In the present study, four new chitosan oligosaccharide derivatives bearing quinolinyl urea groups were syn-thesized by reaction between 2-methoxyformylated chitosan oligosaccharide and aminoquinoline. The chitosan oligosaccharide derivatives were characterized by Fourier Transform Infrared (FTIR) and 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy. The obtained results confirmed that chitosan oligosaccharide quinolinyl urea derivatives were successfully synthesized. Meanwhile, the antioxidant activities of different chitosan oligosac-charide derivatives were examined in vitro. Experimentally, it was demonstrated that chitosan oligosaccharide quinolinyl urea derivatives had superior antioxidant activity compared with chitosan oligosaccharide and the antioxidant effects were concentration-dependent. Especially, when the concentration was 1.6 mg/mL, their superoxide anion radical scavenging rates could reach to 72.35 +/- 0.49%, 100.00 +/- 0.21%, 84.63 +/- 0.49%, and 87.22 +/- 0.32%, respectively. And the hydroxyl radical scavenging rates could reach to 100.00 +/- 0.82%, 98.49 +/- 4.08%, 100.00 +/- 5.76%, and 92.07 +/- 5.10%. In addition, the cytotoxic activity of the prepared chitosan derivatives against L929 cells was determined by CCK-8 assay. The cell survival rates were all higher than 90%, which intuitively indicated that the samples had almost no cytotoxicity. The findings indicated that the enhanced antioxidant property and biocompatibility of these chitosan oligosaccharide quinolinyl urea derivatives could enlarge the scope of the application of chitosan oligosaccharide, particularly as an antioxidant in food packaging, biomedical, pharmaceutical, cosmetics industries and other fields.
