Structural characterization of two polysaccharides from Gastrodia elata Blume and their neuroprotective effect on copper exposure-induced HT-22 cell damage.

In this study, the structural characterization and neuroprotective effects of two Gastrodia elata Blume polysaccharides (GEP-1 and GEP-2) were investigated. GEP-1 and GEP-2, with molecular weights (Mws) of 3.698 kDa and 59.612 kDa, respectively, mainly comprised glucose. Methylation and nuclear magnetic resonance spectroscopic analyses indicated that the structure of GEP-1 was based on →4)-α-D-Glcp-(1 → and →4,6)-α-D-Glcp-(1→, with α-D-Glcp-(1 → and →6)-α-D-Glcp-(1 → as the side chains. The main chain of GEP-2 was →4)-α-D-Glcp-(1→, →4,6)-α-D-Glcp-(1 → and →3,4)-α-D-Glcp-(1→, and α-D-Glcp-(1 → and →6)-α-D-Glcp-(1 → were the side chains. Both GEPs ameliorated copper exposure-induced HT-22 cell damage by inhibiting oxidative stress and inflammation. A comprehensive analysis revealed that the biological activity of GEP-2 was superior to that of GEP-1; this was related to its higher Mw, monosaccharide composition, type of glycosidic bonds, a greater degree of branching, and spatial conformation of GEP-2. These results provide new evidence for the neuroprotective effects of G. elata Blume polysaccharides against heavy metal exposure.