Cytosporone B Affects ATP Production of Trypanosoma cruzi: A Lethal Action Investigation

Chagas disease is a neglected parasitic infection spreading worldwide and affecting 8-10 million people, with 14,000 deaths. The treatment is limited to two toxicity nitroheterocycle drugs, approved more than 50 years ago. Considering the urgent need for new therapies, secondary metabolites isolated from endophytic fungi may represent a useful source of bioactive molecules with antiparasitic activity, as described in the literature. In this study, we investigated the anti-Trypanosoma cruzi activity of seven compounds isolated from endophytic fungi present in leaves of the plant Casearia arborea. The compounds dothiorelones A (1), B (2), P (3), and Q (4), cytosporones A (5) and B (6) were isolated from Phomopsis sp. CarGL23, and cytochalasin H (7), from Diaporthe sp. CarGL8. Compound 6 (Csn-B) was designated the most selective agent of the panel, exhibiting potent activity against both relevant stages of T. cruzi. Specifically, it achieved IC₅₀ values of 36.5 μM against trypomastigotes and 9.1 μM against intracellular amastigotes. Given its superior selectivity index, a key criterion for drug discovery progression, Csn-B was prioritized for mechanistic investigation. Subsequent studies focused on understanding its lethal action profile using advanced spectrofluorimetric and flow cytometry assays. Using JC-1 as a fluorescent probe, our data revealed that Csn-B caused the depolarization of the mitochondrial membrane potential, without affecting the plasma membrane permeability of the trypomastigotes, as observed by the SYTOX Green dye. Targeting the bioenergetic system, Csn-B resulted in a decrease in the ATP levels of the parasite, affecting the viability of the cell. This study revealed a promising and selective anti-T. cruzi profile of these natural compounds and suggests Csn-B as a hit compound for future investigations for Chagas disease.