Investigation of antibacterial properties of ethanolic extracts of seven medicinal plants used in Khorasan province by disk and well diusion methods

Today, due to the increased use of antibiotics and spread of resistant strains, using natural compounds as an alternative to synthetic compounds, with fewer side effects, have been widely importance. The aim of this study was to investigate the antimicrobial activity of ethanolic extracts of seven medicinal herb include green tea (Camellia sinensis), thyme Khorasani (Thymus transcaspicus), ziziphora (Ziziphora clinopodioides), pennyroyal (Mentha pulegium), cumin (Cuminum cyminum), purple basil (Ocimum basilicum var. purpurascence) and peppermint (Mentha piperita) on three gram negative bacteria (Escherichia coli Famp (ATCC 700891, Salmonella enterica TA100 (PTCC 1709) and Pectobacterium caratovoru).
Material and An experimental study was conducted at in vitro condition. Ethanolic extracts of above plants prepared by maceration method. Antimicrobial activity of these extracts at concentrations of 0.1, 0.2, 0.4, 0.8 and 1 mg/ml were evaluated by disk diffusion and well diffusion methods. Variables were included extract types, different concentrations of extracts and bacterial strains.
The results of this study showed that green tea extract had the highest inhibitory effect in both antimicrobial test methods. So that green tea extract in 1 and 0.8 mg/ml concentration had the highest inhibitory effect on E. coli and P. caratovoru showed the lowest and the most resistance, respectively.
It seems the types and concentrations of extracts and also bacterium type are influenced on growth inhibition zone. With increasing concentration, in both disk and well diffusion methods, the inhibition zone was increased. Inhibition zone in well diffusion method was higher than disk diffusion method.