Comparative analysis of antioxidant activity and structural changes of Gastrodiae Rhizoma polysaccharides between sulfur-fumigation and nonsulfur-fumigation

The results showed that the optimal extraction conditions for SGCPs and NGCPs were 67°C for 31 min with a liquid-to-material ratio of 15 mL/g and 64°C for 32 min with a liquid-to-material ratio of 17 mL/g, respectively. Compared with NGCPs, SGCPs exhibited significantly reduced DPPH radical, hydroxyl radical, ABTS⁺ radical scavenging activity, and Fe²⁺ chelating ability. Moreover, both NGCPs and SGCPs offered significant protective effects against H₂O₂ ^-induced oxidative damage in RAW264.7 cells, but the protective effect of SGCPs was significantly lower than that of NGCPs. NMR analyses revealed that the main chain connections of SGCP3 and NGCP3 were both →4)-<i>α</i>-D-Glcp-(1→, and sulfur fumigation increased the number of repeating unit structures →4)-D-Glcp-(1 → in GR polysaccharides. SGCP3 and NGCP3 had the same monosaccharides composition but different molar ratios, with molecular weights of 727,650 and 39,991 Da, respectively. In general, sulfur fumigation reduced the antioxidant activities of GR polysaccharides by altering their structure and composition.