(a) Test technique.

Fifty microliters of culture medium was dispensed into each well of a 96-well plate, followed by the addition of 50 μl of the highest concentration of test compounds (in duplicate wells) in row B. Subsequent 2-fold serial dilutions were prepared, and finally, 50 μl of a 1.0% parasitized cell suspension containing 0.8% parasitemia was added to each well, except for 4 wells in row A, which received a nonparasitized erythrocyte suspension. The plates were incubated at 37°C in a CO₂ incubator in an atmosphere of 5% CO₂ and air, and 72 h later, 100 μl of lysis buffer containing 2× SYBR green I (in nitrogen) was added to each well and incubated for 1 h at 37°C. The plates were examined at 485 ± 20 nm of excitation and 530 ± 20 nm of emission for the number of relative fluorescence units (RFUs) per well, using a fluorescence plate reader (FLX800; Biotek).