title: The metabolomics of (+/-)-arecoline 1-oxide in the mouse and its formation by human flavin-containing monooxygenases.
abstract: The alkaloid arecoline is a main constituent of areca nuts that are chewed by approximately 600 million persons worldwide. A principal metabolite of arecoline is arecoline 1-oxide whose metabolism has been poorly studied. To redress this, synthetic (+/-)-arecoline 1-oxide was administered to mice (20mg/kg p.o.) and a metabolomic study performed on 0-12h urine using ultra-performance liquid chromatography-coupled time-of-flight mass spectrometry (UPLC-TOFMS) with multivariate data analysis. A total of 16 mass/retention time pairs yielded 13 metabolites of (+/-)-arecoline 1-oxide, most of them novel. Identity of metabolites was confirmed by tandem mass spectrometry. The principal pathways of metabolism of (+/-)-arecoline 1-oxide were mercapturic acid formation, with catabolism to mercaptan and methylmercaptan metabolites, apparent CC double-bond reduction, carboxylic acid reduction to the aldehyde (a novel pathway in mammals), N-oxide reduction, and de-esterification. Relative percentages of metabolites were determined directly from the metabolomic data. Approximately, 50% of the urinary metabolites corresponded to unchanged (+/-)-arecoline 1-oxide, 25% to other N-oxide metabolites, while approximately, 30% corresponded to mercapturic acids or their metabolites. Many metabolites, principally mercapturic acids and their derivatives, were excreted as diastereomers that could be resolved by UPLC-TOFMS. Arecoline was converted to arecoline 1-oxide in vitro by human flavin-containing monooxygenases FMO1 (K(M): 13.6+/-4.9muM; V(MAX): 0.114+/-0.01nmolmin(-1)microg(-1) protein) and FMO3 (K(M): 44.5+/-8.0microM; V(MAX): 0.014+/-0.001nmolmin(-1)microg(-1) protein), but not by FMO5 or any of 11 human cytochromes P450. This report underscores the power of metabolomics in drug metabolite mining.
authors.affiliation: Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, United States.
authors.forename: Sarbani
authors.initials: S
authors.lastname: Giri
authors.forename: Kristopher W
authors.initials: KW
authors.lastname: Krausz
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Idle
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Gonzalez
mesh_terms: D000111:Acetylcysteine / Q000737:chemistry / Q000652:urine; D000284:Administration, Oral; D000818:Animals; D001115:Arecoline / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism* / Q000652:urine; D002853:Chromatography, Liquid; D003497:Cyclic N-Oxides / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism / Q000652:urine; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004285:Dogs; D006801:Humans; D007700:Kinetics; D008297:Male; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways; D051379:Mice; D015394:Molecular Structure; D009557:Nipecotic Acids / Q000737:chemistry / Q000652:urine; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D010880:Piperidines / Q000737:chemistry / Q000652:urine; D011994:Recombinant Proteins / Q000378:metabolism; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000652:urine; D016482:Urinalysis / Q000379:methods
chemical_list: C518972:1-methyl-3,4-dehydropiperidine-3-carboxaldehyde; C518973:1-methylnipecotic acid 1-oxide methyl ester; C518974:4-mercapto-1-methylnipecotic acid methyl ester; D003497:Cyclic N-Oxides; D009557:Nipecotic Acids; D010880:Piperidines; D011994:Recombinant Proteins; D013438:Sulfhydryl Compounds; C518971:arecoline 1-oxide; C015688:arecaidine; D001115:Arecoline; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; C020066:dimethylaniline monooxygenase (N-oxide forming); D000111:Acetylcysteine