title: Identification of the human UDP-glucuronosyltransferase isoforms involved in the glucuronidation of the phytochemical ferulic acid.
abstract: Ferulic acid (FA), a member of the hydroxycinnamate family, is an abundant dietary antioxidant that may offer beneficial effects against cancer, cardiovascular disease, diabetes, osteoarthritis and Alzheimer's disease. In this study, evidence for sulfation and glucuronidation of FA was investigated upon incubation with human liver microsomes and cytosol. Two main glucuronides, M1 (ether O-glucuronide) and M2 (ester acylglucuronide), were formed with a similar affinity (apparent K(m) 3.53 and 5.15 mM, respectively). A phenol sulfoconjugate was also formed with a higher affinity (K(m) 0.53 mM). Identification of the UDP-glucuronosyltransferase (UGT) isoforms involved in FA glucuronidation was investigated with 12 human recombinant enzymes. FA was mainly glucuronidated by UGT1A isoforms and by UGT2B7. UGT1A4, 2B4, 2B15 and 2B17 failed to glucuronidate the substance. Examination of the kinetic constants revealed that FA was mainly glucuronidated by UGT1A1 at the two nucleophilic groups. UGT1A3 was able to glucuronidate these two positions with the same, but low, efficiency. UGT1A6 and 1A8 were involved in the formation of the ether glucuronide only, whereas UGT1A7, 1A10 and 2B7 preferentially glucuronidated the carboxyl group. Moreover, octyl gallate, a marker substrate of UGT1A1, competitively inhibited FA glucuronidation mediated by this isoform. Altogether, the results suggest that FA glucuronidation is primarily mediated by UGT1A1.
authors.affiliation: Pharmacology Department of Basic Medical College, Wuhan University, China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Li
authors.forename: Liang
authors.initials: L
authors.lastname: Shang
authors.forename: Yaohua
authors.initials: Y
authors.lastname: Wu
authors.forename: Suzanne
authors.initials: S
authors.lastname: Abbas
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Patrick
authors.initials: P
authors.lastname: Netter
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ouzzine
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Jacques
authors.initials: J
authors.lastname: Magdalou
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology; D003373:Coumaric Acids / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D005260:Female; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D020719:Glucuronides / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism; D000099148:UGT1A1 Enzyme
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D003373:Coumaric Acids; D005707:Gallic Acid; D020719:Glucuronides; D014453:Glucuronosyltransferase; D007527:Isoenzymes; D000099148:UGT1A1 Enzyme; C016627:octyl gallate; C004999:ferulic acid