The structural characteristics of an acid-soluble polysaccharide from Grifola frondosa and its antitumor effects on H22-bearing mice.

The edible mushroom G. frondosa has been used as a kind of functional food for the prevention and therapy of various diseases in Asian countries. In the present work, a novel acid-soluble polysaccharide (GFAP) was successfully isolated from G. frondosa under room temperature and hydrochloric acid solution treatment. Results of chemical composition analysis, UV and HPGPC spectra showed that GFAP mainly contained 94.28% of carbohydrate with the average molecular weight of about 644.9 kDa. GC, FT-IR, NMR and methylation analysis further indicated that GFAP was a neutral sugar mainly composed of (1 → 3)-β-D-Glcp and (1 → 3)-α-D-Manp. The in vivo antitumor experiments demonstrated that GFAP could effectively protect thymuses and spleens of tumor-bearing mice and inhibit the growth of H22 solid tumors with the inhibitory rate of 36.72%. Besides, GFAP could significantly improve the activities of NK cells, macrophages, CD19+ B cells and CD4+ T cells, leading to the apoptosis of H22 cells via G0/G1 phase arrested. Our data demonstrated that GFAP holds great application prospect to be a safe and effective antitumor adjuvant in the future.