In vitro and in vivo evaluation of the trypanocidal activity of the acetone extract of lichen Usnea steineri and its chemical constituents.

More than 2.5 billion people live in endemic areas for neglected tropical diseases caused by the protozoan Trypanosoma cruzi. Which establishes chronic infections and increases public health spending. Thus, this paper describes the chemical study of Usnea steineri acetone extract and evaluations of trypanocidal activity in vitro and in vivo. Four chemical constituents from the acetone extract have been isolated: usnic acid, diffractaic acid, galbinic acid, and norstictic acid. The acetone extract of U. steineri revealed an IC50 of 49.4 ± 1.5 µg/mL regarding the trypomastigote T. cruzi forms. The usnic acid revealed the biggest effectivity regarding the trypomastigote T. cruzi forms. The trypanocidal activity of the usnic acid regarding the amastigote forms revealed promising results, showing IC50 of 67.0 ± 3.8 µM. The in vivo 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.