Ultrasound-assisted deep eutectic solvent extraction of green, high-efficient, and high-bioactive polysaccharides from Glycyrrhiza uralensis.

Licorice (Glycyrrhiza uralensis) roots are among the most widely used medicinal raw materials in traditional medicine and in numerous industries, with their polysaccharides serving as key bioactive constituents responsible for immunomodulation, tissue repair, and drug synergy. However, the low extraction yield and quality of the polysaccharides limit their extensive utilization. Presently, a highly efficient method for the extraction of polysaccharides from G. uralensis roots is lacking. Here, we developed an ultrasound-assisted deep eutectic solvent (UDE) method for extracting high-yield and premium-quality polysaccharides from G. uralensis roots. Eight extraction methods were systematically compared using deep eutectic solvents (DESs) and water as extraction media under various processing modes, including heat conduction, alkaline treatment, enzymatic hydrolysis, microwave irradiation, and ultrasound. Comparative analysis indicated that the UDE method resulted in the highest polysaccharide yield of 18.56% with a 1.71-fold increase over hot water extraction. UDE-extracted polysaccharides exhibited lower molecular weight, smaller particle size, higher solubility, improved thermal stability, and enriched galacturonic acid content, forming a weak gel-like structure with high elastic modulus. Density functional theory and independent gradient model analyses revealed that the DESs interacted with monosaccharide units through extensive hydrogen bonding and van der Waals forces. The UDE-extracted polysaccharides also displayed strong radical scavenging activity similar to vitamin C, and they alleviated IL-13-induced inflammation in BEAS-2B cells by reducing nitric oxide production, restoring antioxidant enzyme activity, and suppressing the STAT6/MYD88 axis. Thus, a green, efficient, and scalable UDE-mediated method is established for extracting highly bioactive polysaccharides for applications in numerous fields.