Activities of 60 μM WLBU2 against C. trachomatis serovars D, E, and L2 in our pH assay. The conditions for the standard MCC assay were followed except that they were carried out in the presence of SPG at various pHs (4, 5.5, 7, and 8). Percent inhibition and SD were calculated as for Fig. 1 but based on a no-drug control with the same pH. An asterisk indicates that the activity is significantly different against serovar D or E than the activity against L2 (Tukey's test; P ≤ 0.05).