Antiprotozoal Effect of Baccharis Spicata and B. Punctulata Volatile Oils and Their Active Components Against Trypanosoma Cruzi

In the current study, the chemical composition of Baccharis spicata (Lam.) Baill. and B. punctulata DC., Asteraceae, aerial parts’ volatile oils were analysed. A higher proportion of monoterpenes than sesquiterpenes was detected in oils of inflorescence of both species. In contrast, a dominance of sesquiterpene components above the monoterpenes was found in the vegetative organs. β-Pinene, limonene, spathulenol and caryophyllene oxide were among the most abundant components along with (−)-alismol, only detected in B. punctulata and described for the first time in Baccharis oils. Storage at room temperature produced considerable changes in both oils’ composition, due to chemical transformation of terpenoids. Cytotoxic and trypanocidal activity of B. spicata and B. punctulata inflorescence volatile oils were evaluated. Bioactivity-guided fractionation yielded five active fractions for each species which effectively inhibited Trypanosoma cruzi epimastigote growth in a concentration-dependent manner (IC50 between 2.15 and 12.49 μg/ml). In order to compare the trypanocidal activity and the cytotoxicity of volatile oils for HepG2/C3A cells, the selectivity index was estimated. All samples showed to be more effective against parasites than human cells, with the selectivity index above 2.0. Among the fractions tested, samples enriched in alismol, spathulenol and caryophyllene oxide were the most active and selective against epimastigote forms.