Optimization of Extraction Process of Polysaccharides from Hovenia dulcis Fruit Pedicels and Its Antioxidant Activity

The aim of this study was to obtain polysaccharides from Hovenia dulcis fruit pedicels, and further evaluate its ability to scavenge free radicals and inhibit the oxidation of biological macromolecules (proteins, lipids, DNA). On the basis of a single-factor experiment, the hot water extraction process of polysaccharides from Hovenia dulcis fruit pedicels was optimized using orthogonal test combined with an analysis of variance. The ability of the extracted polysaccharides to scavenge DPPH and ABTS⁺ free radicals was determined. In addition, Cu²⁺/H₂O₂, FeSO₄ and APPH were used to induce the oxidation of bovine serum albumin, linoleic acid and herring sperm DNA, respectively, to construct in vitro protein, lipid and DNA oxidation models and the ability of the extracted polysaccharides to inhibit biological macromolecule oxidation in vitro was evaluated. The results showed that the volume fraction of ethanol precipitation had a significant effect on the yield of polysaccharides from Hovenia dulcis fruit pedicels (P<0.05). The optimal hot water extraction conditions were as follows: solid-liquid ratio, 1:25 g/mL, extraction temperature 85 ℃, extraction time 1 h, ethanol precipitation volume fraction 80%, with the polysaccharide yield of 3.06%±0.181%. With the increase in the concentration, the effects of the extracted polysaccharides in scavenging free radicals and inhibiting the oxidation of biological macromolecules were gradually improved. The IC₅₀ for scavenging DPPH and ABTS⁺ free radicals were 1.687 and 1.824 mg/mL, and the IC₅₀ for inhibiting bovine serum albumin carbonylation, linoleic acid peroxidation and herring sperm DNA oxidation were 13.84, 10.88 and 74.70 mg/mL, respectively. The results can provide a reference for the extraction of polysaccharides from Hovenia dulcis fruit pedicels and its application in functional food.