Tannins inhibit SARS-CoV-2 through binding with catalytic dyad residues of 3CL: 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) 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 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 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 of SARS-CoV-2. Pedunculagin, tercatain, and castalin interacted with Cys145 and His41 of SARS-CoV-2-3CL. Pedunculagin-SARS-CoV-2-3CL 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.