Abstract:

The ultrasonic-microwave synergistic extraction of total flavonoids from Cichorium endivia L. seeds was
optimized by response surface methodology. The optimum conditions were determined as follows: ratio of liquid to solid,
40:1(mL/g); ethanol concentration, 71%; extraction temperature, 65 ℃; microwave power, 400 W; ultrasonic power,
50 W; and extraction time, 6 min. Under these extraction conditions, the content of total flavonoids in C. endivia seeds was
93.23 mg/g. The optimum dynamic adsorption and desorption conditions for purification of the crude extract obtained with
AB-8 macroporous resin were established as follows: sample pH, 4; sample flow rate, 2 BV/h; and 70% alcohol as eluant
at a flow rate of 2 BV/h. HPLC analysis results showed that total flavonoids from C. endivia seeds were mainly composed
of chlorogenic acid and cynarin. Off-line DPPH-HPLC assays showed that antioxidant activity of cynarin was stronger than
that of chlorogenic acid, which could scavenge 64.11% and 61.65% DPPH free radical, respectively.

Key words: Cichorium endivia L. seeds, flavonoids, response surface methodology, DPPH, cynarin, recognition