Assessing Potential Inhibitors for SARS-CoV-2 Main Protease from Available Drugs using Free Energy Perturbation Simulations

A virtual screening approach using docking and free energy pertubation was successfully validated with previously characterized inhibitors of SARS-CoV-2 main protease (Mpro). This approach and then used to estimate the binding affinity to Mpro of more than 6300 compounds in the ZINC15 database. Delamanid, an anti-tuberculosis agent, has a predicted nanomolar binding affinity for SARS-CoV-2 Mpro and is thus a promissing drug candiate for COVID-19. In addition, several compounds including three antibiotics exhibits femtomolar affinity for SARS-CoV-2 Mpro. The residues around positions 24, 45, 143, 165, and 190 were found to be involved in the binding of the strongest inhibitors.