Drug repurposing of argatroban, glimepiride and ranolazine shows anti-SARS-CoV-2 activity via diverse mechanisms.

Despite the vast vaccination campaigns against SARS-CoV-2, vaccine-resistant variants have emerged, and COVID-19 is continuing to spread with the fear of emergence of new variants that are resistant to the currently available anti-viral drugs. Hence, there is an urgent need to discover potential host-directed - rather than virus-directed - therapies against COVID-19. SARS-CoV-2 enters host cells through binding of the viral spike (S)-protein to the host angiotensin-converting enzyme 2 (ACE2) receptor, rendering the viral port of entry an attractive therapeutic target. Accordingly, this study aimed to investigate FDA-approved drugs for their potential repurposing to inhibit the entry point of SARS-CoV-2. Accordingly, the FDA-approved drugs library was enrolled in docking simulations to identify drugs that bind to the Spike-ACE2 interface. The drugs list retrieved by the docking simulations was shortlisted to 19 drugs based on docking scores and safety profiles. These drugs were screened for their ability to prevent binding between ACE2 and S-protein using an ELISA-based Spike-ACE2 binding assay. Five drugs showed statistically significant inhibition of binding between ACE2 and S-protein, ranging from 4 % to 37 %. Of those five, argatroban, glimepiride and ranolazine showed potential antiviral activity at IC50 concentrations well below their CC50 assessed by the plaque assay. Their mode of antiviral action was then determined using the plaque assay with some modifications, which revealed that argatroban acted mainly through a direct virucidal mechanism, while glimepiride largely inhibited viral replication, and ranolazine exerted its antiviral impact primarily through inhibiting viral adsorption. In conclusion, this study has identified three FDA-approved drugs - argatroban, glimepiride and ranolazine - which could potentially be repurposed and used for the management of COVID-19.