Antioxidant: a new role for RU-486 and related compounds.

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RU-486 and onapristone inhibit low-density lipoprotein oxidation via their dimethylaminophenyl side chains, suggesting these compounds possess potent antioxidant properties distinct from other steroids.

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This study investigated the potential antioxidant properties of RU-486 (mifepristone) and its analog onapristone by examining their ability to inhibit the oxidation of low-density lipoprotein (LDL). Using an in vitro model, the researchers demonstrated that these compounds at micromolar concentrations significantly reduced oxidized LDL formation, an effect attributed specifically to the dimethylaminophenyl side chain moiety present in their chemical structure. The findings indicate that subjects supplemented with RU-486 possessed LDL resistant to oxidation compared to controls, suggesting a protective mechanism distinct from traditional phenolic steroids like estradiol. This paper does not explicitly discuss endometriosis or adenomyosis; it was included in the corpus via a keyword match in the upstream search index.

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Abstract

RU-486 (17 beta-hydroxy-4-dimethylaminophenyl-17-alpha-propenyl estrone 4,9 diene-3-one; mifepristone) is suggested to act by binding to progesterone and glucocorticoid receptors. Based on its chemical nature, we anticipated that RU-486 may have potent antioxidant properties. We used the oxidation of LDL as our model system. RU-486 and a similar compound, onapristone, at 1-5-microM concentrations, decreased the formation of oxidized LDL. LDL isolated from plasma of subjects who were orally supplemented with RU-486 was resistant to oxidation, as compared to LDL isolated from control plasma. The antioxidant effect of RU-486 appears to reside in the dimethylaminophenyl side chain moiety. Reduction of the A-ring of the steroid molecule had no effect on its antioxidant property. Analogs of RU-486 which lack the dimethylaminophenyl group, were without antioxidant activity. Levonorgestrel, which lacks the dimethylaminophenyl group failed to inhibit the oxidation of LDL even at 100-microM levels. In contrast, ethinylestradiol and estradiol which do not possess the dimethylamino group, were able to inhibit the oxidation of LDL by virtue of their phenolic steroid "A" ring. Thus RU-486, with its long half life, high plasma concentrations, association with lipoproteins, and ability to readily enter the cell may have additional intra- and extra-cellular antioxidant effects.
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Advertisement Research Article Free access | 10.1172/JCI117551 Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia 30322. Find articles by Parthasarathy, S. in: PubMed | Google Scholar Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia 30322. Find articles by Morales, A. in: PubMed | Google Scholar Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia 30322. Find articles by Murphy, A. in: PubMed | Google Scholar Published November 1, 1994 - More info Published in Volume 94, Issue 5 on November 1, 1994 J Clin Invest. 1994;94(5):1990–1995. https://doi.org/10.1172/JCI117551. © 1994 The American Society for Clinical Investigation J Clin Invest. 1994;94(5):1990–1995. https://doi.org/10.1172/JCI117551. © 1994 The American Society for Clinical Investigation Published November 1, 1994 - Version history - Abstract RU-486 (17 beta-hydroxy-4-dimethylaminophenyl-17-alpha-propenyl estrone 4,9 diene-3-one; mifepristone) is suggested to act by binding to progesterone and glucocorticoid receptors. Based on its chemical nature, we anticipated that RU-486 may have potent antioxidant properties. We used the oxidation of LDL as our model system. RU-486 and a similar compound, onapristone, at 1-5-microM concentrations, decreased the formation of oxidized LDL. LDL isolated from plasma of subjects who were orally supplemented with RU-486 was resistant to oxidation, as compared to LDL isolated from control plasma. The antioxidant effect of RU-486 appears to reside in the dimethylaminophenyl side chain moiety. Reduction of the A-ring of the steroid molecule had no effect on its antioxidant property. Analogs of RU-486 which lack the dimethylaminophenyl group, were without antioxidant activity. Levonorgestrel, which lacks the dimethylaminophenyl group failed to inhibit the oxidation of LDL even at 100-microM levels. In contrast, ethinylestradiol and estradiol which do not possess the dimethylamino group, were able to inhibit the oxidation of LDL by virtue of their phenolic steroid "A" ring. Thus RU-486, with its long half life, high plasma concentrations, association with lipoproteins, and ability to readily enter the cell may have additional intra- and extra-cellular antioxidant effects. - Version history - Version 1 (November 1, 1994): No description Advertisement Advertisement Copyright © 2026 American Society for Clinical Investigation ISSN: 0021-9738 (print), 1558-8238 (online)

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