Antimicrobial activity of bark extracts of Bridelia ferruginea (Euphorbiaceae)

Water and ethanol extracts of Bridelia ferruginea were examined for phytochemical and antimicrobial properties. The extracts, which were tested at a final concentration of 5 mg/ml, produced in vitro antimicrobial activities in assays against hospital strains of Staphylococcus aureus, Candida albicans, Staphylococcus epidermidis, Escherichia coli, Streptococcus lactis, Proteus vulgaris, Proteus mirabilis, Streptococcus pyogenes and Klebsiella sp. The zones of inhibition produced by the extracts in agar diffusion assays against the test micro-organisms ranged from 4 to 20 mm, while the chloramphenicol antibiotic control produced zones that measured 15-36 mm. Preliminary phytochemical analysis of the plant extracts showed the presence of phenols and tannins. Sesquiterpenes, anthroquinones, and saponins were not detected in the extracts. The Gram-negative bacteria appeared to be more susceptible (4-20 mm) to the antimicrobial effect of the extracts than the Gram-positive organisms (4-18 mm).