ANTIOXIDATIVE MECHANISM OF beta-CAROTENE IN RED BLOOD CELL MEMBRANE

为了了解-胡萝卜素在红细胞（RBC）膜中的抗氧化作用机制，研究了在喂食含有-胡萝卜素（0.6%或3.0%）的小鼠一周后，红细胞、血浆、肝脏和肺中磷脂氢过氧化物和-胡萝卜素异构体的浓度。饮食中补充-胡萝卜素增加了红细胞中-胡萝卜素的浓度，并降低了磷脂酰胆碱和磷脂酰乙醇胺氢过氧化物的浓度。然而，在血浆和其他组织中没有观察到-胡萝卜素的有效抗氧化作用，尽管-胡萝卜素水平升高。与其他组织相比，红细胞中积累的顺式-胡萝卜素水平较高，这表明-胡萝卜素的抗氧化作用仅对红细胞膜具有特异性。摘要采用化学发光检测器对红细胞中β -胡萝卜素的几种过氧化产物进行了检测。过氧化产物与-胡萝卜素与过氧自由基或单线态氧反应时产生的过氧化物相似。光谱分析表明，未知过氧化物推测为内过氧化物，其结构与环氧胡萝卜素和次胡萝卜素的结构有很大不同。由此推测，β -胡萝卜素存在于红细胞磷脂双分子层中，可能通过猝灭单线态氧引起的磷脂过氧化作用而发挥抗氧化作用。

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.