壳聚糖氨基正电性与抑菌活性的量化关系研究

壳聚糖是一种安全无毒、生物量大、可自然降解的天然阳离子氨基多糖。研究表明壳聚糖能有效抑制多种致病性微生物的生长，有望被开发成绿色抑菌剂。基于化学修饰提高壳聚糖的抑菌活性，多年来一直是壳聚糖研究的重点和热点之一。大量研究表明壳聚糖的氨基正电性是影响其抑菌活性的重要因素。本项目旨在研究壳聚糖氨基正电性与其抑菌活性的量化关系。本项目拟借助量子化学，利用Gaussian软件对壳聚糖衍生物进行结构优化、计算氨基正电性，选择氨基正电性高的壳聚糖衍生物作为目标化合物。根据目标化合物的结构设计合成路线，通过有机合成或半合成的方法合成目标化合物，并以危害性大的茶叶炭疽病菌和大肠杆菌等致病微生物为模型测试其抑菌活性。利用数据分析软件处理数据，建立氨基正电性和抑菌率之间的关系模型，量化壳聚糖氨基正电性与抑菌活性的关系，为深入研究壳聚糖抑菌机理和开发具有好的抑菌活性的壳聚糖衍生物提供一定的理论依据。

Chitosan, a kind of renewable, abundant natural cationic polysaccharide, could effectively inhibit growth of many harmful microorganisms. It has already been well studied and sufficiently reported that chitosan is non-toxic, biodegradable, and biocompatible, which make it a promising candidate to be developed as an antibacterial agent. It indicates that the amino cationic property of amino groups of chitosan molecules is a key factor that affects the antimicrobial activity of chitosan. This project plans to adopt quantum chemistry to investigate the relationship between amino cation and antimicrobia activity of chitosan. Especially, the popular software in quantum chemistry Gaussian is used to optimize the structure and calculate amino cation of chitosan derivatives with different substituents. Then the putative chitosan derivatives with high amino cation by Gaussian are selected. After that, according to their sturcure, the synthesis routes of putative chitosan derivatives are designed. The synthesized chitosan derivatives by organic synthesis or semi synthesis method are investigated antimicrobia activity against bacteria and fungi such as Escherichia coli and Gloeosporium theae-sinensis. Based on the analysis by data processing software, the relationship model between amino cation and antimicrobia activity of chitosan is established. This work will provide a practical strategy to explain the antimicrobial mechanism and develop new chitosan derivatives with patent antimicrobial activity.