Ultrasound-assisted combined with natural deep eutectic solvents for complanatoside A extraction: Optimization, identification, and bioactivity evaluation

Astragali complanati Semen (ACS) is frequently used as Chinese medicines and functional foods. Complanatoside A (CA), a key bioactive phytochemical isolated from ACS, exhibits broad-spectrum pharmacological properties. This investigation systematically formulated sixteen natural deep eutectic solvent (NADES) systems by combining three hydrogen-bond acceptors with eleven hydrogen-bond donors at varying molar ratios. These NADES formulations were subsequently employed in tandem with ultrasonic-assisted extraction to isolate CA. Optimization studies identified the following parameters as most effective for extraction using the L -proline/levulinic acid-based NADES (molar ratio 1:2): 60℃, 30 min, 40 % water content, liquid-solid ratio 25 mL/g, achieving an extraction yield of 1.57 %. The adsorption and desorption conditions were optimized employing a macroporous resin for the recovery of CA, while the reusability of the NADES solvent was thoroughly evaluated throughout the extraction process. The CA extract exhibited significant tyrosinase and α-glucosidase inhibitory activity. These findings establish ultrasound-assisted NADES extraction as a sustainable methodology for efficient extraction of CA from ACS, providing valuable insights for eco-friendly extraction and pharmacological exploitation of plant-derived bioactives.