FIGURE 6.

Effect of TyrRS inhibitors on parasite growth and enzyme activity. A, inhibition of promastigote growth in the presence of resveratrol and fisetin. The assay was done in 96-well plates and growth was estimated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Percentage growth of parasite was plotted against different concentrations of inhibitors. B, effect of resveratrol and fisetin on amastigote growth progression was studied by observing Giemsa-stained infected macrophages under a microscope. C, inhibition of rLdTyrRS aminoacylation activity by resveratrol and fisetin. D, comparison of the effect of fisetin activity on WT and genetically manipulated parasites. WT, overexpressors (WT[pTyrRS⁺]), heterozygous mutants (TyrRS/HYG), and add-back (TyrRS/HYG[TyrRS⁺]) parasites were treated with fisetin at a concentration of 35 μm. The cell growth was determined after 72 h. In the absence of drug treatment (untreated), the growth of each parasitic line was normalized to 1.0. After treatment with fisetin (treated), growth was calculated relative to the corresponding untreated control. The bar graph represents the mean ± S.D. with n = 3. Student's t test was performed, and p values are indicated.