Derivatives of 4-styrylpyridines: synthesis, estrogen receptor binding affinity, and photophysical properties

N-Alkoxypyrazoles as biomimetics for the alkoxyphenyl group in tamoxifen

The preparation of a series of novel analogues of the selective antiestrogen tamoxifen is reported. 1Z-alkoxyphenyl group in tamoxifen has been replaced by a N-alkoxypyrazole, while functionalised phenyl groups or heteroaromatics were introduced at the 2Z-position using sequential Suzuki cross coupling of 1,2-(bis)borylpinacol 1-phenylbutene with 4- or 5-iodo-1-N,N-dimethylaminoethyl or propyl-pyrazoles. Approximately 50 tamoxifen analogues were obtained and tested in an estrogen receptor (ERalpha) affinity assay. Several compounds exhibited binding affinities 2-5-fold lower than tamoxifen. Dose-response experiments with six selected compounds were carried out using two different human breast cancer cell lines, MCF-7 and the tamoxifen resistant cell line MCF-/TAM(R)-1. Both cell lines exhibited growth inhibition upon treatment with the tamoxifen analogues. Co-treatment of the cells, with estradiol and the individual compounds, were also performed. The results indicated that the observed growth inhibitory effect was mediated by the ERalpha. Analogues of the potent antiestrogen 4-hydroxytamoxifen (4-OHT) were synthesised where the 1E-4-hydroxyphenyl was replaced by a 1-hydroxypyrazol-4-yl group. However, modest growth inhibition of MCF-7 cells was observed upon treatment with these analogues. In contrast, 1Z-, 2Z-ringclosed tamoxifen analogue (59) was shown to possess antiproliferative effects on MCF-7 and MCF-/TAM(R)-1 cells in lower doses than tamoxifen.

Facile synthesis of high affinity styrylpyridine systems as inherently fluorescent ligands for the estrogen receptor

A series of styrylpyridine derivatives containing two phenols was prepared via an efficient two-step synthesis. These compounds were designed to maximize the estrogen receptor binding affinity of a known series of inherently fluorescent styrylpyridines. While significant improvements were achieved in receptor affinity, the fluorescence intensity of this series of compounds is poor.