Study On The Structure And Hypoglycemic Activity Of Sea Cucumber Tendons Saponins

Sea cucumber tendons is the processing waste of sea cucumber and contains a variety of bioactive substances such as polysaccharides and saponins,but there is little research on sea cucumber tendons,which limits its exploitation.Saponins have various bioactive effects such as antioxidant,hemolysis,hypoglycemia and hypolipidemia,which are important bioactive substances of sea cucumber tendons.This thesis aims to establish the extraction method of saponins from sea cucumber tendons,analyze their structures and explore their hypoglycemic activities,in order to support the development and utilization of sea cucumber tendons.The extraction conditions of sea cucumber tendons saponins were investigated using single-factor and response surface experiments,and the best extraction conditions were determined as follows: material-to-liquid ratio of 1:8.15,ethanol concentration of 80%,extraction temperature of 71.4°C,extraction time of 1 h and extraction times of three times,under which the extraction rate of sea cucumber tendons saponins was 1.42%.The separation and purification of sea cucumber tendons saponins were carried out using D101 macroporous adsorbent resin and semi-preparative liquid chromatography;based on this,the structure of saponins was studied by FT/IR,GC and ESI-IT/TOF-MS/MS instruments.The results showed that the D101 macroporous adsorbent resin could separate the saponins into five fractions,SCTS-I,SCTS-II,SCTS-III,SCTS-IV and SCTS-V;the semi-preparative liquid chromatograph could further separate SCTS-IV into three fractions,SCTS-IV-W,SCTS-IV-20 and SCTS-IV-40;SCTS-IV-W with [M+Na]+ of m/z 1131.6521),sapogenins with [M+Na]+ of m/z 523.3380,containing four sugar groups of quinolose,xylose,3-O-methylglucose and glucose(Molar percentages: 34.33:17.49:11.70:36.48);SCTS-IV-20 with [M+Na]+ of m/ z 1129.4512,[M+Na]+ of sapogenins was m/z 507.2374,containing four sugar groups of quinolose,xylose,3-O-methylglucose and glucose(Molar percentages: 26.99:27.35:24.51:21.16);[M+H]+ of SCTS-IV-40 was m/z 1251.6623,[M+H]+ of sapogenins was m /z 469.2161,containing four sugar groups of quinolose,xylose,3-O-methylglucose and glucose(Molar percentages: 16.43:11.68:1.69:70.22).The hypoglycemic activity of SCTS-IV was most studied using a streptozotocininduced C57BL/6 type 2 diabetic mouse model.The results showed that SCTS-IV significantly(p < 0.01)reduced blood glucose and body weight and improved the regulation of postprandial glucose in type 2 diabetic mice.The serum levels of TC,TG and LDL-C were significantly(p < 0.05)reduced and the levels of HDL-C were significantly increased;and the damage of liver and pancreatic tissues was alleviated;the results of intestinal microassay showed that the ratio of thick-walled phylum/bacillus phylum decreased from 1.59(normal group)to 0.71(model group),and sea cucumber tendons saponins could restore the ratio of thick-walled phylum/bacillus phylum to 1.34 and reduce the The relative abundance of harmful bacteria,such as E.coli and A.verrucosum,increased the diversity of intestinal flora and normalized the intestinal microecology.The relative expression of AMPK was significantly(p < 0.01)increased and the relative expression of TORC2,CREB and G6 pase was significantly(p < 0.01)decreased by the intervention of sea cucumber tendons saponins,indicating that SCTS-IV may achieve hypoglycemic effect by activating AMPK signaling pathway and regulating gluconeogenesis.