Antibacterial effect of two species of Plantago against pathogenic bacteria

Plantago lanceolata and Plantago major are belonging to Plantaginaceae family and many species of that growing in Iran plays a major role in the revival of traditional medicine. Natural products from Plantago species display many activities such as antioxidant properties and also its antibacterial properties are under investigation yet. We studied antibacterial activities of aerial and root parts of two species against various strains of bacteria such as Bacillus cereus, Klebsiella pneumoniae, Proteus vulgaris, Salmonella typhi and Escherichia coli. The antibacterial activity of extracts was assessed by Disc diffusion method. Aerial and root parts extracted by ethanol, methanol (24h), acetone (3h) and water solvents were obtained by the reflex method. Antibacterial effects of the extracts tested at different concentrations (3.125, 6.25, 12.5, 25, 50, 100 and 200 mg.ml-1) and antibacterial activity were detected with the mean zone of inhibition (mm). Kanamycin (12.5, 25 and 50 mg/ml) and DMSO were used as the positive and negative control, respectively. The Minimal Inhibitory Concentration (MIC) of extracts ranged from 100-400 mg.ml-1 against the susceptible bacteria. All the Minimal Bactericidal Concentrations (MBCs) were the same as the MICs. Our results revealed that alcoholic and aqueous extracts did not show inhibitory on all gram¬-positive and negative strains except for acetone extracts, P.major root showed maximum inhibitory activity (12mm) against Proteus vulgaris and any of extracts don’t have effect on Klebsiella pneumoniae bacteria in any of the concentrations and compared with to kanamycin, acetone extracts was not better than antibiotics in any of the concentrations. So we can conclude that this plant has antibacterial properties but all aerial parts show a little antibacterial effect. The result can be related to the nature of the compounds found in this plant.