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. 2021;24(10):1795-1802.
doi: 10.2174/1386207323666201110152615.

Tinocordiside from Tinospora cordifolia (Giloy) May Curb SARS-CoV-2 Contagion by Disrupting the Electrostatic Interactions between Host ACE2 and Viral S-Protein Receptor Binding Domain

Acharya Balkrishna  1 , Subarna Pokhrel  1 , Anurag Varshney  1
Affiliations

Tinocordiside from Tinospora cordifolia (Giloy) May Curb SARS-CoV-2 Contagion by Disrupting the Electrostatic Interactions between Host ACE2 and Viral S-Protein Receptor Binding Domain

Acharya Balkrishna et al. Comb Chem High Throughput Screen. 2021.

Abstract

Background: SARS-CoV-2 has been shown to bind the host cell ACE2 receptor through its spike protein receptor binding domain (RBD), required for its entry into the host cells.

Objective: We have screened phytocompounds from a medicinal herb, Tinospora cordifolia for their capacities to interrupt the viral RBD and host ACE2 interactions.

Methods: We employed molecular docking to screen phytocompounds in T. cordifolia against the ACE2-RBD complex, performed molecular dynamics (MD) simulation, and estimated the electrostatic component of binding free energy.

Results: 'Tinocordiside' docked very well at the center of the interface of ACE2-RBD complex, and was found to be well stabilized during MD simulation. Tinocordiside incorporation significantly decreased the electrostatic component of binding free energies of the ACE2-RBD complex (23.5 and 17.10 kcal/mol in the trajectories without or with the ligand, respectively). As the basal rate constant of protein association is in the order of 5 (105 to 106 M-1S-1), there might be no big conformational change or loop reorganization, but involves only local conformational change typically observed in the diffusion-controlled association. Taken together, the increase in global flexibility of the complex clearly indicates the start of unbinding process of the complex.

Conclusion: It indicates that such an interruption of electrostatic interactions between the RBD and ACE2, and the increase in global flexibility of the complex would weaken or block SARSCoV- 2 entry and its subsequent infectivity. We postulate that natural phytochemicals like Tinocordiside could be viable options for controlling SARS-CoV-2 contagion and its entry into host cells.

Keywords: ACE2-RBD complex; COVID-19; SARS-CoV-2; Tinospora cordifolia; docking; electrostatic component of binding free energy.; molecular dynamics simulation; tinocordiside.

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