CONICET | Buscador de Institutos y Recursos Humanos

Several ortho-naphthoquinones (o-NQs) have shown important trypanocidal activity against Trypanosoma cruzi, the ethiological agent of Chagas´ disease. We have previously demonstrated that the aldo-keto reductase from this parasite (TcAKR) reduces o-NQs, such as -lapachone (-lap) and 9,10-phenanthrenquinone (9,10-PQ), with concomitant reactive oxygen species (ROS) production. TcAKR activity and expression has been recently characterized in two T. cruzi strains, CL and Nicaragua, showing that CL has 2-fold higher TcAKR expression than Nicaragua. Here, we studied the trypanocidal effect and the induction of several death phenotypes by -lap and 9,10-PQ in epimastigotes of these two T. cruzi strains. CL was more resistant to both o-NQs than Nicaragua with IC50s of 4.05 and 1.17 µM, respectively, suggesting TcAKR activity may not be relevant in o-NQs activation in vivo. -lap induced ROS, evaluated with H2DCF-DA probe, in both strains while 9,10-PQ only did it in CL. Staining with annexin V and propidium iodide (A/PI) showed that both drugs induced an increase of A+/IP- (early apoptotic), A+/IP+ (late apoptotic or necrotic) and A-/IP+ (necrotic) cells only in CL. However, 4-fold monodansyl cadaverine (MDC) labelling was observed after treatment in CL and Nicaragua suggesting autophagy may be a common mechanism induced by these drugs. Altogether, these results highlight that death mechanisms used by these o-NQs differ depending on the combination of drug and T. cruzi strain evaluated.To study whether TcAKR participates in o-NQs activation, -lap and 9,10-PQ trypanocidal effect was evaluated in TcAKR-overexpressing parasites. Only -lap induced a greater ROS production and showed a lower IC50 value in TcAKR-overexpressing epimastigotes than in controls (5.1 μM and 7.9 μM, respectively). We conclude that TcAKR may be involved in -lap activation through ROS generation, although TcAKR activity is not a determinant of susceptibility in wild type T. cruzi strains.