An aromatic diamidine that targets the kDNA, impairs the cell cycle in Trypanosoma cruzi and diminishes trypomastigote release from infected mammalian host cells.

Abstract

Trypanosoma cruzi is the etiological agent of Chagas disease, affecting approximately 10 million people in the Americas and with some 40 million people at risk. The objective of this study was to evaluate the anti-T. cruzi activity of three new diamidines that have a 3,4-ethylenedioxy extension of the thiophene core, designated MB17, MB19 and MB38. All three diamidines exhibited dose-dependent inhibition of epimastigote replication. The mechanisms of action of these diamidines were investigated. Unlike MB17 and MB19, MB38 exhibited a significant increase of annexin- plus propidium iodide double-labelled cells compared to control parasites. As MB17 had shown a lower IC50 against epimatigote growth, the mechanism of action of this drug was studied in more detail. MB17 triggered a decrease in the intracellular ATP levels. As a consequence, MB17 affected the genomic DNA and kinetoplast DNA (kDNA), and impaired the parasite cell cycle. Moreover, MB17 caused DNA fragmentation, with a more severe effect on kDNA than nuclear DNA, resulting in dyskinetoplastic cells. MB17 was tested for toxicity and effectiveness for the treatment of infected CHO-K1 cells, exhibiting a CC50 of 13.47 ± 0.37 ¼M and an IC50 of 0.14 ± 0.12 ¼M against trypomastigote release. MB17 also diminished the infection index by 60% at 0.5 ¼M. In conclusion, despite belonging to the same family, these diamidines have different efficiencies. To summarize, MB17 was the most potent of these diamidines against epimastigotes, producing DNA damage preferentially in kDNA, impairing the parasite cell cycle and decreasing the infection index and trypomastigote release from infected mammalian host cells, with a high selectivity index (SI) (<90). These data suggest that MB17 could be an interesting lead compound against T. cruzi. (AU)