<i>In vitro</i> and <i>in vivo</i> evaluation of the trypanocidal activity of the acetone extract of lichen <i>Usnea steineri</i> and its chemical constituents

More than 2.5 billion people live in endemic areas for neglected tropical diseases caused by the protozoan <i>Trypanosoma cruzi</i>. Which establishes chronic infections and increases public health spending. Thus, this paper describes the chemical study of <i>Usnea steineri</i> acetone extract and evaluations of trypanocidal activity <i>in vitro</i> and <i>in vivo</i>. Four chemical constituents from the acetone extract have been isolated: usnic acid, diffractaic acid, galbinic acid, and norstictic acid. The acetone extract of <i>U. steineri</i> revealed an IC₅₀ of 49.4 ± 1.5 µg/mL regarding the trypomastigote <i>T. cruzi</i> forms. The usnic acid revealed the biggest effectivity regarding the trypomastigote <i>T. cruzi</i> forms. The trypanocidal activity of the usnic acid regarding the amastigote forms revealed promising results, showing IC₅₀ of 67.0 ± 3.8 µM. The <i>in vivo</i> evaluation with the usnic acid revealed a decreased parasitemia at 40 mg/kg. Therefore, the results obtained open the perspectives for future studies aiming at its pharmacological application.