TY - JOUR T1 - Metabolic Disposition of a Monoterpene Ketone, Piperitenone, in Rats: Evidence for the Formation of a Known Toxin,<em>p</em>-cresol JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 74 LP - 80 VL - 27 IS - 1 AU - K. Madhava Madyastha AU - Nilesh W. Gaikwad Y1 - 1999/01/01 UR - http://dmd.aspetjournals.org/content/27/1/74.abstract N2 - It was shown earlier that the monoterpene ketone, piperitenone (I) is one of the major metabolites of R-(+)-pulegone, a potent hepatotoxin. In the present studies, the metabolic disposition of piperitenone (I) was examined in rats. Piperitenone (I) was administered orally (400 mg/kg of the b. wt./day) to rats for 5 days. The following urinary metabolites were isolated and identified by various spectral analyses: p-cresol (VI), 6,7-dehydromenthofuran (III), p-mentha-1,3,5,8-tetraen-3-ol (IX), p-mentha-1, 3,5-triene-3, 8-diol (X), 5-hydroxypiperitenone (VIII), 7-hydroxypiperitenone (XI), 10-hydroxypiperitenone (XII), and 4-hydroxypiperitenone (VII). Incubation of piperitenone (I) with phenobarbital-induced rat liver microsomes in the presence of NADPH resulted in the formation of five metabolites which have been tentatively identified as metabolites III, VII, VIII, XI, XII, on the basis of gas chromatography retention time and gas chromatography-mass spectrometry analysis. Based on these results, a probable mechanism for the formation of p-cresol from piperitenone (I) via the intermediacy of metabolite III has been proposed. The American Society for Pharmacology and Experimental Therapeutics ER -