Evaluation of an Integrated In Silico-In Vitro Pipeline for Predicting Mitochondrial Complex I-Mediated Neurotoxicity of Chlorpyrifos.

Chlorpyrifos (CPF) is a broad-spectrum chlorinated organophosphate insecticide. It was classified as a persistent organic pollutant under the Stockholm Convention in 2024 due to its harmful effects on the environment and human health, including neurotoxicity. The classical mechanism of CPF-induced neurotoxicity is attributed to acetylcholinesterase inhibition by its metabolite, chlorpyrifos-oxon (CPO), in cholinergic neurons. Emerging studies indicate that CPF also induces toxicity in dopaminergic neurons through mitochondrial dysfunction. In this study, the molecular mechanisms and targets associated with CPF-induced neurotoxicity in humans were investigated using network toxicology, molecular docking, molecular dynamics, and in vitro study. Comprehensive database analyses identified 271 potential targets associated with CPF-induced neurotoxicity. Gene ontology enrichment and gene-gene interaction analyses revealed significant enrichment related to mitochondria and oxidative phosphorylation. Protein-protein interaction and centrality analyses identified 15 hub targets. Molecular docking and molecular dynamics simulations demonstrated that CPF and CPO bind to mitochondrial Complex I, especially with NDUFA2, more strongly than rotenone, a known Complex I inhibitor. In vitro analysis in SH-SY5Y cells demonstrated that CPF impaired mitochondrial complex I-associated activity in a concentration-dependent manner, with significant inhibition observed at concentrations of 75 µM and higher. These findings suggest that CPF, and to a lesser extent CPO, may exert inhibitory effects on mitochondrial complex I in neurons, thereby contributing to neurotoxicity in humans. Overall, these results are in line with previous experimental reports and highlight the effectiveness of integrated computational approaches in identifying key mitochondrial mechanisms involved in CPF-induced neurotoxicity.