Metabolism and estrogenicity of benzophenone-2 and bisphenol-S in zebrafish in vitro and in vivo models

Among endocrine disruptors, benzophenones and bisphenols detected in human, in the aquatic environment and in fish, are of major concerns to human and wildlife health. Among benzophenones (UV filters) and bisphenols, benzophenone-2 (BP2) and bisphenos S (BPS, bisphenol A substitute) are hormonally active compounds that have been shown to be estrogenic and to disrupt the hormonal regulation in rat and/or fish. Several human and aquatic vertebrate bioassays have been designed over the last years with the aim to characterize the estrogeno-mimetic potential of chemicals. However, the characterization of the biotransformation capability of these biological models, which allows taking into account bioactivation/detoxification processes in effect assessment, is rarely reported. We have recently developed novel zebrafish assays used to assess the estrogenic potency of chemicals. They included ZELH zfERs cell lines based on the expression of zebrafish estrogen receptors in the hepatic cell line ZFL (ZELH zfERs), and the EASZY assay based on the expression of the Green Fluorescent Protein under the control of the cyp19a1b promoter in the zebrafish larva. They were used to investigate in a global approach, the fate and the estrogenic potency of BP2 and BPS. Metabolism of tritium-labeled chemicals was explored using radio-HPLC (metabolic profiling), and metabolite identification was investigated using biochemical tools and high resolution mass spectrometry. Whereas BP2 and BPS were found to be estrogenic in ZELH zfERs cells and in adult zebrafish, no disruption of expression of estrogeno-regulated genes specific of brain and liver in larva was observed. Regarding the BP2 and the BPS metabolism, similar metabolic profiles were shared by zebrafish in vitro and in vivo models suggesting a well conservation of metabolic capabilities. Overall, this study provides new and relevant data concerning the fate and the estrogenic activity of BP2 and BPS in novel zebrafish assays, allowing a better characterization of their respective biotransformation capabilities which is required for their use in the context of endocrine disruptors testing.