杂交构树叶多酚提取工艺优化及其抗氧化活性研究

为建立和优化杂交构树叶多酚的提取工艺，本试验采用超声波辅助提取的方法，以构树叶多酚得率为考察指标，通过单因素试验研究液料比、乙醇浓度、超声时间、超声温度4个因素对构树叶多酚得率的影响；在单因素试验的基础上，借助响应面法设计4因素3水平的试验方案，对构树叶多酚提取的工艺参数进行优化，建立回归模型并进行响应面分析，最终确定最佳的提取工艺参数，并进行3次平行验证；以维生素C为对照，通过测定构树叶多酚对DPPH和ABTS自由基的清除率，评价构树叶多酚的体外抗氧化活性。结果显示：4个因素对构树叶多酚得率的影响顺序依次为：乙醇浓度（B） > 液料比（A） > 超声温度（D） > 超声时间（C），响应面分析结果显示：两两因素之间存在交互作用，但交互作用不显著（P>0.05）；在液料比为70：1、乙醇浓度为60%、超声时间为50 min、超声温度50 ℃的条件下，构树叶多酚的得率最大，为13.62 mg/g，与响应面法的预测值接近；体外抗氧化试验结果表明，构树叶多酚可以清除DPPH和ABTS自由基，并且在高浓度情况下可以达到与维生素C相当的水平。综上，试验建立的构树叶多酚提取工艺准确、可行，同时证明构树叶多酚具有良好的抗氧化活性；该结果可为构树叶多酚的生物活性研究以及构树叶的药用价值开发提供参考。

Optimization of Extraction Process and Antioxidant Activity of Polyphenols from Leaves of Broussonetia papyrifera

In order to establish and optimize the extraction process of polyphenols from Broussonetia papyrifera leaves,the ultrasonic assisted extraction method was used in this experiment.Taking the yield of polyphenols from Broussonetia papyrifera leaves as the index,the effects of the material to solvent ratio,ethanol concentration,ultrasonic time and ultrasonic temperature on the yield of polyphenols from Broussonetia papyrifera leaves were studied by single factor experiment.On the basis of single factor experiment,the experiment of 4 factors and 3 levels was designed by response surface methodology(RSM) to optimize the extraction process parameters of Broussonetia papyrifera leaf polyphenols,a regression model was established and response surface analysis was carried out to determine the optimal extraction process parameters,and three parallel validation were carried out.Taking vitamin C as the control,the antioxidant activity of Broussonetia papyrifera leaf polyphenols on DPPH and ABTS free radical scavenging rate was determined to evaluate in vitro antioxidant activity of Broussonetia papyrifera leaf polyphenols.The results showed that the order of the four factors on polyphenol yield was ethanol concentration (B)>the material to solvent ratio (A)>ultrasonic temperature(D)>ultrasonic time(C).RSM results showed that there was interaction between the two factors,but the interaction was not significant (P>0.05).When the material to solvent ratio was 70:1,ethanol concentration was 60%,ultrasonic time was 50 min,and ultrasonic temperature was 50 ℃,the yield of polyphenols from Broussonetia papyrifera leaves was 13.62 mg/g,which was close to the predicted value of RSM.In vitro antioxidant test showed that Broussonetia papyrifera leaf polyphenols could scavenge DPPH and ABTS free radicals,and could reach the level equivalent to vitamin C at high concentration.In conclusion,the extraction process of polyphenols from Broussonetia papyrifera leaves in this study was accurate and feasible.It was also proved that the polyphenols from Broussonetia papyrifera leaves had good antioxidant activity.The results could provide reference for the study of biological activity of Broussonetia papyrifera leaves and the development of medicinal value of Broussonetia papyrifera leaves.