Preparation and hypoglycemic mechanism of polysaccharide from Lonicera macranthoides

In order to explore the in vitro hypoglycemic effect of lonicerae flos polysaccharides and its mechanism of action, the crude lonicerae flos polysaccharide was prepared by hot water extraction and ethanol precipitation. After sevage, dialysis, DEAE-52 and Sephadex G-100, the homogeneous component lonicerae flos polysaccharide was finally separated and purified. HepG2 cell experiment was used to investigate the hypoglycemic activity and mechanism of lonicerae flos polysaccharide, detecting the active polysaccharide components, and preliminarily analyze its monosaccharide composition, molecular weight and hypoglycemic pathway. The results showed that lonicerae flos polysaccharide was mainly composed of fucose (Fuc, 0.42%), rhamnoose (Rha, 7.81%), arabinose (Ara, 27.54%), galactose (Gal, 7.86%), glucose (Glu, 4.68%), xylose (Xyl, 0.33%) and galacturonic acid (Gal-UA, 51.36%). The results of total sugar, uronic acid, protein and molecular weight showed that total sugar content was 92.13% of lonicerae flos polysaccharide, the content of uronic acid was 48.66%, the protein content was 0.15%, weight average Mw was 121.994 k–Da and the Mn was 37.088 k–Da. In normal HepG2 cells, lonicerae flos polysaccharide could significantly promote glucose transport and increase glucose consumption in HepG2 cells. In insulin-resistant HepG2 cells, lonicerae flos polysaccharide could promoted the uptake of glucose, and there was a positive correlation with the mass concentration. The mechanism of hypoglycemic action showed that the lonicerae flos polysaccharide of 320 μg/mL could significantly regulate the abnormal expression of GLUT4, GSK-3β and IRS1 proteins in insulin-resistant HepG2 cells. This study provides a valuable scientific basis for the mechanism and effect of hypoglycemic action of the active components of lonicerae flos.