B-esterases activities in several tissues of the marine fish: sea bass and hake, as potential biomarkers of bisphenol A derivatives

In the marine environment, a new threat linked to plastic pollution relates to plastic additives. This threat encompasses multiple chemical compound groups with a high bioaccumulation potential for these chemical mixtures. Hence, informative biomarkers are needed to indicate the effects of environmentally realistic mixtures of these additives. This study proposes an in vitro approach using tissue homogenates of two marine fish, the European sea bass and hake, which are both of interest in aquaculture and fisheries. The selected biomarkers are B-esterase activities comprising acetylcholinesterase (AChE) and carboxylesterases (CEs). The physiological role of AChE in brain and muscle is mainly neural transmission, while CEs participate in liver detoxification processes. However, B-esterases are also widely distributed in other tissues/organs, where their role is yet to be determined, but their inhibition may have undesired biological consequences. Here, we compared the interaction of the plastic additives, bisphenol A and some of its derivatives, like tetrabromobisphenol A (TBBPA), with B-esterase activities. We particularly focused not only on the robust and broadly distributed CE enzymes in brain, gonad, liver, kidney, and plasma tissues of two marine fish, but also on the use of two commercial substrates, p-nitrophenyl butyrate and α-naphthyl butyrate, tentatively representing two CE isoforms. The results evidenced specific species and tissue responses that could be due to a diverse isoform composition. They identified sea bass as better protected against neurotoxic exposures, at least in terms of B-esterase composition. The flame retardant TBBPA was the most reactive to B-esterases inhibition, although Bisphenol A bis (2,3-dihydroxy propyl) ether and Bisphenol F bis (3-chloro-2-hydroxypropyl) ether warrant further toxicology assessments.