a, RP-HPLC run. b, Agr inhibition at different concentrations in the luminescence assay. RLU, relative light units. Statistical analysis was by two-way ANOVA with Tukey’s post-test. Comparisons shown are those versus DMSO control. c, Agr inhibition as measured by inhibition of expression of RNAIII by qRT–PCR. *P < 0.0001 (one-way ANOVA with Tukey’s post-test; comparisons shown are those versus 0 μM value). The experiments in b, c were performed with n = 3 independent biological samples. Data are mean ± s.d.