Binding Affinity Evaluation of Monohydroxydinotefuran and Its Isomers to Acetylcholine Receptor

There are some reports that transformation products of a pesticide exist at higher concentrations than their parent pesticide, or their pharmacological activities are comparable to that of a parent pesticide. It is therefore of importance to examine their potential effects on aquatic organisms; however, few studies have focused on the insecticidal activities of a transformation product of dinotefuran, a neonicotinoid pesticide. In this study, dinotefuran’s transformation products were explored by LC-HRMS analyses of dinotefuran aqueous solutions that had been irradiated by a xenon lamp. This exploration resulted in the discovery of two unknown transformation products. Structural elucidations of these two compounds suggested 28 and 82 chemical structures in terms of structural isomers and steric isomers, respectively. Their binding affinities for a glia-derived acetylcholine-binding protein of Lymnaea stagnalis were simulated to estimate their insecticidal activities. Out of 28 candidates, 20 were judged to have significant insecticidal activities. It can be concluded that the simulation of a substance’s binding affinity, the so-called docking simulation, is a promising way to exclude nontoxic substances among a large number of candidate substances.