RESUMEN
Chagas disease, caused by the protozoan Trypanosoma cruzi, is considered a public health problem. The current chemotherapy for this illness causes serious side effects and its use in the chronic phase of the disease is still controversial. In this regard, the investigation of novel therapeutic strategies remains a priority. The essential oils (EOs) from aromatic plants emerge as a promising source of bioactive compounds. In a previous work we reported the trypanocidal activity of the essential oils from the medicinal plants Lippia sidoides (LSEO) and Lippia origanoides (LOEO) against T. cruzi. Herein, we aimed to further investigate, in more details, the mode of action of LSEO and LOEO on the different developmental stages of this parasite. We showed that Lippia sidoides (LSEO) and Lippia origanoides (LOEO) induced a significant reduction in the percentage of macrophages infected by T. cruzi and in the number of intracellular parasites. Ultrastructural analysis showed that the treatment with both oils caused morphological changes consistent with loss of viability and cell death. The reduced staining with calcein and the increase in the proportion of HE-positive cells also demonstrated that LSEO and LOEO caused loss of parasite viability and membrane integrity. A considerable decrease in Rhodamine 123 and an increase in fluorescence intensity of MitoSox in LOEO were indicative of loss of mitochondrial potential and generation of reactive oxygen species, which ultimately lead to parasite death. Moreover, the optical tweezer analysis indicated that LOEO was more effective in reducing the motility of the epimastigotes. Taken together, our results demonstrated that the LSEO and LOEO are active against T. cruzi and constitute a promising drugs for the therapy of Chagas disease.