St.-Petersburg State University, Russia
Title: Antioxidant effect of new synthetic steroid estrogens: New compounds for hormonal replacement therapy
S N Morozkina is working in steroid research at the Department of Natural Chemistry Department at Saint-Petersburg State University start from 2004 after Postdoctoralship in Organic Chemistry. She has 15 patents and more than 45 articles.
Atherosclerosis, hardening of arteries, is the primary cause of cardiovascular disease. Oxidative damage plays an important role in atherogenesis, the key events of which are modifi cation of low density lipoprotein (LDL) and its retention in arterial wall. In addition to atherosclerosis, oxidative stress and lipid peroxidation have been implicated in neurodegenerative diseases and aging. Estrogens are known antioxidants. Th e antioxidant eff ects of estrogens are mainly due to direct free-radical scavenging, independent of binding to estrogen receptors. Other possible mechanisms include reduction or chelation of redoxactive metal ions. Based on previous studies on human endogenous estrogens, the structural determinants for the in vitro antioxidant activity include a phenolic A-ring, 1 or 2 adjacent methoxy groups to the phenolic OH, and incorporation of an aromatic B-ring. In the present study, we describe the synthesis of novel steroidal estrogen analogues with various substitutions in the steroidal skeleton. In addition to develop synthetic methodology, the aim was to study structural determinants of estrogen antioxidant eff ects.We set out to explore the in vitro antioxidant activity of the new estrogen analogues in aqueous LDL solution, in comparison with the principal endogenous estrogen, 17β-estradiol. We tested a wide series of steroidal estrogen analogues (n=45) with unnatural ring junction and having various substituents on the steroidal skeleton, most of these compounds (n=22) were new and thus, their antioxidant or other biological eff ects unknown. Th e synthetic strategy was based on the method of Torgov and Ananchenko, which enables to synthesize steroidal compounds of diverse structures. In summary, our results demonstrate the way of increasing of antioxidant capacity through structural changes. For example in the group of 6-oxa analogues, the extension of D-ring led to increment of activity up to level of 17β-E2. Analogues with fl uorine atom at C-2 exhibited antioxidant eff ects similar or more potent to 17β-E2. Th us, in addition to their metabolic stability, these compounds are of interest as antioxidative agents. Antioxidant activity of estrogen analogues without a free phenolic hydroxyl group was observed for the fi rst time and it is worth further investigations. More studies are also needed to determine the role of steric factors in the interaction between antioxidants and LDL particles, using synthetic estrogen analogues with substitutions in D-ring and diff erent orientation of ring junction.