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Water from wastewater treatment plants contains concentrations of pharmaceutically active compounds as high as micrograms per liter, which can adversely affect fish health and behavior, and contaminate the food chain. Here, we tested the ability of the common carp hepatic S9 fraction to produce the main metabolites from citalopram, metoprolol, sertraline, and venlafaxine. Metabolism in fish S9 fractions was compared to that in sheep. The metabolism of citalopram was further studied in fish. Our results suggest a large difference in the rate of metabolites formation between fish and sheep. Fish hepatic S9 fractions do not show an ability to form metabolites from venlafaxine, which was also the case for sheep. Citalopram, metoprolol, and sertraline were metabolized by both fish and sheep S9. Citalopram showed concentration-dependent N-desmethylcitalopram formation with Vmax = 1781 pmol/min/mg and Km = 29.7 μM. The presence of ellipticine, a specific CYP1A inhibitor, in the incubations reduced the formation of N-desmethylcitalopram by 30–100% depending on the applied concentration. These findings suggest that CYP1A is the major enzyme contributing to the formation of N-desmethylcitalopram. In summary, the results from the present in vitro study suggest that common carp can form the major metabolites of citalopram, metoprolol, and sertraline.

In the present study, we characterized the kinetic parameters of 7-ethoxy-resorufin O-deethylation (EROD) and 7-methoxyresorufin O-demethylation (MROD) in hepatic microsomes from entire and castrated male pigs. Validation parameters of an HPLC-based method to analyse EROD and MROD activities are also described. Eadie-Hofstee plot analysis demonstrated a biphasic kinetic of EROD, indicating that at least two forms of cytochrome P450 are involved in this reaction. MROD followed monophasic kinetic, suggesting that a single enzyme, or enzymes with similar affinities, is responsible for the reaction. Inhibitory effects of α-naphthoflavone (ANF), ellipticine and furafylline were studied using microsomes from entire and castrated male pigs. ANF is a known inhibitor of both cytochrome P450 1A1 and 1A2 (CYP1A1 and CYP1A2); the presence of ANF in the incubations resulted in the inhibition of both EROD and MROD activities in porcine liver microsomes. EROD activities in porcine liver microsomes were also inhibited by selective CYP1A1 inhibitor ellipticine, but not by CYP1A2 inhibitor furafylline. MROD activities were strongly inhibited by ellipticine and to a much lesser extent by furafylline. Further studies are needed to evaluate substrate specificities of porcine CYP1A1 and CYP1A2.

The aim of the study was to evaluate the use of leeches of the genus Erpobdella as a means of assessing polychlorinated biphenyl contamination of watercourses. The River Skalice, heavily contaminated with PCBs, was selected as a model. The source of contamination was a road gravel processing factory in Rožmitál pod Třemšínem from which an estimated 1 metric ton of PCBs leaked in 1986. Levels of PCB were measured in leeches collected between 1992 to 2003 from 11 sites covering about 50 km of the river (the first sampling site upstream to the source of contamination and 10 sites downstream). The PCB indicator congeners IUPA no. 28, 52, 101, 118, 138, 153, and 180 were measured. Levels were highest at the four sampling sites nearest the source of pollution. The highest values of PCB congeners were found in 1992. PCB content decreased from 1992 to 2003 and with distance from the source. The study indicated that leeches of the genus Erpobdella are a suitable bioindicator of contamination in the surface layer of river sediments.