Chitosan-Based Schiff Base Compounds: Synthesis, Chemical Characterization and Antibacterial Properties

The focus of the study was the synthesis, characterization, and investigation of the antibacterial properties of chitosan Schiff bases (CHSB) and crosslinked chitosan Schiff bases (CCHSB) resulting from the reaction of chitosan with 2,3-dihydroxybenzaldehyde and epichlorohydrin. The physicochemical properties of the synthesized compounds were analyzed using 1H NMR, FTIR, XRD, SEM, and TGA techniques. The chemical shifts of chitosan appeared between 1.78 and 4.71 ppm. Aromatic ring protons from the Schiff base appeared between 6.68 and 7.79 ppm. Epichlorohydrin methylene protons for crosslinking were observed as triplets in the range of 1.24-1.04 ppm in the 1 H-NMR spectrum of cross-linked Schiff bases. The antibacterial activity of the chitosan and Schiff base derivatives on gram-negative bacteria (Escherichia coli and Salmonella typhimurium) and gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) was compared with the drugs amikacin and gentamicin. Results showed that the chitosan derivatives exhibited antibacterial properties, with inhibition zones ranging from 8 to 30 mm. Chitosan derivatives demonstrated antibacterial activity comparable to standard drugs like amikacin and gentamicin, suggesting their potential as effective alternatives or adjuncts in treatments. These findings indicate that chitosan and its derivatives have the potential to be utilized as effective antibacterial agents or alternatives in a variety of medical domains. Additionally, chitosan derivatives may serve as natural preservatives in the food industry by inhibiting microbial growth, thereby extending the shelf life of perishable products and ensuring their quality and safety.