Quinol-based cyclic antioxidant mechanism in estrogen neuroprotection.

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 o

SUBMITTER: Prokai L 

PROVIDER: S-EPMC208828 | biostudies-literature | 2003 Sep

REPOSITORIES: biostudies-literature