A novel water-soluble β-(1→6)-d-glucan isolated from the fruit bodies of Bulgaria inquinans (Fries)

A low molecular-weight polysaccharide named BIWP2 was purified from the fruit bodies of Bulgaria Inquinans (Fries) via hot-water extraction, followed by freeze-thawing and gel filtration chromatography on Sephadex G-75. Monosaccharide composition analysis revealed that BIWP2 contained exclusively glucose. High performance size exclusion chromatography (HPSEC) showed that it was a homogeneous polysaccharide fraction. Its molecular weight was estimated to be 2.6 KD and the polydispersity index (Mw/Mn) was calculated to be 1.4. Periodate oxidation, methylation, and NMR analyses indicated that BIWP2 was a linear β-(1→6)-d-glucan without side chains. This is the first time to report a linear β-(1→6)-d-glucan with low molecular weight in non-lichenized ascomycete.