【作者】 王丽丽；

【导师】 赵新淮；

【作者基本信息】 东北农业大学 ， 食品科学， 2007， 硕士

【摘要】 以本地产紫丁香叶为原料，经过干燥、粉碎、溶剂提取、纯化和冷冻干燥得到紫丁香叶多酚提取物的固体产品，确定了其提取和纯化的条件，评价了提取物对体外Cu²⁺诱导低密度脂蛋白（LDL）氧化修饰的抑制作用、对两种自由基的清除能力，并且测定了提取物在两种食用油脂中对自动氧化的抑制情况。主要结果如下：1．通过对提取条件中料液比、乙醇浓度、提取温度、提取时间和提取次数的试验，确定了最佳提取条件为：料液比1：10（m／v），乙醇浓度50％（V／V），提取温度40℃，提取时间2.0h，提取次数为2次，提取率为88.9％。2．通过提取液在两种树脂的静态吸附试验和静态洗脱试验，确定了S-8大孔吸附树脂对紫丁香叶多酚提取物的吸附和洗脱效果，要好于NKA-Ⅱ大孔吸附树脂。3．紫丁香叶粗提物纯化的适宜条件为：动态吸附时上柱速度2.0 BV·h^-1，动态洗脱时乙醇浓度70％，洗脱剂流速2.0 BV·h^-1，洗脱剂体积4BV，多酚提取物的回收率约为79.4％。4．体外Cu²⁺诱导LDL氧化反应，通过对氧化修饰后LDL反应体系中丙二醛（MDA）、脂褐素和LDL相对电泳迁移率的测定，确定了紫丁香叶多酚提取物对体外LDL氧化反应有很好的抑制作用。1)提取物添加量为50mg·L^-1～400mg·L^-1时，对氧化修饰的LDL中MDA的生成量均有明显的抑制作用，抑制率为10.0％～71.9％，呈现明显的剂量-效应关系。2)提取物添加量为50mg·L^-1～400 mg·L^-1时，对氧化修饰的LDL中脂褐素的生成量也有抑制作用，抑制率为29.2％～56.2％，剂量-效应关系明显。3)提取物添加量为100 mg·L^-1、200 mg·L^-1、400 mg·L^-1时，对氧化修饰的LDL相对电泳迁移率也有明显的抑制作用，抑制率分别达到17.5％、22.4％和31.2％。5．评价了紫丁香叶提取物对自由基的清除能力。对于羟自由基（·OH）的清除，反应体系中添加0.0078％～0.250％的提取物，清除率达到20.8％～96.2％，提取物对羟自由基的清除能力强于Vc。对于超氧阴离子自由基（·O₂^-）的清除，提取物的添加浓度为60 mg·L^-1、240mg·L^-1和960mg·L^-1时，对超氧阴离子自由基的生成也具有一定的抑制作用，但提取物对·O₂^-的清除能力不如Vc，只有提取物浓度达到240mg·L^-1时，才与浓度为100 mg·L^-1的Vc的清除效果相接近。6．在食用油脂抗氧化试验中，紫丁香叶提取物对猪油和精炼一级大豆油均有很好的抗氧化作用，可以抑制它们的自动氧化反应。提取物添加量为0.01％时，其抗氧化作用与添加0.01％没食子酸丙酯（PG）的抗氧化作用相近。当提取物添加量增大到0.05％或0.1％时，提取物的抗氧化能力还有所增加，但增幅不明显；使用0.01％～0.05％的紫丁香叶提取物，已经能够达到与PG相等的效果。提取物添加量为0.1％时，在60±1℃的条件下贮藏25天后，猪油的过氧化值为14.5meq·kg^-1(国家标准为≤16 meq·kg^-1)，精炼一级大豆油的过氧化值为9.4 meq·kg^-1(国家标准为≤10 meq·kg^-1)，均符合国家标准。更多还原

