Discovery of a Novel Trifluoromethyl Diazirine Inhibitor of SARS-CoV-2 M.

SARS-CoV-2 M is a chymotrypsin-like cysteine protease playing a relevant role during the replication and infectivity of SARS-CoV-2, the coronavirus responsible for COVID-19. The binding site of M is characterized by the presence of a catalytic Cys145 which carries out the hydrolytic activity of the enzyme. As a consequence, several M inhibitors have been proposed to date in order to fight the COVID-19 pandemic. In our work, we designed, synthesized and biologically evaluated , a novel inhibitor of SARS-CoV-2 M bearing a trifluoromethyl diazirine moiety. displayed in vitro inhibition activity against SARS-CoV-2 M at a low micromolar level (IC = 4.1 μM) in a FRET-based assay. Moreover, an inhibition assay against PL revealed lack of inhibition, assuring the selectivity of the compound for the M. Furthermore, the target compound was docked within the binding site of the enzyme to predict the established intermolecular interactions in silico. was subsequently tested on the HCT-8 cell line to evaluate its effect on human cells' viability, displaying good tolerability, demonstrating the promising biological compatibility and activity of a trifluoromethyl diazirine moiety in the design and development of SARS-CoV-2 M binders.