Superior and distinct antioxidant effects of selected estrogen metabolites on lipid peroxidation.
The effect of the estrogen metabolites, 4-hydroxyestrone and 17alpha-dihydroequilin (metabolites of estradiol-17beta and equilin, respectively), were examined for antioxidant effects on plasma and lipoprotein lipid peroxidation . Lipid peroxidation was evaluated by products of both fatty acid (thiobarbituric acid-reactive substances [TBARS]) and cholesterol (oxysterols) oxidation from lipoproteins or whole plasma. Although all estrogens significantly reduced lipid peroxidation, 4-hydroxyestrone was far more potent than either equilin or 17alpha-dihydroequilin in inhibiting TBARS formation in lipoproteins induced by Cu2+. Similar effects were also noted on TBARS formation in THP-l macrophages in culture. However, 17alpha-dihydroequilin (along with equilin) strongly inhibited oxysterol formation, whereas 4-hydroxyestrone was ineffective. These studies suggest that different estrogens might act preferentially on distinct lipid substrates in exhibiting antioxidant effects.
Tang
M
M
Department of Internal Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267-0540, USA.
Abplanalp
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W
Ayres
S
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Subbiah
M T
MT
D000975:Antioxidants / Q000494:pharmacology*; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism; D004857:Equilin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism; D006801:Humans; D006894:Hydroxyestrones / Q000378:metabolism / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000502:physiology; D008077:Lipoproteins, LDL / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013261:Sterols / Q000097:blood; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D000975:Antioxidants; D005227:Fatty Acids; D006894:Hydroxyestrones; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D013261:Sterols; D017392:Thiobarbituric Acid Reactive Substances; D004857:Equilin; C014482:dihydroequilin; D002784:Cholesterol