A green method of extracting and recovering flavonoids from Acanthopanax senticosus using deep eutectic solvents

In recent years, green extraction of bioactive compounds from herbal medicines has generated widespread interest. Deep eutectic solvents (DES) have widely replaced traditional organic solvents in the extraction process. In this study, the efficiencies of eight tailor-made DESs in extracting flavonoids from Acanthopanax senticosus (AS) were compared. Response surface methodology (RSM) was employed to optimize the influencing parameters including ultrasonic power, HBA-HBD ratio, water content, solid-liquid ratio, extraction temperature and extraction time. DES composed of glycerol and levulinic acid at a 1:1 ratio was established as the most suitable extraction medium. Optimal conditions were ultrasonic power of 500W, water content of 28%, solid-liquid ratio of 1:18 g·mL-1, extraction temperature of 55℃ and extraction time of 73 minutes. The extraction yield of AS total flavonoids reached 23.928±0.071 mg·g-1, which was 86.3% and 43.8% higher compared with traditional solvent soak and etha..., 1. Preparation of DES

HBA and HBD reagents were mixed at specific molar ratios, heated and stirred in a water bath at 80°C until completely dissolved. Since the majority of flavonoids are acidic and easily soluble in polar solvents, choline chloride (ChCl), levulinic acid (La), Lactic acid (Lac), Malic acid (Ma), and Citric acid (Ca), which are environmentally friendly and biodegradable, were selected as HBA and ethylene glycol (Eg), La, 1,4-butanediol (Buta), and glycerol (Gly) as HBD components. According to the self-made combination method and molar ratio, eight different DES types were prepared, all of which were uniform and stable transparent liquids.

2. Impact of different DES types and auxiliary extraction methods

DES (7 mL) configured according to the corresponding molar ratio was added to a 20 mL centrifuge tube, followed by 3 mL water (DES water content was 30%). The solution was heated and thoroughly mixed in a water bath at 80℃ to prepare DES extraction solvent with a sol..., ,