基于对PI3K/AKT信号通路影响及靶点构效关系的茶多糖TPC-3降血糖作用机制研究

China is very rich in tea resources with many varieties, some of which are famous all over the world. However, plenty of the tea resources lack of effective utilization. In our previous studies, tea polysaccharide fraction TPC-3 was found to decrease blood sugar in hyperglycemia mice models. In recent years, more and more people in China are suffered the disease of hyperglycemia. The tea resources need urgently to be utilized. The purpose of this study is to investigate the hypoglycemic mechanism of TPC-3 based on the adjustment of the PI3K/AKT pathway and the targeted structure-activity relationship. By the new established in vivo and in vitro hypoglycemic models, the hypoglycemic mechanism of TPC-3 will be studied based on the PI3K/AKT signal pathway, which involves the critical protein molecules such as PI3K, Akt and Glut-4.So the function mechanism will be illustrated by the adjustment of the mRNA and protein expression of targeted proteins.The molecular docking and molecular dynamics calculation technology will be used to investigate the interation of tea polysaccharide TPC-3 and the targeted proteins.We will also explore the molecular chain conformation of TPC-3 and the targeted structure-activity relationship. The results will provide the theoretical fundation and science basis for the comprehensive utilization and development of tea resources, prevention of diabetes, the exploration of tea polysaccharides. The results of the study will also provide the referential experience and new ideas for the study of structure-activity relationships of the plant polysaccharide.

我国茶叶资源丰富，但远未得到有效利用。在前期发现粗老茶中提取的多糖组分TPC-3具有降血糖作用的基础上,针对我国目前糖尿病患者逐年增加以及茶叶资源亟待有效利用的问题，本项目提出"基于对PI3K/AKT信号通路影响及靶点构效关系的茶多糖TPC-3降血糖作用机制研究"这一课题，旨在以胰岛素信号通路的关键蛋白分子PI3K、Akt、及Glut-4为靶点，通过最新糖尿病动物模型和细胞培养的药理方法及分子模拟、分子对接的方法技术，探究TPC-3对靶点分子的影响，解析TPC-3与靶点分子的相互作用模式及结合位点，从分子、基因水平揭示茶多糖降血糖的作用机制。利用高分子溶液理论和构象研究方法表征TPC-3的分子链构象并构建其分子模型，揭示茶叶中多糖的分子构象与血糖调节活性的靶点构效关系。研究结果将为糖尿病的防治和茶叶资源的综合深度利用提供理论基础和科学依据，为植物多糖的构效关系研究提供新的思路与借鉴。

我国茶叶资源丰富，但远未得到有效利用。在前期发现粗老茶中提取的多糖组分TPC-3具有降血糖作用的基础上，针对我国目前糖尿病患者逐年增加以及茶叶资源亟待有效利用的问题，本项目以2型糖尿病为研究对象，通过体内外活性模型、动物模型评价体系、胰岛素信号理论评价茶多糖对血糖调节的功效作用机制；采用高效凝胶色谱、气相色谱、扫描电镜和原子力显微镜等方法技术比较分析表征了不同茶多糖组分及修饰衍生物的理化性质及结构的变化，探讨了构效关系；研究了茶多糖的体外模拟消化前后的理化性质和α-淀粉酶抑制活性；从动力学和分子对接角度研究了茶多糖和EGCG与α-葡萄糖苷酶的相互作用机制。研究结果表明，茶多糖能够增强糖尿病小鼠的葡萄糖耐受，增加因糖尿病减少的体重，明显提高肝脏和肾脏中的SOD、GPX以及CAT等抗氧化酶活性（p<0.05），同时茶多糖能够上调PT3K/Akt信号通路中的关键靶点分子蛋白如PI3K、p-Akt和GLUT4的表达量（p<0.05）。研究结果为糖尿病的防治和茶叶资源的综合深度利用提供理论基础和科学依据，为植物多糖的构效关系研究提供新的思路与借鉴。