Structural characterization and antitumor activity of a novel polysaccharide from Grifola frondosa

In this study, a novel GFP-A polysaccharide was extracted from Grifola frondosa , and its structural characteristics and in vivo anti-tumor activities were investigated. The contents of total sugar, uronic acid and protein in GFP-A were 90.18% ± 0.15%, 1.43% ± 0.08% and 0.46% ± 0.03%, respectively. By gas chromatography (GC), Monosaccharide analysis showed that GFP-A (about 2484 kDa) was composed of Rha, Xyl, Man, Glc and Gal with molar percentages of 25.98, 9.32, 11.73, 4.74, and 48.22%. FT-IR and NMR analysis also revealed that GFP-A was a neutral polysaccharide mainly composed of α-type rhamnopyranose, β-type mannopyranose and α-type galactopyranose. Besides, GFP-A could enhance the immunostimulatory, and obviously increase the spleen and thymus indices, spleen lymphocyte proliferation, phagocytic index and NK cells killing activity in tumor-mice. By Flow cytometry (FACS), GFP-A treatment could increase cytotoxic activity of CD4+ and CD8+ T cells, and activate helper T cells to play central roles in immunomodulation of tumor-bearing mice. These results suggest that GFP-A has antitumor activity, which could be explored as a novel natural immunomodulatory agent and as a therapeutic compound to lessen chemotherapy.