Tannins inhibit SARS-CoV-2 through binding with catalytic dyad residues of 3CL ^pro : An in silico approach with 19 structural different hydrolysable tannins

Coronavirus epidemic 2019 (COVID-19), instigated by SARS-CoV-2 virus, is recently raising worldwide and inspiring global health worries. The main 3-chymotrypsin-like cysteine protease (3CL^Pro ) enzyme of SARS-CoV-2, which operates its replication, could be used as a medication discovery point. We therefore theoretically studied and docked the effects of 19 hydrolysable tannins on SARS-CoV-2 by assembling with the catalytic dyad residues of its 3CL^pro using molecular operating environment (MOE 09). Results discovered that pedunculagin, tercatain, and castalin intensely interacted with the receptor binding site and catalytic dyad (Cys145 and His41) of SARS-CoV-2. Our analyses estimated that the top three hits might serve as potential inhibitor of SARS-CoV-2 leading molecules for additional optimization and drug development process to combat COVID-19. This study unleashed that tannins with specific structure could be utilized as natural inhibitors against COVID-19. PRACTICAL APPLICATIONS: The 3CL^Pro controls SARS-CoV-2 copying and manages its life series, which was targeted in case of SARS-CoV and MERS-CoV coronavirus. About 19 hydrolysable tannins were computed against 3CL^pro of SARS-CoV-2. Pedunculagin, tercatain, and castalin interacted with Cys145 and His41 of SARS-CoV-2-3CL^pro . Pedunculagin-SARS-CoV-2-3CL^pro remain stable, with no obvious fluctuations. We predicted that the understandings gained in the current research may evidence valued for discovering and unindustrialized innovative natural inhibitors for COVID-19 in the nearby future.

Keywords: COVID-19; hydrolysable tannins; main 3-chymotrypsin-like cysteine protease; molecular docking; structural-relationship activity.