Figure 2.

Effects of various compounds on P. falciparum Na⁺-dependent ATPase activity. The data were obtained by subtracting the amount of P_i produced in the low-[Na⁺] (0.5 mm) medium from that produced in the high-[Na⁺] (125.5 mm) medium. Cipargamin was tested at a concentration of 500 nm; the other compounds (all from the Malaria Box, with 28 of them (white bars) having PfATP4-associated activity and two of them, MMV007839 and MMV000972 (gray bars), having activity against an unrelated transport protein) were tested at a concentration of 4 μm. The crosses indicate the data from the individual independent biological replicates. The ATP concentration was 0.25 mm; the pH was 7.4; and the duration of the reaction was 15 min. The data were obtained with Dd2 parasites and are shown as the mean (+ or − S.D.) from three to five independent experiments, each performed on different days with different membrane preparations. The protein content of the membrane preparations was not quantified in these experiments; each reaction well contained membrane from 3 × 10⁶ cells. For each compound, the data were tested for statistical significance compared with the control (red bar; 0.4% v/v DMSO) using a one-way ANOVA (which yielded an F probability <0.001) followed by a post hoc least significant difference test; ***, p < 0.001.