Ultrasound and enzyme-assisted deep eutectic solvent extraction of polysaccharides from Prunus cerasifera Ehrh.: process comparison and optimization, structural characterization, antioxidant and hypoglycemic activities

In recent years, polysaccharides derived from wild fruit resources have attracted considerable attention due to their significant biological activities. The Prunus cerasifera Ehrh. is an important wild fruit species with a wide range of applications. The polysaccharides found in this plant are among its key bioactive components.This study established a green and efficient ultrasonication-enzyme-assisted deep eutectic solvent method (UE-DES) to extract polysaccharides from Prunus cerasifera Ehrh. (PCCP). Based on yield, composition, and bioactivity, UE-DES was compared with conventional methods, and its extraction process was optimized with mechanistic investigation. Purification led to the acquisition of two homogeneous polysaccharides, PCCP-1 and PCCP-2. Their physicochemical properties were analyzed by spectroscopic and chromatographic techniques, and their structures were elucidated through methylation and Smith degradation. The results indicate that the optimal conditions for UE-DES were determined to be a choline chloride-oxalic acid molar ratio of 1:2, water content of 20%, ultrasonic power of 304 W, liquid–solid ratio of 20:1 mL/g, and ultrasonic temperature of 53 °C. Under these conditions, the yield of PCCP reached 26.23 ± 0.42%. The DES-4 system also demonstrated excellent reusability and stability. Both PCCP-1 and PCCP-2 are triple-helix, pyranose-type acidic polysaccharides. They show a crystalline morphology with coexisting crystalline and amorphous phases, and possess excellent thermal stability. However, their surface morphologies differ significantly. Additionally, the molecular weights of PCCP-1 and PCCP-2 are 253.31 kDa and 231.25 kDa, respectively. Both are primarily composed of fucose, arabinose, glucose, galactose, xylose, and mannose. The main chains are formed by glycosidic bonds → 6)-Glcp-(1 → , → 4)-Glcp-(1 → , → 6)-Galp-(1 → , and → 3)-Galp-(1 → , and contain branch points → 3,6)-Manp-(1 → and → 2,4)-Galp-(1 → .Bioactivity assays show that PCCP-1 has significant antioxidant activity, half-maximal inhibitory concentrations (IC50) of 0.15, 0.18, and 0.12 mg/mL against DPPH·, ABTS·+, and hydroxyl radicals, respectively. Its Fe2+ reduction capacity is 0.21 mg/mL, and it restores viability of H2O2-injured HepG2 cells to 87.56%. PCCP-2 exhibited IC50 values of 0.54 and 0.48 mg/mL for α-amylase and α-glucosidase, respectively, and significantly enhanced glucose consumption and hepatic glycogen synthesis in insulin-resistant cells. This study provides a theoretical basis for the green and efficient extraction of PCCP and its application in drug development.