Synthesis, characterization and antimicrobial activity of a novel chitosan Schiff bases based on heterocyclic moieties.

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 and 1-phenyl-3-(pyridine-3-yl)-1H-pyrazole-4-carbaldehyde were synthesized and reacted with chitosan to form Schiff bases of chitosan. All newly synthesized compounds have been characterized by solubility tests, elemental analysis, spectral (FTIR, 1H NMR) analyses, thermogravimetric analysis and X-ray diffraction (XRD). The 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 (Asperagillus fumigatus and Candida albican). The results indicated that the antimicrobial activity was dependent on the type of the Schiff base moiety. Cytotoxicity of the prepared chitosan derivatives was evaluated by MTT assay and the results indicated the absence of cytotoxic activity.