Medicinal plants are the oldest known source for treatment of disease. Using pharmaceutical plants and plant extracts have been at great attention. In this research, the antibacterial activity of the ethanolic and aqueous extracts of Lemon verbena Leaves cultured in research farm Islamic Azad University , Azadshahr Branch were tested against nine pathogen bacteria strains. Crude extracts were obtained by using ethanol and hot sterile distilled water as the extraction solvent. Four concentrations(1000 mg/ml, 500 mg/ml, 250 mg/ml and 125 mg/ml) were used to check the antibacterial activity of this plant .The antibacterial activity of ethanolic and aqueous extracts was determined by Disk diffusion and agar well diffusion methods. Results of this research indicated that ethanolic Extract despite of aqueous extract was showed considerable antibacterial effects . The most susceptible bacteria were E.feacalis ,S.epidermidis, S.aureus and B. cereus while the most resistant bacteria were gram negative bacteria for example Pseudomonas aeroginosa, Salmonella typhimorium and Shigella dysentriae. The largest zone of inhibition was against E. feacalis , S. epidermidisand S. aureus in agar well diffusion method 24,22,20 (mm) respectively while in disk diffusion methodlarsest zone of inhibition was S. epidermidis and S. aureus 15,12(mm) respectively. Yersinia entrocolitica was the most susceptible among gram negative bacteria. Generally Effect of ethanolic extract of lemon verbena leaves was more than theire aqueous extract and gram positive bacteria were more sensitive than gram negative bacteria.future studies are recommended to determine the Antibacterial effect of ethanolic extract of lemon verbena leaves on animal models.
