Antiprotozoal activities of marine polyether triterpenoids

Chagas disease and leishmaniasis are tropical neglected diseases caused by kinetoplastids protozoan parasites of Trypanosoma and Leishmania genera, and a public health burden with high morbidity and mortality rates in developing countries. Among difficulties with their epidemiological control, a major problem is their limited and toxic treatments to attend the affected populations; therefore, new therapies are needed in order to find new active molecules. In this work, sixteen Laurencia oxasqualenoid metabolites, natural compounds 1–11 and semisynthetic derivatives 12–16, were tested against Leishmania amazonensis, Leishmania donovani and Trypanosoma cruzi. The results obtained point out that eight substances possess potent activities, with IC values in the range of 5.40–46.45 µM. The antikinetoplastid action mode of the main metabolite dehydrothyrsiferol (1) was developed, also supported by AFM images. The semi-synthetic active compound 28-iodosaiyacenol B (15) showed an IC 5.40 µM against Leishmania amazonensis, turned to be non-toxic against the murine macrophage cell line J774A.1 (CC > 100). These values are comparable with the reference compound miltefosine IC 6.48 ± 0.24 and CC 72.19 ± 3.06 μM, suggesting that this substance could be scaffold for development of new antikinetoplastid drugs.
This work was funded by INTERREG-MAC/1.1b/042 (BIOTRANSFER2), PI18/01380 from Instituto de Salud Carlos III, Spain and RICET [RD16/0027/0001 project, from Programa Redes Temáticas de Investigación Cooperativa, FIS (Ministerio Español de Salud, Madrid, Spain), FEDER. IS, ALA and ARDM were funded by the Agustín de Betancourt Programme (Cabildo de Tenerife – ULL). Authors acknowledge the use AFM Service of General Research Support Services of University of La Laguna (SEGAI-ULL).