title: Identification of cytochrome P450 enzymes involved in the metabolism of 4'-methoxy-alpha-pyrrolidinopropiophenone (MOPPP), a designer drug, in human liver microsomes.
abstract: 1. The metabolism of 4'-methoxy-alpha-pyrrolidinopropiophenone (MOPPP), a novel designer drug, to its demethylated major metabolite 4'-hydroxy-pyrrolidinopropio-phenone (HO-PPP) was studied in pooled human liver microsomes (HLM) and in cDNA-expressed human hepatic cytochrome P450 (CYP) enzymes. 2. CYP2C19 catalysed the demethylation with apparent Km and Vmax values of 373.4 +/- 45.1 microM and 6.0 +/- 0.3 pmol min(-1) pmol(-1) CYP, respectively (mean +/- SD). Both CYP2D6 and HLM exhibited clear biphasic profiles with apparent K(m,1) values of 1.3 +/- 0.4 and 22.0 +/- 6.5 microM, respectively, and V(max,1) values of 1.1 +/- 0.1 pmol min(-1) pmol(-1) CYP and 169.1 +/- 20.5 pmol min(-1) mg(-1) protein, respectively. 3. Percentages of intrinsic clearances of MOPPP by particular CYPs were calculated using the relative activity factor (RAF) approach with (S)-mephenytoin-4'-hydroxylation or bufuralol-1'-hydroxylation as index reactions for CYP2C19 or CYP2D6, respectively. 4. MOPPP, HO-PPP and the standard 3',4'-methylenedioxy-pyrrolidinopropio-phenone (MDPPP) were separated and analysed by liquid chromatography-mass spectrometry in the selected-ion monitoring (SIM) mode. 5. The CYP2D6 specific chemical inhibitor quinidine (3 microM) significantly (p<0.0001) inhibited HO-PPP formation by 91.8 +/- 0.5% (mean +/- SEM) in incubation mixtures with HLM and 2 microM MOPPP. 6. It can be concluded from the data obtained from kinetic and inhibition studies that polymorphically expressed CYP2D6 is the enzyme mainly responsible for MOPPP demethylation.
authors.affiliation: Department of Experimental and Clinical Toxicology, University of Saarland, Homburg (Saar), Germany.
authors.forename: D
authors.initials: D
authors.lastname: Springer
authors.forename: R F
authors.initials: RF
authors.lastname: Staack
authors.forename: L D
authors.initials: LD
authors.lastname: Paul
authors.forename: T
authors.initials: T
authors.lastname: Kraemer
authors.forename: H H
authors.initials: HH
authors.lastname: Maurer
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D002853:Chromatography, Liquid; D065731:Cytochrome P-450 CYP2C19; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D018076:DNA, Complementary / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D013058:Mass Spectrometry; D008745:Methylation; D008861:Microsomes; D008862:Microsomes, Liver / Q000187:drug effects*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D008956:Models, Chemical; D011427:Propiophenones / Q000378:metabolism / Q000494:pharmacology*; D020033:Protein Isoforms; D011758:Pyrroles / Q000378:metabolism / Q000494:pharmacology*; D011759:Pyrrolidines / Q000494:pharmacology*; D011802:Quinidine / Q000494:pharmacology; D021241:Spectrometry, Mass, Electrospray Ionization; D013997:Time Factors
chemical_list: C487990:4'-hydroxypyrrolidinopropiophenone; C487469:4'-methoxy-alpha-pyrrolidinopropiophenone; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D018076:DNA, Complementary; D011427:Propiophenones; D020033:Protein Isoforms; D011758:Pyrroles; D011759:Pyrrolidines; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D011802:Quinidine