Quinol-based cyclic antioxidant mechanism in estrogen neuroprotection

Laszlo Prokai, Katalin Prokai-Tatrai, Pal Perjesi, Alevtina D. Zharikova, Evelyn J. Perez, Ran Liu, James W. Simpkins

Research output: Contribution to journalArticle

137 Citations (Scopus)

Abstract

Substantial evidence now exists that intrinsic free-radical scavenging contributes to the receptor-independent neuroprotective effects of estrogens. This activity is inherently associated with the presence of a phenolic A-ring in the steroid. We report a previously unrecognized antioxidant cycle that maintains the "chemical shield" raised by estrogens against the most harmful reactive oxygen species, the hydroxyl radical (.OH) produced by the Fenton reaction. In this cycle, the capture of .OH was shown to produce a nonphenolic quinol with no affinity to the estrogen receptors. This quinol is then rapidly converted back to the parent estrogen via an enzyme-catalyzed reduction by using NAD(P)H as a coenzyme (reductant) and, unlike redox cycling of catechol estrogens, without the production of reactive oxygen species. Due to this process, protection of neuronal cells against oxidative stress is also possible by quinols that essentially act as prodrugs for the active hormone. We have shown that the quinol obtained from a 17β-estradiol derivative was, indeed, able to attenuate glutamate-induced oxidative stress in cultured hippocampus-derived HT-22 cells. Estrone quinol was also equipotent with its parent estrogen in reducing lesion volume in ovariectomized rats after transient middle carotid artery occlusion followed by a 24-h reperfusion. These findings may establish the foundation for a rational design of neuroprotective antioxidants focusing on steroidal quinols as unique molecular leads.

Original languageEnglish
Pages (from-to)11741-11746
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume100
Issue number20
DOIs
StatePublished - 30 Sep 2003

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Hydroquinones
Estrogens
Antioxidants
Reactive Oxygen Species
Oxidative Stress
Catechol Estrogens
Cytoprotection
Estrone
Coenzymes
Reducing Agents
Prodrugs
Neuroprotective Agents
Carotid Arteries
Estrogen Receptors
Hydroxyl Radical
NAD
Reperfusion
Oxidation-Reduction
Free Radicals
Neuroprotection

Keywords

  • Hydroxyl radical
  • Ischemia
  • Prodrug

Cite this

Prokai, Laszlo ; Prokai-Tatrai, Katalin ; Perjesi, Pal ; Zharikova, Alevtina D. ; Perez, Evelyn J. ; Liu, Ran ; Simpkins, James W. / Quinol-based cyclic antioxidant mechanism in estrogen neuroprotection. In: Proceedings of the National Academy of Sciences of the United States of America. 2003 ; Vol. 100, No. 20. pp. 11741-11746.
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Quinol-based cyclic antioxidant mechanism in estrogen neuroprotection. / Prokai, Laszlo; Prokai-Tatrai, Katalin; Perjesi, Pal; Zharikova, Alevtina D.; Perez, Evelyn J.; Liu, Ran; Simpkins, James W.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 100, No. 20, 30.09.2003, p. 11741-11746.

Research output: Contribution to journalArticle

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