Antimicrobial Activity of the Crude Extracts and Fractions of Three Baccharis Species

The antimicrobial activities of crude extracts and fractions from three Baccharis L. species were tested against Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 8738), Pseudomonas aeruginosa (ATCC 9027), and Candida albicans (ATCC 10231) using the microdilution plate method. The results showed that the crude extract from female B. burchellii Baker had moderate activity against S. aureus (minimum inhibitory concentration [MIC], 0.9 mg.mL-1). Among the fractions obtained from this extract, the dichloromethane fraction showed the highest activity against S. aureus (MIC, 0.4 mg.mL-1). The ethyl acetate fractions from female B. burchellii (MIC, 0.6 mg.mL-1 and 1.2 mg.mL-1, respectively) and B. aracatubaensis Malag (MIC, 1.1 mg.mL-1 for both) were moderately effective against S. aureus and P. aeruginosa. The extracts from B. organensis Baker showed no significant activity against any organism tested. None of the extracts from Baccharis species showed any activity against C. albicans. In addition, the chemical investigation of the dichloromethane and ethyl acetate fractions from female B. burchellii was carried out, resulting in the identification of trans-ferulic acid, ethyl caffeoate, naringenin, and 7-hydroxy-benzaldehyde compounds. These phenolic compounds were found in other species of Baccharis and have been shown to possess antimicrobial activity. The results obtained in this work with respect to B. burchellii indicate that this species is a promising source of compounds with antimicrobial activities.