Concentration dependence of prooxidant and antioxidant properties of catecholestrogens.
Concentration dependence of prooxidant and antioxidant properties of catecholestrogens.
复制标题
儿茶酚雌激素的促氧化和抗氧化特性的浓度依赖性。
DOI：
10.1006/abbi.1998.0934
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Liehr,JG
中科院分区：
文献类型：
--
作者：
Markides,CS;Roy,D;Liehr,JG
Estradiol is an established antioxidantin vitroandin vivo.In contrast, prooxidant effects such as 8-hydroxylation of guanine bases of DNA have been induced by various estrogens in hamsters and by 4-hydroxyestradiol or -estrone and a microsomal activating systemin vitro.As part of an examination of these conflicting reports, we studied the enhancement or inhibition of lipid peroxidation (conjugated diene formation monitored at 240 nm) by catecholestrogens in human low-density lipoprotein (LDL) incubated with cupric sulfate in phosphate buffer. Addition of 2- or 4-hydroxyestradiol, 2- or 4-methoxyestradiol, or estradiol or estriol (0.5–50 μM) increased lag times for diene formation by 30 to <300% over control values in the absence of estrogens (lag time, 1.6 h). In contrast, low concentrations (5 pM–100 nM) of catecholestrogens decreased lag times by about 40–50%, demonstrating their prooxidant activities. The prooxidant capabilities of catecholestrogens were examined by assaying the reduction by estrogens of Cu(II) to Cu(I) and of Fe(III) to Fe(II). Both 2- and 4-hydroxyestradiol and 2- and 4-methoxyestradiol reduced Cu(II) and Fe(III) ions to their lower oxidation state. In conclusion, the reduction of Cu(II) to Cu(I) by catecholestrogens is proposed to initiate lipid peroxidation and thus oxidation of LDL. In contrast, at high concentrations of catecholestrogens, the scavenging of oxygen radicals may predominate over lipid peroxidation and free radical generation by analogy to the action of similar phenolic antioxidants. With estradiol, estriol, and the methoxyestrogen metabolites, only antioxidant effects were observed.
