Preparation, characterization and in vivo antidiabetic effects of polysaccharides from Pachyrrhizus erosus.

Polysaccharides were extracted from Pachyrrhizus erosus (PEP) and three fractions (PEP60, PEP80 and PEP95) were separated by ethanol precipitation. Antidiabetic activities of three fractions were evaluated by streptozotocin-induced diabetic mouse model. Three PEP fractions reduced fasting blood glucose levels in mice, and regulated the levels of glycated serum protein, total triglyceride and total cholesterol in serum. In liver, the levels of glycogen content, glutathione peroxidase and superoxide dismutase activities and lipid peroxidation were recovered by PEP fractions. The histological analysis indicated that PEP fractions could protect the tissue structures of pancreas, liver and kidney from diabetic damages. In kidney, PEP fractions decreased the mesangial matrix index and inhibited the expression of transforming growth factor-β1. PEP95 showed stronger antidiabetic activity than PEP60 and PEP80. PEP95-DS was separated from PEP95 by DEAE-cellulose and Sephadex G-100 column chromatography. The chemical characteristics of PEP95-DS were evaluated. The average molecular weight of PEP95-DS was 11.4kDa, and it was composed of mannose: rhamnose: glucosamine: glucose: galactose: xylose: arabinose was 5.4:1.7:8.5:160.7:11.8:1:2.7. Furthermore, the spectral characteristics of PEP95-DS were analyzed. Our results indicated PEP could be used as a function ingredient in foods to prevent oxidation and diabetes.