Study On The Regulation Mechanism Of Malonyl Ginsenosides From American Ginseng Improving IR Of Type 2 Diabetes

Type 2 diabetes mellitus（DM）is a metabolic disease characterized by persistent hyperglycemia.Despite significant efforts that have been made in the awareness and management of diabetes,its prevalence continues to grow.Currently,diabetes as a lifelong disease is incurable,so it is important to find a convenient,economical and effective way to prevent and treat diabetes.American ginseng（Panax quinquefolius L.）is popularly consumed as traditional herbal medicine and health food for the treatment of type 2 diabetes mellitus（T2DM）.The major bioactive ingredients of American ginseng are ginsenosides,which includes neutral ginsenosides,and malonyl ginsenosides.Malonyl ginsenosides（MGR）are natural ginsenosides that exist in both fresh and air-dried American ginseng.Because the malonyl bond in the malonyl ginsenoside structure is unstable,the preparation of its standard is difficult,so there are few reports about it at home and abroad.The chemical and pharmacological studies on MGR are limited.In the present study,the extraction,separation,structure identification and content determination of malonyl ginsenosides were studied.Meanwhile,we reported the hypoglycemic and hypolipidemic effect of PQ-MGR and explored the underlying mechanism in diabetic conditions induced by HFD/STZ in mice for the first time.In this study,the chemical constituents of American ginseng were systematically extracted and separated.The water layer of fresh American ginseng extract was concentrated and slowly added to the D-101 macroporous resin column.Gradient elution was performed with water,30%ethanol,and 60%ethanol.The 60%ethanol phase containing a large amount of saponins was separated by silica gel column chromatography,cation exchange resin,ODS column chromatography and high performance liquid chromatography.Five monomer saponins,named malonyl notoginsenoside A,malonyl ginsenoside-Rb₁,-Rb₂,-Rc,and-Rd,were isolated and identified from American ginseng by one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy(¹³C NMR,¹H NMR,DEPT,HMBC)and high resolution mass spectrometry.Among them,malonyl notoginsenoside A is a new compound discovered for the first time.In this paper,the contents of malonyl ginsenosides and neutral ginsenosides in American ginseng from 9 different regions were studied by HPLC.HPLC was carried out with C18 column using 50m M potassium dihydrogen phosphate aqueous solution-acetonitrile as mobile phase,injection volume 20μL,flow rate 1m L/min,detection wavelength 203nm.The method has good repeatability,precision and stability,and can be used for the determination of ginsenosides in American ginseng.The results showed that there were differences in the content of ginsenosides in American ginseng from different cultivation regions.The content of ginsenosides in American ginseng from Jilin Fusong,Jingyu,Jian and Huinan was relatively high.After a 5 week experiment,our results showed that PQ-MGR significantly reduced the fasting blood glucose（FBG）,triglyceride（TG）,total cholesterol（TC）level and improved glucose tolerance and insulin resistance.Furthermore,Western blot analysis demonstrated that the protein expressions of p-PI3K,p-AKT,p-AMPK,p-ACC,PPARγand GLUT4 in liver and skeletal muscle were significantly upregulated after PQ-MGR treatment.In contrast,the protein expression of p-IRS1and p-JNK were significantly downregulated.The results showed that PQ-MGR could regulate the blood lipid status of T2DM,reduce the blood glucose level of diabetic mice,and effectively reduce the lesions of liver and islet tissues.It can also improve glucose and lipid metabolism and insulin resistance in T2DM by regulating IRS1/PI3K/Akt and AMPK/ACC pathways.