Purification, structural characterization and neuroprotective effect of a neutral polysaccharide from Sparassis crispa

In the present study, a purified polysaccharide (named SCP-1, Mw 1.368 × 104 Da) was isolated from Sparassis crispa, and its biological activity was evaluated in an oxidative stress model caused by H2O2 in hippocampal neuronal HT22 cells. SCP-1 was a heteropolysaccharide mainly comprising glucose, galactose, fucose, and mannose in a molar ratio of 52.10: 31.10: 15.04: 1.76. The main backbone of SCP-1 was predominantly composed of (1 → 6)-α-D-Galp, (1 → 6)-β-D-Glcp, (1 → 3)-β-D-Glcp, (1 → 2,6)-α-D-Galp and (1 → 3,6)-β-D-Glcp. The branches, substituted at the O-2 of Gal and O-3 of Glc, contained (1 → 6)-2-OMe-α-D-Galp, (1 → 4)-β-D-Glcp, (1 → 3)-β-D-Glcp, and terminated by T-α-L-Fucp and T-β-D-Glcp. Besides, SCP-1 could effectively protect the HT22 cells against H2O2-induced oxidative injury via decreasing the intracellular reactive oxygen species levels, modulating antioxidant enzymes, and reducing cell apoptosis. The findings suggested that SCP-1 holds a potential to be a natural antioxidant or as a neuroprotective agent.