Targeting polyamine transport in Trypanosoma cruzi

Abstract

Polyamines play critical roles as regulators of cell growth and differentiation. In contrast with other protozoa, the human parasite Trypanosoma cruzi, the etiological agent of Chagas disease, is auxotrophic for polyamines. Therefore, their intracellular availability depends exclusively on polyamine transport andinhibition of these uptake processes can alter the viability of the parasite. The polyamine analogues used in this work were successfully tested as antiproliferative agents in cancer cells, bacteria, fungi and also showed a potent antiplasmodial effect. We evaluated the activity of these compounds on polyamine transport in T. cruzi and assessed the effects on parasite viability. Three polyamine derivatives,AMXT1501, Ant4 and Ant44, inhibited the putrescine transport in epimastigotes (the insect stage of T. cruzi) with calculated IC50 values of 2.43, 5.02 and 3.98 mM, respectively. In addition, only Ant4 and Ant44inhibited spermidine transport with IC50 of 8.78 mM and 13.34 mM, respectively. The Ant4 analogue showed a high trypanocidal effect on trypomastigotes (the bloodstream stage of T. cruzi) with an IC50 of 460 nM, (SI ¼ 12.7) while in epimastigotes the IC50 was significantly higher (16.97 mM). In addition, we studied the effect of the combination of benznidazole, a drug used in treating Chagas disease, with Ant4 on the viability of epimastigotes. The combined treatment produced a significant increase on the inhibition of parasites growth compared with individual treatments. In summary, these results suggest that Ant4, a putrescine conjugate, is a promising compound for the treatment of Chagas disease because it showed a potent trypanocidal effect via its inhibition of polyamine import.