Effects of different extraction temperatures on the structural characteristics and antioxidant activity of polysaccharides from dandelion leaves

Dandelion polysaccharides contribute to a variety of biological activities. This study evaluated the effect of different extraction temperatures (4 °C and 80 °C) on the structural characteristics and antioxidant activity of dandelion leaf polysaccharides (DLP). The findings demonstrated that the extraction efficiency improved at the higher temperature, while molecular weight exist a trend of degradation with increasing extraction temperature. Ion chromatography (IC) analysis indicated that the polysaccharides DLP4 and DLP80 were structurally complex heteropolysaccharides mainly composed of galactose, arabinose, glucose and mannose, with galactose and arabinose dominating. FT-IR and methylation analysis revealed that DLP4 and DLP80 had similar chemical structures and branches. DLP4 contained a higher amount of 6-Galactose. Microstructure analysis showed that heat treatment caused conformational changes in DLP4 and DLP80. Both had excellent free radical scavenging ability including DPPH·, ABTS·+, OH· and reducing power. The Reactive Oxygen Species assay indicated that the protective effect of DLP4 against H2O2-induced oxidative damage in vitro was stronger than that of DLP80. Superoxide dismutase (SOD) and malondialdehyde (MDA) measurements also confirmed that the antioxidant effect of DLP4 was more prominent. Overall, low temperature extracted DLP can be used as an antioxidant in the areas of food, medicine and biomaterials. •The structure and conformation of dandelion polysaccharides are modified with extraction temperature.•DLP4 and DLP80 obtained at different extraction temperatures all displayed superior scavenging power against free radicals.•DLP4 extracted at low temperature demonstrated stronger protection against H2O2-induced oxidative damage.