Trypanocidal activity of South American Vernonieae (Asteraceae) extracts and its sesquiterpene lactones

Abstract

Chagas disease is caused by <i>Trypanosoma cruzi</i> and affects the poorest population in the Americas. Fourteen plant extracts and seventeen sesquiterpene lactones from the tribe Vernonieae (Asteraceae), were evaluated for the first time against <i>T. cruzi</i>. Cytotoxicity employing HeLa cells was also assessed. The best results were obtained with leaves and flowers rinse extracts from <i>Vernonanthura nebularum</i> (E-1 and E-3) and <i>Elephantopus mollis</i> (E-11 and E-13), with IC₅₀ values <2 µg/mL, being E-1 the most active (IC₅₀ = 0.8 µg/mL). Additionally, these extracts displayed a good selectivity (SI > 10). The most active sesquiterpene lactones, isolated from the extracts, were 2 (2<b>-</b>methoxy-2,5-epoxy-8-methacryloxygermacra-3Z,11(13)-dien-6,12-olide) and 6 (2<b>-</b>ethoxy-2,5-epoxy-8-angeloxygermacra-3Z,11(13)-dien-6,12-olide) from <i>V. nebularum</i> and 12 (8α-methacryloxyhirsutinolide 13-O-acetate) from <i>V. pinguis</i>, with IC₅₀ of 1.5, 2.1 and 2.0 µM, respectively. These compounds showed SI values >14, better than those of the reference drug nifurtimox. Plants living in South American ecosystems could become a potential source of trypanocidal agents.