Virtual Screening of Pentahydroxyflavone - A Potent COVID-19 Major Protease Inhibitor

COVID-19, is a newly spread pandemic disease and is primarily transmitted through nasal droplets which then causes mild to severe respiratory illness. Now this has been the major challenge to the world to tackle and save the lives of people without a proper vaccine. Therefore, there is an urgent need to screen for antiviral bioactive compounds to inhibit COVID-19 development. Among others, the major viral protease is an important target as this enzyme plays an important role in the development of the virus. We were particularly looking for compounds from fruits that are capable of binding to the COVID-19 major protease. Morin, a pentahydroxyflavone is commonly present in guava, tea, kiwi and strawberry. It has been shown to have antiviral, antibacterial and antioxidant properties. Hence, the compound Morin was virtually screened for its ability to bind to major 3CL protease (Mpro) of COVID19. The active site of the enzyme has dyad amino acids; HIS41 and CYS 145. This compound binds to HIS41 in the active site of the protease. The binding ability was studied using Autodock Vina. The binding ability was compared to a synthetic ligand N3 which is already complexed with the main protease with the PDB Id: 7BQY. While the binding efficiency of N3 is -4.6 kcal /mole, it is -7.6 kcal /mole for Morin. Also the LIPINSKI analysis has shown its drug like character. The ADMET analysis has shown that it has no genotoxicity and low drug induced toxicity. Owing to its presence in fruits like strawberry, it could well be a prophylactic medication.