The inhibition of low-density lipoprotein oxidation by 17-beta estradiol.
The antioxidant activities of 17-beta-estradiol (E2) and other steroid hormones were studied by determining their effect on copper-catalyzed (cell-free) and mononuclear cell-mediated oxidation of low-density lipoproteins (LDL), as measured by the production of thiobarbituric acid-reactive substances (TBARS). The oxidation of LDL increased linearly with copper concentrations ranging from 0 to 10 mumol/L. E2 at a concentration of 1 mumol/L inhibited LDL oxidation by 37% to 62% at the various concentrations of copper. In a time-course study, E2 at 1 mumol/L delayed the onset of LDL oxidation in the presence of 5 mumol/L copper. E2 (1 mumol/L) inhibited TBARS production catalyzed by 5 mumol/L copper by 54%, compared with 60% inhibition by 1 mumol/L butylated hydroxytoluene (BHT), a known inhibitor of lipid peroxidation. Estriol at 5 mumol/L decreased LDL oxidation by 49%. Dehydroepiandrosterone (DHEA), testosterone, and estrone had no significant effects. E2 was also an effective inhibitor of mononuclear cell (MNC)-mediated oxidation of LDL, but had no effect on superoxide production by these cells. The onset of TBARS formation from cell-mediated LDL oxidation was also delayed by incubation with 1 mumol/L E2. The results indicate that estrogen may protect against atherosclerosis by inhibiting lipoprotein oxidation.
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Department of Medicine, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick 08903-0019.
Khachadurian
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D000975:Antioxidants / Q000494:pharmacology; D002084:Butylated Hydroxytoluene / Q000494:pharmacology; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D004964:Estriol / Q000494:pharmacology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D013997:Time Factors
D000975:Antioxidants; D008077:Lipoproteins, LDL; D017392:Thiobarbituric Acid Reactive Substances; D013481:Superoxides; D002084:Butylated Hydroxytoluene; D004958:Estradiol; D004964:Estriol