Optimization of Ultrasonic-assisted Extraction of Flavonoids from Artemisia Annua L. Residue and Their Antioxidant Activity

Using ethanol as extraction solvent,flavonoids were extracted under ultrasonic assistance from Artemisia Annua L. residue where artemisinin had been extracted. The optimal ultrasonic-assisted extraction technology was determined by single factor experiment and orthogonal experiment.Meanwhile,the antioxidant activity of flavonoids against oil and fat was evaluated and compared with that of ascorbic acid and citric acid. The results show that the optimal ultrasonic-assisted extraction technology of flavonoids from Artemisia Annua L. residue are as follows: ethanol volume fraction of about 50%,material-to-liquid ratio of 1∶30(30 mL liquid per gram material),ultrasonic power of 200W,ultrasonic-assisted extracting time of about 40 min and extraction temperature at 55 ℃. The extraction rate of flavonoids reaches 9. 10% under the optimal ultrasonic-assisted extraction technology.The removal efficiency of hydroxyl radical increases along with the increase of the concentration of purified flavonoids. The purified flavonoids exhibit obvious antioxidant activity against oil and fat. It is superior to both ascorbic acid and citric acid in terms of its effect on oil,while it is somewhat superior to citric acid but inferior to ascorbic acid in terms of its effect on fat.