Optimization of ultrasound-assisted deep eutectic solvent extraction, characterization, and biological studies of polysaccharide from seeds of Toona sinensis

The present study aimed to evaluate the polysaccharides extracted from Toona sinensis seeds using ultrasound-assisted deep eutectic solvent (DES). The extracted polysaccharides (TSRP) were purified and studied for their hypoglycemic and antioxidant activities. The purified polysaccharides (TSRPs-1) were hydrolyzed and derivatized to study their monosaccharide composition. The optimum extraction conditions were DES (choline chloride to oxalic acid) at a molar ratio of 1.473:1, ultrasound time of 50.643 min, and a material-to-liquid ratio of 1:31.838 g/mL. The ultrasound-assisted DES extraction was more effective (56.1%) as compared to the water extraction (35.89%). The inhibition of alpha-glucosidase by TSRPs-1 was 42.77% at a concentration of 0.8 mg/mL. At 3.2 mg/mL, TSRPs-1 inhibited alpha-amylase by 34.38%. The clearance of DPPH by TSRPs-1 was 24.36% at 3.2 mg/mL. The IC50 for ABTS<middle dot>(+) clearance by TSRPs-1 was 0.233 mg/mL. It was shown that the monosaccharides of TSRPs-1 were composed of Man, Rha, GlcA, GalA, Glc, Gal, Xyl, and Ara in a molar ratio of 1:563.13:41.81:51.20:21.81:2244.58:3.73:1130.48. In this paper, the process of extracting TSRP with ultrasound-assisted DES was investigated and optimized. TSRPs-1 possesses certain hypoglycemic and antioxidant activities. Therefore, this paper can provide an experimental basis for the establishment of an industrialized production process of polysaccharides and the study of their biological activities.