Structural features and hypoglycemic activities of two polysaccharides from a hot-water extract of Agrocybe...

A glucan (AG-HN1, [alpha]D +24 degrees) and a heteroglycan (AG-HN2, [alpha]D +26 degrees) were isolated from a hot-water extract of the fruiting bodies of Agrocybe cylindracea. The structures were investigated by a combination of chemical and spectroscopic methods. The results indicated that high molecular weight glucan AG-HN1 is primarily a beta-(1-->6)-branched (1-->3)-beta-D-glucan containing small amounts of (1-->4)-linked and (1-->6)-linked glucopyranosyl residues. Low molecular weight heteroglycan AG-HN2 gives galactose, glucose, fucose, and mannose on hydrolysis and appears to be chiefly composed of (1-->6)-linked gluco- and galacto-pyranosyl residues, many of them branched, and various nonreducing terminal residues. AG-HN1 showed a remarkable hypoglycemic activity in both normal and streptozotocin-induced diabetic mice by ip administration, and its activity was higher than that of AG-HN2.