Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Organic Chemistry

Three heteroaryl pyrazole derivatives; namely: 1-phenyl-3-(thiophene-2-yl)-1H-pyrazole-4-carbaldehyde,1-phenyl-3-(furan-2-yl)-1H-pyrazole-4-carbaldehyde, 1-phenyl-3-(pyridine-3-yl)-1H-pyrazole-4-carbaldehyde were synthesized. In addition, some Cs-Schiff bases containing thiophene, furan and pyridyl nucleus have been synthesized. Characterizations of the prepared compounds via FTIR ¹ H NMR, elemental analysis, X-ray diffraction, SEM, and TGA were carried out. The prepared Cs-Schiff bases were screened for their biological activity against gram-negative bacteria (Escherichia coli and Klebsiella pneumonia), gram-positive bacteria (Staphylococcus aureus and Streptococcus mutans) and fungi (Aspergillus fumigatus and Candida albican). Preliminary cytotoxicity tests were performed using MTT assay with normal retina cell line. Besides, the prepared Cs-Schiff-bases loaded with different contents of silver nanoparticles (AgNPs) have been synthesized, characterized and preliminary evaluated as Schistosomacidal activity agents. Finally, partially cross-linked chitosan Schiff bases have been synthesized using bis-aldehydes, namely butane-1,4-diyl bis(4-formylbenzoate), N,N'-(butane-1,4-diyl)bis(2-(4-formylphenoxy)acetamide) and 4,4{u2032}-(butane-1,4-diylbis(oxy))dibenzaldehyde. The influence of the type and the amount of used bis-aldehyde and pH of the media on the swelling of the prepared chitosan derivatives was investigated. It was found that the extent of swelling of the chitosan derivative increased with increasing the extent of crosslinking, contrary to the expectation. The loading efficacy of sodium salicylate (SS), as a model of drug, and its release behavior from these derivatives at pH of the media 4.0 and 7.4 were tested. The results showed that the loading efficiency and encapsulation were slightly dependent on the type of cross-linking agent. In vitro, SS release behavior showed that the release was affected by pH of the media and type of the bis-aldehyde crosslinker

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