Evaluation of N-myristoyltransferase Inhibitors as Anti-T. cruzi Agents

Currently, there is only one commercial drug available against Trypanosoma cruzi. This parasite affects millions in Latin America and is an emergent concern in the U.S. New drug-resistant strains clearly point out the urgent need for new drugs. N-myristoyltransferase catalyzes the attachment of myristic acid many eukaryotic proteins. This ubiquitous modification is essential for their localization and function. In T. cruzi, bioinformatics analyses have predicted over one hundred myristoylated-proteins. Therefore, we expect that NMT inhibition would have pleiotropic effects on the physiology of the parasite. Recently, potent inhibitors were identified against T. brucei NMT. We aim to evaluate eight of these inhibitors against T. cruzi. A proliferation assay was performed by incubating the compounds with human osteocytes and trypomastigotes. Moreover, the cytotoxic effects of the inhibitors were assayed on mammalian cells and intracellular amastigotes. To determine the “on-target” effect of inhibitors, metabolic labeling with [³H] myristic acid was performed. Three of the compounds significantly reduced the proliferation of T. cruzi without being cytotoxic on mammalian cells. To determine the specificity of the inhibitors, we next labeled trypomastigotes with [³H] myristic acid after preincubation with or without the inhibitors. We observed a significant reduction in the incorporation of [³H] myristic acid in the samples treated with the inhibitors. Three compounds  showed inhibition of proliferation of intracellular parasites with an IC₅₀ of 0.43 μM, 0.39 μM and 0.22μM, respectively. Moreover, these compounds were not cytotoxic on mammalian cells. Finally, our results indicate that these compounds are acting specifically on NMT.