Yan X, Gu J, Sun C, Liu D
Institute of Military Medicine of Jinan, Jinan 250014, China.
Wei Sheng Yan Jiu. 2001 Nov;30(6):346-9.
In order to investigate the effect of soybean isoflavones(SI) on the oxidative modification to low-density lipoprotein(LDL) and to differentiate the effect of SI and alpha-tocopherol, in vitro and in vivo test were conducted. An in vitro model of LDL oxidative modification induced by copper-ion was established by monitoring the production of thiobarbituric acid-reactive substances (TBARS) and conjugated dienes after SI or alpha-tocopherol was added. The in vivo test was conducted by feeding rats with a high fat diet supplemented with SI and measured the sensitivity of LDL oxidative modification mediated by Cu2+ in vitro. The results revealed that when SI was added into the in vitro LDL oxidation system, the content of TBARS or conjugated dienes in the system was much reduced with a dose-effect relationship, whether lipid oxidation being initiated or not by copper-ion at 37 degrees C. In comparison with SI, only a significant inhibiting effect on lipid oxidation while alpha-tocopherol was added before the initiation of oxidation. High fat diet induced a rising of LDL sensitivity of oxidative stress, and adding SI to the high fat diet could counteract the sensitivity of LDL oxidative modification significantly. It is concluded that SI is a valuable natural antioxidant different from alpha-tocopherol in inhibiting LDL oxidative modification both in vitro and inv vivo.
为了研究大豆异黄酮（SI）对低密度脂蛋白（LDL）氧化修饰的影响，并区分SI与α-生育酚的作用效果，进行了体外和体内试验。通过监测添加SI或α-生育酚后硫代巴比妥酸反应性物质（TBARS）和共轭二烯的生成，建立了铜离子诱导的LDL氧化修饰体外模型。体内试验通过给大鼠喂食添加了SI的高脂饮食，并测定体外Cu2+介导的LDL氧化修饰敏感性。结果显示，在37℃下，无论铜离子是否引发脂质氧化，当将SI添加到体外LDL氧化体系中时，体系中TBARS或共轭二烯的含量均大幅降低，呈现剂量效应关系。与SI相比，α-生育酚仅在氧化开始前添加时对脂质氧化有显著抑制作用。高脂饮食导致LDL氧化应激敏感性升高，而在高脂饮食中添加SI可显著抵消LDL氧化修饰的敏感性。结论是，SI是一种有价值的天然抗氧化剂，在体外和体内抑制LDL氧化修饰方面与α-生育酚不同。
