Antimicrobial and Antioxidant Activities of N-2-Hydroxypropyltrimethyl Ammonium Chitosan Derivatives Bearing Amino Acid Schiff Bases

N-2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC), a cationic quaternary ammonium salt polymer exhibiting good solubility in water, is widely used because of its low toxicity and good biocompatibility. Herein, through ion exchange reaction, we preparedN-2-hydroxypropyltrimethyl ammonium chitosan derivatives bearing amino acid Schiff bases with good biological activities. The accuracy of the structures was verified by FT-IR and1H NMR. The antibacterial activity, antifungal activity, and scavenging ability of DPPH radical and superoxide radical of HACC derivatives were significantly improved compared with that of HACC. In particular, HACGM (HACC-potassium 2-((2-hydroxy-3-methoxybenzylidene)amino)acetate) and HACGB (HACC-potassium 2-((5-bromo-2-hydroxybenzylidene)amino)acetate) showed good inhibitory effect on bacteria and fungi, includingStaphylococcus aureus,Escherichia coli,Botrytis cinerea,andFusarium oxysporumf. sp.cubense. The inhibition rate of HACGB onStaphylococcus aureusandEscherichia colicould reach 100% at the concentration of 0.1 mg/mL, and the inhibition rate of HACGM and HACGB onBotrytis cinereaandFusarium oxysporumf. sp.cubensecould also reach 100% at the concentration of 0.5 mg/mL. Improving antimicrobial and antioxidant activities of HACC could provide ideas and experiences for the development and utilization of chitosan derivatives.Keywords:N-2-hydroxypropyltrimethyl ammonium chloride chitosan;amino acid Schiff bases;antimicrobial activity;antioxidant activity