Table 1.

Inhibitory activities of 9,10-dihydrophenanthrene derivatives against SARS-CoV-2 3CL^pro.

Compds	R1	R2	R3	IC50 ± SD (μM)a
A1	CH3	H		61.15 ± 3.60
A2	C2H5	H		33.06 ± 8.58
A3	isopropyl	H		29.46 ± 1.64
A4	cyclohexyl	H		9.06 ± 0.34
A5	4-Br Phenyl	H		6.44 ± 0.64
A6	4-CN Phenyl	H		19.32 ± 1.92
A7	benzyl	H		11.39 ± 0.64
A8	CH3	4-CH3		>100
A9	CH3	4-OCH3		>100
A10	CH3	4-F		>100
A11	CH3	4-Cl		85.58 ± 2.36
A12	CH3	4-Br		>100
A13	CH3	3-CH3		57.67 ± 2.78
A14	CH3	2-CH3		53.81 ± 8.49
A15	CH3	H		58.91 ± 4.58
A16	CH3	H		68.16 ± 2.64
A17	CH3	H		5.65 ± 1.40
A18	CH3	H		66.80 ± 2.74
A19	CH3	H		35.77 ± 2.96
A20	CH3	H		18.50 ± 0.76
A21	CH3	H		14.17 ± 1.30
A22	CH3	H		11.97 ± 0.68
A23	CH3	H		13.82 ± 0.90
A24	CH3	H		>100
A25	CH3	H		>100
A26	CH3	H		>100
A27	CH3	H		>100
A28	CH3	H		>100
disulfiram	–	–	–	1.04 ± 0.03

^aThe inhibitory effects of these compounds against SARS-CoV-2 3CLpro were determined by the FRET assay. The data are the mean ± SD from at least three independent experiments.