Trypanocidal Activity ofSmallanthus sonchifolius: Identification of Active Sesquiterpene Lactones by Bioassay-Guided Fractionation

Abstract

In order to find novel plant-derived biologically active compounds againstTrypanosoma cruzi, we isolated, from the organic extract ofSmallanthus sonchifolius, the sesquiterpene lactones enhydrin (1), uvedalin (2), and polymatin B (3) by bioassay-guided fractionation technique. These compounds showed a significant trypanocidal activity against the epimastigote forms of the parasite with IC50values of 0.84 μM (1), 1.09 μM (2), and 4.90 μM (3). After a 24 h treatment with 10 μg/mL of enhydrin or uvedalin, parasites were not able to recover their replication rate. Compounds1and2showed IC50values of 33.4 μM and 25.0 μM againstT. cruzitrypomastigotes, while polymatin B was not active. When the three compounds were tested against the intracellular forms ofT. cruzi, they were able to inhibit the amastigote replication with IC50of 5.17 μM, 3.34 μM, and 9.02 μM for1,2, and3, respectively. The cytotoxicity of the compounds was evaluated in Vero cells obtaining CC50values of 46.5 μM (1), 46.8 μM (2), and 147.3 μM (3) and the selectivity index calculated. According to these results, enhydrin and uvedalin might have potentials as agents against Chagas disease and could serve as lead molecules to develop new drugs.