Ultrasonic-assisted extraction and antioxidant activity of flavonoids from water chestnut shell

The microwave-assisted extracting was developed in extracting total flavonoids from water chestnut shell and its antioxidant activity with methanol,Effects of four crucial factors including methanol concentration,liquid/material ratio,extraction times and ultrasonic power in extraction yield of total flavonoids were investigated by one-factor-at-a-time method.The scavenging activities of total flavonoids from water chestnut shell on hydroxyl free-radical(HO·),superoxide anion free-radical(O-2·) and DPPH free-radical(DPPH·) were studied and compared with the L-ascorbic acid and BHT by spectrophotometry.Subsequently,all these factors were optimized using orthogonal array design.The optimal parameters for extracting total flavonoids were as follows: methanol concentration 70%(v/v) and liquid/material ratio 30:1 (mL/g) for extraction time 20 min and ultrasonic power 120 W.The yield of total flavonoids was up to 1.722% under these optimized conditions.The results showed that total flavonoids in water chestnut shell was a natural antioxidation and had a strong antioxidant activity.