Comparison of Antimicrobial effect of different parts of Quercus persica against Escherichia coli O157:H7

As a result of indiscrimate use of antimicrobial drugs in the treatment of infectious diseases, microorganisms especially gram negative bacteria, have developed resisrtance to many antibiotics and there is a need to develop antimicrobial drugs.One approach is use of local medicinal plants which represent a rich source of novel antimicrobial agents. Due to rapid increase of antibiotics resistance, fewer side effects of chemical drugs, antibacterial properties of oaks and other reasons, this study was carried out. In this experimental study the antibacterial activity of methanolic extract of oak bark,fruit hull,fruit and leaves was evaluated and compared with some in-use antibiotics.Milled oak sample was extracted with methanol in Soxhleťs apparatus. Extracts in three concentration(25,50,75mg/ml) were tested using agar diffusion method on Escherichia coli. Results showed that the effect of the extracts on E.coli was concentration-dependent. also antibacterial effect of fruit was better than leaf, bark, fruit hull and tested antibiotics. antibacterial effect of leaf, bark and fruit hull was similar together and often lesser than antibiotics. This results suggest that Quercus persica possesses compounds with antibacterial properties. Probably this antibacterial activity is due to presence of tannins in the plant extract. Because Tannin is one of the major components of Q.persica with contractive,disinfective,antimicrobial and... effects. Importance of oak trees is most due to presence of tannins in their different partes.