Abstract:

The ultrasonic-assisted extraction of total flavonoids from mung bean (Phaseolus radiates) hull using deionized
water as the extraction solvent was optimized by response surface analysis, and the antioxidant capacity of total flavonoids
purified with macroporous adsorption resin was studied. On the basis of single factor experiments, a central composite design
involving four crucial variables including ultrasonic extraction time, ultrasonic power, temperature and liquid-to-solid ratio
was developed to evaluate the significance of the four variables and their interactive effects on the extraction yield of total
flavonoids. Results showed that the optimal extraction parameters were as follows: ultrasound power, 419 W; temperature,
70 ℃; ultr asound time, 75 min; and liquid-to-solid ratio, 45:1 (mL/g). leading to the maximum extraction yield of of (10.18 ±
0.03) mg/g. In vitro antioxidant assay, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) radical scavenging activity of total
flavonoids from mung bean hull was close to that of vitamin C, while the hydroxyl radical scavenging activity was lower
than that of vitamin C. IC50 of total flavonoids from mung bean hull against the above two free radicals were 6.57 and
54.21 μg/mL respectively, compared to 6.12 and 16.58 μg/mL for vitamin C, respectively.

Key words: mung bean (Phaseolus radiates) hull, ultrasonic-assisted extraction, flavonoid, antioxidant activity