In silico investigation of saponins and tannins as potential inhibitors of SARS-CoV-2 main protease (Mpro).

It is no longer news that a novel strain of coronavirus named SARS-CoV-2 is ravaging the health sector worldwide, several attempts have been made to curtail this pandemic via repurposing of old drugs but at the present, available drugs are not adequately effective. Over the years, plant phytochemicals are increasingly becoming alternative sources of antimicrobial agents with novel mechanisms of action and limited side effects compared to synthetic drugs. Isolated saponins and tannins were evaluated for antiviral activity against SARS-CoV-2 (M^pro) via Molecular Docking and it was observed that a handsome number of the phytochemicals had binding affinities much better than Remdesivir, Dexamethasone, and N3 inhibitor which were used as the standards in this study. Further investigation of drug-likeness, ADMET profile, PASS profile, oral bioavailability, bioactivity, binding mode, and molecular interactions of these phytochemicals revealed that binding affinity alone is not enough to justify the potency of a molecule in the drug discovery process, as only 4 among the screened compounds passed all the analyses and are identified as potential inhibitors of SARS-CoV-2 (M^pro). This preliminary study thereby recommends Ellagic acid (- 8.4 kcal/mol), Arjunic Acid (- 8.1 kcal/mol), Theasapogenol B (- 8.1 kcal/mol), and Euscaphic Acid (- 8.0 kcal/mol) as potential inhibitors of SARS-CoV-2 (M^pro) with better pharmacokinetics and bioavailability compared to Remdesivir which is currently used compassionately.