Characterization of water and alkali-soluble polysaccharides from Pleurotus tuber-regium sclerotia

Pleurotus tuber-regium sclerotia, an edible and medicinal mushroom, is a rich source of polysaccharides used as a functional food to promote health and longevity. The crude polysaccharides were isolated from the P. tuber-regium by hot aqueous and alkali extraction and then further purified by DEAE-52 cellulose chromatography and Sephadex G-100 chromatography. Two polysaccharides, water and alkaline extraction of polysaccharides (W-PTR and A-PTR), were obtained and their extraction process were optimized through orthogonal array design. Structure characteristics (physicochemical property analysis, molecular weight, monosaccharide composition, sulfate and uronic acid contents, triple helical structures, ultraviolet spectrum and infrared spectroscopy) of the two polysaccharides were investigated. Results showed that the main difference between the two polysaccharides is reflected in color, solubility, molecular weight and monosaccharide composition. Conformational analysis showed that both W-PTP and A-PTP had triple-helix conformation. The 3D structure of the two polysaccharides and their structure-function relationship will be challenge in the future.