Purification and structural elucidation of a water-soluble polysaccharide from the fruiting bodies of the Grifola frondosa

Grifola frondosa is a polypore mushroom, which has been used for many centuries by traditional Chinese and Japanese herbalists as a medicinal mushroom. A water-soluble polysaccharide (code as GFP30-2-a, molecular weight: 2.04 × 106 Da) was isolated from the fruiting bodies of G. frondosa by hot water extraction, ethanol precipitation and chromatography. Its structure was elucidated from its monosaccharide composition, methylation analysis, together with 1D NMR (1H NMR and 13C NMR) and 2D NMR (COSY, TOCSY, HSQC, HMBC and NOESY spectra). GFP30-2-a consists of D-Glc and D-Gal in the molar ratio of 1:0.098 and the structure of the repeating units was identified to be β‑d‑Glcp‑(1 → [4)‑α‑d‑Glcp‑(1 → 4)‑α‑d‑Glcp‑(1]m → 4)‑α‑d‑Glcp.