An ultrasound-assisted extraction using an alcohol-based hydrophilic natural deep eutectic solvent for the determination of five flavonoids from Platycladi Cacumen

Deep eutectic solvents and ultrasonic extraction were combined to establish an efficient green method for extracting myricitrin, isoquercitrin, quercitrin, amentoflavone and hinokiflavone from Platycladi Cacumen. During the screening of natural deep eutectic solvents, it was found that the extraction efficiency of natural deep eutectic solvents prepared by short-chain alcohols and organic acids was significantly higher than that of choline chloride-based deep eutectic solvents. Finally, 1,4-butanediol-lactic acid was found as the best natural deep eutectic solvent (molar ratio 1:3). Plackett-Burman Design combined with Box-Behnken Design was used to optimize the extraction parameters, and the optimum extraction conditions were obtained as follows: ultrasonic time 60 min, liquid/solid ratio 20:1, and water content 35 %. The total yield of flavonoids after optimization was 23.11 ± 0.35 mg/g, which was significantly higher than that of traditional organic solvents. Compared with the traditional solvent methanol, the antioxidant activity of the best natural deep eutectic solvent is also significantly improved. Consequently, this study provides a suitable strategy for efficiently extracting bioactive compounds from Platycladi Cacumen, and NADESs prepared by short-chain alcohols and organic acids can be employed as green extraction media for obtaining flavonoids.