Abstract:
Plants possess a wide variety of secondary metabolites which have been found to exhibit
antimicrobial, antioxidant and anti tumor activities. In Ethiopia, a number of plant species are
traditionally used for the treatment of many diseases. Among these, Phytolacca dodecandra and
Schinus molle which are abundantly available in many areas of the Country and they are widely
known for their traditional medicinal values. This study was conducted with the objective of
evaluating crude extracts of the leaves of Phytolacca dodecandra and Schinus molle for their
antibacterial activities against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli
O157:H7 and Pseudomonas aeruginosa some selected human pathogenic bacteria species.
Extraction was done by maceration using ethanol and hexane solvents. Antibacterial activities of
the leaf extracts were determined by the disc diffusion and broth dilution methods. Comparison
between extracts and the negative control showed that all types of extracts in all tested
concentrations significantly inhibited the growth of all test pathogens. However, the isolates
showed a sensitivity difference to different extracts. When compared with the commercial
antibiotic, however, all extracts at all tested concentrations (100mg/ml, 125mg/ml and
150mg/ml) had low level of inhibitory activities against all test pathogens. The MIC required for
inhibiting the growth of the test pathogens ranged from 20.8-83.33mg/ml showing variations
within bacterial species and extract types. In general, the study revealed that ethanolic extracts
of leaves showed more antibacterial activities against all tested bacteria than hexanic extracts of
leaves. These findings suggest that Phytolacca dodecandra and Schinus molle ethanolic extracts
might have great potentials in the development of antimicrobial agents useful for the treatment of
diseases caused by the tested pathogens provided that additional in-depth studies are made using
purified active principles of the crude extracts
