Antiparasitic Activity of Diterpenoids Against Trypanosoma cruzi

Abstract

Twenty-seven diterpenes, including abietanes, labdanes, abeoabietanes, halimanes, and pimaranes, have been evaluated against epimastigote and intracellular amastigote forms of <i>Trypanosoma cruzi</i> and also against LC5 and NCTC cell lines. Royleanones (<b>3, 4</b>, and <b>5</b>) and a further abietane (<b>12</b>), obtained by purification of <i>Plectranthus</i> spp. extracts, were the most active compounds on epimastigotes, showing IC₅₀ values similar (1.73 µg/mL, <b>12</b>) or even lower (0.39, 0.99, and 1.20 µg/mL, <b>3, 4</b>, and <b>5</b> respectively) than the positive control nifurtimox (2.3 µg/mL). On intracellular amastigotes, abietanes <b>3, 4</b>, and <b>5</b> showed a significant activity with IC₅₀ values of 0.83, < 0.31, and 0.62 µg/mL, respectively, but were less potent than the positive control nifurtimox (IC₅₀ < 0.16 µg/mL). Compounds <b>3, 4</b>, and <b>5</b> were not cytotoxic to LC5 and NCTC 929 cells at 1 µg/mL.