Optimizing the extraction of Polygonum capitatum by PB-BBD response surface method and its antioxidant research
BJECTIVE To optimize the ultrasonic extraction process of total flavonoids and total polyphenols from Polygonum capitatum by PB design and BBD response surface metohd,and research its antioxidant effects.METHODS Using the yield of total flavonoids and total polyphenols as the indexes,several influencing factors were investigated and Plackett-Burmandesign was used to screen the significant factors.Box-Behnken response surface method was used to optimize the extraction of Polygonum capitatum.Theantioxidant activity of Polygonum capitatum was evaluated by examining the scavenging rate of DPPH and hydroxyl radicals and its ability to reduce Fe3+.RESULTS The significant factors were ultrasonic power,temperature andtime.The optimal extraction method was as follows:the ultrasonic power of 160W,temperature of 58℃,time of 38min,ethanol concentrations of 40％and liquid-to-material ratio of 25∶1(mL·g-1).Under the optimal condition,the comprehensive yield of total flavonoids and total polyphenols was 68.79mg·g-1,the relative error was 4.15％.The in vitro scavenging rates of the extracts at 5mg·mL-1 against DPPH free radicals and hydroxyl radicals were 81.66％and 84.93％,respectively.The total reducing capacity reached 2.48.CONCLUSION The ultrasonic extraction process of total flavonoids and total polyphenols from Polygonum capitatum optimized by PB-BBD is simple,stable and practicable.The extract of Polygonum capitatum in thi sresearch had a strong antioxidant activity.
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