60Co-γ射线辐照修饰毛木耳多糖及其降血脂活性构效关系的研究

Polysaccharide is the main active ingredient of Auricularia polytricha with a wide range of pharmacological effects which was developed as an important functional material. However, there is lack of adequate structure characterization of Auricularia polytricha polysaccharide (APP) , and structure-activity relationship of the polysaccharide is unclear. Our previous study found that the solubility and lipid-lowering activity of APP significantly increased after 60Co-γ ray irradiation. This may be related to changes in the physical and chemical properties and structure of APP modified by irradiation. In order to clarify the relationship between APP structure and lipid-lowering activity, the structure characterization of APP modified by irradiation is analyzed, including physical and chemical properties (solubility, viscosity, molecular weight) and structure characterization (monosaccharide components and glycoside bond configuration) .In addition, lipid-lowering activity is investigated to explore the effects of changes in physical and chemical properties and structure of APP after γ ray irradiation. This study will contributed to reveal the mechanism of lipid-lowering activity and provide a theoretical basis for the development of APP product and other polysaccharides drugs design.

多糖是毛木耳的主要活性成分，具有广泛的药理作用，是一种亟待开发的重要功能产品原料。但目前毛木耳活性多糖片段的结构信息缺乏，多糖结构与功能间的构效关系尚不明确。课题组在前期研究中发现，毛木耳多糖经60Co-γ射线辐照后，其溶解度与降血脂活性显著提高。这可能与辐照处理改变了毛木耳多糖的理化性质和结构有关。因此，本项目拟通过60Co-γ射线辐照对毛木耳多糖进行分子修饰，系统研究毛木耳多糖的溶解度、黏度及分子量等理化特性的变化，重点分析毛木耳多糖的单糖组分和连接方式、糖苷键构型等结构，从而明确γ射线对毛木耳多糖的理化性质及结构的影响。此外，项目进一步评价毛木耳多糖理化性质及结构的变化对降血脂活性的影响，解析具有活性的多糖片段的关键结构特性，探讨毛木耳多糖的结构与其降血脂活性的构效关系，揭示毛木耳多糖降血脂活性的作用机制，为毛木耳多糖类药物的开发及其他多糖产品的设计提供理论依据。

毛木耳是我国大宗优势药食两用的食用菌代表品种，不仅营养丰富还具有多种药理活性。多糖是毛木耳的主要活性成分之一，但是由于木耳多糖的分子量较大，溶解性低，限制了木耳多糖的进一步开发及利用。本项目利用高效提取技术获得毛木耳精多糖，通过不同剂量的60Co-γ射线辐照处理，结果发现毛木耳多糖的粘度和分子量有不同程度的下降，溶解度增加，热稳定性也发生改变，扫描电镜结果发现辐照修饰的多糖表明光滑、断裂明显。进一步结构分析发现多糖的糖苷键断裂并且伴随着双键的形成，这说明毛木耳多糖在辐照处理后发生降解并且伴随着氧化反应的发生。此外，辐照修饰后的毛木耳多糖能够降低高血脂小鼠的体重，并且显著降低血清中的总胆固醇、低密度脂蛋白的含量，降血脂活性有明显的提高。项目采用γ射线辐照修饰多糖，并探讨毛木耳多糖的理化性质、结构与其降血脂活性之间的关系，为毛木耳多糖类产品的开发提供理论依据，也为食用菌多糖的修饰提供了新的途径。