(A) Compound 17’s formula. (B) Dose-response antiviral activity of compound 17 on the replication of group B enteroviruses in a CPE reduction assay. Data are mean values ± SD of three independent experiments. (C) Validation of the dose-response effect of compound 17 on CVB3 virus yield (viral RNA and infectious viral particles). Data are mean values ± SD of three independent experiments. (D) Time-of-drug-addition assay. Data are mean values ± SD of at least two independent experiments. (E) Thermostability assay in the presence or absence of compound 17 or the inactive analogue, compound 15. Values are the mean ± SD of three independent experiments. *p < 0.05, **p < 0.01 by unpaired t test. (F) Combination study of compound 17 with pleconaril. The graph is a plot of combination indices (CIs) versus the EC50 values of compounds at different combination ratios. Data are mean values ± SD of two independent experiments. The raw data of figures are presented in S1 raw data. CI, combination index; CPE, cytopathic effect; CVB, Coxsackievirus B; EC50, 50% effective concentration; TCID50, 50% tissue culture infective dose.