title: Mechanism-based inactivation of human liver microsomal CYP3A4 by rutaecarpine and limonin from Evodia fruit extract.
abstract: Evodia fruit (Evodiae Fructus) is used as a herbal medicine prepared from the matured fruit of the Evodia rutaecarpa Bentham or Evodia officinalis Dode, of the Rutaceae plant family. An extract of Evodia fruit in the presence of NADPH was shown to inhibit human liver microsomal erythromycin N-demethylation activity, mediated by cytochrome P450 3A4 (CYP3A4), in a preincubation-time dependent manner. The present study was conducted to identify components of Evodia fruit extract having preincubation-time dependent inhibitory effects on CYP3A4 by analyzing human liver microsomal erythromycin N-demethylation activity. Rutaecarpine, a major component of Evodia fruit, and limonin caused the most dramatic decrease in residual CYP3A4 activity (IC50 before and after 20 min preincubation with: rutaecarpine, >100 microM and 1.4 microM; limonin, 23.5 microM and 1.8 microM, respectively). Furthermore, rutaecarpine and limonin were identified as mechanism-based inhibitors of CYP3A4 from the following observations: 1) The inhibitory effects of rutaecarpine and limonin on CYP3A4 activity were dependent on the preincubation time, 2) The inhibition required NADPH, 3) The inhibition was depressed in the presence of the competitive CYP3A4 inhibitor, ketoconazole, 4) Dialysis resulted in no recovery of CYP3A4 activity. The kinetic parameters for inactivation k(inact) and K(I) were: 0.387 min-1 and 107.7 microM for rutaecarpine, 0.266 min-1 and 23.2 microM for limonin, respectively. These results indicate that rutaecarpine and limonin are mechanism-based inhibitors of CYP3A4.
authors.affiliation: Division of Natural Products Chemistry, Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwata
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tezuka
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Kadota
authors.forename: Akira
authors.initials: A
authors.lastname: Hiratsuka
authors.forename: Tadashi
authors.initials: T
authors.lastname: Watabe
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D032086:Evodia; D005638:Fruit; D006801:Humans; D026121:Indole Alkaloids; D007700:Kinetics; D036701:Limonins / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008862:Microsomes, Liver / Q000201:enzymology*; D010936:Plant Extracts / Q000494:pharmacology*; D011799:Quinazolines; D052999:Quinazolinones
chemical_list: D000470:Alkaloids; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System; D004791:Enzyme Inhibitors; D026121:Indole Alkaloids; D036701:Limonins; D010936:Plant Extracts; D011799:Quinazolines; C028632:rutecarpine; D052999:Quinazolinones; C104464:CYP3A protein, human; C510163:CYP3A4 protein, human; C001546:limonin