In-silico identification of natural antiviral drug against SARS-CoV-2 and comparison with potential FDA approved drug targets

Abstract

Antimalarial drugs Chloroquine and Hydroxychloroquine have garnered most attention recently as a successful remedy for COVID19. However, the use of these drugs is still questionable due to its undetermined efficacy and side effects. The present study utilizes in-silico high throughput screening of FDA approved antiviral compounds and secondary plant metabolites against spike protein of novel coronavirus (SARS-CoV-2). This target was chosen because it is instrumental in entry of virus into human cells. It is observed that the plant compound Tocopheryl-curcumin has more affinity for spike protein of SARS-CoV-2 in comparison to the majority of FDA approved drugs. Tocopheryl-curcumin binds with the binding site of RBD domain of spike protein (6VSB, chain A) with free energy (∆G) of binding of -11.20 kcal/mol and makes strong hydrogen bonds with amino acid residues of S366, V367, L368, S373, and K529. Among the FDA approved drugs, Pibrentasvir obtains top rank with free energy (∆G) of binding of -9.69 kcal/mol. whereas; surprisingly Chloroquine (-6.87 kcal/mol) and Hydroxychloroquine (-7.24 kcal/mol) ranked lower in our docking study. The toxicity prediction by VEGA predicts that tocopheryl-curcumin shows no toxicity as compared to FDA approved drugs. Therefore, we infer that the plant-based tocopheryl-curcumin could be considered as potential and safer drug against COVID 19 disease as compared to chemical based drugs.