Figure 2. Parasite reduction ratios of clinically used anti-malarials and E209.

(a) In vitro PRR—number of viable parasites after E209 treatment (10 × IC₅₀) is compared with the profile shown by standard anti-malarials (b) Lag phase, log₁₀PRR and parasite clearance time (PCT) values for E209 and a selection of standard anti-malarials. The in vitro parasite reduction rate assay was used to determine onset of action and rate of killing as previously described²⁰. P. falciparum was exposed to E209 at a concentration corresponding to 10 × EC₅₀. The number of viable parasites at each time point was determined as described by Sanz et al.²⁰ Four independent serial dilutions were done with each sample to correct for experimental variation; error bars, s.d. Previous results reported on standard anti-malarials tested at 10 × EC₅₀ using the same conditions are shown for comparison.