In silico, in vitro, and in vivo assessment of anti-Trypanosoma cruzi activity of the 1H-indazole-containing ruthenium complex FOR0E2.

There is a need for new therapeutic agents against Trypanosoma cruzi, the etiologic agent of Chagas disease. Current treatments, such as benznidazole and nifurtimox, have limited efficacy in the chronic phase and cause significant side effects. Here we tested the effects of three ruthenium complexes against trypomastigote and amastigote forms of T. cruzi and evaluated their possible mechanisms of action. FOR0E2 was the most active among the three compounds, with IC50 values of 0.3, 0.4 and 0.6 µM against trypomastigote forms of the Y, Tulahuen, and Colombian strains, respectively. Under the same conditions, benznidazole exhibited IC50 values of 12.5, 2.17 and 13.6 µM against the Y, Tulahuen, and Colombian strains, respectively. In addition, this compound significantly inhibited amastigote proliferation of Y strain in vitro. Transmission and scanning electron microscopies revealed morphological and structural damage to the parasite, especially in the mitochondria and nuclear DNA following treatment with FOR0E2, which were confirmed by flow cytometry. Molecular docking studies demonstrated strong interactions between FOR0E2 and the enzyme trypanothione reductase, a key component of the parasite's antioxidant defense. Moreover, FOR0E2 (20 mg/kg) reduced parasitemia by 36.7% in an acute infection model, though benznidazole (100 mg/kg) reduced 100% parasitemia. In conclusion, this study highlights the potential of FOR0E2, particularly due to its ability to disrupt mitochondrial function and potential inhibitory activity on trypanothione reductase, making it a promising candidate for further development as an antiparasitic agent.