title: Identification of a hydroxylamine glucuronide metabolite of an oral hypoglycemic agent.
abstract: Glucuronides of piperazine hydroxylamines are rarely reported in the literature, and even more rarely are their structures unambiguously identified. One major metabolite was detected by liquid chromatography/mass spectrometry-radioactivity in urine from monkeys treated with the aryl piperazine oral hypoglycemic agent 9-[(1S,2R)-2-fluoro-1-methylpropyl]-2-methoxy-6-(1-piperazinyl) purine hydrochloride (1). The mass spectrum of this metabolite indicated that it was both monooxygenated and glucuronidated on the piperazine ring. Possible structures included the N- or O-glucuronic acid conjugates of a carbinolamine, hydroxylamine, or N-oxide. Treatment with beta-glucuronidase gave a monooxygenated derivative of the parent compound. 1H NMR analysis of either the glucuronic acid conjugate or the monooxygenated product provided insufficient evidence to unambiguously determine their structures. Incubation of 1 with pig liver microsomes resulted in formation of the same monooxygenated derivative derived from beta-glucuronidase treatment of the glucuronide metabolite. This in vitro system was used to generate sufficient material for analysis by 13C NMR, and the metabolite was identified as a hydroxylamine derivative 2. Incubation of the hydroxylamine with monkey liver microsomes and uridine diphospho-5'-glucuronic acid gave the same glucuronic acid conjugate as that observed in monkey urine. 13C NMR analysis of this biosynthetic product led to its unequivocal structure assignment as the O-glucuronic acid conjugate of the hydroxylamine 3.
authors.affiliation: Department of Drug Metabolism, Merck Research Laboratories, Rahway, NJ 07065, USA. randy_miller@merck.com
authors.forename: Randall R
authors.initials: RR
authors.lastname: Miller
authors.forename: George A
authors.initials: GA
authors.lastname: Doss
authors.forename: Ralph A
authors.initials: RA
authors.lastname: Stearns
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D020719:Glucuronides / Q000096:biosynthesis / Q000378:metabolism* / Q000652:urine; D006898:Hydroxylamines / Q000378:metabolism* / Q000652:urine; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine; D066298:In Vitro Techniques; D008253:Macaca mulatta; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000201:enzymology; D010879:Piperazines / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine; D013045:Species Specificity; D013552:Swine
chemical_list: D020719:Glucuronides; D006898:Hydroxylamines; D007004:Hypoglycemic Agents; C091354:L 686398; D010879:Piperazines