title: Roles of human CYP2A6 and 2B6 and rat CYP2C11 and 2B1 in the 10-hydroxylation of (-)-verbenone by liver microsomes.
abstract: (-)-Verbenone, a monoterpene bicyclic ketone, is a component of the essential oil from rosemary species such as Rosmarinus officinalis L., Verbena triphylla, and Eucalyptus globulus and is used for an herb tea, a spice, and a perfume. In this study, (-)-verbenone was found to be converted to 10-hydroxyverbenone by rat and human liver microsomal cytochrome p450 (p450) enzymes. The product formation was determined by high-performance liquid chromatography with UV detection at 251 nm. There was a good correlation between activities of coumarin 7-hydroxylation and (-)-verbenone 10-hydroxylation catalyzed by liver microsomes of 16 human samples, indicating that CYP2A6 is a principal enzyme in (-)-verbenone 10-hydroxylation in humans. Human recombinant CYP2A6 and CYP2B6 catalyzed (-)verbenone 10-hydroxylation at Vmax values of 15 and 21 nmol/min/nmol p450 with apparent Km values of 16 and 91 microM, respectively. In contrast, rat CYP2A1 and 2A2 did not catalyze (-)-verbenone 10-hydroxylation at all, suggesting that there were species-related differences in the catalytic properties of human and rat CYP2A enzymes in the metabolism of (-)-verbenone. In the rat, recombinant CYP2C11, CYP2B1, and CYP3A2 catalyzed (-)-verbenone 10-hydroxylation with Vmax and Km ratios (ml/min/nmol p450) of 0.73, 0.20, and 0.03, respectively. Male-specific CYP2C11 was a major enzyme in (-)-verbenone 10-hydroxylation by untreated rat livers, and CYP2B1 catalyzed this reaction in liver microsomes of phenobarbital-treated rats. Rat CYP2C12, a female-specific enzyme, did not catalyze (-)verbenone 10-hydroxylation. These results suggest that human CYP2A6 and rat CYP2C11 are the major catalysts in the metabolism of (-)-verbenone by liver microsomes and that there are species-related differences in human and rat CYP2A enzymes and sex-related differences in male and female rats in the metabolism of (-)-verbenone.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, Kowakae, Higashiosaka, Osaka, Japan. miyazawa@apch.kindai.ac.jp
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Miyazawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sugie
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Shimada
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000502:physiology*; D000081008:Bicyclic Monoterpenes; D002460:Cell Line; D065637:Cytochrome P-450 CYP2A6; D019362:Cytochrome P-450 CYP2B1 / Q000502:physiology*; D065702:Cytochrome P-450 CYP2B6; D000072467:Cytochrome P450 Family 2; D004789:Enzyme Activation; D004790:Enzyme Induction; D005260:Female; D015870:Gene Expression; D006801:Humans; D006900:Hydroxylation; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000502:physiology*; D009249:NADP / Q000096:biosynthesis / Q000378:metabolism; D010089:Oxidoreductases, N-Demethylating / Q000502:physiology*; D010634:Phenobarbital / Q000008:administration & dosage / Q000493:pharmacokinetics; D011284:Pregnenolone / Q000008:administration & dosage / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013237:Stereoisomerism; D039181:Steroid 16-alpha-Hydroxylase / Q000502:physiology*; D013729:Terpenes / Q000378:metabolism* / Q000493:pharmacokinetics; D019324:beta-Naphthoflavone / Q000008:administration & dosage / Q000493:pharmacokinetics
chemical_list: D000081008:Bicyclic Monoterpenes; D013729:Terpenes; D009249:NADP; D019324:beta-Naphthoflavone; D011284:Pregnenolone; C052875:verbenone; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C585710:CYP2A6 protein, human; C585599:CYP2B6 protein, human; C450279:CYP2C11 protein, rat; D065637:Cytochrome P-450 CYP2A6; D019362:Cytochrome P-450 CYP2B1; D065702:Cytochrome P-450 CYP2B6; D000072467:Cytochrome P450 Family 2; D039181:Steroid 16-alpha-Hydroxylase; D010089:Oxidoreductases, N-Demethylating; D010634:Phenobarbital