الفهرس 
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Abstract
Plants are very good sources of medicinal compounds that have continued to play a dominant role in the maintenance of human health. The use of crude extracts of plants parts and phytochemicals, of known antimicrobial properties, can be of great significance in the therapeutic treatments.
The present work was designed to investigate the antibacterial, antibiofilm and anticancer activity (cytotoxic) of some Egyptian plant extracts and evaluate bioactive compounds. Thus, they can be used in the pharmaceutical industries and food preservation, as well as the possibility of using these plant extracts as a food supplement.
Results could be summarized in the following points:
1. Fourty five pathogenic bacteria were collected from different Egyptian hospitals being 35, 6 and 4 isolates collected from El- Helal, Ahmed Maher and Abbasiya Fever hospitals, respectively.
2. These isolates were identified based on phenotypic characteristics, 16 isolates classified as Staphylococcus aureus St1-16, 15 isolates belonged to Pseudomonas aeruginosa Ps1-15, 10 isolates belonged to Escherichia coli Ec1-10 and 4 isolates identified as Salmonella sp. Sa1-4.
3. Ten ethanol extracts from leaves of grape, mulberry, mallow, lemon, purslane, rosemary & ficus, bark of black & cinnamon, and root of ginger were tested for antibacterial activity against 45 isolates. Four extracts from leaves of mulberry, grape, mallow and lemon seemed to be antibacterial agents more than another extracts.
4. Efficient leaves of mulberry, grape, mallow and lemon were selected and exposed to gamma irradiation with two doses (5 and 10 kGy), then treated by different solvents (ethanol, methanol and n-hexane) for extraction of bioactive compounds. The ethanol leaf extracts from of non-irradiated plants (non-irradiated) were preferred as antimicrobial agents against tested bacteria (which gave a large diameter zone) than irradiated plants.
5. The most sensitive isolates being S. aureus )St3(, Ps. aeruginosa )Ps9(, E. coli )Ec3( and Salmonella sp. )Sa1( were chosen, which recorded the largest diameter of inhibition zone (DIZ) with 4 selected ethanol extracts ranged from 24.5 - 32.2 mm, 23.0 - 33.2 mm, 21.5 - 31.2 mm and 16.7 - 29.2 mm, respectively
6. Minimum inhibitory concentration (MIC) values of lemon, mallow, mulberry and grape leaves ethanol extracts were 0.32 mg/ml against all selected isolates except Ps. aeruginosa Ps9 which found to be the most sensitive to lemon & mulberry extracts with MIC of 0.08 mg/ml and mallow & grape with MIC of 0.16 mg/ml.
7. Minimum bactericidal concentration (MBC) was determined for grape, mulberry, mallow and lemon leaves ethanolic extract, it was found that the MBC value of tested ethanol extracts was 0.64 mg/ml against both isolates Staph. aureus St3 & E. coli Ec3 and 1.28 mg/ml against Salmonella sp. Sa1. Whereas, the lowest MBC value was 0.32 mg/ml of all tested extracts toward to Ps. aeruginosa Ps9 except mallow extract which has MBC of 0.64 mg/ml.
8. Results cleared that 4 selected plant extracts had a bactericidal effect against both Staph. aureus St3 (Gr+ve bacteria) and E. coli Ec3 (Gr-ve bacteria) with 2 of MBC/ MIC ratio, and had bacteriostatic effect against Salmonella sp. Sa1 and Ps. aeruginosa Ps9 (as Gr-ve bacteria with ≥ 4 of MBC/ MIC ratio) except grape extract had bactericidal effect against Ps. aeruginosa Ps9 .
9. The results also showed that four tested clinical bacterial isolates were formed a strong biofilm (cells adherence) in wells with cell density ranged between 0.67 and 0.80.
10. Effect of mulberry, grape, mallow and lemon ethanol extracts on biofilm formation by selected pathogenic bacteria was tested. It was found that all plant extracts showed a remarkable effects on biofilm inhibition with percentage ranged from 41.0 to 66.% at subinhibitory concentration (SIC) ranged from 0.04 to 0.16 mg/ml.
11. Effect of different concentrations (50,100,150 & 200 μg/ml) of selected ethanol plant extracts on HCT-16 cells viability were investigated. These results indicated that ethanol extracts prepared from grape, mulberry and lemon leaves can reduce the viability of HCT-16 cells ranged from 2.8 to 21.5 %. While, viability cells was 100% in the presence of mallow extract concentrations.
12. Phenolic compounds from mulberry and grape leaves ethanolic extracts were identified qualitatively and quantitively by HPLC. Five phenolic compounds were found from both plant extracts being gallic acid (1.28, 1.82 µg/ml), coumaric acid (2.38, 4.64 µg/ml), ferulic acid (1.19, 6.56 µg/ml), chlorogenic (3.56, 2.67 µg/ml) and caffeic acid (2.6, 3.96 µg/ml) were appeared at retention time ranged between 2.51 and 9.53 min .