Antitrypanosomal Activity of a Semi-Purified Subfraction Rich in Labdane Sesquiterpenes, Obtained from Flowers of Anthemis Tinctoria, Against Trypanosoma Cruzi

In Brazil and several other Latin American countries, Chagas' disease still constitutes a serious medical and social problem, and there is a need to develop new, more-potent drugs with fewer side effects to effectively treat this disease. We investigated the antitrypanosomal effect of a crude extract, fractions, and a semi-purified subfraction rich in a mix- ture of isomeric labdane sesquiterpenes, obtained from flowers of Anthemis tinctoria, against Trypanosoma cruzi. In epimastigote forms, the aqueous crude extract, dichloromethane fraction, and semi-purified subfraction showed a dose-dependent inhibitory activity, with IC50 of 2.3 μg/ml, 1.8 μg/ml, and 0.2 μg/ml, respectively. In the interaction in- dex, the semi-purified subfraction showed a reduction in both the percentage of infected LLCMK2 cells and the mean number of amastigotes per infected cell. The cytotoxicity evaluation demonstrated that the cytotoxic concentrations of the semi-purified subfraction were higher for LLCMK2 cells than for the protozoans, with a selectivity index of 35.0. Epimastigote forms treated with the semi-purified subfraction showed ultrastructural and morphological alterations such as rounding of the cells and bleb formation in the flagellum and cytoplasmic membrane. These results show that the flowers from A. tinctoria may be a source of new drugs with antiprotozoal activity. However, additional in vitro and in vivo studies are needed to validate the use of A. tinctoria in the treatment of Chagas’ disease.