Zebrafish Oatp1d1 Acts as a Cellular Efflux Transporter of the Anionic Herbicide Bromoxynil

Abstract

Toxicokinetics (TK) of ionic compounds in the toxico-/pharmacological model zebrafish embryo (Danio rerio) depend on absorption, distribution, metabolism, and elimination (ADME) processes. Previous research indicated involvement of transport proteins in the TK of the anionic pesticide bromoxynil in zebrafish embryos. We here explored the interaction of bromoxynil with the organic anion-transporting polypeptide zebrafish Oatp1d1. Mass spectrometry imaging revealed accumulation of bromoxynil in the gastrointestinal tract of zebrafish embryos, a tissue known to express Oatp1d1. In contrast to the Oatp1d1 reference substrate bromosulfophthalein (BSP), which is actively taken up by transfected HEK293 cells overexpressing zebrafish Oatp1d1, those cells accumulated less bromoxynil than empty vector-transfected control cells. This indicates cellular efflux of bromoxynil by Oatp1d1. This was also seen for diclofenac but not for carbamazepine, examined for comparison. Correspondingly, internal concentrations of bromoxynil and diclofenac in the zebrafish embryo were increased when coexposed with BSP, inhibiting the activities of various transporter proteins, including Oatp1d1. The effect of BSP on accumulation of bromoxynil and diclofenac was enhanced in further advanced embryo stages, indicating increased efflux activity in those stages. An action of Oatp1d1 as an efflux transporter of ionic environmental compounds in zebrafish embryos should be considered in future TK assessments.

Electrochemical Oxidative Cross-Coupling for the Construction of C(sp3)–C(sp3) Bonds

“…Their derivatives exhibit remarkable bioactivity and find extensive applications in both pharmaceutical 12 and pesticide 13 fields, exemplified by antipyretic and non-steroidal anti-inflammatory analgesic Acetaminophen 14 and the herbicide Bromoxynil (Scheme 1b). 15 The C-H/X-H oxidative cross-coupling presents an efficient method for constructing substituted phenols, eliminating the need for pre-functionalization of the substrate. 16 However, the conventional oxidative cross-coupling process for functionalizing Synthesis Paper / PSP / Special Topic Template for SYNTHESIS Thieme C(sp 3 )-H bonds in para-substituted phenols typically relies on stoichiometric chemical oxidant such as copper salts or oxone.…”