Isolation, purification and immunobiological activity of a new water-soluble bee pollen polysaccharide from Crataegus pinnatifida Bge.

A novel water-soluble polysaccharide was obtained from bee pollen of Crataegus pinnatifida Bge. Two fractions of this polysaccharide, CPP-1 and CPP-2, were first extracted by hot-water and purified. The average molecular weight of CPP-1 and CPP-2 were approximately 3.7 × 105 Da and 7.8 × 104 Da, and their chemical structures were studied by gas chromatography (GC), Fourier transform-infrared (FT-IR) spectroscopy, methylation analysis. We evaluated the effects of CPP-1 and CPP-2 on the basis of phagocytosis of macrophage assay, natural killer cells cytotoxicity assay and spleen lymphocyte proliferation assay. The results showed CPP-1 and CPP-2 significantly induced phagocytic rates and phagocytic indexes by peritoneal macrophages. Moreover, these two fractions caused a significant stimulation of rat spleen cell proliferation. At 50 μg/mL, CPP-2 activated NK cells more significantly than CPP-1. These findings suggest that they should be explored as a novel potential immunostimulants.