Searching for Natural Bioactive Compounds in Four <i>Baccharis</i> species from Bolivia

Abstract

The volatile oil composition of four Baccharis species ( Baccharis papilosa, B. polycephala, B. buxifolia, and B. convawyi) growing wild in Bolivia were studied by GC and GC/MS. The antimicrobial activity of the oils was determined by the agar diffusion and bioautography methods. Solvent extracts, polar and non-polar, of the same species were also tested for antimicrobial and antioxidant activities. Extracts from B. polycephala, B. papilosa and B. convawyi presented significant antioxidant activity, determined using the DPPH radical scavenging method, showing EC 50 values of 4.74, 7.17 and 7.97 μg/mL, respectively. Screening for antimicrobial activity was conducted using the agar diffusion test. The most active extracts (% inhibition ≥ 50) were further examined by the dilution method. All the plant extracts studied showed higher antimicrobial activity against S. aureus (Gram-positive) than against E. coli and P. fluorescens (Gram-negative).