ANTIOXIDATION OF HUMAN LOW-DENSITY-LIPOPROTEIN BY UNCONJUGATED AND CONJUGATED BILIRUBINS

We demonstrate here that both unconjugated bilirubin (Bu) and conjugat ed bilirubin (Bc) can protect human low density lipoprotein (LDL) agai nst oxidation by oxyradicals generated by 2,2'-azo-bis(2-amidinopropan e) dihydrochloride at 37 degrees. The oxidation was assessed by agaros e gel electrophoresis and was further corroborated by assaying the mal ondialdehydes and lipid peroxides formed throughout oxidation. On a pe r mole basis, Bu and less so Be was more effective than ascorbate in p reventing LDL oxidation. Since oxidative modification of human LDL was implicated in plaque formation in blood vessels leading to atherogene sis, the data suggested that either bile pigment may help reduce the r isk of atherogenesis.