Ultrasound-assisted extraction of flavonoids from Blumea balsamifera using deep eutectic solvents: optimization, characterization, and antioxidant evaluation

Blumea balsamifera , a traditional medicinal herb rich in flavonoids, is recognized for its strong antioxidant potential. In this study, a sustainable extraction strategy combining deep eutectic solvents (DES) and ultrasound-assisted extraction (UAE) was developed to enhance flavonoid recovery. Extraction parameters were optimized using response surface methodology (RSM) for DES screening, and further refined by an artificial neural network–genetic algorithm model (ANN-GA). Choline chloride-glycerol (ChCl-Gly, 1:2, 40% water) was selected as the optimal solvent. Under the ANN-GA conditions of 40:1 mL/g, 77 °C, 45 min, and 300 W, the total flavonoid yield reached 3.52 ± 0.01%, which was 73.40% higher than that obtained by 50% ethanol heat-assisted extraction. Factorial, kinetic, rated-power-based operational, and SEM analyses were consistent with ultrasound-associated matrix disruption and mass-transfer intensification, while FTIR and 1 H NMR supported hydrogen-bond network reorganization in the DES. Antioxidant evaluation through DPPH, ABTS, and reducing power assays showed superior activity of DES extracts, with DES-3 achieving a DPPH IC 50 of 0.1443 ± 0.0063 mg/mL. Total flavonoid content was positively correlated with DPPH ( r = 0.82, p < 0.01) and ABTS ( r = 0.75, p < 0.05) radical-scavenging activities. A cell-based H 2 O 2 -injury model in L02 hepatocytes further demonstrated cytoprotective effects of the DES-UAE extract. UPLC–Q–Orbitrap HRMS identified fifteen flavonoids, several of which were reported in this species for the first time. After three recovery and reuse cycles, the regenerated DES retained 90.57% of its initial extraction yield, with limited changes in viscosity, density, and principal 1 H NMR signals. These findings demonstrate that DES-UAE provides a green and efficient approach for extracting bioactive compounds from B. balsamifera , offering a sustainable foundation for natural antioxidant production.