ROLES OF HUMAN CYP2A6 AND 2B6 AND RAT CYP2C11 AND 2B1 IN THE 10-HYDROXYLATION OF (–)-VERBENONE BY LIVER MICROSOMES

• Published in: Drug metabolism and disposition Vol. 31; no. 8; pp. 1049 - 1053
• Main Authors: MIYAZAWA, Mitsuo, SUGIE, Atsushi, SHIMADA, Tsutomu
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Pharmacology and Experimental Therapeutics 01.08.2003
• Subjects: Animals; Aryl Hydrocarbon Hydroxylases - physiology; beta-Naphthoflavone - administration & dosage; beta-Naphthoflavone - pharmacokinetics; Biological and medical sciences; Cell Line; Cytochrome P-450 CYP2A6; Cytochrome P-450 CYP2B1 - physiology; Cytochrome P-450 CYP2B6; Cytochrome P450 Family 2; Enzyme Activation; Enzyme Induction; Female; Gene Expression; General pharmacology; Humans; Hydroxylation; Male; Medical sciences; Microsomes, Liver - enzymology; Mixed Function Oxygenases - physiology; NADP - biosynthesis; NADP - metabolism; Oxidoreductases, N-Demethylating - physiology; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Phenobarbital - administration & dosage; Phenobarbital - pharmacokinetics; Pregnenolone - administration & dosage; Pregnenolone - pharmacokinetics; Rats; Rats, Sprague-Dawley; Species Specificity; Stereoisomerism; Steroid 16-alpha-Hydroxylase - physiology; Terpenes - metabolism; Terpenes - pharmacokinetics; Human; Terpenoid; Hydroxylation; Rat; Enzyme; Isozyme; Cytochrome P450; Liver; Rodentia; Microsome; Metabolism; In vitro; Vertebrata; Mammalia; Animal; Plant origin; Drug-metabolizing enzyme; Monoterpene; Mechanism of action
• ISSN: 0090-9556; 1521-009X
• DOI: 10.1124/dmd.31.8.1049

(–)-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 V max values of 15 and 21 nmol/min/nmol P450 with apparent K m values of 16 and 91 μM, 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 V max and K m 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.