Optimizing the ultrasound-assisted deep eutectic solvent extraction of flavonoids in common buckwheat sprouts

•Choline chloride (CC)-based deep eutectic solvent (DES) extraction was evaluated.•80% CCTG (CC:triethylene glycol + 20% water), MeOH and EtOH had comparable efficacies.•The ultrasound-assisted DES (80% CCTG) extraction of flavonoids was optimized.•Flavonoids in buckwheat sprouts were efficiently extracted by the optimized method.•Flavonoids in the DES extract were easily recovered with C18 solid-phase extraction. In this study, deep eutectic solvents (DESs) coupled with ultrasound-assisted extraction (UAE) were evaluated and optimized for the extraction of major flavonoids from common buckwheat sprouts. Initially, 18 different choline chloride (CC)-based DESs were evaluated as potential extraction solvents, and 80% CCTG (CC-based DES composed of triethylene glycol and 20 vol% water) extracted significantly higher (p