Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
J Biosci Bioeng. 2011 Feb;111(2):212-6. doi: 10.1016/j.jbiosc.2010.09.018. Epub 2010 Oct 29.
In this study, the antioxidant activities of different molecular weights (M(w)) and grafting ratios of chitosan-caffeic acid derivatives were investigated. The grafting process was achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) as covalent connector under different conditions such as molecular-weight of chitosan, molar ratio of chitosan and caffeic acid, reaction temperature, pH, and reaction time. The half-inhibition concentrations (IC₅₀) of products were calculated by reduction of the 1,1-diphenyl picryl hydrazyl in the radical-scavenging assay and reduction of the Fe³+/ferricyanide complex to the ferrous form in reducing power assay. The EDAC showed maximum activity at 3-h, pH 5.0 and room temperature conditions, except high-molecular-weight chitosan in pH 2.0. The products were water-soluble in all pH and showed lower viscosity than native chitosan. The highest grafting ratio of caffeic acid was observed at 15% in low-molecular-weight chitosan. After 5% grafting of caffeic acid into chitosan, the grafting efficiency was increased by decreasing molecular-weight of chitosan at the same conditions. Caffeic acid has main role in the antioxidant activity of products. The maximum IC₅₀ of radical-scavenging activity (0.064 mg/ml) was observed at the highest caffeic acid containing derivative. Water-soluble chitosan and caffeic acid derivatives were obtained by this study without activity loss.
在这项研究中，研究了不同分子量（M(w)）和接枝率的壳聚糖-咖啡酸衍生物的抗氧化活性。接枝过程是在不同条件下使用 1-乙基-3-(3-二甲基氨基丙基)碳二亚胺盐酸盐（EDAC）作为共价连接物实现的，如壳聚糖的分子量、壳聚糖和咖啡酸的摩尔比、反应温度、pH 值和反应时间。通过自由基清除测定中 1,1-二苯基-2-三硝基苯肼（1,1-diphenyl picryl hydrazyl）的还原和还原力测定中三价铁/铁氰化物复合物还原为二价铁的方式计算产物的半抑制浓度（IC₅₀）。EDAC 在 3 小时、pH5.0 和室温条件下表现出最大活性，但在 pH2.0 下高分子量壳聚糖除外。产物在所有 pH 值下均为水溶性，且比天然壳聚糖的粘度低。在低分子量壳聚糖中观察到最高的咖啡酸接枝率为 15%。在相同条件下，当壳聚糖的分子量降低时，咖啡酸的接枝效率增加，接枝 5%的咖啡酸后。产物的自由基清除活性的最大 IC₅₀（0.064mg/ml）出现在含咖啡酸衍生物最高的情况下。本研究获得了水溶性壳聚糖和咖啡酸衍生物，没有活性损失。
