Structural characterization of Lanzhou lily (Lilium davidii var. unicolor) polysaccharides and determination of their associated antioxidant activity

Abstract BACKGROUD The Lanzhou lily ( Lilium davidii var. unicolor ) is the only Lilium species that is used for both culinary and medicinal purposes in China. Its bulbs contain various bioactive substances, such as polysaccharides, saponins and colchicine. Lanzhou lily polysaccharides are known to have anti‐immunity, anti‐tumor and anti‐oxidation functions. RESULTS The present study used a Box–Behnken design to optimize the ultrasound‐assisted extraction of Lanzhou lily polysaccharides. Compared to other enzymes, trypsin significantly increased the polysaccharide yields, whereas the protein content of polysaccharides extracted with trypsin was the lowest. Monosaccharide mainly includes glucose (> 50%) and mannose (> 10%). 1,1‐Diphenyl‐2‐picrylhydrazyl radical scavenging activity, chelating activity, total antioxidant capacity and hydroxyl radical scavenging activity of Lanzhou lily polysaccharides extracted with trypsin were stronger than those extracted without enzymes (control). Structural characteristics of Lanzhou lily polysaccharides extracted with trypsin and extracted without enzymes were characterized by scanning electron microscopy and nuclear magnetic resonance spectroscopy. When water extracted polysaccharide and trypsin extracted polysaccharide concentrations were 200 μg mL –1 , Raw264.7 proliferation rates were 101.69% and 159.41%, respectively. CONCLUSION The Lanzhou lily polysaccharide was identified as α‐(1 → 6)‐ d ‐glucan. Consequently, the effects of both potential antioxidant and proliferative activity of trypsin are significant. © 2020 Society of Chemical Industry