KH-TFMDI, a novel sirtuin inhibitor, alters the cytoskeleton and mitochondrial metabolism promoting cell death in Leishmania amazonensis

Treatment of leishmaniasis involves the use of antimonials, miltefosine, amphotericin B or pentamidine. However, the side effects of these drugs and the reports of drug-resistant parasites demonstrate the need for new treatments that are safer and more efficacious. Histone deacetylase inhibitors are a new class of compounds with potential to treat leishmaniasis. Herein, we evaluated the effects of KH-TFMDI, a novel histone deacetylase inhibitor, on Leishmania amazonensis promastigotes and intracellular amastigotes. The IC50 values of this compound for promastigotes and intracellular amastigotes were 1.976 and 1.148 μM, respectively, after 72 h of treatment. Microscopic analyses revealed that promastigotes became elongated and thinner in response to KH-TFMDI, indicating changes in cytoskeleton organization. Immunofluorescence microscopy, western blotting and flow cytometry using an anti-acetylated tubulin antibody revealed an increase in the expression of acetylated tubulin. Furthermore, transmission electron microscopy revealed several ultrastructural changes, such as (a) mitochondrial swelling, followed by the formation of many vesicles inside the matrix; (b) presence of lipid bodies randomly distributed through the cytoplasm; (c) abnormal chromatin condensation; and (d) formation of blebs on the plasma membrane. Physiological studies for mitochondrial function, flow cytometry with propidium iodide and TUNEL assay confirmed the alterations in the mitochondrial metabolism, cell cycle, and DNA fragmentation, respectively, which could result to cell death by mechanisms related to apoptosis-like. All these together indicate that histone deacetylases are promising targets for the development of new drugs to treat Leishmania, and KH-TFMDI is a promising drug candidate that should be tested in vivo.