Antimicrobial activity of extracts and fractions from aerial parts of selected plants (Garcinia achachairu, Macrosiphonia velame, Rubus niveus and Pilea microphylla) against some pathogenic microorganisms.

As part of the program of our research group to search for new and effective substances from the Brazilian biodiversity, the present work evaluates the antibacterial activity of four species from the Brazilian flora (Garcinia achachairu, Macrosiphonia velame, Rubus niveus and Pilea microphylla) against Bacillus subtilis, Staphylococcus aureus and S. saprophyticus (Gram-positive bacteria), Escherichia coli (Gram-negative bacterium) and Candida albicans (yeast). The extracts of R. niveus and M. velame showed promising antibacterial activity with MICs, ranging from 1000 to 125 microg/mL. Bio-guided fractionation of M. velame yielded four compounds, with the highest inhibition being observed for compound 3, with a MIC of 125 microg/mL against S. aureus. The combinations of fractions 2 and 4 showed beneficial effect against Gram-positive bacteria (additive effect), suggesting a possible synergistic effect.