Extraction of flavonoids from Artemisia argyi using deep eutectic solvents and its antioxidant activities

Deep eutectic solvents (DES) are regarded as eco-friendly alternatives for extracting bioactive substances from natural products. In this study, the DES with varying compositions were employed to extract flavonoids from Artemisia argyi H.Lév. & Vaniot ( A. argyi ) with the assistance of ultrasound, and optimized the extraction conditions through a Box-Behnken design (BBD). The results indicated that the choline chloride (ChCl) / lactic acid (LAC) (molar ratio 1:2) was the best DES for extracting flavonoids from A. argyi with an extraction power of 150 W. The optimal process condition was identified as DES with a water content of 40.0 %, a material-liquid ratio of 1:22.4 g·mL −1 , and the extraction temperature of 44.8 °C. This method demonstrated superior performance compared to the traditional ethanol method. The biological activities in vitro revealed that the extracts exhibited desirable antioxidant activity, and the extraction mechanism of flavonoids was investigated by density functional theory. Furthermore, five distinct types of macroporous resins (HPD826, AB8, YKDH-3, D101, and NKA-9) were selected for the recovery of DES. YKDH-3 exhibited the strongest adsorption capacity, and HPD826 the weakest. The extraction rate of recycled DES reached 84.5 %, the number of recycling was up to more than 6 times. In short, this method, combined with macroporous resin enrichment, can be used as an alternative method for green and efficient extraction of bioactive flavonoids from plants.