Ultrasound‐Assisted Deep Eutectic Solvent Extraction of Quercetin From Dandelion: Process Optimization, Purification, and Bioactivity

ABSTRACT The integration of ultrasound‐assisted deep eutectic solvents (UA‐DES) technology into the extraction of traditional Chinese medicine offers a promising, eco‐friendly, and highly efficient strategy for enhancing the yield of bioactive components. Among the tested solvent systems, a betaine‐glucose‐based deep eutectic solvent (DES) was identified as the most effective for obtaining crude extract of quercetin (CEQ). The extraction parameters were optimized through single‐factor experiments followed by response surface methodology (RSM), resulting in a maximum CEQ yield of 5.29 mg/g under optimal conditions. Scanning electron microscope (SEM) analysis revealed that the UA‐DES system effectively disrupted plant cell walls, improving extraction yield. Further purification was performed using AB‐8 macroporous resin, significantly increasing the concentration of the purified extract of quercetin (PEQ). Antioxidant assays demonstrated that PEQ exhibited strong DPPH and ABTS + free radical scavenging activities. Cytocompatibility assessments using mouse NIH/3T3 fibroblasts showed different concentrations of PEQ maintained high green fluorescence intensity, confirming excellent biocompatibility. Hemolysis tests indicated that the hemolysis rate remained below 5%, reflecting favorable blood compatibility. Collectively, this study is the first to report the optimal UA‐DES combination for extracting quercetin from dandelion, thereby advancing green chemistry and offering valuable insights for the high‐value utilization of natural products.