Table 1.

Active polycyclic ketals

Structure7G8 GB4 HB3 Dd2 CP250
Formula2.5 μM (0.6, n = 2) 6.5 μM (0, n = 2)3.8 μM (0.6, n = 4) 4.0 μM (0.2, n = 4)8.7 μM (0.7, n = 2)
Formula1.7 μM (0.1, n = 2) 1.3 μM (0.1, n = 2)2.9 μM (0.9, n = 2) 9.0 μM (1.5, n = 2)na
Formula1.0 μM (0.2, n = 2) 4.2 μM (0.4, n = 2)2.5 μM (0, n = 2) 1.9 μM (0.5, n = 2)6 μM (0.5, n = 2)

Results are reported as effective concentration values needed to inhibit parasite growth at 50% (IC50) in μM. Standard deviation and number of replicates are reported in parentheses. Replicate numbers > 2 represent assays carried out under identical conditions on different days. Compounds were retested in an intraplate titration format using twelve-point, threefold dilutions.