Synthesis of selenylated polysaccharides from Momordica charantia L. and its hypoglycemic activity in streptozotocin-induced diabetic mice

In order to obtain the effective antidiabetic polysaccharide derivative, a selenylated polysaccharide (Se-MCPIIa-1), with an average molecular weight (MW) of 4.0038 × 104 Da, was synthesized by reduction of sodium selenite with ascorbic acid in the presence of Momordica polysaccharides (MCPIIa). The selenium (Se) content of Se-MCPIIa-1 was up to 445.0 μg/g, and its average diameter of monodisperse spherical particle size was around 63.78 nm. The morphology and physicochemical properties of Se-MCPIIa-1 were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), Fourier transform infrared spectrometry (FT-IR) and Raman spectroscopy, respectively. The results indicated that Se was conjunct with MCPIIa by esterification. Moreover, the oral administration of Se-MCPIIa-1 showed a gradual normalization in the levels of hypoglyemic test in the STZ-induced diabetic mice. The anti-diabetic effects of Se-MCPIIa-1 in vivo showed that Se-MCPIIa-1 can significantly reduce fasting blood glucose levels and enhance insulin levels as well as antioxidant enzyme activities in diabetic mice with an optimal dosage of 20 mg/kg/body weight. In addition, it was found from histopathological data that Se-MCPIIa-1 could prevent pancreatic islets, liver and kidney damage from diabetes, which suggested that Se-MCPIIa-1 is a promising novel Se supplement and could be applied in the field of food and medicine.