Computational and experimental investigations on the interactions of aryloxy-phenoxy-propionate herbicides to estrogen receptor alpha in zebrafish

When the amount of pesticide exceeds the self-purification ability of the environment, it will be enriched in the human body through the atmosphere, soil, water circulation, etc., threatening human health. Aryloxy-phenoxy-propionate (APP) herbicides are a class of acetyl-CoA carboxylase (ACCase) inhibitor herbicides, widely used in field-weeding of soybean, cabbage, peanut and other crops. However, due to the water circulation, surface runoff and the agronomic practices such as watering irrigation, APP herbicides have the risk of polluting water and destroying the living environment of aquatic organisms. In this paper, a multistep framework combining homology modeling, molecular docking and molecular dynamic simulations were adopted to explore the interactions between APP herbicides and zebrafish estrogen receptor α (ERα) to investigate the estrogenic activities of the herbicides. The structure of zebrafish ERα was modeled by homology modeling, using the human's estrogen receptor α (PDB ID:2YJA) as the template. Then, eight typical APP herbicides were selected to dock with the zebrafish ERα, and it was determined that there were clear interactions between the herbicides and the receptor. The binding patterns of Quizalofop-P-ethyl (QPE), Clodinafop-propargyl (CP) and Haloxyfop-P (HP) with ERα were further investigated by molecular dynamics and binding free energy calculation. The results showed the van der Waals force and electrostatic force were the main driving forces for maintaining the stability of the complex system. In order to verify the theoretical prediction, an exposed experiment was conducted to study the effects of different concentrations of herbicides on VTG level of zebrafish in vivo and the results were consistent with the computational method. The results of this study revealed the mechanism of the action between APP herbicides and zebrafish estrogen receptors, and also provided ideas for optimizing the herbicides.