SARS-CoV-2(22) inhibitor(14) COVID-19 pandemic(13) protease(11) M pro(11) inhibitors(11) COVID-19(9) Analysis(9) variants(8) drug target(8) antiviral agent(7) Antiviral agents(7) effort(7) death(6) Compound(6) molecular(6) variant(6) in vitro(6) Infection(6) Antiviral(5) structures(5) main protease(5) Follow-up(4) susceptible(4) B.1.351(4) Aloesin(4) anticipated(4) natural(4) SARS-CoV-2 main protease(4) P.2(4)