zeylanicum, L. nobilis L., J. foetidissima, A. sativum L., and M. fragrans Houtt. had good antibacterial activities against the Gram-negative bacteria, whereas the rest of the studied extracts were ineffective. Table 2 http://www.selleckchem.com/products/Belinostat.html Number of Gram-negative isolates susceptible to each plant extract The MIC50 values for these plant extracts and oils were 12.5, 12.5, 25, 12.5, 12.5,

25, 12.5, and 6.25 µl/ml, respectively, against E. coli O157:H7; and 1.5, 6.25, 6.25, 6.25, 6.25, 25, 6.25, and 12.5 µl/ml, respectively, against Y. enterocolitica O9; and 1.5, 3.125, 1.5, 1.5, 3.125, 12.5, 3.125, and 12.5 µl/ml, respectively, against Proteus spp.; and 6.25, 3.125, 1.5, 3.125, 6.25, 12.5, 6.25, and 6.25 µl/ml, respectively, Inhibitors,research,lifescience,medical Inhibitors,research,lifescience,medical against K. pneumoniae (table 3). Table 3 Minimum inhibitory concentrations (MICs) for the selected technical support essential oils and extracts against some Gram-negative bacteria In contrast, when studying the optimal concentrations that could inhibit 50% of the bacterial isolates, the X 2 values were not significant (P>0.05) for all the studied concentrations, indicating adequate fit of the Probit regression models (table 4). Table 4 Optimal inhibitory concentrations of the selected essential oils and extracts against some Gram-negative bacteria Table 5 also shows that

Ceftazidime, Cefotaxime, and Ciprofloxacin were the most effective antibiotics against E. coli O157:H7 (MIC50= 0.25, 0.5, and 2 µg/ml, respectively). Moreover, Ceftazidime and Ciprofloxacin Inhibitors,research,lifescience,medical were the most effective antibiotics against Y. enterocolitica O9 (MIC50= 0.25 and 0.5 µg/ml, Inhibitors,research,lifescience,medical respectively) and against Proteus spp. (MIC50= 4 and 2 µg/ml, respectively) and Ceftriaxone, Cefotaxime, and Ciprofloxacin were the most effective antibiotics against K. pneumoniae (MIC50= 0.25, 0.25, and 0.5 µg/ml, respectively). Table 5 Minimum inhibitory concentrations Inhibitors,research,lifescience,medical (MICs) of some antibiotics against Gram-negative bacteria Discussion Because of their safety and low cost as well as their impact on a large number of microbes,25medicinal plants may have the ability to treat bacterial resistance to many

types of antibiotics. The antimicrobial effects of aromatic oils extracted Brefeldin_A from a large number of plants have been evaluated and reviewed,26,27 and the mechanisms that enable the natural ingredients of herbs and spices to resist microbes have been discussed.28 The results show that these mechanisms vary greatly depending on the components of the essential oil.29,30 In the present study, the efficacy of some plant extracts and oils was determined, quantitatively, by measuring the diameter of the inhibition zones around the discs (table 2). Only O. syriacum. L., T. syriacus Boiss., S. aromaticum L., C. zeylanicum L., L. nobilis L., J. foetidissima Wild, A. sativum L., and M. fragrans Houtt. extracts inhibited the growth of the tested bacteria. In addition, O. syriacum. L., T. syriacus Boiss., S. aromaticum L., and C. zeylanicum L. essential oils were the most effective, and their MIC50 values varied from 1.