Extracts and Terpenoids from Stevia Species as Potential Anthelmintics for Neglected Tropical Diseases Caused by Cestode Parasites

Cestodes are etiological agents of neglected diseases such as echinococcosis and cysticercosis, which are major public health problems. Antiparasitic treatment relies on a small number of approved drugs, which are often only partially effective, poorly tolerated and require prolonged administration. Thus, the discovery of novel potential treatments is critical. The Stevia genus (Asteraceae) includes species that are associated with medicinal uses and are considered a source of bioactive compounds. Here, we analyzed four South American Stevia species that have previously demonstrated antiprotozoal properties. The effect of dichloromethane extracts of these species was determined by motility assays on Mesocestoides vogae, a laboratory model of cestodes. Stevia alpina showed the highest anthelmintic potential followed by S. maimarensis and S. multiaristata, while S. aristata was the least active. The sesquiterpene lactones estafietin and eupatoriopicrin were purified from S. alpina and S. maimarensis, respectively. Estafietin showed cestocidal activity, inhibiting parasite viability in a dose-dependent manner, even from the first day of incubation. Consistent with the motility effects, the extract of S. alpina and estafietin induced major alterations on the morphology of the parasite. The results of this report show that Stevia species represent a source of new molecules with potential for the treatment of neglected tropical diseases caused by cestodes.