Nutritional and Cooking Studies on Antioxidant Activity of Ukogi Leaves

1. 用0.1M磷酸缓冲液对鲜乌木叶片进行匀浆，用ESR自旋捕获法测定上清液中活性氧（超氧化物、羟基自由基、过氧化物自由基、单线态氧）的清除能力。各活性氧的清除活性均有季节变化，夏季清除活性较高。这些发现表明木叶的抗氧化活性是抵御阳光胁迫的防御系统。Ukogi叶片的超氧化物清除能力极强，sod样活性是菠菜、欧芹和青椒的8倍。研究了不同烹饪方法（水煮、蒸煮、微波加热）对木叶清除超氧化物活性的影响。研究了不同蒸煮方式对木叶中多酚和维生素C含量的影响。微波加热法对其抗氧化活性的影响最小。多酚损失最少的最有效烹饪操作。维生素C含量为蒸法测定。体内实验采用维生素E缺乏大鼠。维生素E缺乏大鼠饲喂含10%乌木叶粉的日粮6周。维生素E缺乏大鼠溶血率几乎为100%，表明体内维生素E完全缺乏。实验结束时，Ukogi组溶血率降低，溶血活性基本消失。上述结果提示，乌柯木具有类似维生素的作用，可改善维生素E缺乏状态下的溶血。Ukogi组小鼠血清过氧化脂浓度显著降低，直至与对照组相当。这些结果表明，木叶在体内具有良好的抗氧化作用，并能抑制脂质过氧化的产生。此外，血清总胆固醇水平表明Ukogi具有较强的降胆固醇作用。

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.