A New Source of (R)-Limonene and Rotundifolone from Leaves of Lippia pedunculosa(Verbenaceae) and their Trypanocidal Properties

Investigation by GC-FID and GC-MS of the essential oil (LPOE) from the leaves of Lippia pedunculosarevealed, as the major compounds, the monoterpenes rotundifolone (71.7%) and (R)-limonene (21.8%). These two compounds and the minor constituent piperitenone (1.2%) were also isolated from the leaves and identified by spectrometric analysis. LPOE and isolated compounds were evaluated for their trypanocidal activity against epimastigote and trypomastigote forms of Trypanosoma cruzi. Significant results with IC50values lower than 34.0 μg.mL−1were observed against these forms of T. cruzifor LPOE and isolated compounds. Rotundifolone was the most active compound with an IC50lower than 10.0 μg.mL–1for both forms of T. cruzi. The effects of LPOE and isolated compounds were also evaluated in cultures of macrophages infected with T. cruzi. Treatment with (R)-limonene and rotundifolone caused a moderate reduction in the percentage of macrophages infected by T. cruziand in the number of intracellular parasites at concentrations non-toxic to macrophages.