Probing the potential mechanism of permethrin exposure on Alzheimer's disease through enantiomer-specific network toxicology, multi-spectroscopic, and docking approaches

Latest observations indicated that exposure of organic environmental neurotoxins may increase the potential risk of Alzheimer's diseases (AD). As a suspected food-derived risk factor, permethrin, composed of cis-isomer and trans-isomer, is widely used as a broad-spectrum pyrethroid insecticide in agricultural crops for the arthropod pests controlling. Thus, evaluating the impact of permethrin exposure is of great importance to human health. In this study, we performed the toxicological network approach to decipher AD-related mechanisms of cis-permethrin and trans-permethrin. Based on the toxicological network construction and central network topological analysis, human serum albumin (HSA) was selected as the core targets in AD-related developing. From the analysis of the steady state and time-resolved fluorescence quenching of HSA in presence of permethrin mixture, it has been inferred that the nature of the quenching mainly originates from the dynamic modes. Experimentally, the thermodynamic parameters revealed hydrophobic interactions and van der Waals forces played a major role during quenching process. Tryptophan synchronous fluorescence spectra were blue shifted whereas the position of tyrosine synchronous spectra was red shifted during the complex formation. Three-dimensional fluorescence together with FT-IR experiment confirmed that permethrin caused the secondary structure changes in HSA. To better understand the binding patterns between HSA and cis/trans -permethrin, theoretical calculation and molecular docking were implemented. According to the electrostatic potential map, the electrophilic attack region corresponds for electron rich oxygen atoms, while the nucleophilic attack regions were mainly located at over the benzene rings and methyl on cyclopropane ring of permethrins. Docking results shown that cis-permethrin and trans-permethrin located in hydrophobic pocket nearby Domain IIA with the different binding affinity (−7.6 and −9.2 kcal/mol), which consistent with the competitive displacement experiment. All these findings generated in the present study facilitated the elucidation of the molecular mechanism details between permethrin mixture and HSA, which provided fresh insights into the links between environmental exposure and AD-related adverse health outcomes.