Native populations of South America have employed herb-based preparations for the treatment
of parasite diseases. In this review, some examples of South American medicinal plants from which
bioactive molecules have been isolated are presented. Results of our research related to the study of novel
compounds with antiprotozoal activity are also presented herein. Peruvin and psilostachyin, two sesquiterpene
lactones isolated from the Argentine medicinal species Ambrosia tenuifolia, presented significative in
vitro activity on Trypanosoma cruzi epimastigotes and trypomastigotes. Psilostachyin also presented in vivo
activity in T. cruzi infected mice. Both compounds were also active on Leishmania spp. The results obtained
suggest that psilostachyin could be considered a potential lead molecule in the development of novel
trypanocidal agents.