title: Stereoselective metabolism of the herbicide fluroxypyr methylheptyl ester in rabbits.
abstract: We investigated the stereoselective degradation kinetics of fluroxypyr methylheptyl ester (FPMH) in rabbits using a chiral high-performance liquid chromatographic method. In 20% rabbit plasma, the half lives of (+)-FPMH and (-)-FPMH were 2.5 and 10.9 min, respectively. Thus, the enantioselective degradation was faster for (+)-FPMH than for (-)-FPMH in rabbit plasma in vitro, and there was no chiral conversion or transformation during incubation of the plasma. The degradation of (+)-FPMH was also much faster than that of the (-)-FPMH in the kidney, lung, and muscle after the intravenous administration of 50 mg/kg racemic FPMH (rac-FPMH), whereas the concentrations of FPMH were below the limit of quantification in other tissues. Furthermore, 98% rac-FPMH was quickly (within 10 min) hydrolyzed to fluroxypyr (FP) in rabbit liver microsomes. Therefore, we examined FP in rabbit plasma and tissues in vivo. We detected FP in all tissues; its concentration was higher in the urine than in the other tissues. FP was rapidly excreted unchanged, principally in the urine. The data presented here are important for a more thorough understanding of this pesticide and should be useful for its full environmental assessment.
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing, China.
authors.forename: Xinyuan
authors.initials: X
authors.lastname: Xu
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Shen
authors.forename: Jinling
authors.initials: J
authors.lastname: Diao
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Jiazhen
authors.initials: J
authors.lastname: Jiang
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D000085:Acetates / Q000032:analysis / Q000493:pharmacokinetics*; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006016:Glycolates / Q000493:pharmacokinetics*; D006540:Herbicides / Q000032:analysis / Q000493:pharmacokinetics; D006868:Hydrolysis; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D010949:Plasma / Q000737:chemistry* / Q000378:metabolism; D011725:Pyridines / Q000032:analysis / Q000493:pharmacokinetics*; D011817:Rabbits; D013237:Stereoisomerism; D014018:Tissue Distribution / Q000502:physiology; D014556:Urine / Q000737:chemistry*
chemical_list: D000085:Acetates; D006016:Glycolates; D006540:Herbicides; D011725:Pyridines; C078450:fluroxypyr methylheptyl ester; C416382:4,5-amino-3,5-dichloro-6-fluoro-2-pyridinyloxyacetic acid