Table 3. Antiviral Evaluation of Series 2 against EV-D68^a in RD Cells^b.

compound	R2	EC50 (μM)b	CC50 (μM)c	SId
19	CF3	0.05 ± 0.01	>2.5	>50
20	CH3	0.28 ± 0.03	>2.5	>9
21	C2H5	0.10 ± 0.007	>2.5	>25
22	n-C3H7	0.41 ± 0.03	>0.8	>2
23	i-C3H7	0.40 ± 0.37	>0.8	>2
24	n-C4H9	0.71 ± 0.05	>2.5	>3
25	t-C4H9	4.22 ± 0.12	>7.4	>2

^aEV-D68 strain: STL-2014-12.

^bEC₅₀: concentration that effectively inhibited the cytopathic effect by 50% in Rhabdomyosarcoma cell lines (RD cells).

^cCC₅₀: concentration that inhibited the normal uninfected cell viability by 50%, or the maximum soluble concentration which started from 200 μM in serial 3-fold dilutions.

^dSelectivity index (SI) calculated as CC₅₀/EC₅₀ ratio.