Steroidal bivalent ligands for the estrogen receptor: Design, synthesis, characterization and binding affinities

Steroidal bivalent ligands for the estrogen receptor (ER) were designed using crystal structures of ER alpha dimers as a template. The syntheses of several 17 alpha-ethynylestradiol-based bivalent ligands with varying linker compositions and lengths are described. The binding affinities of these bivalent ligands for ERa and ER beta were determined. In the two series of bivalent ligands that we synthesized, there is a clear correlation between linker length and binding affinity, both of which reach a maximum at the same tether length. Further studies are underway to explore aspects of bivalent ligand and control compound binding to the ERs and their effects on ER dimer formation; these results will be reported in a subsequent publication. (C) 2009 Elsevier Ltd. All rights reserved.