TY - JOUR T1 - Characterization of Catechol Glucuronidation in Rat Liver JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 199 LP - 207 DO - 10.1124/dmd.30.2.199 VL - 30 IS - 2 AU - Laurence Antonio AU - Joël-Paul Grillasca AU - Jyrki Taskinen AU - Eivor Elovaara AU - Brian Burchell AU - Marie-Helene Piet AU - Brian Ethell AU - Mohamed Ouzzine AU - Sylvie Fournel-Gigleux AU - Jacques Magdalou Y1 - 2002/02/01 UR - http://dmd.aspetjournals.org/content/30/2/199.abstract N2 - Catechols are a class of substances from natural or synthetic origin that contain a 1,2-dihydroxybenzene group. We have characterized the glucuronidation by rat liver microsomes and by the rat liver recombinant UDP-glucuronosyltransferase isoforms UGT1A6 and UGT2B1 of a series of 42 structurally diverse catechols, including neurotransmitters, polyphenols, drugs, and catechol estrogens. Small catechols (4-nitrocatechol, 2,3-dihydroxybenzaldehyde, 4-methylcatechol, and tetrachlorocatechol), tyrphostine A23, and octylgallate were glucuronidated at the highest rate by rat liver microsomes and the recombinant enzymes. By contrast, polyphenols from green tea (catechin and related compounds), 3,5-dinitrocatechol, the catechol-O-methyltransferase inhibitor drugs (entacapone, nitecapone, and tolcapone), the carboxyl catechols (gallic acid and dihydroxybenzoic acid derivatives), and the neurotransmitters and dopaminergic drugs, except dobutamine, were glucuronidated at low rate. Glucuronidation of most catechols was increased upon treatment of rats by 3-methylcholanthrene (3-MC) or Aroclor 1254. No induction was observed after administration of phenobarbital and clofibrate or treatment with catechols. Partial least-squares modeling was carried out to explain the variations of glucuronidation activity by liver microsomes of nontreated and 3-MC-treated rats. The model developed explained 82% and predicted 61% of the variations of glucuronidation activities. Among the 17 electronic and substructure parameters used that characterize the catechols, the hydrophobicity/molar volume ratio of catechols showed a strong positive correlation with the glucuronidation rate. The effect of the pKaof the catechol group was modeled to be nonlinear, the optimal pKa value for glucuronidation being between 8 and 9. Hydrogen bonding and steric effects also were important to account for to predict the glucuronidation rates. The American Society for Pharmacology and Experimental Therapeutics ER -