不同品种桑葚叶总酚含量及其抗氧化活性比较

Comparison of Total Phenol Content and Antioxidant Activity from Different Mulberry Leaves

为了研究不同品种桑葚叶的总酚含量差异及应用价值,以收集引种的40个品种桑葚叶为研究对象,采用超声波辅助提取桑葚叶中酚类物质,以总酚提取率为指标,利用单因素试验和正交试验考察各因素对超声辅助提取桑葚叶总酚提取率的影响;采用DPPH自由基清除能力评价不同品种桑葚叶提取物的抗氧化能力,同时对不同品种桑葚叶中总酚含量及其抗氧化能力进行相关性分析。结果表明:超声辅助提取桑葚叶总酚的最佳工艺条件为:超声温度65℃、超声时间30 min、固液比1∶45(g/mL)、乙醇浓度60%,4个因素对桑葚叶总酚提取率影响大小顺序为:超声温度>超声时间>固液比>乙醇浓度。不同品种桑葚叶总酚含量差异较大,其中‘条桑五号’总酚含量最高,为(26.35±0.29)mg/g,‘滇桑’总酚含量最低,为(20.44±0.15)mg/g;不同品种桑葚叶抗氧化活性也存在差异,且趋势与总酚含量基本一致,‘条桑五号’桑葚叶抗氧化活性最强,清除DPPH自由基能力IC50为(77.64±0.34)mg/L,总抗氧化能力(FRAP)TEAC值为(2.58±0.11)mmol/g;‘滇桑’桑葚叶抗氧化活性最弱,清除DPPH自由基能力IC_(50)为(210.30±0.19)mg/L,总抗氧化能力(FRAP)TEAC值为(0.73±0.04)mmol/g。桑葚叶总酚含量与其提取物抗氧化能力呈正相关,选择总酚含量高的桑葚品种栽培,可提高桑葚的综合附加值。

In order to compare the contents of total phenol in different mulberry leaves and the different application,single-factor experiments and a four-variable,three-level orthogonal array design were performed to study on the extraction of total phenols from 40 mulberry leaves.The optimal conditions were:temperature 65℃,time 30 min,solid/liquid ratio 1∶45(g/mL),and ethanol concentration 60%.The effect of extraction condition were temperature>time>solid/liquid ratio>ethanol concentration.Under the optimal conditions,the highest content of total phenol in‘Tiaosang 5’mulberry leaves was(26.35±0.29)mg/g.The least content of total phenol in‘Diansang’mulberry leaves was(20.44±0.15)mg/g.Furthermore,the most antioxidant activity of the extracts from‘Tiaosang 5’mulberry leaves and lowest one from‘Diansang’mulberry leaves was(77.64±0.34)mg/L and(210.30±0.19)mg/L(IC_(50)),respectively,according to the DPPH radical-scavenging assay.According to the FRAP,TEAC of‘Tiaosang 5’mulberry leaves and‘Diansang’mulberry leaves was(2.58±0.11)mmol/g and(0.73±0.04)mmol/g,respectively.The total phenol content was positively correlated with the capacity of DPPH radical scavenging.Choosing varieties with high total phenol content in mulberry leaves could improve the economic values of mulberry.