Jin Xiaoxiao, Wang Jiangtao, Bai Jie
Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China.
Carbohydr Res. 2009 Apr 21;344(6):825-9. doi: 10.1016/j.carres.2009.01.022. Epub 2009 Feb 21.
Chitosan, a biocompatible, biodegradable, non-toxic polymer, is prepared from chitin, which is the second most naturally occurring biopolymer after cellulose. The Schiff base of chitosan was synthesized by the reaction of chitosan with citral working under high-intensity ultrasound. The effect of the molar ratio of chitosan to citral, reaction time, and temperature on the yield has been investigated. The optimal conditions were a temperature of 50 degrees C, a molar ratio of chitosan to citral of 1:6, and a reaction time of 10h. The maximum yield achieved was 86.4% under optimum conditions. The structure of the Schiff base was characterized by FTIR spectroscopy, elemental analysis, and X-ray diffraction studies. The strong peaks at 1648.3 and 1610.6 cm(-1) are due to C=N and C=C stretching vibrations. The results confirmed that amino groups on chitosan reacted with citral to form the Schiff base. The antimicrobial activities of chitosan and Schiff base of chitosan were investigated against Escherichia coil, Staphylococcus aureus, and Aspergillus niger. The results indicate that the antimicrobial activity of the Schiff base increases with an increase in the concentration. It was also found that the antimicrobial activity of the Schiff base was stronger than that of chitosan.
壳聚糖是一种生物相容性、可生物降解、无毒的聚合物，由几丁质制备而成，几丁质是仅次于纤维素的第二大天然存在的生物聚合物。壳聚糖席夫碱通过壳聚糖与柠檬醛在高强度超声作用下反应合成。研究了壳聚糖与柠檬醛的摩尔比、反应时间和温度对产率的影响。最佳条件为温度50℃、壳聚糖与柠檬醛的摩尔比为1:6、反应时间为10小时。在最佳条件下获得的最大产率为86.4%。通过傅里叶变换红外光谱（FTIR）、元素分析和X射线衍射研究对席夫碱的结构进行了表征。1648.3和1610.6 cm-1处的强峰归因于C=N和C=C伸缩振动。结果证实壳聚糖上的氨基与柠檬醛反应形成了席夫碱。研究了壳聚糖及其席夫碱对大肠杆菌、金黄色葡萄球菌和黑曲霉的抗菌活性。结果表明，席夫碱的抗菌活性随浓度增加而增强。还发现席夫碱的抗菌活性比壳聚糖强。