【Abstract】 With the Syringa oblata lind L. leaf as raw material, the solid polyphenol extract was obtainedfrom the treatment of drying, smashing, and extracting leaf, and then purifying and freeze-dryingextract. The conditions for extracting and purifying were determined. The inhibition of extract onthe oxidation of low-density lipoprotein, which was induced by cupric in vitro, the scavengingactivity of extract on free radicals and the antioxidation of extract in two edible oils were allevaluated.1. The optimum extracting conditions for the polyphenol extract from Syringa oblata LindL. leaf according to the screening experiment were selected. The ratio of raw material to solvent,the concentration of ethanol, temperature, times and time of the extraction were following: 1: 10,50%, 40℃, twice for 2 h. The extracting rate of polyphenols was 88.9%.2. The S-8 macroporous resin had better static adsorption and static desorption thanNKA-Ⅱmacroporous resin. The S-8 macroporous resin was more suitable to purify the rudeextract.3. The optimum purifying conditions for the rude extract to the screening experiment wereselected. The flow velocity for dynamic adsorption was 2.0 BV·h^-1. For dynamic desorption, theconcentration of ethanol was 70%, the flow velocity of ethanol was 2.0 BV·h^-1, and the volume ofthe ethanol was 4 BV. The recovery of polyphenols was 79.4%.4. Through oxidative modification of low-density lipoprotein （LDL） which was induced bycupric in vitro, the formation of MDA, lipofuscin, and the relative electrophoretic mobility of LDLoxidized were determined. The results showed that the extract had good inhibition to the LDLoxidation.1) When the addition levels of the extract of Syringa oblata Lind L. leaf were 50mg·L^-1～400mg·L^-1, the inhibition to the formation of MDA in Ox-LDL were significant. The inhibiting extentswere 10.0%～71.9% respectively. There is strong correlation between dose and effect.2) When the addition levels of the extract of Syringa oblata Lind L leaf were 50 mg·L^-1～400mg·L^-1, the inhibition to the formation of lipofuscin in Ox-LDL were significant. The inhibitingextents were 29.2%～56.2% respectively. There is strong correlation between dose and effect.3) When the addition levels of the extract of Syringa oblata Lind L.leaf were 100 mg·L^-1, 200mg·L^-1, 400 mg·L^-1, the inhibition to the relative electrophoretic mobility of Ox-LDL weresignificant. The inhibiting extents were 17.5%, 22.4% and 31.2% respectively.5. The scavenging activity of extract from Syringa oblata Lind L.leaf on hydroxyl free radicaland superoxide anion free radical were studied. The final results showed that the extract hadsignificantly scavenging activity to the hydroxyl free radical. The addition levels of the extract of Syringa oblata Lind L.leaf were 0.0078%～0.250%. The scavenging extents were 20.8%～96.2%,respectively. The extract had higher scavenging activity to hydroxyl free radical than ascorbic acid.When the addition levels of ascorbic acid were 0.0625% and 0.125%, the scavenging extents were87.4% and 91.1%. The addition levels of the extract of Syringa oblata Lind L.leaf were 60 mg·L^-1,240 mg·L^-1 and 960 mg·L^-1, it had some scavenging activity to the superoxide anion free radical.The scavenging activity of the extract to the superoxide anion free radical was increased asaddition level increased. But the extract had lower scavenging activity to superoxide anion freeradical than ascorbic acid. Only when the addition level of the extract was 240 mg·L^-1, it had thesame scavenging activity as ascorbic acid which was 100 mg·L^-1.6. The extract from Syringa oblata Lind L. leaf had good antioxidation on the lard and refinedsoybean oil. The effect was similar to that of propyl gallate when they were at the same additionlevel （0.01%）. When the addition levels increased to 0.05% and 0.1%, the antioxidation of theextract still increased in the two edible oils. But the extent increased was not significant. Thismeant that when the addition level of the extract was 0.01～0.05% in the experiment, it had thesame antioxidation as propyl gallate. When the addition level was 0.1%, the storage temperaturewas 60±1℃, 25 days later, the POV of lard sample was 14.5 meq·kg^-1(GB≤16 meq·kg^-1) andthe POV of refined soybean oil was 9.4 meq·kg^-1(GB≤10 meq·kg^-1), which conformed tonational standard.更多还原