الفهرس 
Natural antimicrobialsOnly 14 pages are availabe for public view
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Abstract
In traditional medicine plant extracts and essential oils are known to have a bactericidal or at least a bacteriostatic effect on bacteria and /or fungi. In Egypt, medicinal plants have been used safely since ancient times as herbal medicine, for food preservation and embalming the dead. Recent years witnessed an increasing interest in medicinal plants due to the rise in multi-resistant pathogens to chemical agents, and environmental problems resulted from using chemical pesticides in agriculture.
Looking at the importance of plant antimicrobials over others, this study was carried to investigate the antimicrobial activity of Deverra tortuosa DC against three pathogenic bacteria including Escherichia coli, Bacillus subtitles and Pseudomonas fluorescence and five plant pathogenic fungi including local isolates of Fusarium oxysporum, Fusarium solani, Fusarium moniliforme, Rhizoctonia solani and Botrytis fabae.
Aerial parts of D. tortuosa DC collected from Sadat city in April 2011 subjected to hydrodistillation by a Clevenger type apparatus for essential oil. Also, aqueous and alcoholic extract was prepared using distilled water and methyl alcohol. Well diffusion method and agar dilution method are used to evaluate the antibacterial activity and antifungal activity of plant extracts. from the results, Essential oil showed bactericidal effect on all gram positive and gram negative bacteria. While, Methanol extract showed bactericidal effect on gram positive bacteria and bacteriostatic effect on gram negative one. Aqueous extract did not exhibit antibacterial effect against any of tested bacteria. Furthermore, minimum inhibition concentrations and minimum bactericidal concentrations were determined by broth dilution method. MICs - values ranged from (50 to 100 mg/ml) and from (15.6 to 62.5 μl/ml) as well as MBCs value ranged from (100 to 200 mg/ml) and (31.3 to 125 μl/ml) for methanolic extract and essential oil respectively. Among tested bacteria B.subtilis was the most susceptible to plant extracts and E. coli was the most resistant.
from the results of antifungal assay, all extracts of Deverra tortuosa exhibited antifungal activity against tested fungi in vitro. The results indicated that methanol extract was more effective than aqueous extract and essential oil exhibited the best significant activity against tested fungi. Essential oil showed complete inhibition 100% in radial growth of all tested fungi at 4 μl/ml concentration. Minimum Inhibitory Concentrations (MICs -value) of plant extracts ranged from (100 to 400mg/ml), (25 to 100 mg/ml) and from (3 to 3.4 μl/ml) as well as Minimum Fungicidal Concentrations (MFC- value) ranged from (200 to 400 mg/ml), (50 to 200 mg/ml) and (3.1 to 3.6 μl/ml) for aqueous, methanolic extract and essential oil, respectively. For both antibacterial and antifungal activities the inhibitory effect of plant extracts increased with increasing extract concentration or dose.