Mechanistically, it was reasonable to postulate that the collapse of the ΔΨm was mediated by ROS generation in the treated parasites. In this context, the fluorescent probe DHE was used for intracellular ROS detection, and AA was added as a positive control because it inhibits the electron flow through the electron transport

chain, leading to the accumulation of superoxide [33]. Among the four NQs tested, only NQ8 led to a discrete increase in the percentage of DHE + epimastigotes, giving addition evidence for the strong effect of this quinone on the parasite ΔΨm. Indeed, the pool of MK0683 in vitro anti-oxidant defenses in epimastigotes Selleck GSI-IX that includes trypanothione, tryparedoxin peroxidase and other

redox enzymes leads to a protective effect in this parasite stage, as previously described [34]. Thus, one plausible hypothesis to explain the absence of oxidative stress triggered by NQ1, NQ9 and NQ12 could be the existence of more than one mechanism of action involved in the trypanocidal find more activity of these compounds, leaving ROS generation suppressed by the detoxification system of the parasite. Possibly, the strong redox effect of NQ8 could be associated to the presence of the acetyl group in its structure facilitating quinone reduction, as previously demonstrated by electrochemical analysis [35]. Further experiments using different biochemical and molecular

approaches must be performed to better characterize ROS participation in the mechanism of action of these compounds. Electron microscopy evidence of induction of the autophagic pathway by naphthoquinones and their derivatives has also been previously reported [24–26, 28]. The presence of large profiles of endoplasmic reticulum surrounding 3-oxoacyl-(acyl-carrier-protein) reductase different cellular structures, such as lipid droplets and organelles, and the appearance of bizarre membranous structures with a myelin-like aspect are the most common characteristics. The autophagic process represents a fundamental constitutive pathway in eukaryotic cells that is responsible for remodeling cellular structures and maintaining homeostasis. In trypanosomatids, other roles for autophagy have been proposed, including in the parasite’s differentiation [36]. In a great variety of cell models, the loss of the balance between anabolic and catabolic processes leads to non-apoptotic death [37]. In the last decade, it has been demonstrated that the induction of autophagy in T. cruzi trypanosomatids is triggered by several classes of drugs, in particular naphthoquinones and their derivatives [25, 26, 38]. Our transmission electron microscopy analysis suggested the involvement of endoplasmic reticulum and cytosolic membranous structures in pre-autophagosomal formation, as previously postulated by Yotimitsu & Klionsky [39].