Ultrasonic-Assisted Deep Eutectic Solvent Extraction, Characterization, and Bioactivities of Arctium lappa L. Polysaccharides.

Although Arctium lappa L. polysaccharides (ALPs) possess recognized pharmacological potential, their green extraction using deep eutectic solvents (DESs) combined with ultrasound has not been previously explored. This study reports, for the first time, an optimized DES-based ultrasound-assisted extraction (DES-UAE) protocol for ALPs. Response surface optimization identified the following conditions: choline chloride/oxalic acid molar ratio of 2:1, water content of 18.508%, liquid-to-solid ratio of 37.425 mL/g, extraction time of 97.262 min, and ultrasonic power of 275.787 W, yielding 16.581% polysaccharides. Sequential chromatographic purification afforded a homogeneous fraction, ALPs-1, with a weight-average molecular weight of 8827 Da. Monosaccharide analysis revealed that ALPs-1 is composed of rhamnose, glucuronic acid, glucose, and galactose at a molar ratio of 2.18:1.00:6.62:7.17. Functionally, ALPs-1 exhibited moderate α-glucosidase inhibition, weak DPPH• scavenging, and notable ABTS•+ scavenging (IC50 = 0.87 mg/mL). Importantly, ALPs-1 significantly suppressed NO, TNF-α, and IL-1β production in LPS-stimulated BV2 microglia and protected zebrafish keratinocytes from metronidazole-induced oxidative injury. These results demonstrate that ALPs-1 possesses promising antioxidant, hypoglycemic, and anti-neuroinflammatory activities. This work provides the first evidence for the effective application of DES-UAE in extracting bioactive ALPs, supporting their potential use in functional foods and pharmaceuticals.