In-vitro trypanocidal activity evaluation of crude extract and isolated compounds from Baccharis dracunculifolia D.C. (Asteraceae).

We have performed a trypanocidal bioactivity-guided study of Baccharis dracunculifolia (Asteraceae), the main botanical origin of Brazilian green propolis. The leaf rinse extract of B. dracunculifolia, at a concentration of 3.0 mg mL(-1), displayed 100% lysis of trypomastigote forms of the Y strain of Trypanosoma cruzi (2 x 10(6) parasites mL(-1)). The chromatographic fractionation of the leaf rinse, using several techniques, afforded the isolation of the compounds isosakuranetin (1), aromadendrin-4'-methylether (2), baccharis oxide (3), ferulic acid (4), dihydrocinnamic acid (5), 3-prenyl-4-(dihydrocinnamoyloxy)-cinnamic acid (6), and friedelanol (7). The chemical structures of all compounds were established by UV-vis, (1)H and (13)CNMR data analysis in comparison with the literature. Compounds 1 and 3 were the most active in the trypanocidal assay, showing IC50 values (inhibitory concentration required for 50% inhibition) of 247.6 and 249.8 microM, respectively. Compounds 2, 4, and 6 displayed moderate activity, whilst compounds 5 and 7 were inactive.