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Chemistry and Industry of Forest Products ›› 2018, Vol. 38 ›› Issue (5): 85-92.doi: 10.3969/j.issn.0253-2417.2018.05.012

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Extraction of Total Polyphenols from Eucommia ulmoides Oliver Leaves Assisted by Ultrasound-microwave and Their Antioxidant Activity

WANG Xiang1,2, PENG Sheng1, PENG Mijun2   

  1. 1. National & Local United Engineering Laboratory of Integrative Utilization Technology of Eucommia ulmoides, Key Laboratory of Human Forest Products and Chemical Industry Engineering, Jishou University, Zhangjiajie 427000, China;
    2. Guangdong Provincial Key Laboratory of Emergency Test for Dangerous Chemicals, Guangdong Institute of Analysis, Guangzhou 510070, China
  • Received:2018-06-26 Online:2018-10-25 Published:2018-11-06

Abstract: The extraction technology of total polyphenols from Eucommia ulmoides Oliver leaves was optimized by ultrasound-microwave assisted method and their antioxidant activity were investigated. Experiments were conducted to investigate the effects of 6 factors, such as ethanol volume fraction, solid-liquid ratio, ultrasound power, ultrasound extraction time, microwave power, and microwave extraction time on the yield of total polyphenols from E. ulmoides leaves by Plackett-Burman design. After screening the four significant factors including ethanol volume fraction, solid-liquid ratio, microwave power and ultrasound extraction time, the process optimization was carried out by the steepest ascent design and response surface. The optimal extraction conditions were as follows:ethanol volume fraction 46%, solid-liquid ratio 1:20.70(g:mL), microwave power 154 W, microwave extraction time 140 s, ultrasound power 350 W and ultrasound extraction time 31 min. Under this condition, the yield of total polyphenols was 8.491%, which was improved by 33.57% compared with the traditional method. The extract of total polyphenols has been obtained by optimal process and the results of antioxidant assay in vitro showed that the extract of total polyphenols from E. ulmoides leaves had obvious scavenging capacity for DPPH·, ABTS·and·OH, with the inhibitory concentration 50% (IC50) values of 31.21, 24.50 and 311.8 mg/L respectively, and the antioxidant activity is equivalent to BHT and lower than Vc.

Key words: Ultrasound-microwave assisted extract, Placket-Burman design, response surface, total polyphenols, antioxidant activity

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