Ultrasound-assisted deep eutectic solvent extraction of polyphenols from Cornus officinalis: Optimization, mechanisms, and bioactivity

This study investigated the combined use of deep eutectic solvents (DESs) and ultrasound-assisted extraction (UAE) for extracting polyphenols from Cornus officinalis (COF). The results revealed that DESs containing choline chloride-acetamide (ChCl-Ace, 1 : 2) yielded the highest extraction efficiency. Optimal extraction conditions included an ultrasonic power of 350 W, a liquid-to-solid ratio of 24 : 1 mL/g, and 45% water content. Eight phenolic compounds in the COF extract were identified using high-performance liquid chromatography-mass spectrometry. According to the SEM observations, the surface structure of the samples was modified by UAE, as indicated by an average pore size of 770 ± 14.32 nm in ChCl-Ace-UAE, which helped release phenolic compounds. Molecular dynamics simulations showed that ChCl-Ace significantly enhanced solute-solvent interactions, particularly with gallic acid and cyanidin-3-O glucoside, leading to improved extraction efficiency. In vitro chemical and cellular assays confirmed that DES-Ace displayed superior antioxidant properties. In addition, the ChCl-Ace-UAE extract (0.5 mg/mL) demonstrated 91.25 ± 0.15% Staphylococcus aureus, 95.48 ± 0.17% Escherichia coli and 93.72 ± 0.36% Propionibacterium acnes inhibition in the antibacterial assay. In summary, the combined use of UAE and DESs offers a promising and eco-friendly approach for extracting valuable compounds from botanical sources.