Effect of estrogens on the oxidative damage induced by ferrylmyoglobin

The effect of estrogens, including estrone (E1), estradiol-17beta (E2), estriol (E3) and 2-hydroxyestradiol (2-OH-E2), on the oxidative damage induced by ferrylmyoglobin (ferrylMb) was investigated. These estrogens inhibited lipid peroxidation induced by ferrylMb. The ability of 2-OH-E2 to inhibit lipid peroxidation was much greater than the other estrogens. Furthermore, 2-OH-E2 trapped 2,2'-azobis-(2-amidinopropane)-dihydrochloride peroxyl radicals more rapidly, and among these estrogens only 2-OH-E2 reacted with 2,2-diphenyl-1-picrylhydrazyl. These results suggest that the ability of 2-OH-E2 to inhibit lipid peroxidation is because it scavenges lipid peroxyl and carbon-centered radicals. Estrogens, except for 2-OH-E2, partially prevented the inactivation of alcohol dehydrogenase (ADH) induced by ferrylMb. Of interest, however, the exposure of sulfhydryl (SH) enzymes to ferrylMb in the presence of 2-OH-E2 dramatically increased the inhibition of the enzyme activity. Ascorbic acid (ASA) and reduced glutathione (GSH) strongly inhibited the inactivation of ADH induced by ferrylMb in the presence of 2-OH-E2. During the reaction of ferrylMb with ASA or GSH in the presence of 2-OH-E2, large amounts of oxymyoglobin were formed, suggesting the involvement of the semiquinone from 2-OH-E2 in the reduction of metmyoglobin. Presumably, the semiquinone formed from 2-OH-E2 oxidizes the SH group of enzymes to facilitate the rapid inactivation of the SH enzymes induced by ferrylMb.