الفهرس 
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Abstract
The present study is concerned with the design and synthesis of new hybrids of benzimidazole-oxadiazole and the biological evaluation of their anticancer activities. The thesis consists of four main sections: introduction, the aim of the work, results & discussion, and experimental sections in addition to references and summary.
1-Introduction
The Introductory chapter consists of three sections; The first section gives an overview of cancer’s meaning, causes, symptoms, and statics. The second section of the introduction involves a brief look at molecular hybridization’s meaning and advantages. The third section includes the anticancer activity of benzimidazoles as a potent anticancer scaffold with different mechanisms of action such as induction of apoptosis or ferroptosis, inhibition of one or more of the following targets: BRAF, EGFR, tubulin polymerization, topoisomerase I & II, glutathione S-transferase enzyme and COX-2 enzyme, cell cycle arrest at different phases, and DNA interaction.
2-Aim of the work
This section covers the major aims and rationale for this effort, which includes the synthesis of target compounds, biological assessment of the anticancer activity of the generated compounds, and investigation of the mechanism of the anticancer activity induced by the prepared compounds as EGFR, BRAF, induction of apoptosis, and studying their effect on inhibition of tubulin polymerization.
3- Results and discussion
This chapter deals with a discussion of the results obtained and it is subdivided into three main sections:
A- Chemistry section:
Chemistry section, which includes description of the different methods used for the synthesis of intermediates and the final target compounds by the alkylation reactions of benzimidazole-oxadiazole derivatives with 2-bromo-N-(4-(3-arylacryloyl)-phenyl) acetamides/acetate derivatives, allyl bromide/benzyl bromide, 2-bromo-N-phenyl-acetamides and formation of oxime to give one hundred and thirty final compounds 12a:o,13a-k, 19a-x, 20a-f, 21a-j, 22a-c, 23a-c, 24a-e, 25a-e, 28a-r and 29-58. In this thesis, we reported the synthesis of fifty-nine intermediates including thirteen new intermediates 6a, 6c-e, 17a-b,17d-e, and 18a-e.
Structures of the final compounds were elucidated by different spectroscopic techniques including 1H-NMR, 13CNMR, HRMS as well as elemental microanalyses.
B- Biology section:
Biology is subdivided into three parts:
I. Evaluation of the antiproliferative activity:
from the final synthesized hybrids, one hundred and nine compounds; (12a-o, 19a-h, 19k-r, 19u, 19v, 20a-f 21a-j, 22a-c, 24a-c, 23a-e, 25a-e, 28a-r, 29-53, and 55) were chosen by National Cancer Institute (NCI) for the in vitro anticancer screening against different cell lines. Results revealed that some of the tested compounds exhibited moderate to remarkable anticancer activity against some of the tested cell lines. Moreover, seventeen compounds 21f-i, 23b, 25b-c, 28b-d, 28g-j, 28n, and 36-37 were selected for five-dose assay and the tested compounds exhibited a remarkable and broad-spectrum antitumor activity with no selectivity towards the tested cancer cell lines except compounds 28g and 28j which showed moderate selectivity against prostate cancer cell line.
II-In vitro toxicity assay in normal cells (cell viability assay)
Evaluation of the safety profile of some of the target compounds; 12a–o, 13a–k, 19a-x, 20a-f, and 21a-j on a normal human mammary epithelial cell line (MCF‐10A) was done.
III- In vitro antiproliferative assay
Evaluation of the effect of compounds 12a–o, 13a–k, 19a-x, 20a-f, and 21a-j on the proliferation of four cancer cell lines: epithelial line (A‐549), colon cancer cell line (HT‐29), breast cancer cell line (MCF‐7), and pancreatic cancer cell line (Panc‐1). Additionally, compounds 19g, 19l, 19p, 19q, and 19v were examined for their anti-proliferative effect on LOX-IMVI cells and results showed that these compounds showed significant activity and they were more potent than the reference drug Staurosporine against LOX-IMVI cells.
V- EGFR inhibitory activity assay
Compounds 12g-i and 13g-i, 19e, 19g, 19h, 19k-n, 19p, 19q, 19v, 20a, 20b, 21e, 21f, 21i and 21j were used for evaluation of their EGFR inhibitory activity. Results showed moderate to potent activity of the compounds versus EGFR.
VI-BRAFV600E inhibitory activity
Evaluation of BRAF inhibitory activity were done by using compounds 12g-i and 13g-i, 19e, 19g, 19h, 19k-n, 19p, 19q, 19v, 20a, 20b, 21e, 21f, 21i and 21j. All compounds displayed moderate to potent BRAFV600E inhibitory activity.
VII- Tubulin polymerization inhibitory activity
Evaluation of the effect of compounds 12g-i and 13g-i on inhibition of tubulin polymerization and results showed that the tested compounds displayed a weak effect on inhibition of tubulin polymerization.
VIII- Apoptosis assay
Compounds 12g, 12h, and 19k were used for cell cycle analysis and apoptosis detection. All compounds arrested the cell cycle by induction of apoptosis.
VIIIa- Caspases assays
Evaluation of the effect of compounds 19k, 19l, and 19m on caspases (3, 8, and 9). Results showed that compounds induced overexpression of caspases (3, 8, and 9) levels and activated both the intrinsic and extrinsic pathways.
VIIIb- Cytochrome C Assay
Compounds 19k, 19l, and 19m were used to evaluate cytochrome c levels. Results showed that the compounds increased levels of cytochrome C.
VIIIc-Expression levels of BAX and Bcl-2 proteins
The effect of compounds 19k, 19l, and 19m on BAX and Bcl-2 protein levels in the MCF-7 breast cancer cell lines was studied further using Doxorubicin as a positive control. Results indicated that compounds decreased Bcl-2 and increased BAX levels. Moreover, compound 19k induced BAX levels like doxorubicin.
c- Molecular modeling section:
In this section, molecular docking simulation was used to investigate the binding mode of the most potent final compounds on different proteins according to the mechanism of action within the EGFR enzyme and BRAF enzyme.
4. Experimental
This section describes the detailed protocols for the various experiments that were used. It is subdivided into three sections:
a-Chemistry section:
chemistry section: This section explains the various processes utilized to produce intermediates and final compounds. This section also includes all the newly prepared compounds’ full spectroscopic and analytical data.
b-Biology section:
Biology section, which outlines the procedures used to investigate the anticancer activity of the synthesized compounds. It is formed from two parts; the first one includes the methodology for measuring the anticancer activity at the National Cancer Institute (NCI) of the selected compounds. The second part includes the procedure of antiproliferative assay of all the synthesized compounds studying the mechanism of cytotoxicity.