Deproteinization and structural characterization of bioactive exopolysaccharides from Ganoderma sinense mycelium

Deproteinization was comparatively employed for the purification of crude exopolysaccharide (CEP) of Ganoderma sinense mycelium. Results showed that ammonium sulfate (70% saturation) salting out could remove 95% proteins of CEP, whereas 20% trichloroacetic acid precipitation was best with a polysaccharide loss less than 20%. Protein-bound polysaccharides could be removed by both methods, and polysaccharides with high molecular weight dominated in the lost polysaccharides. Through anion-exchange chromatography, a highly branched -(16)-D-mannan and a protein-bound heteropolysaccharide were prepared from CEP. Both fractions could inhibit the in vitro proliferation of tumor cells BEL-7402, and induce TNF- secretion of murine splenocytes.