Fruiting bodies of Basidiomycetes mushrooms have been attracted increasing attention of pharmaceutical and functional food industry because of their health promotion and disease alleviation effects on human health. 1) On account of bioactive and medicinal activities, immune stimulation, anti inflammatory antimicrobial, antitumoral, hepatoprotective, cholesterol lowering properties are representative as well as antifibrotic, antidiabetic and hypoglycemic activities.2 6) The origin of these effects are best known to be derived from polysaccharides belonging to β glucans. Recently, the importance of β glucans contained in the mushrooms was reviewed by several authors. 1,7)The fruiting body of Hericium erinaceum called Yamabushitake in Japan is growing much attention as a source of β glucans based on recent success of commercial availability. Mizuno et al . reported that β glucan from H. erinaceum had antitumor activity. 8) We are, therefore, interested about β glucans in H. erinaceum and previously reported about extractability of β glucans from its pulverized fruiting body by using microwave heating in water.9) The results showed that only 22.0% of β glucans were extracted by this treatment. The reason of this low extractability of β glucans may be due to their complex distribution in cell wall.In the case of Schizophyllum commune, three types of glucan were present in the multi layered cell walls; (1 3) β D glucan with branches of single glucose units attached by (1 6) linkages in the outer layer, (1 3) α D glucan in the middle layer and covalently linked chitin (1 3;1 6) β D glucan complex in the inner layer. 12) Our previous results further showed the presence of water soluble (1 3;1 6) β D glucan extractable by microwave irradiation in water 9) and alkali soluble (1 3;1 6) β D glucan having (1 6) linked branch points at every five (1 3) linked glucose residues.13) Use of alkali was shown to be effective for extraction of glucans amounting to 42.3% of the total quantity in H. erinaceum. However, since substantial amount (35.7%) of glucan is still remained in the alkali extracted residue, development of method for extraction of whole β glucans and characterization of their chemical structures are necessary for utilization of H. erinaceum as an origin of β glucans in future.In this study, an effective procedure to extract β glucan from the residue given after microwave irradiation in water was developed by stepwise treatments with alkali, enzyme microwave irradiation followed by re extraction with alkali, taking the multi layered cell wall structure into consideration.In addition, since alkali split hydrogen bonds connecting mainly hydroxyl groups in the cell wall of H. erinaceum to solubilize β glucans, urea which was known as a strong hydrogen bond disrupting reagent 14) could be used as an extraction reagent alternative to alkali. Therefore we tried to use 8 M urea as an extraction solvent for β glucan and structure of the extracted material was compared to that of alkali extracted materia1, in order to get in...

To examine the applicability of microwave irradiation for the extraction of polysaccharides in the fruiting body of Hericium erinaceum, structures of polysaccharides obtained by microwave irradiation in water were compared to those obtained by hot water extraction using conventional external heating. A major polysaccharide obtained by microwave irradiation in water (140 C, 5 min) was (1 3;1 6)-β-D glucan rich in (1 3) linkages, whereas polysaccharides obtained by hot water extraction using conventional external heating (100 C, 6 h) were fucogalactan and (1 3;1 6)-β-D glucan rich in (1 6) linkages. In the case of microwave irradiation in water, fucogalactan was suggested to be depolymerized during heating. Microwave heating in water has an advantage over the conventional external heating for extraction of β-glucan rich in (1 3) linkages from the fruiting body of H. erinaceum.