title: Metabolism of apigenin by rat liver phase I and phase ii enzymes and by isolated perfused rat liver.
abstract: The metabolism of apigenin, a low estrogenic flavonoid phytochemical, was investigated in rat using liver models both in vitro (subcellular fractions) and ex vivo (isolated perfused liver). In vitro, phase I metabolism led to the formation of three monohydroxylated derivatives: luteolin which was the major metabolite (K(m) = 22.5 +/- 1.5 microM; V(max) = 5.605 +/- 0.090 nmol/min/mg protein, means +/- S.E.M.), scutellarein, and iso-scutellarein. These oxidative pathways were mediated by cytochrome P450 monooxygenases (P450s). The use of P450 inhibitors and inducers showed that CYP1A1, CYP2B, and CYP2E1 are involved. In vitro studies of phase II metabolism indicated that apigenin underwent conjugation giving three monoglucuronoconjugates and one monosulfoconjugate. Luteolin led to the formation of four monoglucuronoconjugates, two sulfoconjugates, and one methylconjugate identified as diosmetin. Ex vivo during the apigenin perfusion of an isolated rat liver, none of the phase I metabolites could be recovered. In contrast, two monoglucuronoconjugates and one of the sulfoconjugates of apigenin already identified in vitro were recovered. Moreover, two new derivatives were isolated and identified as a diglucuronoconjugate and a glucuronosulfoconjugate. This work provides new data about the metabolism of apigenin and shows the interest value of using various experimental models in metabolic studies.
authors.affiliation: Unité Mixte de Toxicologie Alimentaire, Institut National de la Recherche Agronomique, 17 rue Sully, BP 86510, 21065 Dijon cedex, France. angeline.gradolatto@dijon.inra.fr
authors.forename: Angéline
authors.initials: A
authors.lastname: Gradolatto
authors.forename: Marie-Chantal
authors.initials: MC
authors.lastname: Canivenc-Lavier
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Basly
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Siess
authors.forename: Caroline
authors.initials: C
authors.lastname: Teyssier
mesh_terms: D000818:Animals; D047310:Apigenin; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D038181:FMN Reductase / Q000378:metabolism; D005260:Female; D005419:Flavonoids / Q000378:metabolism* / Q000493:pharmacokinetics; D020719:Glucuronides / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D047311:Luteolin; D008297:Male; D013058:Mass Spectrometry; D008745:Methylation; D009249:NADP / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012727:Sex Characteristics; D013056:Spectrophotometry, Ultraviolet; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D020719:Glucuronides; D013431:Sulfates; D009249:NADP; D047310:Apigenin; D003577:Cytochrome P-450 Enzyme System; D038181:FMN Reductase; D047311:Luteolin