Structure and Antitumor Activity of 1,3-b-Glucan from Cultivated Fruit Bodies of Culinary-Medicinal Mushroom Hypsizygus marmoreus (Peck) Bigel. (Agaricomycetideae)

Hypsizygus marmoreus is an edible mushroom widely cultured in Japan. Polysaccharide fractions were prepared from the cultured H. marmoreus by repeated extraction with hot water (HmHWE), cold NaOH, and then hot NaOH. The residue was further treated with NaClO and prepared extract (HmCHAE) and residue (HmCHAR). The cold NaOH extract was further separated into water-soluble (HmCAEE) and -insoluble (HmCAER) fractions. The hot NaOH extract was also separated into water-soluble (HmHAEE) and -insoluble (HmHAER) fractions. Cold and hot NaOH extracts showed antitumor activity to the solid form of Sarcoma 180 in ICR mice. By chemical, enzymic, and NMR analyses, HmCAEE and HmHAEE contained significant amounts of 6-branched 1,3-b-glucan. In addition to 6-branched 1,3-b-glucan, NaOH extracted, water-insoluble fraction contained 1,3-a-glucan. Purified 1,3-a-glucan did not show antitumor activity. These facts strongly suggested that b-glucans but not a-glucans show antitumor activity in H. marmoreus.