Purification and characterization of acidic proteo-heteroglycan from the fruiting body of Phellinus linteus (Berk. & M.A. Curtis) Teng

Phellinus linteus is a well-known oriental medicinal fungus that has various biological activities such as stimulation of humoral and cell mediated immunity, anti-mutagenicity activity, and anti-cancer activity. The process of isolating and purifying a water-soluble glycan from P. linteus was achieved by hot water extraction, filtration, solvent precipitation, dialysis, and freeze-drying. Acidic fractions of the polysaccharide were separated from crude polysaccharides by DEAE-cellulose anion exchange chromatography at 0.4 M NaCl. The molecular weight of the proteo-heteroglycan after Sepharose CL-4B gel filtration chromatography was about 150,000. The acidic proteo-heteroglycan consisted of 72.2% polysaccharide and 22.3% protein. The sugar of the proteo-heteroglycan was composed of mannose, galactose, glucose, arabinose, and xylose. The amino acid pattern showed that the fractions contained large amounts of aspartic acid, glutamic acid, alanine, glycine, and serine. The fractions for both α-glycan at 860 cm−1 and β-glycan at 910 cm−1 had the characteristics of IR spectrum absorption as compared to those for β-glucan derived from Lentinus edodes. A 13C and 1H NMR spectroscopy showed that the acidic proteo-heteroglycan was a noble biomolecule mixed both α- and β-linkages, and a (1,6) branched type (1,3) glycan.