Antitumor Activity of a Polysaccharide−Protein Complex Isolated from a Wood-Rotting Polypore Macro Fungus Phellinus rimosus (Berk) Pilat

: A protein-bound, water-soluble polysaccharide-protein complex was isolated from a medicinal mushroom, Phellinus rimosus (Berk) Pilat (PPC-Pr). The isolation was achieved by hot water extraction, filtration, solvent precipitation, dialysis, and freeze-drying. The proximate analysis showed that PPC-Pr comprised 54.8% polysaccharide and 28.6% protein. The molecular weight of the compound was determined by gel filtration using a Sephadex G 100. The molecular weight of PPC-Pr was approximately 1,200,000 D. The thin-layer chromatography analysis of PPC-Pr after acid hydrolysis with trifluroacetic acid showed that it was composed of glucose as the only monosaccharide unit. The amino acid profile analysis of PPC-Pr revealed that it contained large amounts of aspartic acid, glutamic acid, alanine, glycine, and serine. Thus, the results indicated that PPC-Pr is a glucan-protein complex. The PPC-Pr did not show in vitro cytotoxic activity against Dalton's lymphoma ascites and Ehrlich's ascites carcinoma cell lines. The PPC-Pr was found to be effective in increasing the life span of ascites tumors induced by Ehrlich's ascites carcinoma cell line in mice. PPC-Pr also was found to have significant preventive and curative effects on solid tumors induced by the Dalton's lymphoma ascites cell line. The experimental results thus indicated that protein-bound polysaccharide (PPC-Pr) isolated from P. rimosus possessed profound antitumor activity. The findings suggest the potential therapeutic use of this compound as an antitumor agent.