Structure characterization and hypoglycemic activity of a polysaccharide isolated from the fruit of Lycium barbarum L.

An acidic polysaccharide LBP-1 isolated from the fruit of Lycium barbarum L. was purified by ion-exchanged column. Structure characterization and in vitro hypoglycemic activity of LBP-1 were determined. Chemical analysis indicated LBP-1 was composed with rhamnose, arabinose, xylose, galactose, mannose, galacturonic acid = 1.00:7.85:0.37:0.65:3.01:8.16 with average molecular weight of 2.25 × 106 Da. The structure features of LBP-1 were investigated by FT-IR, GC–MS, 1H-NMR and 13C-NMR. The backbone were mainly composed of (1,5)-linkage arabinose, (1,4)-linkage galacturonic acid, -(1)-mannose-(3,6)-linkage and terminated with -(1)-mannose. LBP-1 protected the pancreatic islets cells from oxidative damage and enhanced cell survival ratio significantly. Moreover, its application inhibited the development of insulin resistance in HepG2 cells. This paper indicates the beneficial effect of LBP-1 and explores a potential hypoglycemic functional food and pharmaceuticals with definitely structure.