ANTI-BACTERIAL EFFECTS OF THE CRUDE EXTRACTS OF PHYTOLACCA DODECANDRA L. AND SCHINUS MOLLE L. LEAVES ON SELECTED HUMAN PATHOGENIC BACTERIA

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