Antiparasitic Activity of Diterpenoids Against Trypanosoma cruzi.

Twenty-seven diterpenes, including abietanes, labdanes, abeoabietanes, halimanes, and pimaranes, have been evaluated against epimastigote and intracellular amastigote forms of Trypanosoma cruzi and also against LC5 and NCTC cell lines. Royleanones ( 3, 4 , and 5 ) and a further abietane ( 12 ), obtained by purification of Plectranthus spp. extracts, were the most active compounds on epimastigotes, showing IC 50 values similar (1.73 µg/mL, 12 ) or even lower (0.39, 0.99, and 1.20 µg/mL, 3, 4 , and 5 respectively) than the positive control nifurtimox (2.3 µg/mL). On intracellular amastigotes, abietanes 3, 4 , and 5 showed a significant activity with IC 50 values of 0.83, 50 3, 4 , and 5 were not cytotoxic to LC5 and NCTC 929 cells at 1 µg/mL.