Structure, molecular size and antitumor activities of polysaccharides from Poria cocos mycelia produced in fermenter

Mycelia of Poria cocos were obtained from a pilot-scale 50-L fermenter by submerged cultivation biotechnology. Six polysaccharide fractions were extracted sequentially from the P. cocos mycelia with 0.9% NaCl (Pi-PCM1), hot water (Pi-PCM2), 0.5 M NaOH (Pi-PCM3-I and -II), and 88% formic acid (Pi-PCM4-I and -II). The supernatant of the culture media was spray-dried to obtain the extracellular polysaccharide (Pi-PCM0) produced by the mycelia. The results from Fourier transform infrared spectroscopy, gas chromatography, and 13C NMR revealed that the water-soluble fractions including Pi-PCM0, Pi-PCM1, and Pi-PCM2 were heteropolysaccharides mainly containing glucose, galactose, and mannose, whereas Pi-PCM3-I and Pi-PCM4-I had (1 → 3)-α-d-glucan characteristics. The weight-average molecular mass (Mw) and intrinsic viscosity ([η]) of the polysaccharide were measured by laser light scattering (LLS) and viscometry, respectively. Results indicated that Pi-PCM1 and Pi-PCM2 existed as a compact random coil in aqueous solution, close to the global shape. Interestingly, the three water-soluble polysaccharides (Pi-PCM0 to Pi-PCM2) all exhibited antitumor activities in vivo (Sarcoma 180 solid tumor implanted in BALB/c mice), and in vitro (HL-60 tumor cell).