ANTIOXIDATIVE MECHANISM OF beta-CAROTENE IN RED BLOOD CELL MEMBRANE

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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.