Superior and distinct antioxidant effects of selected estrogen metabolites on lipid peroxidation☆☆☆
Abstract
The effect of the estrogen metabolites, 4-hydroxyestrone and 17α-dihydroequilin (metabolites of estradiol-17β 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 17α-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, 17α-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.
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☆ Supported in part by Grant No. HL-50881 from the National Heart, Lung, and Blood Institute.
☆☆ Presented in abstract form at the Experimental Biology 95 Meeting, Atlanta, GA, April 9–13, 1995 (FASEB J 9:A891, 1995).
PII: S0026-0495(96)90212-7
© 1996 Published by Elsevier Inc.
