Antiprotozoal activity of extracts and isolated triterpenoids of ‘carnauba’ (Copernicia prunifera) wax from Brazil

Abstract

Context: ‘Carnauba’ wax is a natural product obtained from the processing of the powder exuded from Copernicia prunifera (Miller) H. E. Moore (Arecaceae). This material is widely used in the Brazilian folk medicine, including the treatment of rheumatism and syphilis. Objective: To investigate the antiprotozoal activity of hexane and EtOH extracts from the ‘carnauba’ wax as well as from the isolated compounds from the bioactive extracts. Material and methods: Two different samples of ‘carnauba’ (C. prunifera) waxes–types 1 and 4–were individually extracted using hexane (EH) and EtOH (EE). Aliquots of hexane (type 1–EH-1 and EH-4) and EtOH (type 4–EE-1 and EE-4) extracts were tested against promastigote (2–200 μg/mL in DMSO during 48 h at 24 °C) and amastigote (3–150 μg/mL in DMSO during 120 h at 37 °C) forms of Leishmania infantum as well as against trypomastigote (3–150 μg/mL in DMSO during 24 h at 37 °C) forms of Trypanosoma cruzi. Bioactive extracts EH-1 and EE-4 were subjected to a bioactivity-guided fractionation to afford three dammarane-type triterpenoids (1–3). The in vitro antiprotozoal activities of the obtained compounds were evaluated as described above. Additionally, the cytotoxicity activity of compounds 1–3 against mammalian conjunctive cells (NCTC–2–200 μg/mL in DMSO during 48 h at 37 °C) was determined. Results: From the bioactive hexane and EtOH extracts from the ‘carnauba’ (C. prunifera) wax, were isolated three dammarane-type triterpenoids: (24R*)-methyldammar-25-ene-3β,20-diol (carnaubadiol, 1), (24R*)-methyldammara-20,25-dien-3-one (2) and (24R*)-methyldammara-20,25-dien-3α-ol (3). These compounds were identified based on the analysis of NMR and MS spectroscopic data. Compounds 1–3 were effective against the intracellular amastigotes of L. infantum, with IC 50 values ranging from 8 to 52 μM, while compounds 1 and 3 displayed activity against trypomastigote forms of T. cruzi with IC 50 values of 15 and 35 μM, respectively. The mammalian cytotoxicity assay demonstrated no damage to NCTC conjunctive cells up to 200 μM, except for compound 1, which demonstrated a CC 50 value of 34 μM. Conclusion: Based on the results, it was possible to conclude that the detected antiprotozoal bioactivity of ‘carnauba’ (C. prunifera) wax extracts could be related to the presence of the natural dammarane triterpenoid derivatives. The results suggested that these compounds could be used as promising scaffolds for drug design studies for leishmaniasis and Chagas disease.