Background: The current pandemic outbreak of COVID-19 due to viral infections by SARS-CoV-2 has now become associated with severe commotion on global healthcare and the economy.Objective: In this extreme situation, when vaccine or effective new drugs against COVID-19 are still not available, the only quick and feasible therapeutic alternative would be the drug repurposing approach. Methods: In the present work, in silico screening of some anti-viral and antiprotozoal drugs was performed based on docking using Autodock. Results: Two known anti-viral drugs, sorivudine and noricumazole B, are predicted to bind to the active site of the viral proteases, namely cysteine-like protease or 3CL protease (3CLpro) and papain- like protease (PLpro), respectively, with a highly favorable free energy of binding. Further, the promising molecules were subjected for checking their activity on other molecular targets in SARS-CoV-2 like spike protein S1, RNA dependent RNA polymerase (RdRp), and angiotensin converting enzyme 2 (ACE2) receptor. But the compounds were found non-effective on the rest of the molecular targets. Conclusion: Sorivudine alone or a combination of sorivudine and noricumazole B may be administered to impede viral replication, though the predicted drug likeliness of noricumazole B is not much satisfactory. These observations are solely based on the results from blind docking with protein molecules and need to be further corroborated with experimental results.
Keywords: Cysteine like protease, papain-like protease, molecular docking, anti-viral repurposing, sorivudine, noricumazole B.