As a continuation of our research on the Baccharis genus, the evaluation of the antioxidant effect by TRAP and TBARS assays of three isolated compounds from n-butanol fractions of B. articulata and B. usterii is reported. The structures of these compounds were established as 4-O-β-D-glucopyranosyl-3,5-dimethoxybenzyl-methanol (1), 5-O-[E]-dicaffeoylquinic acid (2), and 7-hydroxy-5,4′-dimethoxyflavone (3). In the TRAP assay it was possible to observe an antioxidant effect of both n-butanol fractions at 1.25 μg/mL. Among the isolated compounds, compound 2 displayed a remarkable contribution to the total antioxidant capacity of the n-butanol fraction of B. usterii. Moreover, the n-butanol fractions of both species, compounds 1 and 2 at 40.0 μg/mL were efficient in protection of lipid peroxidation in the TBARS experiment. They are promising lead compounds for use in medicinal chemistry studies.
