Novel 7α-alkoxy-17α-(4′-halophenylethynyl)estradiols as potential SPECT/PET imaging agents for estrogen receptor expressing tumours: Synthesis and binding affinity evaluation

Article abstract of DOI:10.1016/j.steroids.2012.05.004

In order to develop potential radiolabelled probes for imaging estrogen receptor (ER) positive tumours, we have synthesized and characterized a series of novel 7α-alkoxy-17α-(4′-iodophenylethynyl)estra-1,3,5(10)- triene-3,17β-diols and 7α-alkoxy-17α-(4′- fluorophenylethynyl)estra-1,3,5(10)-triene-3,17β-diols. The fluoro-substituted compounds showed a higher ER binding affinity than the corresponding iodo-derivatives, where 7α-methoxy- and 17α-(4′- fluorophenylethynyl)estra-1,3,5(10)-triene-3,17β-diol showed the highest ER binding affinities (RBA = 80.9% and 78.9%, respectively), among the halophenylethynyl compounds studied and should be further explored as potential PET biomarkers for imaging of ER expressing tumours.