Open AccessIdentification of some benproperine metabolites in humans and investigation of their antitussive effect 1
Author(s) -
LI Yan,
ZHONG Dafang,
CHEN Siwei,
MAEBA Isamu
Publication year - 2005
Publication title -
acta pharmacologica sinica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.514
H-Index - 90
eISSN - 1745-7254
pISSN - 1671-4083
DOI - 10.1111/j.1745-7254.2005.00212.x
Subject(s) - metabolite , urine , chemistry , chromatography , citric acid , mass spectrometry , mass spectrum , liquid chromatography–mass spectrometry , organic chemistry , biochemistry
Aim: To identify 4 unknown metabolites of benproperine (BPP, 1) in human urine after a po dose, and to investigate the antitussive effect of monohydroxylate metabolites. Methods: The putative metabolite references were prepared using chemical synthesis. Their structures were identified using 1 H and 13 C nuclear magnetic resonance, and mass spectrometry. The metabolites in human urine were separated and assayed using liquid chromatography‐ion trap mass spectrometry (LC/MS/MS), and further confirmed by comparison of their mass spectra and chromatographic retention times with those of synthesized reference substances. The antitussive effects of metabolites were evaluated on coughs induced by 7.5% citric acid in conscious guinea pigs. Results: 1‐[1‐Methyl‐2‐[2‐(phenylmethyl)phenoxy]‐ethyl]‐4‐piperidinol (2), 1‐[1‐methyl‐2‐[2‐(phenylmethyl) phenoxy] ethyl]‐3‐piperidinol (3) and their glucuronides 4 and 5 were obtained from chemical synthesis. Four urinary metabolites in human urine showed peaks with the same chromatographic retention times and mass spectra in LC/MS/MS as synthetic substances 2, 3, 4 and 5. Phosphates of compounds 2 and 3 prolonged the latency of cough and reduced the number of coughs during the 3 min test using citric acid, but did not reduce the number of coughs during the 5 min immediately after the test in conscious guinea pigs. Conclusion: Compounds 2, 3, 4, and 5 were identified as the metabolites of BPP in human urine. Among them, compounds 2 and 3 are inactive in the antitussive effect.