title: Liquid chromatography/quadrupole time-of-flight mass spectrometry in combination with online hydrogen/deuterium exchange technique for structural elucidation of phase I metabolites of iso-phenylcyclopentylamine in rat bile.
abstract: MS/MS experiment and accurate mass measurement are powerful tools in metabolite identification. However, sometimes these data do not provide enough information to assign an unambiguous structure to a metabolite. In combination with MS techniques, hydrogen/deuterium (H/D) exchange can provide additional information for structural elucidation by determination of the number of exchangeable hydrogen atoms in a structure. In this study, the principal phase I metabolites of iso-phenylcyclopentylamine in rat bile were identified by high-performance liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS). Since N-oxidation may occur because of the existence of the primary amino group in the structure, it was difficult to differentiate the hydroxylated metabolites from N-oxides by ESI-Q-TOF-MS alone. Therefore, online H/D exchange technique was applied to solve this problem. Finally, 25 phase I metabolites were detected and structurally described, in which 11 were confirmed to be N-oxides. This study demonstrated the effectiveness of high-resolution mass spectrometry in combination with an online H/D exchange technique in rapid identification of drug metabolites, especially in discriminating hydroxylated metabolites from N-oxides.
authors.affiliation: Department of Pharmaceutical Analysis, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing, 210009, China.
authors.forename: Xiaoxue
authors.initials: X
authors.lastname: Liu
authors.forename: Suilou
authors.initials: S
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Ding
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Chen
authors.forename: Wenbin
authors.initials: W
authors.lastname: Shen
authors.forename: Xin
authors.initials: X
authors.lastname: Dong
authors.forename: Changhong
authors.initials: C
authors.lastname: Yun
authors.forename: Hongda
authors.initials: H
authors.lastname: Lin
mesh_terms: D000588:Amines / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D000818:Animals; D001646:Bile / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D041961:Deuterium Exchange Measurement; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D008958:Models, Molecular; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000588:Amines; C072530:1-phenylcyclopentylamine
keywords: HPLC/ESI-Q-TOF-MS; N-oxides; hydrogen/deuterium exchange; iso-phenylcyclopentylamine; metabolite identification