Antibacterial activity of traditional Australian medicinal plants

Fifty-six ethanolic extracts of various parts of 39 plants used in traditio nal Australian Aboriginal medicine were investigated for their antibacteria l activities against four Gram-positive (Bacillus cereus, Enterococcus faec alis, Staphylococcus aureus and Streptococcus pyogenes) and four Gram-negat ive (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Sa lmonella typhimurium) bacterial species. In a plate-hole diffusion assay, 1 2 extracts inhibited the growth of one or more of the bacteria, with five e xtracts showing broad spectrum antibacterial activity against Gram-positive bacteria. B. cereus was the most susceptible bacterium, with all 12 extrac ts displaying activity against this organism. Extracts from the leaves of E remophila species (Myoporaceae) were the most active, with Eremophila dutto nii exhibiting the greatest activity (against Gram-positive bacteria). The antibacterial effects of E. duttonii were further investigated by time-cour se growth assays which showed that significant growth inhibition was observ ed in cultures incubated in the presence of the extract within I h for B. c ereus, E. faecalis and S. aureus and 2 h for S. pyogenes. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.