ANTIOXIDATIVE MECHANISM OF beta-CAROTENE IN RED BLOOD CELL MEMBRANE

为了解β-胡萝卜素在红细胞膜上的抗氧化作用机制，测定了红细胞、血浆中磷脂过氧化氢和β-胡萝卜素异构体的含量，喂食含β-胡萝卜素饲料的小鼠的肝和肺（饮食中0.6%或3.0%）一周。饮食中β-胡萝卜素的摄入增加了β-胡萝卜素的浓度，β-胡萝卜素可降低红细胞内磷脂酰胆碱和磷脂酰乙醇胺的过氧化氢浓度，血浆和其他组织中β-胡萝卜素的抗氧化作用不明显，但β-胡萝卜素的含量增加，红细胞中顺式β-胡萝卜素的积累量高于其他组织，表明β-胡萝卜素的抗氧化作用胡萝卜素对红细胞膜具有特异性，用化学发光检测器检测红细胞中β-胡萝卜素的几种过氧化产物，这些过氧化产物与β-胡萝卜素反应时产生的过氧化物相似，但在红细胞膜上的过氧化产物与β-胡萝卜素反应时产生的过氧化产物相似，而在红细胞膜上的过氧化产物与β-胡萝卜素反应时产生的过氧化产物相似。胡萝卜素和过氧自由基或单线态氧。光谱分析表明，未知的过氧化物被推测为内过氧化物，其结构与根据这些结果，推测存在于红细胞磷脂双层中的β-胡萝卜素可通过淬灭引起磷脂过氧化的单线态氧而显示抗氧化作用。

TO KNOW THE MECHANISM OF ANTIOXIDANT EFFECT OF beta-CAROTENE IN RED BLOOD CELL (RBC) MEMBRANE,CONCENTRATIONS OF PHOSPHOLIPID HYDROPEROXIDES AND beta-CAROTENE ISOMERS IN RBC,PLASMA,LIVER AND LUNGS IN MICE FED DIETS CONTAINING beta-CAROTENE (0.6% OR 3.0% IN DIETS) FOR A WEEK.DIETARY SUPPLEMENTATION OF beta-CAROTENE INCREASED THE CONCENTRATION OF beta-CAROTENE AND DECREASED THE CONCENTRATION OF HYDROPEROXIDES FROM PHOSPHATIDYLCHOLINE AND PHOSPHATIDYLETHANOLAMINE IN RBC WITH INCREASED ADMINISTRATION LEVEL OF beta-CAROTENE.HOWEVER,NO POTENT ANTIOXIDANT EFFECT OF beta-CAROTENE WAS OBSERVED IN PLASMA AND OTHER TISSUES ALTHOUGH beta-CAROTENE LEVELS INCREASED.HIGHER LEVELS OF CIS beta-CAROTENE ACCUMULATED IN RBC COMPARED WITH OTHER TISSUES SHOWED THAT AN ANTIOXIDANT EFFECT OF beta-CAROTENE WAS SPECIFIC TO RBC MEMBRANE.SEVERAL PEROXIDATION PRODUCTS OF beta-CAROTENE PRESENT IN RBC WERE DETECTED BY HPLC EQUIPPED WITH A CHEMILUMINESCENCE DETECTOR.THE PEROXIDATION PRODUCTS WERE SIMILAR TO PEROXIDES PRODUCED DURING THE REACTION OF beta-CAROTENE AND PEROXY RADICAL OR SINGLET OXYGEN.SPECTROSCOPIC ANALYSIS INDICATED THAT THE UNKNOWN PEROXIDES WERE CONJECTURED TO BE ENDOPEROXIDES OF WHICH STRUCTURE WAS QUITE DIFFERENT FROM THOSE OF beta-CAROTENE EPOXIDES AND APOCAROTENAL.FROM THESE RESULTS,IT WAS SUPPOSED THAT beta-CAROTENE PRESENT IN RBC PHOSPHOLIPID BILAYER COULD SHOW AN ANTIOXIDANT EFFECT BY QUENCHING SINGLET OXYGEN WHICH CAUSED PEROXIDATION OF PHOSPHOLIPIDS.