SARS-CoV-2 Mpro-IN-34 (Compound 26) is an inhibitor for SARS-CoV-2 Mpro with an IC 50 of 6 nM. SARS-CoV-2 Mpro-IN-34 exhibits inhibitory efficacy against OC43 Mpro with an IC 50 of 33 nM. SARS-CoV-2 Mpro-IN-34 exhibits antiviral activity in SARS-CoV-2 infected Vero E6 cell with an EC 50 of 0.103 μM.