Investigations on the effects of basic side chains on the hormonal profile of (4R,5S)/(4S,5R)-4,5-bis(4-hydroxyphenyl)-2-imidazolines.

Basic side chains determine the pharmacology of selective estrogen receptor modulators such as tamoxifen or raloxifene. In this study we tried to turn the hormonal profile of (4R,5S)/(4S,5R)-4,5-bis(4-hydroxyphenyl)-2-imidazolines from agonistic to antagonistic by introduction of a dimethylaminoethane, a piperidin-1-ylethane, or a pyrrolidin-1-ylethane side chain into one of the 4-hydroxyphenyl rings. The compounds were tested for agonistic and antagonistic activity on hormone sensitive, ERalpha-positive MCF7-2a cells, stably transfected with the plasmid ERE(wtc)luc and on U-2 OS cells transiently transfected with plasmids encoding for ERalpha (pSG5-ERalpha) or ERbeta (pSG5-ERbeta FL) as well as the reporter plasmid (ERE)(2)luc(+).

A molecular docking study of estrogenically active compounds with 1,2-diarylethane and 1,2-diarylethene pharmacophores.

Numerous selective estrogen receptor modulators (SERMs) have been synthesized and assayed in recent years. The focus of this study is to apply coarse-grain molecular docking procedures coupled with fine-grain all-atom force field optimization strategies to shed light on the binding mechanisms of currently available estrogen receptor-active compounds. Although the mechanics of ligand binding in estrogen receptors is generally well understood, there is room for surprises.

Effects of C2-alkylation, N-alkylation, and N,N'-dialkylation on the stability and estrogen receptor interaction of (4R,5S)/(4S,5R)-4,5-bis(4-hydroxyphenyl)-2-imidazolines.

(4R,5S)/(4S,5R)-4,5-Bis(4-hydroxyphenyl)-2-imidazolines bearing 2,2'-H (3a), 2,2'-Cl (3b), 2,2',6-Cl (3c), and 2,2'-F (3d) substituents in the aromatic rings were C2-alkylated (5a-i), N-alkylated (7, 7a-c), and N,N'-dialkylated (9a-c). The synthesis started from the diastereomerically pure (1R,2S)/(1S,2R)-1,2-diamino-1,2-bis(4-methoxyphenyl)ethanes 1a-d, which were cyclized to the imidazolines 2a-d and 4a-i with triethylorthoesters or iminoethers. Ether cleavage with BBr(3) yielded the (4R,5S)/(4S,5R)-4,5-bis(4-hydroxyphenyl)-2-imidazolines 3a-d and 5a-i.

Invesgations [correction investigations] on the influence of halide substituents on the estrogen receptor interaction of 2, 4, 5-tris(4-hydroxyphenyl)imidazoles.

Previously, we reported on the synthesis and estrogen receptor (ER) interaction of imidazoles, which had to be 1-alkyl-4, 5-bis(2-halo-4-hydroxyphenyl) substituted for a high relative binding affinity (RBA >1 %). This led to the assumption that a shielding of the polar heterocyclic system is a prerequisite for ER binding. In continuation of this study we synthesized 2, 4, 5-tris(4-hydroxyphenyl)imidazoles with Cl-or F-atoms in the ortho-positions of the aromatic rings and evaluated whether they mediate sufficient hydrophobicity for ER interaction.

Synthesis, structural evaluation, and estrogen receptor interaction of 4,5-bis(4-hydroxyphenyl)imidazoles.

4,5-Bis(4-hydroxyphenyl)imidazoles with 2,2'-H (1),2,2'-F (2),2,2'-Cl (3), and 2,2'6-Cl (4) substituents in the aromatic rings were synthesized by oxidation of the respective methoxy-substituted (R,S)/(S,R)-4,5-diaryl-2-imidazolines with MnO2 and subsequent ether cleavage with BBr3. N-alkylation of 1 and 3 with ethyl iodide yielded the compounds 5 and 6. The imidazoles were characterized by NMR spectroscopy and tested for estrogen receptor binding in a competition experiment with [3H]estradiol using calf uterine cytosol.

(4R,5S)/(4S,5R)-4,5-Bis(4-hydroxyphenyl)-2-imidazolines: ligands for the estrogen receptor with a novel binding mode.

(4R,5S)/(4S,5R)-4,5-Bis(4-hydroxyphenyl)-2-imidazolines 1-7 were synthesized by the reaction of the methoxy-substituted (1R,2S)/(1S,2R)-1,2-diarylethylenediamines 1b-7b with triethyl orthoformate and subsequent ether cleavage with BBr(3). All compounds were tested for estrogen receptor (ER) binding in a competition experiment with [(3)H]-estradiol and for gene activation in a luciferase assay using ER positive MCF-7-2a breast cancer cells stably transfected with the plasmid ERE(wtc)luc. The relative binding affinities of the 2-imidazolines were very low (RBA < 0.