Table 2.

Inhibition of M^pro activity by small molecules. Percentage inhibition at a ligand concentration of 50 μM and IC₅₀ values calculated using an ELISA.

Compound	IC50 (μM) Average ± SEM	% Protease inhibition at 50 μM ligand concentration
Hypericin	63.6 ± 5.7	42.8 ± 8.2
Cyanidin-3−0-glucoside	65.1 ± 14.6	22.6 ± 4.3
SRT2104	85.0 ± 16.8	19.4 ± 6.4
SRT1720	NA*	9.3 ± 2.2
Resveratrol	NA*	1.8 ± 0.9
L-sulforaphane	NA*	8.4 ± 2.7

^*Compound concentrations of up to 128μM were used in our experiments; the IC₅₀ could not be reached for the ligands noted.