Because the values of minimum bactericidal concentration (MBC) and MIC are usually very similar,31 it can be logically assumed that the above-mentioned plant extracts and oils have a bactericidal effect on Gram-negative bacteria, especially against Proteus spp. and K. pneumoniae. The Probit Analysis (table 4) revealed that the minimum concentrations of the essential oils that could inhibit 50% of the various bacteria were T. syriacus
Boiss. for E. coli O157H7 (7.85 µl/ml), O. syriacum. L. for Proteus spp. and Y. enterocolitica (1.12 and 1.59 µl/ml, respectively), and S. aromaticum for K. pneumoniae (1.33 µl/ml). Ooi et al.32 reported that Cinnamomum verum shows excellent activities against E. coli and Proteus vulgaris. Preuss et al.33 Inhibitors,research,lifescience,medical found that origanum essential oil proves cidal to E. coli and K. pneumoniae.
In addition, Barbosa et al.34 found that the MIC90 of Origanum vulgare essential oil is 0.46% (v/v) against E. coli. López et al.35 found that 8-10% Inhibitors,research,lifescience,medical (v/v) concentrations of Origanum vulgare essential oil can completely inhibit the growth of E. coli and other Gram-negative bacteria. Elsewhere, Mkaddem et al.36 reported that Mentha essential oils are very active against K. pneumoniae Inhibitors,research,lifescience,medical bacteria, whereas they are less effective against E. coli. Furthermore, Mentha longifolia oil is thought to exhibit an antimicrobial activity against some Gram-positive bacteria such as Streptococcus mutans and Staphylococcus Inhibitors,research,lifescience,medical aureus, but without affecting Pseudomonas aeruginosa.37 Since the antibacterial effectiveness of medicinal plants varies dramatically depending on the phytochemical characteristics of plant families and subfamilies, it is not surprising to note the difference in this efficacy even when using samples taken from the same plant, but from two different regions.38 Our Inhibitors,research,lifescience,medical results reveal that the cephalosporins were the most effective antibiotics against almost all the studied bacteria, and only
Ciprofloxacin, one of the fluoroquinolones group, was effective against these bacteria. Conclusion O. syriacum. L., T. syriacus Boiss., S. aromaticum L., C. zeylanicum L., J. foetidissima Astemizole Wild, A. sativum L., and M. fragrans Houtt. oils and L. nobilis L. extract were the most effective plant extracts against the Gram-negative bacteria studied in this work. These plant extracts could be a potential source of new antibacterial agents. Further and more specific studies, in vivo, are recommended to determine the efficacy of these essential oils in the treatment of gram-negative bacterial infections. Acknowledgment The Cyclopamine chemical structure authors would like to thank the Director General of the Atomic Energy Commission of Syria (AECS) and the head of the Department of Molecular Biology and Biotechnology for their support. Conflict of Interest: None declared.
Background: Application of follicular fluid (FF) and platelet-activating factor (PAF) in artificial insemination improves sperm motility.