title: Metabolism of olaquindox in rat and identification of metabolites in urine and feces using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry.
abstract: Olaquindox (OLA), N-(2-hydroxyethyl)-3-methyl-2-quinoxalincarboxamide-1,4-dioxide, is an antimicrobial and growth-promoting agent for animals, which has been banned or allowed only limited use for its potential toxicity. To thoroughly understand the metabolic pathways, metabolism of OLA in rat was studied using ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry with MS(E) and mass defect filtering techniques. Twenty metabolites (M1-M20) were detected in rat feces and urine, of which nine phase I metabolites (M6, M7, M11-M16) and four phase II metabolites (M17-M20) were found in vivo for the first time. The structures of metabolites were reliably characterized on the basis of accurate mass and fragment ions in MS(E) spectra. The major metabolic pathways reported previously in pigs, including reduction of N→O groups, oxidation of the alcohol and hydrolysis, were also confirmed in this study. In addition, hydroxylation of the methyl group, N-dehydroxyethylation and glucuronidation were also proved to be the important metabolic pathways, which contribute to improving our knowledge about in vivo metabolism of OLA.
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100193, PR China.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Bi
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.forename: Shixin
authors.initials: S
authors.lastname: Xu
authors.forename: Lei
authors.initials: L
authors.lastname: Sun
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Feng
authors.initials: F
authors.lastname: Zhong
authors.forename: Shuhuai
authors.initials: S
authors.lastname: Wang
authors.forename: Shuangyang
authors.initials: S
authors.lastname: Ding
authors.forename: Xilong
authors.initials: X
authors.lastname: Xiao
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005243:Feces / Q000737:chemistry; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D011810:Quinoxalines / Q000032:analysis* / Q000378:metabolism / Q000652:urine; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D011810:Quinoxalines; C013168:olaquindox