In this study, phytochemical characterization was conducted and the in vitro antibacterial activity of extracts of Ageratum conyzoides L. (whiteweed), Gossypium hirsutum (cotton), Phyllanthus tenellus (shatterstone) and Polygonum hydropiperoides (swamp smartweed) was evaluated against Staphylococcus aureus and Escherichia coli. To assess the antibacterial activity, the agar diffusion method was used. Tests were performed with the extract at alcoholic contents from 0 to 100% (v/v), at 20% proportion (m/v - mass/extractor). Phytochemical tests indicated the presence of reducing sugars, phenolic compounds, flavonoids, tannins, triterpenes and steroids in all four species. The growth of S. aureus cultures was inhibited by all extracts, except for whiteweed extract. The highest inhibitory activity was observed for shatterstone. However, none of the extracts was capable of inhibiting the growth of E. coli strains. Results are promising since three of the four selected plants showed to have antibacterial substances, which stimulates further studies for the isolation and the identification of active principles responsible for this activity, with potential to be used in the pharmaceutical industry.
Phytotherapy; Escherichia coli; Staphylococcus aureus
