The mitochondrion of Trypanosoma cruzi is a target of crystal violet toxicity.

The first morphological alteration observed in Trypanosoma cruzi different stages upon incubation with crystal violet was mitochondrial swelling. The use of digitonin to solubilize T. cruzi plasma membrane allowed the demonstration of an uncoupling action of crystal violet on epimastigote mitochondria in situ. Low concentrations of crystal violet (20-50 microM) or carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP; 0.5 microM) uncoupled the respiratory control mechanism. The inhibition of State 3 respiration by oligomycin was released by crystal violet or FFCCP. Crystal violet released respiratory control, and enhanced ATPase activity of digitonin-permeabilized epimastigotes. Higher concentrations of crystal violet inhibited mitochondrial respiration. The uncoupled effect of crystal violet was stimulated by inorganic phosphate. In addition, crystal violet inhibited endongenous and glucose-stimulated respiration of the intact epimastigotes, and inhibited the Mg2+-ATPase in the epimastigote mitochondrial fractions. The inhibition of this Mg2+-ATPase increased up to pH 9.0 and decreased with increasing protein concentration. These data indicate that the T. cruzi mitochondrion is apparently the main target of crystal violet toxicity.