Structure-Activity Relationship of Some Type-II Pyrethroids: A Study Based on Atomic Charges, Molecular Electrostatic Potential Surfaces and Molecular Orbitals Analysis

摘要

Synthetic pyrethroids form a group of widely used insecticides in agriculture and home formulations. The widespread use of these pyrethroids and the corresponding increase in animal and human exposure had led to sustained interest in their toxicology. alpha-cypermethrin and lambda-cyhalothrin are two important type-II pyrethroids which intensively control a wide range of pests. Most of the SAR studies done so far on pyrethroids are based on the consideration of stereochemical properties and very little attention has been given to SAR studies based on electronic properties. An effort has been made to explain the activity and preferred sites of electrophilic attack in alpha-cypermethrin and lambda-cyhalothrin on the basis of atomic charges, molecular electrostatic potentials at surfaces, distribution of frontier molecular orbitals, highest occupied molecular orbital energy (E-HOMO), lowest unoccupied molecular orbital energy (E-LUMO) and HOMO-LUMO gap of two molecules.