人参属药用植物中MGR类化学成分改善2型糖尿病IR的构效关系及作用机制研究

Ginsenosides are the characteristic and major constituents of the Panax genus species,including neutral ginsenosides(NGR)and acidic ginsenosides (AGR).Malonyl ginsenosides (MGR) are also called acidic ginsenosides. Previous studies have shown that the content of malonyl ginsenosides represents up to 50% of the total content in ginsenosides of Panax ginseng root. However, MGR are more polar and water-soluble than NGR, and MGR are more difficult to isolate and characterize than NGR.Therefore,very little work has been carried out on the chemical constituents,and the pharmacological effects of MGR have not been explored so far.These will cause negative effect on the clinical application and international development of Panax species. In the previous investigation, we reported the significant hypoglycemic effects of MGR extracted from panax ginseng for the first time, and MGR exhibited significantly more potent antihyperglycemic activity than NGR. Further experiments revealed that the hypoglycemic effects of MGR were associated with amelioration of insulin resistance (IR).. On the basis of our previous research, this project will establish a rapid method to systematically isolate, prepare, and identity MGR from Panax ginseng,Panax quinquefolius,and Panax notoginseng. Studies will also be carried out on the biological activites of MGR on glucose metabolism with insulin-resistance cells, as well as their structure-activity relationship and qulity evaluation. Further, we use quantitative proteomic approach with isobaric labeling (iTRAQ) to examine the differential proteins among pathological organ and tissue in type 2 diabetes mice treated with MGR compared to untreated diabetes mice. Mass spectrometry is applied to identify the differentially expressed proteins. Meanwhile, we analyze their biological function with proteomics bioinformatics analysis. Our study for the first time couple iTRAQ with TOF/MS on IR of type 2 diabetes mice to discover new information about the malonyl ginsenosides mechanism of action and drug target. These results of the project would provide not only a renewed knowledge on the material basis of Panax species but also a theoretical basis for anti-diabetic lead compounds of ginseng saponins.

人参皂苷是人参属植物的特征性成分，可分为中性皂苷和酸性皂苷;丙二酰基人参皂苷（MGR）是一种酸性皂苷，其含量在人参中约占总皂苷的50%，然而这类皂苷的化学成分研究报道较少，药理活性几乎处于空白。这严重的影响了人参属植物的临床应用和国际推广。我们在前期的工作中，首次发现了MGR具有显著的降糖活性，且明显强于中性皂苷，进一步发现其降糖作用与改善胰岛素抵抗(IR)有关。.为此本项目拟通过建立MGR快速的识别和分离方法，对人参属植物人参、西洋参和三七中MGR进行系统的分离，评价和研究其改善IR的生物活性和构效关系。同时采用同位素标记相对和绝对定量蛋白质组学技术，对2型糖尿病IR靶器官进行高通量的“全组”蛋白鉴定和定量分析，筛选出差异蛋白；并结合生物信息学手段对其生物学功能进行分析，阐明作用机制。本项目将使我们对人参属植物抗糖尿病的物质基础有一个全新的认识，为创制新型抗糖尿病药物提供活性先导化合物。

丙二酰基人参皂苷（MGR）是人参属植物的特征性成分，其含量较高，然而这类皂苷的化学成分研究报道较少，药理活性几乎处于空白。为此本项目对人参属植物人参、西洋参和三七根中MGR进行了系统的分离和评价，同时研究了MGR改善2型糖尿病（T2DM）胰岛素抵抗的生物活性和构效关系，并阐明其作用机制。主要研究结果如下：（1）通过HPLC和LC-MS/MS技术，构建了快速发现、定向分离MGR类化合物的方法，从人参、西洋参和三七根中，共分离鉴定了18个MGR类化合物，其中鉴定出新化合物10个。（2）采用高脂饮食联合STZ建立T2DM小鼠模型，观察了MGR提取物和丙二酰基人参皂苷Rb1（mRb1）对T2DM的治疗作用；结果表明，MGR提取物和mRb1均具有显著的降血糖、降血脂和改善胰岛素抵抗的作用。（3）构效关系实验结果表明，MGR的降糖作用与其分子结构中具有丙二酰基这一结构密不可分，然而其体内作用有效，体外活性却较弱。（4）应用转录组学和TMT联合LC-MS/MS的定量蛋白质组学技术，研究mRb1抗T2DM的作用机制；蛋白质组学研究得出mRb1可能通过调节 PEPCK、CYP7A1、FATP、G6Pase、ITGA、HMGCS2、CYP4A、LCAT 和 ACBP 等蛋白，参与胰岛素信号传导途径、胰岛素抵抗、PPAR信号通路、糖酵解/糖异生等途径抗T2DM。转录组学研究得出mRb1可能通过调节 Cyp7a1、Slc27a1、G6pc、Cyp2c70、Gsta4、Gstt2等基因，参与胆固醇代谢、花生四烯酸代谢、胰岛素抵抗、PPAR信号通路等途径在基因层面调节T2DM。组学联合分析进一步发现，Cyp7a1、Slc27a1、G6pc、Cyp4a14和Aldh3a2可能是mRb1治疗T2DM的潜在靶点。本项目为人参属植物临床治疗T2DM提供了科学的指导，为创制新型抗T2DM药物提供活性先导化合物。