In silico study of some selective phytochemicals against a hypothetical SARS-CoV-2 spike RBD using molecular docking tools.

Background: This world is currently witnessing a pandemic outbreak of 'COVID-19' caused by a positive-strand RNA virus 'SARS-CoV-2'. Millions have succumbed globally to the disease, and the numbers are increasing day by day. The viral genome enters into the human host through interaction between the spike protein (S) and host angiotensin-converting enzyme-2 (ACE2) proteins. S is the common target for most recently rolled-out vaccines across regions. A recent surge in single/multiple mutations in S region is of great concern as it may escape vaccine induced immunity. So far, the treatment regime with repurposed drugs has not been too successful.

Hypothesis: Natural compounds are capable of targeting mutated spike protein by binding to its active site and destabilizing the spike-host ACE2 interaction.

Materials And Methods: A hypothetical mutated spike protein was constructed by incorporating twelve different mutations from twelve geographical locations simultaneously into the receptor-binding domain (RBD) and docked with ACE2 and seven phytochemicals namely allicin, capsaicin, cinnamaldehyde, curcumin, gingerol, piperine and zingeberene. Molecular Dynamic (MD) simulation and Principal Component Analysis (PCA) were finally used for validation of the docking results.

Result: The docking results showed that curcumin and piperine were most potent to bind ACE2, mutated spike, and mutated spike-ACE2 complex, thereby restricting viral entry. ADME analysis also proved their drug candidature. The docking complexes were found to be stable by MD simulation.

Conclusion: This result provides a significant insight about the phytochemicals' role, namely curcumin and piperine, as the potential therapeutic entities against mutated spike protein of SARS-CoV-2.