TABLE 1

IC50s of drugs by growth cyclea

DrugNo. of exptsIC50 (mean ± SD) (μM)
Cycle 1, 48 hCycle 2, 120 h
Chloroquine20.032 ± 0.0020.018 ± 0.002
Atovaquone20.0008 ± 0.00030.0007 ± 0.0001
Azithromycin39.8 ± 1.00.06 ± 0.02
Fosmidomycin31.0 ± 0.10.8 ± 0.2
  • a A drug targeting apicoplast housekeeping functions (azithromycin) has a substantially lower IC50 in the 2nd asexual erythrocytic growth cycle. Drugs with targets outside the apicoplast (chloroquine and atovaquone) or targeting apicoplast metabolism (fosmidomycin) show little change with prolonged exposure to the drug. Each drug concentration was assayed in triplicate.