Optimization of Ultrasound-Assisted Deep Eutectic Solvents Extraction, Characterization, and Hypoglycemic Activity of Polysaccharides from Abri Herba

The ultrasonic-assisted deep eutectic solvents (DES) method was used to extract the polysaccharides from Abri Herba(AHPs), and the extraction process was optimized by Box-Behnken response surface. The optimal conditions were determined as follows: the molar ratio of choline chloride and urea of 1:3, water content of DES of 70%, ultrasonic temperature of 61 °C, ultrasonic time of 58 min and the ratio of liquid to solid of 50 mL/g. Under these conditions, the extraction yield of AHPs reached 8.49 ± 0.34%. After purification of AHPs using a DEAE-52 cellulose column, the fraction designated as AHPs-1 displayed a single symmetrical peak. The molecular weight ( M W ) of AHPs-1 was determined to be 4.74 × 10 4 Da by HPSEC-MALLS-RID chromatography system, with a narrow polydispersity index of 1.89, confirming its homogeneous nature. FT-IR spectra demonstrated typical characteristic peaks of polysaccharides, while Congo red assay ruled out a triple-helix structure. The scanning electron microscope (SEM) showed that AHPs-1 exhibited a rough surface morphology with irregular granular protuberances. Hypoglycemic activity assays demonstrated significant inhibitory effects of AHPs-1 on both α-glucosidase and α-amylase. Therefore, this study establishes an efficient DES-based extraction method for AHPs and identifies AHPs-1 as a potential hypoglycemic agent for functional foods and pharmaceuticals.