Chain conformation and anti-tumor activities of phosphorylated (1→3)-β-d-glucan from Poria cocos

(1→3)-β-d-Glucan isolated from Poria cocos was phosphorylated to obtain a series of phosphorylated derivatives. Their structures, weight-average molecular weights (Mw), and chain conformation were studied by 13C NMR, 31P NMR, static laser light scattering and viscometry. The experimental results revealed that the phosphorylated glucan existed as relatively extended flexible chain in 0.15 M NaCl aqueous solution, and exhibited relatively strong inhibition against S-180 tumor cell in vitro and in vivo. In vivo, the fractions with relatively high molecular weight at low dosage exhibited stronger anti-tumor activities. The results revealed that the molecular weights and molecular conformation could influence the anti-tumor activities. The molecular weight ranging from 2.6 × 104 to 26.8 × 104 and the extended chain conformation were beneficial to enhance the anti-tumor activity, as a result of the increasing of the interaction between polysaccharide and immune system.