Theoretical study on endocrine disrupting effects of polychlorinated dibenzo-p-dioxins using molecular docking simulation.

Polychlorinated dibenzo-p-dioxins (PCDDs) are hypothesized to exert their toxic effects in wildlife and humans via endocrine disruption. However, very scanty information is available on the underlying molecular interactions that trigger this disruption. In this study, molecular docking simulation was used to predict the susceptibility of 12 nuclear receptors to disruption via PCDD bindings. Findings revealed that androgen (AR and AR an), estrogen (ER α and ER β), glucocorticoid (GR) and thyroid hormone (TR α and TR β) receptors are the most probable protein targets that bind to PCDDs. Further molecular docking analyses showed that PCDD molecules mimic the modes of interaction observed for the co-crystallized ligands of the affected receptors, resulting in the formation of ligand-receptor complexes that were stabilized through electrostatic, van der Waals, pi-effect and hydrophobic interactions with 18, 17, 17, 16, 18, eight and four amino acid residues in the active sites of AR, AR an, ER α, ER β, GR, TR α and TR β respectively. The commonalities of these interacting amino acid residues with those utilized by dihydrotestosterone in AR, bicalutamide in AR an, 17β-estradiol in ER α, 17β-estradiol in ER β, cortisol in GR, thyromimetic GC-1 in TR α and thyromimetic GC-1 in TR β are 86%, 74%, 94%, 80%, 82%, 50% and 43% respectively. The results obtained in this study provide supporting evidence that PCDD molecules may interfere with the endocrine system via binding interactions with some vital amino acid residues in the binding pockets of AR, ERs, GRs and TRs.