Table 2.

Inhibition of SARS‐CoV PL^pro by isoindoline derivatives.

Compd	Structure	IC50 [μM]/%[a]
		SARS‐CoV PLpro	SARS‐CoV‐2 PLpro
20		0.15±0.01 [21]
14 a		45 %[c]	n.a.[b]
14 b		n.d. (insoluble)[d]
14 c[e]		n.a.[b]
14 d		14±1	n.a.[b]
14 e		n.a.[c]
14 f		n.a.[b]
14 g		n.d. (insoluble)[d]
14 h[e]		2.9±0.2	7.6±0.2
14 i		n.a.[b]	n.a.[b]
14 j		32±2	n.a.[b]
14 k[e]		4.9±0.3	57±1
14 l		4.5±0.4
17		55 %

[a] The fluorometric assay was performed in duplicate. Data are reported as mean±standard deviation. Percentage inhibition was measured at 100 μM inhibitor concentration [b]. Compounds with inhibitory effects of less than 50 % at 100 μM compared to DMSO were labelled as not active (n.a.). [c] Percentage inhibition was measured at 10 μM inhibitor concentration with the addition of 0.005 % Brij 35. [d] IC₅₀ values that could not be determined because of limited solubility at 100 μM under the conditions used in the assay are labelled as not determined (n.d.). [e] Compounds could only be obtained with a purity of 85–95 %. To complete the SAR study, the inhibitory effect was nevertheless tested.