基于细胞膜和DNA双重靶标壳寡糖基抗菌剂的设计、合成及抗菌机制研究

Food safety is a very serious problem in the global. At present, some traditional chemical preservatives, such as benzoic acid and sodium benzoate, has aroused people's attention for its strong toxicity, which has caused food safety and the green barrier problem. Antimicrobial agent with novel action mode were urgently needed than ever before. Chitosan Oligosaccharides (COS), extracted from waste of aquatic products, such as shrimp and crab shells, which is a natural polymer amino polysaccharide that have better biocompatibility, degradability, biological nontoxic, and antimicrobial activity. Hence, there is broad application prospect, for COS as natural biological antimicrobial agent. However, COS can not be used directly as a single antimicrobial agent, for its high dose, low antimicrobial activity, and narrow antimicrobial spectrum. In our study, active site of COS were modified to improve the antimicrobial activity and broaden the antimicrobial spectrum. The highest antimicrobial activity derivatives and the precise structure information of them can be obtained. After separation, purification, and structure characterization, the most efficient derivatives can also be screened through the antimicrobial activity research. Combined with molecular dynamics theory, so as to the quantitative structure-activity relationship equation can be constructed and the antimicrobial mechanism of derivatives can also be illustrated. The implementation project aims at lay the foundation of the development of high efficiency, broad spectrum, and safe biological antimicrobial agent. And there is great significance for development of marine biological resources and the high value utilization waste of aquatic products.

食品安全问题已经成为全球公众关注的焦点。目前，一些传统化学防腐剂如苯甲酸和苯甲酸钠等，因其毒性太强而引起的食品安全和绿色壁垒问题已引起人们的重视。因此，亟需开发安全安全高效的新型抗菌剂。壳寡糖是从虾、蟹壳等水产品废弃物中提取的具有良好生物相容性、生物无毒性和抗菌活性的天然高分子氨基多糖，然而壳寡糖作为单一活性组分直接用于食品防腐时，存在用量大、抗菌活性低和抗菌谱窄等问题，因此限制了其应用。本项目拟通过对壳寡糖分子链中的活性位点进行结构修饰，致力于提高其抗菌活性，拓宽抗菌谱；通过对其理化性质和活性研究，筛选出具有最强抗菌活性、安全无毒和生物相容性好的壳寡糖基抗菌剂；通过研究抗菌剂分别与细菌细胞膜和DNA的相互作用、波谱分析结合分子动力学模拟等探讨构效关系，阐明作用机制。本项目的开展将对开发安全高效的抗菌剂、完善以细胞膜和DNA为双重靶标抗菌机制的研究提供思路和基础，具有重要的理论和现实意义。

食品安全问题已经成为全球公众关注的焦点。目前，一些传统化学防腐剂如苯甲酸和苯甲酸钠等，因其毒性太强而引起的食品安全和绿色壁垒问题已引起人们的重视，因此，亟需开发安全安全高效的新型抗菌剂。壳寡糖是壳聚糖主链经物理、化学或酶降解断裂后的低分子量碱性氨基寡糖。壳寡糖具有良好的生物相容性、易降解性、生物无毒性、抗菌性和溶解性，是一种天然、绿色、安全的食品防腐剂，已成为当今国内外研究和开发的热点。但壳寡糖的抗菌活性有限，从而限制了其在食品工业中的应用，而通过对壳寡糖进行化学修饰是一种可以提高其抗菌活性的有效方法。因此，本项目通过在壳寡糖的分子链上导入具有高抗菌活性的基团，合成出一系列新型、高效的壳寡糖衍生物，对合成出的壳寡糖衍生物采用紫外-可见吸收光谱、红外光谱、核磁共振波谱、X-射线结晶衍射、热稳定性分析等检测手段，对其结构和理化性质进行全面解析，研究了壳寡糖衍生物的对金黄色葡萄球菌(Staphylococcus aureus, ATCC 25923)，酿脓链球菌(Streptococcus pyogenes, ATCC 12344)，枯草芽孢杆菌(Bacillus subtilis, ATCC 21332)；大肠杆菌(Escherichia coli, ATCC 25922)，鼠伤寒沙门氏菌(Salmonella typhimurium, CMCC 50013)，痢疾志贺氏菌(Shigella dysenteriae, CMCC 51302)等六种细菌的抗菌活性，筛选出具有最强抗菌活性、安全无毒和生物相容性好的壳寡糖基抗菌剂；通过研究抗菌剂与菌体细胞的相互作用、波谱分析等探讨构效关系并阐明作用机制。本项目的开展将对开发安全高效的抗菌剂，并对其抗菌机制的研究提供思路和基础，具有重要的理论和现实意义。