超声辅助乙醇提取荞麦黄酮及抗氧化活性研究

Ultrasound assisted extraction of flavonoids from buckwheat and its antioxidant activity

以乙醇为提取剂,采用单因素和响应面分析法相结合的手段优选荞麦黄酮超声辅助提取工艺,并研究其体外抗氧化活性。首先通过单因素试验初步探讨了液料比、乙醇体积分数和超声时间3个主要因素对黄酮得率的影响。然后,采用Box-Behnken中心组合设计试验,根据紫外可见分光光度法测的提取效率,建立了回归方程的预测模型。方差和响应面分析结果表明:液料比和乙醇体积分数、及其之间的交互因素对黄酮提取率影响显著,三个因素二次项对黄酮提取率影响均显著。最终,确定荞麦黄酮超声提取的最佳的工艺条件为:液料比36m L/g、乙醇体积分数94%和超声时间41min,此时黄酮的提取率为1.5042mg/g,略低于模型预测值1.5467mg/g。通过DPPH自由基清除率表征提取液抗氧化活性,结果表明荞麦黄酮提取液的抗氧化活性与质量浓度之间具有一定依赖性,其半抑制浓度为0.0162mg/m L。

The optimal ultrasound assisted extraction process of flavonoids from buckwheat were investigated using ethanol as solvent by single factor experiment and response surface methodology and in-vitro antioxidant activity. The effects of liquid-solid ratio, ethanol concentration, and extraction time on the flavonoids yield were discussed. Further, the predictive model of regression equation was established by Box-Behnken design based on the results of UV-VIS spectrophotometry. The results of Anova and response surface analysis indicate that, the flavonoids yield was significantly influenced by liquid-solid ratio, ethanol concentration and their interactions, as well as the quadratic term of 3 factors. Ultimately, the optimum extraction conditions were obtained as follows ： liquid-solid ratio 36mL/g, ethanol concentration 94%, and extraction time 41min. Under these conditions, the extraction rate is 1.5042mg/g, which is lower than the model predicting of 1.5467mg/g. In-vitro antioxidant assays showed that the extract exhibited a strong DPPH radical-scavenging ability with IC50 value of 0.0162 mg/mL.