ABSTRACT
Apart from chemical and allopathic drugs, several medicinal plants contain phytochemicals that are potentially useful to counter the COVID-19 pandemic. Withania somnifera (Ashwagandha), which has a good effect on some viral infections, can be considered as a candidate against the virus. In the present study, thirty-nine natural compounds of Ashwagandha were investigated in terms of their binding to the important drug targets to treat the COVID-19. Although the molecular docking calculations reveal the binding affinities of the compounds to Mpro, TMPRSS2, NSP15, PLpro, Spike RBD + ACE2, RdRp and NSP12 as targets in controlling the coronavirus enzymes, Withanoside II is expected to be the most effective compound due to the high affinity in binding with many of considered targets. Furthermore, the Withanoside III, IV, V, X, and XI have favorable binding affinities as ligands with respect to the MM/GBSA calculations. The molecular dynamics simulations MD explore a stable hydrogen bond network between ligands and the active sites residues. Also, the dynamic fluctuations of the binding site residues verify their tight binding to ligands. Moreover, the stability of ligand-protein complexes is approved by the RMSD ranges lower than 0.5 Å in equilibration zone for all mentioned complexes. The TMPRSS2-Withanolide Q and Mpro-Withanoside IV complexes are the most stable pairs using the MM/GBSA calculations and MD simulation.Communicated by Ramaswamy H. Sarma.
TMPRSS2 receptor in terms of human relative proteins and Mpro and NSP15 receptors on coronavirus itself target are the effective target for inhibitory effects of Withania somnifera compounds.The highest binding affinity is related for WithanolideD, WithanolideQ, WithanosideIV, WithanosideIII, WithanosideV, WithanosideII, and 2,3-Didehydrosomnifericin ligands on the Spike RBD + ACE2, TMPRSS2, Mpro, PLpro, RdRp, NSP15, and NSP12 receptors, respectively.Withanolide compounds on human related proteins targets and Withanoside structures on coronavirus itself receptors have the highest inhibitory potential.Withanoside II ligand is expected to be the most effective compound due to the high affinity to bind to many considered targets.The stability of ligand-protein complexes is approved by the RMSD ranges lower than 0.5 Å in equilibration zone for WithanolideQ-TMPRSS2 and WithanosideIV-Mpro complexes.
