Molecular Docking of Ecdysone Agonists and Limonoid Components of Calamondin Seeds to Tobacco Budworm Ecdysone Receptor

Abstract

Molecular docking of calamondin limonoids to tobacco budworm ecdysone receptor was performed to calculate binding affinities and evaluate their potential as an insecticide. Results were compared to those of 20-hydroxyecdysone, ponasterone A, and known ecdysone agonists by examination of binding interactions between the ligands and receptor. While an earlier study by other researchers attributed the stronger binding of ponasterone A to (de)solvation effects, molecular dynamics simulations in this study revealed stronger hydrogen bonds between the receptor and ponasterone A, consistent with calculated binding affinities from molecular docking. None of the limonoids and ecdysone agonists showed stronger binding affinity than 20-hydroxyecdysone, suggesting that site-specific docking may not be suitable to predict the binding interactions of these non-steroidal ligands with tobacco budworm ecdysone receptor. The computational approach described in this study can be used in the preliminary screening of compounds for bioactivity against receptors with known active sites.