Nitric oxide donor trans-[RuCl([15]aneN4)NO]2+ as a possible therapeutic approach for Chagas' disease


Paulo MM Guedes, Department of Biochemistry and Immunology, School of Medicine at Ribeirão Preto, Laboratory of Immunoparasitology, University of São Paulo, Avenue dos Bandeirantes 3900, Monte Alegre, 14049-900 Ribeirão Preto, São Paulo, Brazil. E-mail:


Background and purpose:  Benznidazole (Bz) is the therapy currently available for clinical treatment of Chagas' disease. However, many strains of Trypanosoma cruzi parasites are naturally resistant. Nitric oxide (NO) produced by activated macrophages is crucial to the intracellular killing of parasites. Here, we investigate the in vitro and in vivo activities against T. cruzi, of the NO donor, trans-[RuCl([15]aneN4)NO]2+.

Experimental approach: Trans-[RuCl([15]aneN4)NO]2+was incubated with a partially drug-resistant T. cruzi Y strain and the anti-proliferative (epimastigote form) and trypanocidal activities (trypomastigote and amastigote) evaluated. Mice were treated during the acute phase of Chagas' disease. The anti-T. cruzi activity was evaluated by parasitaemia, survival rate, cardiac parasitism, myocarditis and the curative rate.

Key results: Trans-[RuCl([15]aneN4)NO]2+ was 10- and 100-fold more active than Bz against amastigotes and trypomastigotes respectively. Further, trans-[RuCl([15]aneN4)NO]2+ (0.1 mM) induced 100% of trypanocidal activity (trypomastigotes forms) in vitro. Trans-[RuCl([15]aneN4)NO]2+ induced permanent suppression of parasitaemia and 100% survival in a murine model of acute Chagas' disease. When the drugs were given alone, parasitological cures were confirmed in only 30 and 40% of the animals treated with the NO donor (3.33 µmol·kg−1·day−1) and Bz (385 µmol·kg−1·day−1), respectively, but when given together, 80% of the animals were parasitologically cured. The cured animals showed an absence of myocarditis and a normalisation of cytokine production in the sera. In addition, no in vitro toxicity was observed at the tested doses.

Conclusions and implications:  These findings indicate that trans-[RuCl([15]aneN4)NO]2+is a promising lead compound for the treatment of human Chagas' disease.

This article is commented on by Machado et al., pp. 258–259 of this issue. To view this commentary visit and to view a related paper in this issue by Silva et al. visit