title: Species difference in enantioselectivity for the oxidation of propranolol by cytochrome P450 2D enzymes.
abstract: We examined and compared enantioselectivity in the oxidation of propranolol (PL) by liver microsomes from humans and Japanese monkeys (Macaca fuscata). PL was oxidized at the naphthalene ring to 4-hydroxypropranolol, 5-hydroxypropranolol and side chain N-desisopropylpropranolol by human liver microsomes with enantioselectivity of [R(+)>S(-)] in PL oxidation rates at substrate concentrations of 10 microM and 1 mM. In contrast, reversed enantioselectivity [R(+)<S(-)] in PL 5-hydroxylation and N-desalkylation rates at the same substrate concentrations was observed in monkey liver microsomes, although the selectivity was the same for PL 4-hydroxylation between the two species. All oxidation reactions of the PL enantiomers in human liver microsomes showed biphasic kinetics, i.e. the reactions could be expressed as the summation of a low-K(m) phase and a high-K(m) phase. Inhibition studies using antibodies and characterization of CYP2D6 enzymes expressed in insect cells or human lymphoblastoid cells indicated that the enantioselectivity of PL oxidation, especially the ring 4- and 5-hydroxylations reflected the properties of CYP2D6 in human liver microsomes. In monkey liver microsomes, all of the oxidation reactions of S(-)-PL showed biphasic kinetics, whereas ring 4- and 5-hydroxylations were monophasic and side chain N-desisopropylation was biphasic for R(+)-PL. Similarly, from the results of inhibition studies using antibodies and inhibitors of cytochrome P450 (P450), it appears that the reversed selectivity [R(+)<S(-)] of PL oxidation rates is catalyzed by CYP2D enzyme(s) in monkey liver at low substrate concentrations. These results indicate that different properties of P450s belonging to the 2D subfamily cause the reversed enantioselectivity between human and monkey liver microsomes.
authors.affiliation: Laboratory of Health Chemistry, Faculty of Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama, Japan. shizuo@pharm.okayama-u.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Narimatsu
authors.forename: N
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Masubuchi
authors.forename: T
authors.initials: T
authors.lastname: Horie
authors.forename: T
authors.initials: T
authors.lastname: Kakegawa
authors.forename: H
authors.initials: H
authors.lastname: Kobayashi
authors.forename: J P
authors.initials: JP
authors.lastname: Hardwick
authors.forename: F J
authors.initials: FJ
authors.lastname: Gonzalez
authors.forename: N
authors.initials: N
authors.lastname: Shimada
authors.forename: S
authors.initials: S
authors.lastname: Ohmori
authors.forename: M
authors.initials: M
authors.lastname: Kitada
authors.forename: K
authors.initials: K
authors.lastname: Asaoka
authors.forename: H
authors.initials: H
authors.lastname: Kataoka
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Satoh
mesh_terms: D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006900:Hydroxylation; D007700:Kinetics; D008251:Macaca; D008862:Microsomes, Liver / Q000201:enzymology*; D010084:Oxidation-Reduction; D011433:Propranolol / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013045:Species Specificity; D018411:Spodoptera / Q000378:metabolism; D013237:Stereoisomerism; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D011994:Recombinant Proteins; D011433:Propranolol; D019389:Cytochrome P-450 CYP2D6