A green and recyclable ternary deep eutectic solvent for extracting flavonol glycoside from Ginkgo leaves: Mechanism insights based on molecular level

A novel ternary deep eutectic solvent (DES) was designed for the green and efficient extraction of flavonol glycosides (FG) from Ginkgo leaves. The DES consisted of a molar ratio of choline chloride/acetic acid/1,2-propylene glycol of 1:2:3. The optimal extraction conditions were determined to a solid–liquid ratio of 42 mg/mL, an extraction time of 11.8 h, and an extraction temperature of 51 ℃. The extraction yield of FG was 7.8 mg/g, which demonstrated a notable enhancement in comparison to conventional extraction. Kinetics and morphology analysis revealed that the extraction process involved considerable dissolution and diffusion of the solute. Additionally, a molecular investigation using density functional theory (DFT) indicated that the interaction between the DES and FG was primarily governed by hydrogen bonding and van der Waals force. Notably, the ternary DES exhibited stronger interactions with FG, which were the key factors for better extraction efficiency. Furthermore, efficient recovery of FG from the DES solution was also achieved, with a recovery rate of 94.63 %. Moreover, the recovered DES could be reused directly at least five cycles.