Selective and potent agonists for estrogen receptor beta derived from molecular refinements of salicylaldoximes

In a continuing effort to improve the subtype selectivity and agonist potency of estrogen receptor beta (ER beta) ligands, we have designed and developed a thus far unexplored structural series obtained by molecular refinements of monoaryl-substituted salicylaldoximes (Salaldox B). The most interesting compounds in this series (2c, d) show remarkably high ER beta-binding affinities, with K-i values reaching the sub-nanomolar range (K-i = 0.38 nM for 2c and 0.57 nM for 2d), and have very high levels of ER beta-subtype selectivity. Both compounds show a potent full agonist character on ER beta (EC50 = 0.23 nM for 2c and 1.3 nM for 2d). Furthermore, 2d shows a remarkable functional subtype selectivity, with a beta/alpha transcription potency ratio 50-fold higher than that of estradiol. (C) 2011 Elsevier Masson SAS. All rights reserved.