Nutritional and Cooking Studies on Antioxidant Activity of Ukogi Leaves

1.Ukogi叶抗氧化活性的定量分析用0.1M磷酸盐缓冲液匀浆，用常规的ESR自旋捕捉法测定上清液中活性氧(超氧阴离子自由基、羟基自由基、过氧化氢自由基、单线态氧)的清除能力。各活性氧清除活性均表现出季节性变化，夏季活性较高。这些发现表明，乌木树叶的抗氧化活性是抵御阳光胁迫的防御系统。Ukogi叶的超氧阴离子自由基清除能力极强，其类超氧化物歧化酶活性是菠菜、欧芹和青椒的8倍。研究了不同蒸煮方式(煮沸、蒸煮、微波加热)对Ukogi叶清除超氧化物歧化酶活性的影响。研究了不同蒸煮方式对烟叶中多酚类物质和维生素C含量的影响。微波加热法的抗氧化活性下降幅度最小。最有效的烹饪操作，最大限度地减少多酚的损失。蒸制工艺对维生素C含量影响较大。体内实验采用维生素E缺乏大鼠。维生素E缺乏大鼠喂饲含10%Ukogi叶粉的饲料6周。维生素E缺乏大鼠的溶血率接近100%，表明体内完全缺乏维生素E。实验结束时，Ukogi组的溶血率降低，几乎未观察到溶血活性。这些结果表明，Ukogi发挥了维生素E样效应，并改善了维生素E缺乏状态下观察到的溶血。Ukogi组大鼠血清过氧化脂质浓度明显降低，直至对照组。这些结果表明，熊果叶在体内具有良好的抗氧化性和防止脂质过氧化的产生。此外，血清总胆固醇水平表明Ukogi具有很强的降胆固醇作用。

1. Ouantitative analysis of antioxidative activity in Ukogi leavesFresh Ukogi leaves were homogenized with 0.1M phosphate buffer and the scavenging ability of active oxygen (superoxide, hydroxyl radical, peroxide radical, singlet oxygen) in the supernatant was measured by usual ESR spin trapping method. The scavenging activities of all active oxygen species in Ukogi leaf indicated seasonal variation and were considerable high in summer time. These finding suggest that antioxidative activity of Ukogi leaves is defense system against sunlight stress. Super oxide scavenging activity of Ukogi leaves was extremely strong and the SOD-like activity was 8 times higher than that of spinach, parsley and green pepper. Changes of superoxide scavenging activity of Ukogi leaves by various cooking (boiling, steaming, microwave-heating) were examined. Effects of various cooking on poly- phenols and vitamin C contents in Ukogi leaves was also investigated. Minimum decrease of antioxidative activity was observed by microwave-heating method. The most effective cooking operation for least loss of polyphenols. and vitamin C contents was steaming technique.2. In vivo experiment used vitamin E deficient rats.Vitamin E deficient rats were fed with diet containing 10% Ukogi leaf powder for 6 weeks. Hemolysis rate of vitamin E deficient rat was almost 100%, indicating vitamin E deficiency completely in vivo. The hemolysis rate of Ukogi group was decreased and hemolytic activity was hardly observed at the end of experiment. These results suggest that Ukogi exerts vitamin E-like effect and improves the hemolysis observed in vitamin E deficiency state. The serum lipid peroxide concentration of Ukogi group was significantly reduced until that of control group. These results indicate that Ukogi leaves exert as excellent antioxidant and prevent the production of lipid peroxide in vivo. Moreover, total serum cholesterol level indicates that Ukogi have strong cholesterol-lowering effect.