Ultrasonic microwave-assisted micellar extraction and purification of flavonoids from licorice by metal complex and antisolvent recrystallization

Abstract This study aims to extract and purifiy flavonoids from licorice by an efficient and environmentally friendly approach. The ultrasonic microwave-assisted micellar extraction (UMAME) method was used to extract licorice flavonoids (LFs). The optimal extraction parameters including lauryl sodium sulfate concentration, microwave power, solvent-material ratio and extraction time were investigated by a single factor method and response surface methodology. The extraction rate of LFs was up to 3.65% under the optimal conditions. The extraction solution was pretreated with ethyl acetate and the purity of raw LFs reached 36.47%. The purity of raw LFs was increased from 36.47% to 90.32% by metal complex method and antisolvent recrystallization method. The antioxidant test results showed that the finally purified LFs with an IC50 value of 3.519 μg/mL had a strong scavenging ability on DPPH free radical.