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.