A novel molecule inhibits SARS-CoV-2 RBD binding to the ACE2 receptor, blocks viral entry and exhibits antiviral activity in a murine model

SARS-CoV-2 utilizes the cell surface receptor angiotensin-converting enzyme 2 (ACE2) for entry and infection in the host cell. Thus, the molecular interface of the receptor binding domain (RBD) and ACE2 is a potential clinical target for SARS-CoV-2 infection. A small molecule inhibitor of ACE2 could block the entry of SARS-CoV‐2 and its emerging variants. This study characterizes the RBD-ACE2 interaction inhibition activity and antiviral activity of GR 127935. The binding affinity of GR 127935 to ACE2 was confirmed using Surface Plasmon Resonance (SPR). The compound inhibited RBD-ACE2 interaction in the ELISA assay (IC₅₀ = ~ 17 µM) and effectively blocked the entry of SARS-CoV-2 pseudovirus into HEK293T-ACE2-TMPRSS2 (IC₅₀ = ~ 1.2 µM). Further, the anti-SARS-CoV-2 activity of GR 127935 was evaluated in vitro using the Vero cell line and a SARS-CoV-2 clinical isolate. The most prominent inhibition (EC₅₀ = ~ 1.6 µM) was observed when the compound was added during the virus entry step. Finally, the GR 127935 treatment of BALB/c mice infected with the mouse-adapted strain of SARS-CoV-2 resulted in decreased viral load in the lungs along with a lower histopathology score. In summary, the GR 127935 molecule binds to ACE2, inhibits the molecular interaction between RBD and ACE2, and is effective in inhibiting virus replication. Thus, it is a promising potential therapeutic compound for treating human SARS-CoV-2 infections.