Assessments on the molecular toxic mechanisms of fipronil and neonicotinoids with glutathione transferase Phi8

As the most widely used pesticides, fipronils and neonicotinoids exhibit harmful effects to many species including crops mainly via the oxidative damages. However, the potential toxic mechanisms of these pesticides to plants remain unclear. In this work, glutathione S-transferase Phi8 was employed as the biomarker to assess the adverse oxidative effects of these two kinds of pesticides. The structural changes and binding characteristics of AtGSTF8 with the pesticides were investigated by multispectral techniques and the latest generation neonicotinoid dinotefuran exhibited the most evident effects on the structure of AtGSTF8. Then dinotefuran displayed weak binding ability to AtGSTF8 comparing with fipronil and clothianidin based on the bio-layer interferometry technique. Besides, the glutathione S-transferase activities of AtGSTF8 were decreased upon binding with these two kinds of pesticides but dinotefuran displayed minor effect on the enzyme activity. At last, dinotefuran and clothianidin were presumed to locate on the molecular surface of AtGSTF8, while fipronil was predicted to insert into the cavity of AtGSTF8 which was adjacent to the active G-site based on the molecular docking results. The molecular investigations on the toxic mechanisms would help to evaluate the harmful effects of these two kinds of prevalent pesticides to plants.