protease source % inhibition @ 10 μMa IC50 (μM)a 3CLpro SARS CoV-1   0.004 ± 0.0003b 3CLpro SARS CoV-2 0.00027 ± 0.0001b cathepsin B human 93 1.3 ± 0.1 cathepsin D human 3 >10 leukocyte elastase human –31 >10 chymotrypsin human 8 >10 thrombin human –28 >10 pepsin human –2 >10 caspase 2 human –20 >10 HIV-1 HIV-1 0 >10 HCV HCV 16 >10 HRV HRV   1.7 ± 1 hCoV 229E human   0.004 ± 0.0004