The aim of the present study was to study the trypanocidal activity of nanoparticles loaded with
nifurtimox in comparison with the free
drug against Trypanosoma cruzi, responsible for
Chagas' disease. Ethylcyanoacrylate nanoparticles acted as the delivery system into cells. As the obligate replicative intracellular form is amastigote, in vitro studies were performed on this form of parasite as well as on cell culture derived trypomastigotes. The fluorescence method used here was very useful as it allowed for the simultaneous study of trypanocide activity and cytotoxicity by determining living or dead parasites within living or dead host cells. According to these results, the greatest trypanocide activity on cell culture-derived trypomastigotes was recorded for
nifurtimox-loaded nanoparticles with a 50% inhibitory concentration (IC50) twenty times less than that of the free
drug. The cytotoxicity of unloaded nanoparticles at low concentrations was similar to that obtained by free
drug when evaluated on Vero cells. Furthermore,
nifurtimox-loaded nanoparticles showed increased trypanocide activity on intracellular amastigotes with an IC50 thirteen times less than that of
nifurtimox. We also observed that the unloaded nanoparticles possess the previously-described trypanocide activity, similar to the standard
solution of
nifurtimox, although the mechanism for this has not yet been elucidated. In conclusion, it was possible to establish in vitro conditions using
nifurtimox encapsulated nanoparticles in order to decrease the doses of the
drug and thus to obtain high trypanocidal activity on both free trypomastigotes and intracellular amastigotes with low cytotoxicity for the host cell.