Optimization, characterization, rheological study and immune activities of polysaccharide from Sagittaria sagittifolia L.

To improve the extraction efficiency of polysaccharides from Sagittaria sagittifolia L. (SPU) by ultrasonic assisted extraction (UAE), the optimal extraction conditions were optimized as follows: extraction temperature of 85℃, extraction time of 15 min and ratio of liquid to raw material 43 mL/g, under these conditions, the yield of SPU increased by about 168 % compared with hot water extraction (HWE). After separation and purification by DEAE-52 cellulose column and Sephadex G-50 column, the pure polysaccharide fraction (SPU70-W1) was obtained, and its structure, rheology and immune activity were analyzed. The results indicated that SPU70-W1 (7.70 kDa) contained mannose, glucose and galactose in the molar ratio of 2.06:93.58:4.36 with typical pseudoplasticity fluids behavior and possessed the backbone of →2,6)-α-D-Glcp-(1→, →3,6)-α-D-Glcp-(1→, α-D-Glcp-(1→ and 6)-α-D-Glcp-(1→. In addition, SPU70-W1 exhibited remarkable immunomodulatory activity. Thus, SPU70-W1 could contribute to the food, medicine, cosmetics as a functional additive.