辣木叶多糖提取分离及其抗氧化研究

Extraction and Isolation of Polysaccharides from Moringa Leaves and Their Antioxidant Activities

以辣木叶为原料,首先对植物多糖提取的影响因素及工艺进行研究,其次通过不同体积分数乙醇分级醇沉多糖探索辣木叶多糖的抗氧化性。采用热水浸提法,在单因素的基础上进行正交试验,考察辣木叶多糖得率的影响因素,通过乙醇梯度沉淀分级的方法得到3种辣木叶多糖,分别命名为MP-1(40%乙醇)、MP-2(60%乙醇)、MP-3(80%乙醇),真空冷冻干燥后得到这3种辣木叶粗多糖,并探讨辣木叶多糖体外抗氧化活性。通过单因素及正交试验得出辣木叶多糖的最佳提取工艺为:料液比1∶20 g/mL、提取温度85℃、提取时间2.5 h、提取次数2次,在此条件下,辣木叶多糖得率为2.039%。体外抗氧化实验表明,MP-1、MP-2、MP-3均具有良好的DPPH自由基清除活性,在辣木叶多糖浓度为25μg/mL时,MP-1的DPPH自由基清除能力最低,此时MP-3的DPPH自由基清除能力最高,达到85.34%。该提取工艺条件稳定可行,多糖得率较高,且具有较强的抗氧化能力;该提取方法无需特殊设备,生产工艺成本低,安全,适合工业化大生产,是一种可取的提取方法。

Polysaccharides were extracted from the leaves of Moringa oleifera.The influencing factors and technology of the polysaccharide extraction were optimized,and the antioxidant activities of the polysaccharides extracted from the leaves of M.oleifera by ethanol fractional precipitation were analyzed.The hot water extraction method was used to conduct orthogonal experiments based on the single factor experiments to investigate the factors influencing the yield of polysaccharides extracted from the Moringa leaves.Three polysaccharides were fractionated from the Moringa leaves by graded ethanol precipitation,which were named MP-1 (40%ethanol),MP-2 (60%ethanol),MP-3 (80%ethanol).These crude polysaccharides extracted from the Moringa leaves were vacuum freeze-dried,and their antioxidant activities in vitro were analyzed.Single factor and orthogonal experiments showed that the optimal extraction for Moringa leaf polysaccharides is done when the material-to-liquid ratio is 1:20 g·mL^(-1),extraction temperature 85℃,extraction time 2.5 h and extraction frequencies 2 times.Under these optimal conditions the extraction yield of polysaccharides from M.oleifera leaves is 2.039%.Antioxidant activity test in vitro of the polysaccharides showed that MP-1,MP-2,and MP-3 all have good DPPH free radical scavenging activity.When the concentration of the M.oleifera leaf polysaccharides is 25μg·mL^(-1),MP-1 has the lowest DPPH free radical scavenging ability,while MP-3 has the highest DPPH free radical scavenging ability,which is upto 85.34%.This extraction is feasible under these stable conditions,and has a high yield of polysaccharides,and the polysaccharides extracted under these conditions have high antioxidant activities,which lays the foundation for the in-depth study of M.oleifera leaf polysaccharides.The extraction method does not require special equipment,has low extraction cost,and is safe and suitable for large-scale industrial production of the polysaccharides,and it is hence a desirable extraction method.