本文以紫金蜜桑叶为研究对象，采用超声波辅助乙醇同时提取紫金蜜桑叶活性成分（多酚、黄酮和多糖），并制备桑叶提取物。以3种活性成分含量为考察指标，通过单因素试验考察乙醇浓度、料液比、提取温度和提取时间对活性成分提取效果的影响，在此基础上进行正交试验以优化得到最佳提取工艺，并对桑叶提取物的抗氧化能力进行探究。结果表明，紫金蜜桑叶活性成分的最佳提取工艺条件为乙醇浓度60%、料液比1:35 g/mL、提取温度45 ℃、提取时间70 min。在此条件下，紫金蜜桑叶活性成分的提取率高达20.49%，其中，多酚、黄酮和多糖的平均含量分别为12.13 mg/g、1.79 mg/g和58.74 mg/g。所得桑叶提取物对DPPH自由基、羟自由基以及超氧阴离子自由基的半数清除率（IC50）分别为0.06 mg/mL、3.13 mg/mL和1.15 mg/mL。由此可见，紫金蜜桑叶提取物具有较强的抗氧化能力。

A combination of ultrasound-assisted and ethanol extraction was used to simultaneously isolate several active compounds, including polyphenols, flavonoids, and polysaccharides, from Morus macroura. The relative content of each these three classes of active compound where then used as indicators to explore the effects of various factors, including ethanol concentration, raw material-to-solvent ratio and extraction temperature and duration, on the efficacy of compound extraction using single-factor experiments. Orthogonal tests based on the experimental results were conducted to optimize the extraction parameters. In addition, the antioxidant capacities of the extracts were also analyzed. The results of these assays reveal that the most favorable conditions for extracting active components from Morus macroura are as follows: an ethanol concentration of 60%, a raw material-to-solvent ratio of 1:35 g/mL, an extraction temperature at 45 ℃, and an extraction duration of 70 min. Under these conditions, the active component extraction rate reaches up to 20.49%. In particular, the average polyphenol, flavonoid, and polysaccharide content increased to 12.13 mg/g, 1.79 mg/g, and 58.74 mg/g, respectively. The 50% inhibitory concentrations (IC50) of the mulberry leaf extracts against DPPH, hydroxyl, and superoxide anion free radicals were also shown to increase to 0.06 mg/mL, 3.13 mg/mL, and 1.15 mg/mL, respectively, when using these extraction conditions. Thus, Morus macroura extracts can produce promising antioxidant effects when produced using optimized extraction conditions.

国家自然科学基金项目（31701565）；川大-泸州市科技项目（2017CDLZ-N19）；烹饪科学重点实验室开放基金项目（2017LF3020）；川菜发展研究中心规划项目（CC17Z14）