Table 5  Protease Inhibition by 4
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
a  See the Experimental Section for details on assay methods; the values were calculated from at least eight data points with at least two independent determinations.
b  For SARS CoV-1 and CoV-2 3CLpro, Ki values are reported here.