TABLE 2.

Evaluation of compounds against drug-resistant P. falciparum strains^a

Compound	Mean (SD) EC50 (μM)
	3D7b	K1	Dd2	W2mef	W2mef3	Cam3 R539Tc	Cam3 Revc
2	0.084 (0.023)	0.144 (0.073)	0.150 (0.063)	0.147 (0.039)	0.138 (0.075)	0.115 (0.005)	0.162 (0.041)
4	0.082 (0.024)	0.167 (0.040)	0.154 (0.047)	0.163 (0.042)	0.151 (0.078)	0.133 (0.002)	0.176 (0.049)
Chloroquine	0.007 (0.008)	0.237 (0.049)	0.114 (0.032)	0.115 (0.038)	0.097 (0.055)	0.131 (0.025)	0.114 (0.013)
Mefloquine	0.012 (0.004)	0.006 (0.001)	0.018 (0.002)	0.017 (0.001)	0.043 (0.013)	0.041 (0.010)	0.042 (0.013)
Dihydroartemisininc	1.7%	NDd	ND	ND	ND	31%	10.1%

^aEC₅₀ data represent means and SDs for two biological replicates each from three technical experiments measuring the viability of P. falciparum drug-resistant asexual-stage parasites following exposure to compounds in a 10-point dilution series for 72 h. Parasitemia was quantified by flow cytometry using SYBR green.

^b3D7 was used as a drug-sensitive control strain.

^cSurvival in the presence of 700 nM dihydroartemisinin was tested. Cam3 R539T was used as the artemisinin-resistant control strain, and the bottom row of data confirm its resistance phenotype relative to the phenotype of reversed strain Cam3 Rev and 3D7 (30) in the ring-stage survival assay following the previously described protocol (44).

^dND, not determined.