A nanodelivered Vorinostat derivative is a promising oral compound for the treatment of visceral leishmaniasis

There is currently no satisfactory treatment for visceral leishmaniasis; the disease is thus in desperate need of novel drugs. The ideal candidate should be effective, safe, affordable, and administered via the oral route. Histone deacetylases (HDACs) are involved in silencing critical regulatory pathways, including pro-apoptotic programs, and represent potential therapeutic targets for pharmacological interventions. O-alkyl hydroxamates have traditionally been considered to exert no effect on mammal HDACs. The aim of this study was to evaluate the effect of MDG, a SAHA derivative of the O-alkyl hydroxamate family with no activity on human histone deacetylase enzymes, on the visceral leishmaniasis causative agents and in a murine model of the disease. The effects of vorinostat, tubacin and valproic acid (well-known mammal HDAC inhibitors) on the parasite were also evaluated. MDG was found to be highly active against Leishmania infantum and L. donovani intracellular amastigotes in vitro but not against the promastigote stage. In contrast, vorinostat, tubacin and valproic acid showed no activity against the parasite. Assays investigating hERG and Cav1.2 channels in vitro found no evidence of MDG-driven cardiotoxicity. MDG showed neither hepatotoxicity nor mutagenicity, nor did it exert activity on cytochrome P450 enzymes. MDG was adsorbed onto gold nanoparticles for the in vivo experiments, performed on infected Balb/c mice. MDG was effective at reducing the parasite load in major target tissues (bone marrow, spleen and liver) in more than 70% at 25 mg/kg through both the oral and intraperitoneal route, proving more active than the reference compounds (meglumine antimoniate, MA) without showing toxicity. In addition, the combination of MDG and MA was very effective.