SARS-CoV-2(18) inhibitor(14) COVID-19 pandemic(13) inhibitors(11) protease(11) M pro(11) Analysis(9) COVID-19(9) variants(8) drug target(8) Antiviral agents(7) effort(7) antiviral agent(7) molecular(6) SARS-CoV-2.(6) in vitro(6) Infection(6) death(6) variant(6) Compound(6) main protease(5) structures(5) Antiviral(5) expressed(4) virus(4) HIV(4) aloeresin D.(4) enzyme(4) natural products(4) Missense mutation(4)