Evaluation of Antibacterial Activity of Alcoholic Extract of Rosemary Leaves against Pathogenic Strains

Background: Today, the increased use of antibiotics leads to the incidence of resistant strains. We are faced with lack of new antimicrobial drugs that have fewer side effects than antibiotics. Rosemary is a medicinal plant that has many uses in traditional medicine. In this study, ethanol leaves extract of this plant is tested on various pathogens.

Materials and Methods: In this experimental study, Rosmarinus officinalis was used to evaluate the antimicrobial effects on pathogens. Ethanol extract of the leaves of this plant, with concentrations of 400, 200, 100 and 50 mg/l were prepared, and antibacterial activities were evaluated by well diffusion method on strains of Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was determined by the microplate method.

Results: In this study, ethanol extract of rosemary leaves at concentrations of 400 mg/ml was active against Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus aureus and Escherichia coli. Minimum inhibitory concentration of the extract on the growth of these bacteria from 6.25 mg/ml to 100 mg/ml was change. Also MBC of extract showed range from 12.5 to 200 mg/ml respectively.

Conclusion: Result from these finding suggest that, rosemary extract, on all strains, including Staphylococcus aureus, Escherichia coli, Bacillus cereus and Pseudomonas aeruginosa, has an inhibitory effect. Also, the effect of extract, risesed by increasing the concentration.