低水平大豆异黄酮对血清脂蛋白氧化修饰的影响

目的 :　评价低水平 (0 .5～ 1 0μmol/L)大豆异黄酮组分 (染料木素、大豆素和染料木甙 )对血清脂蛋白氧化修饰过程作用的效果及其特点。方法 :　采用 Cu2 +诱导全血清脂蛋白氧化修饰模型 ,通过检测体系中共轭双烯和硫代巴比妥酸反应物质 (TBARS)生成量变化反映异黄酮组分对脂蛋白氧化修饰过程和结局的影响。结果 :　启动氧化前向血清脂蛋白体系中加入 0 .5～1 0 μmol/L的染料木素、大豆素或染料木甙和 α-生育酚均显著减少共轭双烯和 TBARS的生成 ,并存在剂量相关关系。当血清脂蛋白氧化启动后 ,加入 1 0μmol/L异黄酮组分仍显示有较强的抑制作用 ,只是作用强度比启动前加入时减弱 ;而相同浓度的α-生育酚仅对共轭双烯生成显示有一定抑制作用 ,对 TBARS生成甚至呈现促进趋势。结论 :　低水平异黄酮组分即能对血清脂蛋白氧化修饰产生抑制作用 ,且在氧化启动后的效果优于 α-生育酚

EFFECT OF LOW LEVEL SOYBEAN ISOFLAVONES ON THE OXIDATIVE MODIFICATION OF LIPOPROTEINS IN HUMAN SERUM

Objective: To investigate the action of low level soybean isoflavones (genistin, genistein and daidzein) on the oxidative modification of lipoproteins in serum. Methods: After a system of lipoprotein oxidation mediated by Cu 2+ was established in a dilute serum, the effects of soybean isoflavones on the course and the end of lipoprotein oxidation could be reflected by monitoring the production of conjugated dienes and thiobarbituric acid-reactive substances (TBARS) respectively when isoflavones were added. Results: After 0.5-10 μmol/L genistein, daidzein, genistin or α-tocopherol was added into the lipoprotein system respectively before the oxidation initiated by Cu 2+ , the production of conjugated dienes or TBARS in the system was significantly reduced with a dose-dependent relationship. When the lipoprotein oxidation was initiated by Cu 2+ at 37 ℃ for 1 h or 1.5 h, soybean isoflavones also revealed strong inhibition on the oxidation in a weakening way. In comparison with soy isoflavones, α-tocopherol had smaller inhibition on the production of conjugated dienes, but had promotion on the increase of TBARS. Conclusion: Lipoprotein oxidative modification in serum was weakened by low level soybean isoflavones, and its action after the oxidation initiated was more effective than that of α-tocopherol.