Euphane and Tirucallane Triterpenes with Trypanocidal Activity from Euphorbia desmondii .

The phytochemical investigation of Euphorbia desmondii resulted in the isolation of 15 previously undescribed triterpenoids (desmondiins A, C-P) and 8 already described compounds. The structures of the isolated compounds were determined by extensive spectroscopic analyses. The compounds were identified as tirucallane and euphane triterpenes based on 7-keto-8-ene, 11-keto-8-ene, or 7,11-diketo-8-ene skeletons. Additionally, the selective trypanocidal activities of these compounds against Trypanosoma cruzi were evaluated. Desmondiins A, C, D, F, H, and M exhibited IC 50 values in the range of 3-5 μM, and selectivity indices between 5-9, against T. cruzi epimastigotes over the host cell (RAW264.7 macrophages). Furthermore, desmondiin A efficiently inhibited amastigote replication in host cells (IC 50 = 2.5 ± 0.3 μM), which was comparable to that of the positive control, benznidazole (3.6 ± 0.4 μM). Overall, the isolated euphane and tirucallane triterpenoids could act as antichagasic lead scaffolds.