Structural Characterization of a Water-Soluble Polysaccharide from the Fruiting Bodies of Agaricus bisporus

An edible fungal polysaccharide termed as ABP was obtained by extraction with hot water, and followed successive chromatographic purification using DEAE-Sepharose Fast Flow column and Sephacryl S-300 High-Resolution column. A symmetrical peak was obtained on high-performance size-exclusion chromatography with an average molecular weight of 5.17 × 104 Da, which was named ABP, and its main components were D-glucose and D-mannose. Based on the study of methylation analysis, along with FT-IR, GC, GC-MS, 1D 1H and 13C NMR and 2D NMR (H-HCOSY, TOCSY, HMQC, and NOESY), its chemical structure was featured with a repeating unit (1→6) linking β-D-Glcp as the main backbone with (1→4)-linked α-D-Manp units. The structure of the mainly repeating units of ABP was established as: →6)-β-D-Glcp-(1→4)-α-D-Manp(1→6)-β-D-Glcp-(1→6)-β-D-Glcp-(1→.