Investigation of the transformation and toxicity of trichlorfon at the molecular level during enzymic hydrolysis of apple juice.

• The effect of enzymolysis on trichlorfon was analyzed. • The properties of trichlorfon molecules were analyzed. • The transformation pathway of trichlorfon was proposed. • The toxicity of the trichlorfon and transformation products were evaluated. Trichlorfon is one of the most widely used organophosphorus pesticides in agriculture. In this study, the extent of transformation of trichlorfon to dichlorvos (DDVP), during the polygalacturonase (PG) treatment of apple pulp was monitored. A transformation pathway is proposed for trichlorfon molecules, based on density functional theory (DFT) calculations. The transformation of trichlorfon involves hydroxyl substitution and cleavage, which was confirmed by molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) theory. In addition, the toxicity of trichlorfon and its transformed products was analyzed using Ecological Structure Activity Relationships (ECOSAR) software. The binding sites of the two pesticides are located in the hydrophobic grooves of the acetylcholinesterase (AChE) active site region and both pesticides form hydrophobic interactions and hydrogen bonds with a large number of surrounding amino acid residues. DDVP binds more strongly with AChE, so it is a better AChE inhibitor and more toxic than trichlorfon. [ABSTRACT FROM AUTHOR]