Preparation of Novel Chitosan Oligosaccharide Quaternary Ammonium Derivatives Bearing Quinoline with Antioxidative and Antibacterial Activities

Abstract

AbstractIn this study, five new chitosan oligosaccharide quaternary ammonium derivatives bearing quinoline are synthesized by reaction between 6‐O‐chloroacetyl‐2‐N, N, N‐trimethyl quaternary ammonium salt chitosan oligosaccharide (CTCOS, compound 1) and quinoline derivatives. The derivatives are characterized by analytical techniques including Fourier Transform Infrared (FTIR), 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy, and elemental analysis. The obtained results confirm that quinoline groups are successfully introduced into the CTCOS molecule. Meanwhile, the antioxidant activities of the prepared chitosan oligosaccharide derivatives are evaluated in vitro. The experimental results show that the derivatives have excellent free radical scavenging ability. The free radical scavenging abilities are all over 75% at the concentration of 1.6 mg mL−1. Moreover, antibacterial tests show that derivative 2e has the best antibacterial activities. Its minimum inhibitory concentration (MIC) value and minimum bactericidal concentration (MBC) value against Staphylococcus aureus and Escherichia coli are 0.0625 and 0.03125 mg mL−1, respectively. In addition, the cytotoxicity of chitosan oligosaccharide and its derivatives is examined by MTT colorimetric assay in RAW 264.7 macrophages, observing that all derivatives are non‐cytotoxic. Consequently, the findings indicate that the enhanced antioxidant activity, antibacterial activity, and biocompatibility of these chitosan oligosaccharide derivatives can enlarge the scope of the application of chitosan oligosaccharides, particularly as antioxidant and antibacterial agents in food packaging, pharmaceutical, cosmetics industries, and other fields.