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目的筛选微波辅助提取印楝叶总多酚的工艺条件,并测定印楝叶总多酚的体外抗氧化活性。方法通过单因素和响应曲面法设计实验,考察萃取温度、萃取时间、乙醇体积分数3个响应变量以及变量之间交互作用对印楝叶多酚提取效果的影响,对提取工艺进行优化。以清除2,2-联苯基-1-苦基肼基(DPPH·)自由基、羟自由基(·OH)及还原力测定实验评价印楝叶多酚的抗氧化能力。结果微波辅助印楝叶多酚提取的最佳工艺条件为萃取温度62℃,萃取时间40 min,乙醇体积分数48%;响应变量影响顺序为萃取温度>乙醇体积分数>萃取时间;验证实验得到印楝叶中多酚提取得率平均为2.96%,与理论值相对误差为1.33%。印楝叶多酚清除DPPH·自由基的半数抑制质量浓度(IC50)约为2.6 mg·L?1,·OH自由基的IC50约为15 mg·L?1,在较低浓度时印楝叶多酚具有较强还原能力。结论印楝叶多酚在低浓度时表现出较维生素C更强的抗氧化活性。
Objective To screen the microwave-assisted extraction of total polyphenols from neem leaves and determine the antioxidant activity of total polyphenols in neem leaves. Methods The single factor and response surface methodology were used to design the experiment. The effects of extraction temperature, extraction time and ethanol volume fraction on the response of three neem leaf polyphenols were studied, and the extraction process was optimized. The antioxidative capacity of neem leaf polyphenols was evaluated by eliminating DPPH radical, hydroxyl radical (· OH) and determination of reducing power by 2,2-diphenyl-1-picrylhydrazyl radical. Results The optimal extraction conditions for microwave-assisted neem leaf polyphenol extraction were as follows: extraction temperature 62 ℃, extraction time 40 min, ethanol volume 48%; response variable order of extraction temperature> ethanol volume fraction> extraction time; validation experiment The extraction yield of polyphenols from neem leaves was 2.96% on average, with a relative error of 1.33% from the theoretical value. The half-maximal inhibitory concentration (DP) of DPPH radical scavenging neem leaf polyphenol was about 2.6 mg · L -1, and the IC50 of · OH radical was about 15 mg · L -1. At the lower concentration, Polyphenols have a strong reduction ability. Conclusion Neem leaf polyphenols showed stronger antioxidant activity than vitamin C at low concentration.