Isolation and Purification of Polysaccharides with Anti-tumor Activity from Pholiota adiposa (Batsch) P. Kumm. (Higher Basidiomycetes)

Abstract

Pholiota adiposa is a mushroom with excellent medicinal and nutritional properties. After culture in fermentation medium, Ph. Adiposa mycelia were filtered, lyophilized, and powdered. A crude polysaccharide (PAP) of Ph. Adiposa was prepared from the mycelial powder with hot water, centrifuged, and the resulting supernatant lyophilized. PAP was fractionated by 30%, 60%, and 80% ethanol precipitation steps to yield PAP30, PAP60, and PAP80. Subsequently PAP30-1 and PAP30-2, PAP60-1 and PAP60-2, and PAP80-1 and PAP80-2 were isolated from PAP30, PAP60, and PAP80, respectively, by ion-exchange chromatography on a DEAE-Sepharose column. Polysaccharide content increased from 43.8% in PAP to 50.54%~73.19% in PAP30-1~PAP80-2. The protein content was 4.92% at minimum in these polysaccharide products. In order to identify the chemical composition, the six polysaccharides (PAP30-1, PAP30-2, PAP60-1, PAP60-2, PAP80-1, and PAP80-2) were further purified by gel filtration on Sephacryl S-100-500. Finally, three water-soluble polysaccharides (PAP30-2a, PAP60-2b, and PAP80-2a) were obtained. HPLC analysis revealed that PAP30-2a, PAP60-2b, and PAP80-2a exhibited a molecular weight of 6.6 × 105 Da, 8.4 × 103 Da, and 3.5 × 103 Da, respectively. The glucose content in PAP80-2a, PAP60-2b, and PAP30-2a was 57.8%, 72.7%, and 68.9%, respectively. PAP30-2a, PAP60-2b, and PAP80-2a demonstrated significant differences in anti-tumor activity in mice. PAP80-2a is the optimal bioactive constituent with anti-tumor and T-lymphocyte proliferation stimulating effects.