Organometallic Gold(III) Complex [Au(Hdamp)(L14)]+ (L1 = SNS-Donating Thiosemicarbazone) as a Candidate to New Formulations against Chagas Disease.

Chagas disease remains a serious public health concern with unsatisfactory treatment outcomes due to strain-specific drug resistance and various side effects. To identify new therapeutic drugs against Trypanosoma cruzi, we evaluated both the in vitro and in vivo activity of the organometallic gold(III) complex [Au(III)(Hdamp)(L14)]Cl (L1 = SNS-donating thiosemicarbazone), henceforth denoted 4-Cl. Our results demonstrated that 4-Cl was more effective than benznidazole (Bz) in eliminating both the extracellular trypomastigote and intracellular amastigote forms of the parasite without cytotoxic effects on mammalian cells. In in vivo assays, 4-Cl in PBS solution loses the protonation and becomes the 4-neutral. 4-Neutral reduced parasitaemia and tissue parasitism in addition to protecting the liver and heart from tissue damage at 2.8 mg/kg/day. All these changes resulted in the survival of 100% of the mice treated with the gold complex during the acute phase. Analyzing the surviving animals of the acute infection, the parasite load after 150 days of infection was equivalent to those treated with the standard dose of Bz without demonstrating the hepatotoxicity of the latter. In addition, we identified a modulation of interferon gamma (IFN-γ) levels that may be targeting the disease's positive outcome. To the best of our knowledge, this is the first gold organometallic study that shows promise in an in vivo experimental model against Chagas disease.