Green and efficient extraction of polyphenols from Lycium barbarum leaves using a betaine-based natural deep eutectic solvent: Process optimization, mechanistic elucidation, and bioactivity evaluation.

To overcome the inefficient and unsustainable extraction of polyphenols from Lycium barbarum leaves (LBL), the study developed an ultrasound-assisted ternary natural deep eutectic solvent (NADES) system. The optimized solvent, betaine-1,3-butanediol-lactic acid (NADES-11), achieved a high total polyphenol yield of 34.75 ± 0.43 mg GAE/g under optimized conditions of 35 min extraction time, 21.7% water content, 31.4 mL/g liquid-solid ratio, and a 1:2.5:0.5 M ratio. The purified extract (PLLP) was identified as containing 25 compounds, the main constituents of which include chlorogenic acid (142.26 ± 0.50 μg/mg) and rutin (132.26 ± 0.84 μg/mg). Mechanistic analysis revealed that NADES-11 promotes extraction via hydrogen-bond networks, matrix disruption, and enhanced electrostatic/van der Waals interactions. The polyphenol extract demonstrated significant antioxidant, anti-aging (in Caenorhabditis elegans), and lipid-lowering activities, supporting its potential as a functional ingredient obtained through a green and efficient process.