印楝叶多酚提取及体外抗氧化活性

Antioxidant Capacity and Extraction Technique of Polyphenol from the Leaf of Azadirachta indica

摘要:

摘要：采用福林-肖卡法，以没食子酸为对照品，在750nm波长测定印楝叶中多酚含量。用单因素和响应曲面法设计实验，考察了提取温度、提取时间、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。同时，体外实验评价印楝叶多酚的抗氧化能力。结果表明，印楝叶多酚提取的最佳工艺条件为：提取温度77℃，提取时间80min，乙醇体积分数50%；响应变量影响顺序为：提取温度＞提取时间＞乙醇体积分数；印楝叶中多酚提取得率平均为3.12%，与模型预测值相符。相同浓度下印楝叶多酚的抗氧化能力强于Vc，其清除DPPH自由基的半数抑制质量浓度（IC50）约为4.6mg/L，低于Vc的半数抑制质量浓度（IC50）9.8mg/ L。清除羟自由基（OH）的半数抑制质量浓度（IC50）约为23 mg/L，低于Vc的半数抑制质量浓度（IC50）85 mg/L。

Abstract:

Abstract: Polyphenol content from neem leaf was measured at 750nm wavelength with gallic acid as standard by the using Folin-Ciocalteu method. The extraction conditions of total polyphenol from the neem leaf were optimized by solvent refluxing method. The interactions between the variables, and three response variables such as extract temperature, time and ethanol concentration affected on the extraction of polyphenol from neem leaf were investigated by the single factor experiment and response surface method. And the extraction process was optimized. Moreover, antioxidant activity of polyphenol in leaves of neem was evaluated by in vitro. Experimental results show: (1) the optimum extraction conditions of polyphenol from the neem leaf were temperature 77 ℃, extraction time 80 min and ethanol concentration 50 %; (2) the influence order of response variables was extraction temperature, extraction time, ethanol concentration; (3) the average extract ratio of polyphenol in the neem leaf was 3.12 %; (4) under the same concentration, the antioxidant activity of polyphenol extracted from neem leaf was stronger than that of Vc, and the IC50 values of phenolics scavenging activity on DPPH was approximately 4.6 mg/L. It was less than that of Vc which was approximately 9.8 mg/L. (5) the 23 mg/L of IC50 values of neem leaf phenolics scavenging activity on OH was less than that of Vc which was about 85 mg/L.