Carboxylesterase in Sparus aurata: characterisation and sensitivity to organophosphorus pesticides and pharmaceutical products

Abstract

Organophosphorus (OP) and carbamate (CB) pesticides cause inhibition of acetylcholinesterase (AChE, which is the target enzyme) and carboxylesterase (CbE). However, some studies have suggested that CbE could have a potential protective role on AChE since CbE seems to be more sensitive to the inhibition by OP and CB compounds than the target enzyme. In addition, there is a great deal of concern about the presence of pharmaceutical products in the seas, and some studies have pointed out the utility of CbE as a biomarker and scavenger of them. Thus, our main aim was to study the inhibition caused by the OPs chlorpyrifos-oxon (CP-O) and dichlorvos (DCV), and the carbamate eserine on the hepatic CbE and the brain AChE of Sparus aurata. Another goal was to determine the hepatic CbE inhibition caused by ibuprofen, fenofibrate, simvastatin, carbamazepine, and triclosan. To achieve these goals, we studied the localisation of CbE in Sparus aurata and estimated the kinetic parameters of hepatic CbE. The results of this study indicate that most CbE activity occurs in the plasma and liver. However, the kinetic parameters of hepatic CbE measured on the three substrates used appeared to be very similar. Hepatic CbE was more sensitive to DCV than brain AChE, suggesting a possible protective role of CbE on AChE. Finally, CbE was shown to be sensitive to the inhibition caused by triclosan and simvastatin, indicating its utility as a biomarker and as a scavenger of these compounds to reduce the possible adverse effects on the organisms.