Ultrastructural alterations and peroxide formation induced by naphthoquinones in different stages of Trypanosoma cruzi.

Addition of beta-lapachone, an o-naphthoquinone with bactericidal, cytotoxic, and trypanocidal activities, to Trypanosoma cruzi epimastigote and amastigote stages induced the release of O2- and H2O2 from the whole cells into the suspending medium. In the presence of reduced nicotinamide adenine dinucleotide as reductant beta-lapachone was also able to stimulate O2- and H2O2 production by homogenates of these stages. Electron micrographs showed that in beta-lapachone-treated amastigotes and trypomastigotes, the chromatin is arranged in patches, clearly differing from the normal pattern of chromatin distribution. Alterations of the nuclear, mitochondrial, and cytoplasmic membranes, as well as swelling of the mitochondria were also observed.