Ebselen derivatives are very potent dual inhibitors of SARS-CoV-2 proteases - PL ^pro and M ^pro in in vitro studies

Proteases encoded by SARS-CoV-2 constitute a promising target for new therapies against COVID-19. SARS-CoV-2 main protease (M ^pro , 3CL ^pro ) and papain-like protease (PL ^pro ) are responsible for viral polyprotein cleavage - a process crucial for viral survival and replication. Recently it was shown that 2-phenylbenzisoselenazol-3(2H)-one (ebselen), an organoselenium anti-inflammatory small-molecule drug, is a potent, covalent inhibitor of both the proteases and its potency was evaluated in enzymatic and anti-viral assays. In this study, we screened a collection of 23 ebselen derivatives for SARS-CoV-2 PL ^pro and M ^pro inhibitors. Our studies revealed that ebselen derivatives are potent inhibitors of both the proteases. We identified three PL ^pro and four M ^pro inhibitors superior to ebselen. Our work shows that ebselen constitutes a promising platform for development of new antiviral agents targeting both SARS-CoV-2 PL ^pro and M ^pro .