人参皂苷增强自噬的构效关系以及改善阿尔茨海默症的作用研究

Studies have shown that ginsenosides have better effects on improving neurodegenerative diseases. Our previous work found that ginsenoside Rg2 reduced Aβ oligomer in Alzheimer's (AD) mouse brain through the activation of autophagy, thereby improving mouse learning and memory function. After that, we also found that the abilities of protopanxadiol type ginsenosides to induce autophagy were closely related to their sugar chain structure. On this basis, this project will study the structure-activity relationship of ginsenosides on enhancing autophagy and their roles in improving of AD. The research includes: using 3 types of neural cells, GFP-LC3 stable cell and transgenic mice to study the effects of 12 protopanxadiol type ginsenosides and 7 protopanxatriol type ginsenosides on autophagy induction, analyze different types of ginsenosides and different sugar chain structures in the same ginsenoside on their ability to induce autophagy; to study the mechanisms of ginsenosides on autophagy activation, such as whether they are all related to the AMPK/mTOR/ULK1 signaling pathway; using AD mice and autophagy-deficient AD mice, the two ginsenosides with strongest autophagy induction were examined for their roles in improving AD by enhancing autophagy and reducing Aβ oligomers; then three ginsenosides with different mechanisms were combined to study the roles of ginsenosides in the cooperative therapy of AD. The results provide theoretical basis for further understanding of the pharmacological effects of ginseng and candidates for the development of treatment of AD.

研究已经表明人参皂苷能够较好地改善神经退行性疾病。我们前期工作发现人参皂苷Rg2激活自噬，减少阿尔茨海默症（AD）小鼠脑中Aβ寡聚体，从而改善小鼠的学习和记忆。进一步研究发现原二醇型皂苷诱导自噬能力与其糖链结构相关。因此，本项目拟研究人参皂苷增强自噬的构效关系以及改善AD的作用。研究内容包括：利用3种神经细胞、GFP-LC3稳转细胞和转基因小鼠，研究12种原二醇型和7种原三醇型人参皂苷诱导自噬作用，分析两类皂苷及同一类皂苷分子中不同的糖链结构对其诱导自噬能力的影响；基于AMPK/mTOR/ULK1信号通路，研究人参皂苷激活自噬的机制；利用筛选出的诱导自噬最强的2种人参皂苷，运用AD小鼠和自噬缺陷AD小鼠，研究人参皂苷通过增强自噬改善AD的作用；再将3种不同作用机理的人参皂苷联合用药，研究人参皂苷协同治疗AD的作用。研究结果为深入了解人参的药理作用提供理论，为开发AD的治疗药物提供候选分子。

阿尔茨海默症（AD）严重损伤患者的认知和记忆能力，目前临床药物对中重度AD患者的治疗并不理想。因此，开发一类多靶点、多途径、安全低毒的天然药物分子具有重要意义。人参皂苷是人参主要活性成分，具有多种生物活性。本项目基于课题组转化制备的16人参皂苷，从细胞和动物水平上对人参皂苷诱导自噬能力进行研究，发现原二醇型皂苷激活自噬能力更强；C-20位带有葡萄糖时诱导自噬的能力更强；糖基数量越少，自噬能力越强，且糖基必不可少；糖基数量相同时，葡萄糖在C-20位激活能力较强。于是，我们获得了激活自噬能力最强的人参皂苷CK。人参皂苷CK以AMPK/ULK1依赖的方式激活自噬。利用5×FAD小鼠及5×FAD Becn1+/-小鼠，通过动物行为学实验分析发现，人参皂苷CK和Rg2均能改善AD小鼠学习和记忆能力，但在Becn1+/-小鼠中，人参皂苷CK和Rg2改善学习及记忆能力受损，说明人参皂苷CK和Rg2均能通过自噬改善AD。进一步利用5×FAD小鼠，通过单独给药及联合给药三种不同作用机理的人参皂苷CK、Rb1和Rg1，根据其行为学分析，发现三种皂苷均能很好改善AD，且它们具有协同改善AD的作用。本项目丰富了人参皂苷的构效关系研究，为深入了解人参的药理作用提供理论支持，为AD治疗药物的开发提供候选分子。