To improve the solubility and bioactivity of chitosan, a new class of carboxymethyl chitosan derivatives possessing sulfonium salts was successfully designed and synthesized, including Methyl sulfide carboxymethyl chitosan (MCMCS), Ethyl sulfide carboxymethyl chitosan (ECMCS), Propyl sulfide carboxymethyl chitosan (PCMCS), and Butyl sulfide carboxymethyl chitosan (BCMCS). To determine the structure of the new class of the derivatives, methods of the Fourier transform infrared spectroscopy (FT-IR), 1 H nuclear magnetic resonance spectrometer ( 1 H NMR), and 13 C nuclear magnetic resonance spectrometer ( 13 C NMR) were used. Moreover, the antioxidant activity of the derivatives for three types of free radicals, i.e., hydroxyl radical, superoxide radical, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical was evaluated in vitro. In addition, the L929 cells were adopted to test the cytotoxicity of chitosan and its derivatives by CCK-8 assay. The class of the carboxymethyl chitosan derivatives showed a strong scavenging ability against the three free radicals at 1.6 mg/mL, with scavenging rate of over 70％ and some up to 100％. At this high rate, the overall cell viability in the toxicity test reached more than 80％, indicating that the synthetic derivative had a little cytotoxicity. The results show that the introduction of carboxymethyl group to chitosan increased the water-solubility of chitosan, and the combination of sulfonate ions with different chain lengths further enhanced the antioxidant activity of chitosan. Therefore, the sulfonium-containing carboxymethyl chitosan derivatives had excellent bioactivity with good application prospects in food, biomedicine, and medical fields.

Xueqi SUN;Jingjing ZHANG;Yingqi MI;Qin MIAO;Wenqiang TAN;Qing LI;Zhanyong GUO

Key Laboratory of Coastal Biology and Bioresource Utilization,Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences,Yantai 264003,China;Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China;University of Chinese Academy of Sciences,Beijing 100049,China

海洋湖沼学报（英文版）

[1]Xueqi SUN;Jingjing ZHANG;Yingqi MI;Qin MIAO;Wenqiang TAN;Qing LI;Zhanyong GUO-.Synthesis, characterization, and antioxidant activity of carboxymethyl chitosan derivatives containing sulfonium salt)[J].海洋湖沼学报（英文版）,2022(01):284-295

sulfonium,MCMCS,ECMCS,PCMCS,BCMCS

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