Effect of LysRS-1 inhibitors on parasite growth. (A) Chemical structure of cladosporin, isocladosporin, and 3-epi-isocladosporin. (B) Dose-response inhibition of WT promastigote growth in the presence of cladosporin, 3-epi-isocladosporin, and isocladosporin. Inhibitor concentrations are plotted on a log scale on the x axis. The assay was done in 96-well plates, and growth was estimated by MTT assay. Percent parasite survival was plotted against different concentrations of inhibitors. (C) The intracellular parasite load was determined using propidium iodide staining of the infected THP-1 cells, 72 h after treatment with the various concentrations of cladosporin, 3-epi-isocladosporin, and isocladosporin. The graph depicts the parasite load relative to untreated controls. The results were obtained in duplicates as representative of 2 independent experiments.