Efficient Extraction of Flavonoids from Lotus Leaves by Ultrasonic-Assisted Deep Eutectic Solvent Extraction and Its Evaluation on Antioxidant Activities

The discovery of a green extraction solvent for natural plants could promote related research. In this study, deep eutectic solvents (DES) were used as coupled with an ultrasound-assisted method (UAE) to extract flavonoids from lotus leaves. Thirty-four different DES performed and choline chloride/urea 40% water was chosen the most promising one, parameters in procedures optimized, resulting highest amount D-101 selected four macroporous resins separate DES. Moreover, be recycled efficiently reused times satisfactory performances. addition, leaf exhibited antioxidant activities five kinds assays including DPPH, ABTS, Fe3+ reducing, FRAP, Fe2+ chelating. It also showed antibacterial on Staphylococcus aureus Escherichia coli bacterial strains minimal inhibitory concentrations at 1666 μg/mL 208 μg/mL, respectively. HPLC analysis, three main components identified astragalin, hyperoside, isoquercitrin. conclusion, developed UAE-DES followed by resin treatment become efficient environmentally friendly enrichment leaves other products.