Determination And Biological Enrichment Effect Of Antagonist Hormone Drugs In Fish Tissues

Hormone antagonists are a class of chemicals that inhibit the function of the endocrine glands widely used for the therapy of hormone-dependent diseases like breast cancer and carcinoma of testis. Antiestrogen tamoxifen has been found comprehensively in aquatic environment while letrozole might be used in aquaculture. These drugs are potentially harmful to the aquatic organisms including fish. In this study, analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of hormone antagonists and related metabolites in fish tissues. After that, bioconcentration, distribution and elimination of mifepristone, a typical anti-progesterone drug, by Carassius auratus was investigated. This will provide useful information for relevant residues determination and environmental risk assessment. The main results are as follows:(1) A comprehensive analytical method based on ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) has been developed for simultaneous determination of6antiestrogens (toremifene, clomiphene. tamoxifen, raloxifene. anastrozole and letrozole) in fish muscle and liver. Homogeneous fish tissue samples were ultrasonically extracted with acetonitrile, and then the supernatant was diluted by water. Target compounds were concentrated and purified by a mixed-mode canonic-exchanger (MCX) cartridge. The limits of quantification(LOQ, S/N=10) of the6antiestrogens were0.1-0.3μg/kg. The average recoveries of target compounds (spiked at four concentration levels) based on internal standard calibration were in the range of84.9-112.2%with the relative standard deviations (RSDs) of0.9%-14.3%. This method can be applied to the trace analysis of target drugs in fish muscle and liver samples.(2) An UPLC-MS/MS method was established to analyze the antiprogesterones mifepristone and its metabolites in fish tissues. The samples were extracted with acetonitrile and the supernatant was diluted by0.1mol/L acetic acid, and then the target compounds were concentrated and purified by a MCX cartridge. The average recoveries of target compounds in muscle^liver and plasma ranged from66.8%to107.3%. with RSDs no more than19.3%. The limit of quantification for4target compounds was1.0μg/kg in fish muscle and liver, while it was2.0μg/L in plasma.(3) Bioconcentration and elimination of mifepristone (exposed concentration:1μg/L and10μg/L) by Carassius auratus was studied by using a conventional semi-static exposure method. As a result the bioconcentration of mifepristone in the dosed fish approached the stabilization in4days, while it took11days for the removal of most of bioaccumulated mifepristone (>95%) in Carassius auratus. Bioconcentration factors of the ding in muscle and liver of crucian were28.86and94.03. respectively in low dose group, as well as29.33and51.80, respectively in high dose group. The distribution of mifepristone in fish tissues followed the order of liver> muscle> plasma. The major metabolite of mifepristone in Carassius auratus was N-demethyl mifepristone.