الفهرس 
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Abstract
SUMMARY
In the earliest recorded history , the use of plants as medicinal agents presumably predates the other natural products . A great variety of medicinal and aromatic plants as well as lichens may release allelopathic compounds that are phytotoxic and cause a disturbance for most metabolic processes resulting in reducing growth and performance.
The main objective of this study is to test the potentially of allelochemicals extracted from various plants on the growth and protein of some pathogenic microorganisms. Moreover, these antimicrobial substances will be identified.
The results are summarized as follows:
1- Extraction of the essential oils from Thymus vulgaris L (thyme) and Syzygium aromaticum L (clove) by water distillation method. The percentage of extracted oils was determined in the air- dried herb according to British Pharmacopoeia. The amount of the extracted thyme oil was (7.1ml / Kg), while the extracted clove oil was (24ml / Kg ).
2- Infra – red (IR) spectrophotometer was used to analyze the extracted thyme and clove oils to gain information on the structural properties of their components through a large number of absorption bands; each band is an indicator for a specific functional group. The major functional groups of the thyme oil were (Alkyl Halide , 1º,2º Amines, Alkene, Amine, Aromatics, 1ºAmines, Alkynes, Nitriles, Aldehydes, Alkanes, Alchols and phenols); Although the Clove oil constituents were (Alkyl Halide , 1º,2º Amines, Alkenes, Aliphatic Amines, Aromatics, 1ºAmines, Aromatics, Alkynes, Carboxylic acids, Aldehydes, Alchols and phenols).
3- The extracted oils (Thyme and Clove oils) were diluted in diethyl ether (1ml in 20ml) and analyzed with GC-MS to identify different substances within a test sample. The percentage of majors constituents of the thyme oil were thymol (49.35%), phenol,5-methyl-2-(1-methyl ethyl) (24.66%), para-cymene (7.64%), carvacryl-acetate (1.79%), trans-caryophyllene bicyclic (1.49%) and alpha-pinene (1.17%); although the clove oil constituents were eugenol (95.17%), trans (beta)-caryophyllene (2.13%) and isoeugenol (2.11%).
4- The effect of the extracted thyme and clove oils on 6 pathogenic bacteria was examined by the semi-quantitative clear zone method. Statistical analysis reveals the significance of the oil concentrations (100%, 80%, 60%, 40%, 20% & 10%) at probability level (α= 0.05) within all bacterial species. This finding determines that by increasing the concentration of both thyme and clove oils separately the inhibitory effect on the selected pathogenic bacterial species increases.
5- The absolute unit (AU) of inhibition zones for the extracted thyme and clove oils with its different concentrations were calculated. The inhibitory effect of thyme oil on all bacterial species tested was greater compared to the clove oil.
6- To predict the allelopathic effect of the extracted Thymus vulgaris L oil (thyme oil ) and Syzygium aromaticum L oil (clove oil ) three bacterial species (Agrobacterium tumefaciens, Erwinia sp. and Escherichia coli) were selected. The growth of the 3 bacterial species was monitored on LB broth in the presence and absence of (1%) thyme and clove oils separately. The presence of both thyme and clove oils in culture medium decreased the growth of the 3 bacterial species however thyme oil show more potent effect than clove oil. This allelopathic effect of the tested oils is due to its phenolic compounds such as thymol and euganol.
7- The extracellular proteins of the 3 selected bacterial species grown in absence and presence of (1%) thyme and clove oils on LB broth culture medium. The extracellular proteins were measured by Lowry method. The results reveal that thyme oil is more effective than clove in reducing the extracellular proteins of Agrobacterium tumefaciens and Escherichia coli. However, clove oil had more potent effect on Erwinia sp. extracellular proteins than thyme oil.
8- The extracted Thymus vulgaris L oil (thyme oil) and Syzygium aromaticum L oil (clove oil) caused dramatic morphological and cytological modifications to the cells of E-coli in comparison with untreated cells. The results of SEM show the damage to the E-coli cells by aggregation and collapse to each other, the treated cells size also became smaller and shrinkage in comparison with untreated cells. While the results of TEM showed an alteration in the bacterial cytoplasmic membrane and the cell wall has been disrupted and damaged, compared to untreated bacterial cells used as control the cytoplasm material was also, coagulated and aggregated near cell membrane. The results from TEM showed that thyme and clove oils affected the cytoplasmic membrane and the osmolarity of bacterial cells.
9- To predict the cytotoxicity of the extracted oils on cancer cell lines Both of thyme oil and clove oil were tested on breast cancer cell lines (MCF7), several concentrations from thyme oil and clove oil were prepared and tested on MCF7, the results show that increasing in the concentrations of thyme and clove oils increased the inhibition of growth of MCF7 cell lines.