Structural characterization and antioxidant activities of polysaccharides extracted from Polygonati rhizoma pomace.

The present study aimed to prepare polysaccharides from the pomace of rhizome and characterize their structural features and biological activities. After hot water extraction and DEAE-52 cellulose fractionation, a neutral polysaccharide (PKP) was obtained with 91.85% sugars and 0.45% proteins. Structural characterization indicated that PKP contained a main fraction with a molecular weight of 4.634 × 10 Da and was composed of →1)--D-Fru-(2→ and →6)--D-Fru-(2→ residues. PKP was a semi-crystalline polymer, and the Congo red assay suggested the presence of triple-helix structure in PKP. PKP exhibited moderate radical scavenging activity (including 15.55% inhibition of DPPH, 21.48% inhibition of ABTS, and 22.52% inhibition of ·OH) and could effectively protect MRC-5 cells from HO-induced oxidative damage at 0.01 mg/mL through inhibiting apoptosis, decreasing SA--galactosidase activity, and downregulating the expression levels of p16 and p53. Therefore, PKP could be used in functional foods and pharmaceuticals as an antioxidant. This study provides an attractive method for utilizing polysaccharides from waste materials.