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Protective effect of estrogens and catecholestrogens against peroxidative membrane damage in vitro
Author(s) -
Lacort Mercedes,
Leal Ana M.,
Liza Mariana,
Martín César,
Martínez Rosa,
RuizLarrea M. Begoña
Publication year - 1995
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02538267
Subject(s) - chemistry , lipid peroxidation , antioxidant , estrone , estrogen , microsome , thiobarbituric acid , tbars , biochemistry , medicine , endocrinology , pharmacology , in vitro , hormone , biology
The antioxidant effects of natural estrogens (estrone E 1 ; 17β‐estradiol), synthetic estrogens (17α‐ethynylestradiol, EE 2 ; mestranol, MES; diethylstilbestrol, DES) and catechle‐strogens (2‐hydroxyestradiol; 4‐hydroxyestradiol 4‐OHE 2 ) on lipid peroxidation induced by different means in rat liver microsomes were investigated. The extent of lipid peroxidation was determined by measuring thiobarbituric acid reactive substances. Prooxidants included Fe 3+ /ADP/reduced NADPH, Fe 2+ /ascorbate, tert ‐butyl hydroperoxide ( t ‐BOOH) and 2,2′‐azo bis (2‐amidinopropane) (AAPH). Estrogens and catecholestrogens decreased lipid peroxidation in all four systems tested. In the iron/ascorbate model it was shown that (i)‐OHE 2 and DES had analogous patterns of inhibition, irrespective of the presence of NADPH or the functional integrity of the microsómes, and (ii) the antioxidant activities of E 1 , EE 2 and MES were dependent on the assay conditions with the activity being markedley higher when estrogen metabolism was favored. When peroxidation was initiated by the peroxyl radical generator AAPH, the inhibitory effects observed were least pronounced. Our data also showed that, in each of the systems, all inhibitors displayed the same order of inhibitory potency with DES and catecholestrogens being the most potent antioxidants under all experimental conditions used. The present results confirm earlier findings and point toward a link between estrogen metabolism and estrogen antioxidant activity. The data also indicate that estrogens and catecholestrogens interact with the peroxidative process at different levels with their interactions with iron or the metal‐derived species being the most important modes of inhibition.