液相色谱-四级杆/线性离子阱复合质谱法分析恩诺沙星在海参体内的代谢产物

为鉴定恩诺沙星给药后其在海参(Stichopus japonicas)体内的主要代谢产物,取药浴后均质的海参样品,经酸化乙腈提取、浓缩、正己烷净化后,利用液相色谱-四级杆/线性离子阱复合质谱法进行分析。采用电喷雾离子源在正离子模式下进行多反应选择监测结合实时触发增强子离子模式(MRM-IDA-EPI)扫描,分析恩诺沙星在海参体内的代谢产物。实验结果表明,给药6 h后海参体内共鉴定出10种恩诺沙星代谢产物,包括恩诺沙星异构化产物(M3)、脱乙基产物环丙沙星(M1)及其异构体(M2)、加氢还原产物及其异构体(M4、M5和M6)、羟基化恩诺沙星及其异构体(M7和M8)和加氧恩诺沙星及其异构体(M9和M10)。恩诺沙星在海参体内的代谢产物M2~M5以峰面积计,均高于环丙沙星(M1)。研究发现恩诺沙星在海参体内主要发生脱乙基反应和加氢还原反应,其主要代谢产物为M2和M4。

Analysis of Sea Cucumber (Stichopus japonicas) Enrofloxacin Metabolites by Liquid Chromatography Coupled with Quadrupole-linear Ion Trap Mass Spectrometry

Homogenized sea cucumber (Stichopus japonicas) samples were collected after incubating in medicated enrofloxacin bath. Metabolites were extracted from samples using acidified acetonitrile to identify the major metabolites of enrofloxacin in sea cucumber. The extracts were concentrated and purified using hexane, and analyzed by liquid chromatography coupled with quadrupole-linear ion trap mass spectrometry. Multiple reaction monitoring-information dependent acquisition-enhanced product ion (MRM-IDA-EPI) scanning was performed using an electrospray ionization source operated in positive mode to elucidate the structures of the major sea cucumber enrofloxacin metabolites. Ten potential metabolites were found after 6 h of drug administration: an isomerization product of enrofloxacin (M3); a deethylation product, ciprofloxacin (M1), and its isomer (M2); a hydrogenation reduction product and its isomers (M4, M5, and M6); a hydroxylation product and its isomer (M7 and M8); and an oxygenation product and its isomers (M9 and M10). The peak areas of sea cucumber enrofloxacin metabolites M2~M5 were higher than that of ciprofloxacin (M1). Metabolism of enrofloxacin primarily occurred by deethylation and hydrogenation reduction reactions, and M2 and M4 were the major enrofloxacin metabolites identified in sea cucumber.