Fractionation and purification of the polysaccharides with marked antitumor activity, especially lentinan, from Lentinus edodes (Berk.) Sing. (an edible mushroom).

Six polysaccharide preparations, lentinan, LC-11, LC-12, LC-13, EC-11, and EC-14, were isolated from the watersoluble extracts of Lentinus edodes (Berk.) Sing., an edible mushroom, by fractional precipitation with ethanol and cetyltrimethylammonium hydroxide, fractional solubilization with acetic acid, and diethylaminoethyl cellulose column chromatography. The first two polysaccharide preparations have a strong antitumor effect; lentinan, especially, markedly inhibited the growth of Sarcoma 180 implanted s.c. in mice, inducing almost complete regression of tumors at doses of 1 mg/kg X 10 with no sign of toxicity. LC-11 was also effective in 5 to 25 mg/kg X 10 doses. The purity and properties of these antitumor polysaccharides are discussed.