Structure and antitumor activity of extracellular polysaccharides from mycelium

Two heteropolysaccharides coded as EPF1 and EPF2 were obtained from the crude extracellular polysaccharide (CEP) of Ganoderma tsugae mycelium by elution with DEAE-Sepharose CL-6B column. Their chemical structures and molecular mass were characterized by infrared, gas chromatography, 13C NMR and size exclusion chromatography combined with laser light scattering (SEC-LLS). The results indicated that they were mainly composed with mannose, fucose, xylose, galactose and glucosamine. EPF2 was confirmed to be mainly a β-d-galacto-α-d-mannan. The weight-average molecular mass of the samples EPF1, EPF2 and CEP were 92.0×104, 8.35×104 and 23.8×104, respectively. The EPF1 existed as a compact coil chain in 0.2 M NaCl aqueous solution at 25 °C, while EPF2 as a flexible chain. The antitumor activities against Sarcoma 180 were tested both in vitro and in vivo. All the samples exhibited high inhibition ratio against Sarcoma 180 in mice, and the CEP has higher inhibition effect both in vivo and in vitro than EPF1 and EPF2. In view of these results, the presence of bound protein and mannose, and relatively expanded chain would be helpful to the enhancement of antitumor activities. This study suggested that the extracellular polysaccharides had a potential application as natural antitumor drugs.