Physical-chemical properties of heteropolysaccharides from different processed forms of Rehmanniae Radix

The crude heteropolysaccharides from four forms of Rehmannia glutinosa were extracted by boiling water, then purified and named FRP, DRP, HRP and NRP, respectively. The physicochemical properties, blood-enriching and immunomodulatory activities of the heteropolysaccharides were analyzed. Mg, Ca and K were the dominant metal elements in all four fractions; galactose and galacturonic acid were the predominant monosaccharides. All fractions had good thermal stabilities. The bioactive tests showed that the levels of HCT and HGB in all four groups were significantly higher than that in the model group. In addition, FRP, DRP, HRP and NRP can significantly stimulate mRNA levels of tumor necrosis factor- α (TNF- α ), interleukin-6 (IL-6), interleukin-4 (IL-4), and interleukin-10 (IL-10). The immunomodulatory activities of HRP and NRP were better than that of DRP and FRP, while immunomodulatory activities of HRP were better than that of NRP. The results demonstrated that the heteropolysaccharides from different R. glutinosa products can improve blood-enriching activities and immunomodulatory activities. These results provide experimental evidence to justify further research of heteropolysaccharides from R. glutinosa in pharmaceuticals and functional foods. • The polysaccharides for four processed products of Rehmanniae Radix were obtained. • The physical-chemical properties and activities of FRP, DRP, HRP, and NRP were identified. • All four fractions are pectin polysaccharides with low degrees of substitution. • FRP, DRP, HRP and NRP have certain degrees of blood-enriching activities. • All four fractions have immunomodulatory activities, and the activity of HRP was the best.