Nishshanka Upul, Chu Pak-Sin, Evans Eric, Reimschuessel Renate, Hasbrouck Nicholas, Amarasinghe Kande, Jayasuriya Hiranthi
Center for Veterinary Medicine, U.S. Food and Drug Administration, Laurel, Maryland 20708, United States.
J Agric Food Chem. 2015 Jun 24;63(24):5753-60. doi: 10.1021/jf506151g. Epub 2015 Jun 9.
Methyltestosterone (MT), a strong androgenic steroid, is not approved for use in fish aquaculture in the United States. It is used in the U.S. under an investigational new animal drug exemption (INAD) only during the early life stages of fish. There is a possibility that farmers feed fish with MT to enhance production for economic gains. Therefore, there is a need to develop methods for the detection of MT and its metabolite residues in fish tissue for monitoring purposes. Previously, our laboratory developed a liquid chromatography-quadrupole time-of-flight (LC-QTOF) method for characterization of 17-O-glucuronide metabolite (MT-glu) in bile of tilapia dosed with MT. The system used was an Agilent 6530 Q-TOF equipped with electrospray jet stream technology, operating in positive ion mode. Retrospective analysis of the data generated in that experiment by a feature-finding algorithm, combined with a search against an in-house library of possible MT-metabolites, resulted in the discovery of a major glucuronide metabolite of MT in the bile extracts. Preliminary data indicate it to be a glucuronide of a hydroxylated MT (OHMT-glu) which persists in tilapia bile for at least 2 weeks after dosing. We present the tentative structural assignment of the OHMT-glu in tilapia bile and time course of development. This glucuronide can serve as a marker to monitor illegal use of MT in tilapia culture.
甲基睾酮（MT）是一种强效雄激素类固醇，在美国未被批准用于鱼类养殖。在美国，仅在鱼类的早期生命阶段，根据新动物药物研究豁免（INAD）使用它。养殖者有可能用MT投喂鱼类以提高产量从而获取经济利益。因此，需要开发用于检测鱼类组织中MT及其代谢物残留的方法以进行监测。此前，我们实验室开发了一种液相色谱 - 四极杆飞行时间（LC - QTOF）方法，用于表征用MT处理的罗非鱼胆汁中的17 - O - 葡萄糖醛酸代谢物（MT - glu）。所使用的系统是配备电喷雾射流技术的安捷伦6530 Q - TOF，以正离子模式运行。通过特征发现算法对该实验中产生的数据进行回顾性分析，并与针对可能的MT代谢物的内部库进行搜索，结果在胆汁提取物中发现了MT的一种主要葡萄糖醛酸代谢物。初步数据表明它是一种羟基化MT（OHMT - glu）的葡萄糖醛酸，在给药后至少在罗非鱼胆汁中持续存在2周。我们给出了罗非鱼胆汁中OHMT - glu的初步结构归属以及其形成的时间进程。这种葡萄糖醛酸可作为监测罗非鱼养殖中MT非法使用的标志物。
