Comprehensive evaluation of alkali-extracted polysaccharides from Agrocybe cylindracea: Comparison on structural characterization

Agrocybe cylindracea is a common source of active polysaccharides, but their fine structures are not clearly elucidated. In the present study, four fractions were purified from the alkaline extract of A. cylindracea (JACP), and their chemical components and structures were compared by HPAEC-PAD, methylation combined with GC–MS, and 1D/2D NMR analysis. Results showed the purified fractions' physicochemical properties, including monosaccharide compositions, molecular weights, viscosities and surface morphology considerably varied. JACP-30 was identified as a fucoglucogalactan with a α-(1 → 6)-galactopyranosyl as main chain. JACP-50p and JACP-80r were characterized as β-(1 → 6)-glucans with side chains composed of terminal and 3-substituted β-glucopyranosyl residues attached at O-3 for every three residues. Similarly, the backbone of JACP-80 was β-(1 → 6)-linked glucopyranosyl and β-(1 → 3,6)-linked glucopyranosyl residues at a ratio of 4:1. This work provides more information to the understanding of polysaccharides from A. cylindracea, further guiding its biological researches and developing the application in food and biomedicine industries.