FIG. 1.

Titration of inhibitory activities of compounds against the binding of VA387 to the A antigen. All compounds that revealed significant blocking activities against VA387 binding to the A antigen (>50% reduction rate) were further titrated to determine the EC₅₀s (effective concentrations causing 50% reduction of binding activity). The results for the 14 compounds with the greatest blocking activities among 153 compounds tested are shown. The concentrations of the compounds used in the assays were adjusted according to their blocking activities in the primary screening. The concentration ranges for compounds 1 and 2 were 0.1 to 10 μM and 0.5 to 50 μM, respectively. The concentration range for compounds 3 to 14 was 1 to 100 μM. Triplicate tests for each compound were performed, and the mean binding activity reduction and standard deviation are presented. The EC₅₀ of each compound (Table 4) was calculated based on the data presented in this figure.