Ultrasound‐assisted ionic liquid extraction of polysaccharides from Crataegus songarica K. Koch fruits: Structural characterization and Antioxidant Activity

In this study, we optimal the ultrasound‐assisted ionic liquid extraction (UAILE) process of polysaccharides from Crataegus songarica K. Koch fruits. The optimal conditions determined were: ultrasonic power of 400 W, temperature of 79 ℃, extraction time of 78 min, Ethylammonium dodecyl sulfate (EADS) concentration of 1.52 mg/mL, and liquid‐solid ratio of 51:1 mL/g. Under these conditions, the polysaccharides yield was 34.37%, which was significantly higher than that obtained by the conventional ultrasound‐assisted extraction (UAE) and hot water extraction (HWE) methods. After purification, we studied the chemical composition, physicochemical properties and structural characteristics of polysaccharides (CSP). The results showed that CSP is a heteropolysaccharide containing α‐linkage glucopyranose, which is mainly composed of mannose, arabinose, galactose and glucose, with a molecular weight (Mw) of 27.82×104 Da. In addition, CSP demonstrated significant free radical scavenging ability, and was able to efficiently reduce the H2O2‐induced HepG2 cellular malondialdehyde (MDA) content, while enhancing superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) activities, showing its superior antioxidant activity. Based on these properties, CSP is expected to be used as a novel efficacy factor in the food and pharmaceutical industries.