Table 2.

Structure-Activity Relation of Derivatives of 1 and 11.

Compound	X	R1	R2	IC50(μM)a	CC50(μM)b	SIc
1	H	3-CH3O-PhCH2	H	5.6	>25	4.5
12	H	2-CH3O-PhCH2	H	3.8	>25	7
13	H	2-OH-PhCH2	H	3.6	>25	7
14	H	3,4-F2-PhCH2	H	4.6	23.0	5
15	H	4-F-PhCH2	H	4.6	14.4	3
16	H	2-NO2-PhCH2	H	3.3	>25	8
17	H	3-NO2-PhCH2	H	6.1	>25	4
18	H	4-NO2-PhCH2	H	2.7	>25	8
19	H	2-CN-PhCH2	H	>25	>25	1
20	H	3-CN-PhCH2	H	0.157 ± 0.002	3.59 ± 1.1	25
21	H	4-CN-PhCH2	H	4.8	>25	5
22	H	3-H2NCO-PhCH2	H	>25	>25	1
23	H	3-CF3-PhCH2	H	2.3	9.2	4
24	H	n-butyl	n-butyl	>25	>25	1
25	H	cyclohexyl	H	15	>25	1
26	H	CH3CO	H	>25	>25	1
27	H	3-CN-PhCO	H	>25	>25	1
28	H	3-CN-trans-cynnamoyl	H	>25	>25	1
29	OMe	3-CN-PhCH2	H	5.8	13.2	2
30	OH	3-CN-PhCH2	H	>25	>25	1
11	H	3-CH3O-PhCH2	H	1.8	>25	1
31	H	2-CN-PhCH2	H	>25	>25	1
32	H	3-CN-PhCH2	H	3.6	>25	7
33	H	4-CN-PhCH2	H	4.1	>25	6
34	H	3-NO2-PhCH2	H	3.7	>25	7
35	H	4-NO2-PhCH2	H	3.3	>25	8

^a,bIC₅₀ and CC₅₀ were derived from the results of at least two dependent experiment in Vero cells infected with MERS-CoV.

^cSI (selective index) = CC₅₀/IC₅₀ for inhibiting MERS-CoV infection.