FIG 7.

Effects of 4-nitrobenzoate on parasitic growth and ubiquinone biosynthesis. (a) 4-NB IC₅₀ value at 72 h indicated by bar graphs showing its deviation in the presence of different compounds (mean of three identical experiments). IC₅₀ assays for 4-nitrobenzoate (4-NB) were performed at 72 h and in the presence of 10 μM decyl-UQ (dUQ), 0.5 mM 4-hydroxybenzoate (4-HB), or 0.5 mM p-aminobenzoic acid (pABA) (mean of three experiments). (b and c) 4-NB IC₅₀ value at 48 and 72 h (mean of three experiments). The data were analyzed using unpaired t test in comparison to the untreated control. *, P < 0.05, **, P < 0.01, ***, P < 0.001. (d) RP-HPLC metabolic profiles of [³H] GGPP-radiolabeled P. falciparum-infected erythrocytes untreated/treated with 4-NB 1 mM for 48 h. In all experiments, the samples were co-injected with UQ standards. The fractions were collected at 0.75 min. UQ-8, ubiquinone-8; UQH₂-8, ubiquinol-8; UQ-9, ubiquinone-9; UQH₂-9, ubiquinol-9. This experiment was performed twice with similar results.