gms | German Medical Science

A variety of nonsteroidal compounds with five-membered hetetocyclic core like furans, pyrazoles and imidazoles might act as potent ligands for the estrogen receptor (ER). In this study, we prepared tetrasubstituted pyrroles and assessed their behavior as ER ligands. To investigate the influence of the hydrophilic character and the potency to function as N-H donor we synthesized 2,3,5-triaryl-1H-pyrroles (1) and 1,3,5-triaryl-1H-pyrroles (2). Different from 1, type 2 compounds are unable to form hydrogen bondings to amino acids in the ligand binding domain of the ER due to the arylation of the nitrogen. We found practical and facile syntheses to get these two pyrrole types of different substitution pattern. The synthesis based on cyclisation of arylated 1,4-diones. We converted them easily into the corresponding pyrroles in case of type 1 with NH4CH3COO and in case of type 2 with aniline and anisidine respectively. The ether cleavage was realized with borontribromide. In order to analyze the estrogenic potency 4-hydroxyphenylpyrroles were evaluated in the luciferase assay using the ERα-positive MCF-7 2a cell line. Both types of compounds (1, 2) proved to be potent ER agonists, but type 2 pyrroles showed to be more potent as their analogue type 1 compounds. We investigated the influence of the degree of hydroxylation of the aromatic rings, alkylation of the pyrrole ring and chlorine substitution of the aromatic rings. The hydroxylation and alkylation degree increases but chlorination decreases the estrogenic potency. To investigate the stability of the compounds under test conditions, we incubated them at 37 °C for 48 h and analyzed their HPLC-spectra. They showed a high stability.