title: Identification of 2-aminothiazolobenzazepine metabolites in human, rat, dog, and monkey microsomes by ion-molecule reactions in linear quadrupole ion trap mass spectrometry.
abstract: 2-Aminothiazolobenzazepine (2-ATBA), 7-[(1-methyl-1H-pyrazol-4-yl)methyl]-6,7,8,9-tetrahydro-5H-[1,3]thiazolo[4,5-h][3]benzazepin-2-amine, is a D2 partial agonist that has demonstrated antipsychotic effects in a rodent in vivo efficacy model. The metabolite profile showed that 2-ATBA is mainly metabolized by oxidation. However, identification of the oxidation site(s) in the 2-aminothiazole group presents a challenge for the traditional metabolite identification methods such as liquid chromatography/mass spectrometry and NMR due to the lack of unique tandem mass spectrometry fragmentation patterns for ions with the 2-aminothiazole group oxidized at different sites and the lack of stability for purification or reference standard synthesis. We describe the characterization of the oxidized heteroatoms of the 2-aminothiazole group via gas-phase ion-molecule reactions (GPIMR) in a modified linear quadrupole ion trap mass spectrometer. The GPIMR reagents used were dimethyl disulfide, tert-butyl peroxide, and tri(dimethylamino)borane. Each reagent was introduced into the ion trap through the helium line and was allowed to react with the protonated metabolites. The ionic ion-molecule reaction products and their fragmentation profiles were compared with the profiles of the ionic ion-molecule reaction products of protonated reference compounds that had specific heteroatom functionalities. The oxidized 2-aminothiazole metabolite of 2-ATBA showed a similar GPIMR profile to that of the reference compounds with a tertiary N-oxide functionality and distinct from the profiles of the reference compounds with N-aryl hydroxylamine, nitroso, or pyridine N-oxide functionalities. This study demonstrates the feasibility of fingerprinting the chemical nature of oxidized nitrogen functional groups via GPIMR profiling for metabolite structure elucidation.
authors.affiliation: Drug Metabolism and Pharmacokinetics (M.Z.), and Medicinal Chemistry (Y.W., R.U.), AstraZeneca Pharmaceuticals, Boston, Massachusetts; Department of Chemistry, University of Arizona, Tucson, Arizona (R.E.); Department of Chemistry, Purdue University, West Lafayette, Indiana (H.K.); Avid Radiopharmaceuticals, Philadelphia, Pennsylvania (H.X.); Novartis Institutes for BioMedical Research, Boston, Massachusetts (D.B.) minli.zhang@astrazeneca.com.
authors.forename: Minli
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Drug Metabolism and Pharmacokinetics (M.Z.), and Medicinal Chemistry (Y.W., R.U.), AstraZeneca Pharmaceuticals, Boston, Massachusetts; Department of Chemistry, University of Arizona, Tucson, Arizona (R.E.); Department of Chemistry, Purdue University, West Lafayette, Indiana (H.K.); Avid Radiopharmaceuticals, Philadelphia, Pennsylvania (H.X.); Novartis Institutes for BioMedical Research, Boston, Massachusetts (D.B.).
authors.forename: Ryan
authors.initials: R
authors.lastname: Eismin
authors.affiliation: Drug Metabolism and Pharmacokinetics (M.Z.), and Medicinal Chemistry (Y.W., R.U.), AstraZeneca Pharmaceuticals, Boston, Massachusetts; Department of Chemistry, University of Arizona, Tucson, Arizona (R.E.); Department of Chemistry, Purdue University, West Lafayette, Indiana (H.K.); Avid Radiopharmaceuticals, Philadelphia, Pennsylvania (H.X.); Novartis Institutes for BioMedical Research, Boston, Massachusetts (D.B.).
authors.forename: Hilkka
authors.initials: H
authors.lastname: Kenttämaa
authors.affiliation: Drug Metabolism and Pharmacokinetics (M.Z.), and Medicinal Chemistry (Y.W., R.U.), AstraZeneca Pharmaceuticals, Boston, Massachusetts; Department of Chemistry, University of Arizona, Tucson, Arizona (R.E.); Department of Chemistry, Purdue University, West Lafayette, Indiana (H.K.); Avid Radiopharmaceuticals, Philadelphia, Pennsylvania (H.X.); Novartis Institutes for BioMedical Research, Boston, Massachusetts (D.B.).
authors.forename: Hui
authors.initials: H
authors.lastname: Xiong
authors.affiliation: Drug Metabolism and Pharmacokinetics (M.Z.), and Medicinal Chemistry (Y.W., R.U.), AstraZeneca Pharmaceuticals, Boston, Massachusetts; Department of Chemistry, University of Arizona, Tucson, Arizona (R.E.); Department of Chemistry, Purdue University, West Lafayette, Indiana (H.K.); Avid Radiopharmaceuticals, Philadelphia, Pennsylvania (H.X.); Novartis Institutes for BioMedical Research, Boston, Massachusetts (D.B.).
authors.forename: Ye
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Drug Metabolism and Pharmacokinetics (M.Z.), and Medicinal Chemistry (Y.W., R.U.), AstraZeneca Pharmaceuticals, Boston, Massachusetts; Department of Chemistry, University of Arizona, Tucson, Arizona (R.E.); Department of Chemistry, Purdue University, West Lafayette, Indiana (H.K.); Avid Radiopharmaceuticals, Philadelphia, Pennsylvania (H.X.); Novartis Institutes for BioMedical Research, Boston, Massachusetts (D.B.).
authors.forename: Doug
authors.initials: D
authors.lastname: Burdette
authors.affiliation: Drug Metabolism and Pharmacokinetics (M.Z.), and Medicinal Chemistry (Y.W., R.U.), AstraZeneca Pharmaceuticals, Boston, Massachusetts; Department of Chemistry, University of Arizona, Tucson, Arizona (R.E.); Department of Chemistry, Purdue University, West Lafayette, Indiana (H.K.); Avid Radiopharmaceuticals, Philadelphia, Pennsylvania (H.X.); Novartis Institutes for BioMedical Research, Boston, Massachusetts (D.B.).
authors.forename: Rebecca
authors.initials: R
authors.lastname: Urbanek
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods; D004285:Dogs; D000882:Haplorhini; D006801:Humans; D007477:Ions / Q000737:chemistry*; D008252:Macaca fascicularis; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D008862:Microsomes, Liver / Q000378:metabolism*; D011725:Pyridines / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013844:Thiazoles / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D007477:Ions; D011725:Pyridines; D013844:Thiazoles; C004483:2-aminothiazole; C013229:pyridine N-oxide