【摘要】 以壳寡糖(COS)为原料，利用漆酶/2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)体系对其进行选择性氧化，使其C6上的羟基变为羧基，制备出氧化壳寡糖(C-COS)。选取不饱和脂肪酸卵磷脂和亚油酸作为实验对象，进行自由基诱导的体外氧化实验。在加入COS和C-COS后，通过比较共轭二烯、丙二醛的生成量和过氧化值来考察COS和C-COS对脂质过氧化反应的抑制效果，并根据FT-IR和~1H NMR谱图比较脂肪酸的结构变化。实验结果表明，C-COS的最大抗脂质氧化抑制率为87%,相较于COS本身有显著提高，提升量最大达到55%。推断C-COS抗脂质氧化的机理是其氨基与羧基的协同作用，氨基可以提供电子来捕获自由基，羧基可以螯合金属离子同时将更多的氨基暴露在糖链的外侧，进而更有效地保护不饱和脂肪酸。更多还原

【Abstract】 Carboxylated chitosan(C-COS) is prepared by selective oxidation of chitosan(COS) using laccase/2,2,6,6-tetramethylpiperidine-1-oxyl radical(TEMPO) system to change its hydroxyl group on C6 to carboxyl group. Free radical-induced in vitro lipid oxidation experiments are performed using lecithin and linoleic acid as the experimental subject. After the addition of COS and C-COS, the inhibitory effect of COS and C-COS on lipid peroxidation is investigated by comparing the production and peroxide value of conjugated diene and malondialdehyde, and the structural changes of fatty acids are compared according to FT-IR and ~1H NMR spectra. Results show that the maximum anti lipid oxidation inhibition rate of C-COS is 87%, which is higher than that of COS, and the maximum increase is 55%. The amino and carboxyl groups on C-COS act together to effectively capture free radicals from providing electrons and chelating metal ions, so as to avoid lipid peroxidation.更多还原