Uptake and Biotransformation of Guvermectin in Three Crops after In Vivo and In Vitro Exposure

Abstract

Guvermectin, as a novel nucleoside-like biopesticide, could increase the rice yield excellently, but the potential environmental behaviors remain unclear, which pose potential health risks. Therefore, the uptake and biotransformation of guvermectin in three types of crops (rice, lettuce, and carrot) were first evaluated with a hydroponic system. Guvermectin could be rapidly absorbed and reached equilibrium in roots (12−36 h) and shoots (24−60 h) in three plants, and guvermectin was also vulnerable to dissipation in roots (t 1/2 1.02−3.65 h) and shoots (t 1/2 9.30−17.91 h). In addition, 8 phase I and 2 phase II metabolites, transformed from guvermectin degradation in vivo and in vitro exposure, were identified, and one was confirmed as psicofuranine, which had antibacterial and antitumor properties; other metabolites were nucleoside-like chemicals. Molecular simulation and quantitative polymerase chain reaction further demonstrated that guvermectin was metabolized by the catabolism pathway of an endogenous nucleotide. Guvermectin had similar metabolites in three plants, but the biotransformation ability had a strong species dependence. In addition, all the metabolites exhibit neglectable toxicities (bioconcentration factor <2000 L/kg b.w., LC 50,rat > 5000 mg/kg b.w.) by prediction. The study provided valuable evidence for the application of guvermectin and a better understanding of the biological behavior of nucleoside-like pesticides.