic glucuronidation in rat, mouse and dog was about 10.6-, 6.0- and 2.3-fold of that in human, respectively. Among the 12 recombinant human UGTs, UGT1A7, UGT1A8, UGT1A9 and UGT1A10 catalyzed the glucuronidation. UGT1A10, which are expressed in extrahepatic tissues, showed the highest activity of Picroside II glucuronidation (K(m) = 45.1 μM, V(max) = 831.9 pmol/min/mg protein). UGT1A9 played a primary role in glucuronidation in human liver microsomes (HLM; K(m) = 81.3 μM, V(max) = 242.2 pmol/min/mg protein). In addition, both mycophenolic acid (substrate of UGT1A9) and emodin (substrate of UGT1A8 and UGT1A10) could inhibit the glucuronidation of Picroside II with the half maximal inhibitory concentration (IC(50)) values of 173.6 and 76.2 μM, respectively. Enzyme kinetics was also performed in HIMs. The K(m) value of Picroside II glucuronidation was close to that in recombinant human UGT1A10 (K(m) = 58.6 μM, V(max) = 721.4 pmol/min/mg protein). The intrinsic clearance was 5.4-fold of HLMs. Intestinal UGT enzymes play an important role in Picroside II glucuronidation in human.
authors.affiliation: School of Pharmacy, China Pharmaceutical University, Nanjing, P R China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Li
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.forename: Feifei
authors.initials: F
authors.lastname: Fu
authors.forename: Hui
authors.initials: H
authors.lastname: Ji
authors.forename: Xijing
authors.initials: X
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.forename: Di
authors.initials: D
authors.lastname: Zhao
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Lingli
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000818:Animals; D055162:Biocatalysis; D002851:Chromatography, High Pressure Liquid; D002934:Cinnamates / Q000737:chemistry / Q000378:metabolism*; D004285:Dogs; D020719:Glucuronides / Q000737:chemistry / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000378:metabolism*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D057888:Iridoid Glucosides / Q000737:chemistry / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism*; D013045:Species Specificity; D013379:Substrate Specificity
chemical_list: D002934:Cinnamates; D020719:Glucuronides; D057888:Iridoid Glucosides; D007527:Isoenzymes; D011994:Recombinant Proteins; C416837:picroside II; D014453:Glucuronosyltransferase