Structural characterization and hypoglycemic activity of an intracellular polysaccharide from Sanghuangporus sanghuang mycelia

A neutral polysaccharide (SSIPS1) was isolated and purified from cultured mycelia of Sanghuangporus sanghuang by DEAE Sepharose Fast Flow and Sephacryl S-100 columns. Basic monosaccharide composition indicated that SSIPS1 was mainly composed of d-glucose. The results of methylation and 2D-NMR analysis suggested that the glycosidic linkages of SSIPS1 were elucidated to consisted of 1,4-linked α-d-glucopyranose (Glcp) residues with two branched points at O-6. The two branches were composed of 1,4-linked α-D-Glcp terminated with α-D-Glcp, 1,4-linked α-D-Glcp and 1,4-linked β-Galp terminated by α-D-Glcp. Moreover, its chain conformation was revealed to present a flexible chain conformation in 0.1 NaNO3 with a hydrodynamic radius and radius of gyration of 3.26 and 6.45 nm by multi-angle laser light scattering, with a single chain of 0.559 nm observed by atomic force microscopy. Further, SSIPS1 exhibited a potential inhibitory activity against α-amylase and α-glucosidase, and it had hypoglycemic effects on in vitro insulin resistance of HepG2 cells as well.