Structure-Diversity Oriented Synthesis And Biological Evaluation Of Novel Selective Estrogen Receptor Modulators

Estrogens are important endocrine hormones in human body, and they play an important role in almost all the cells and tissues, its disorder can cause several diseases, such as breast cancer, endometrial cancer, osteoporosis, inflammation and so on. Estrogens are mediated by Estrogen Receptors (ERs) which have two subtypes, ERa and ER?. ERa can promote the cell proliferation, while ER? reduces or regulates it. Nowadays, the drugs targeting on ER signal pathway are wildly used, eg. Selective Estrogen Receptor Modulators, SERMs. But with time went by, they can cause serious primary and secondary drug resistance. So, it's important to find some novel compounds as candidates of ideal SERMs and ER?-selective ligands.In knowledge of the development of SERMs and ER?-selective ligands, base on the researches in our lab, we carry out our works in three parts:1) In order to obtain some ER?-selective ligands, by applying the "bioisostere" concept and use C=C double bond or B-N bond core structrue compounds as lead, we synthesized a serial of tri-aryl and di-aryl Schiff base ligands by simple condensation reaction without hydroxyl goup protection in moderate yields. Relative binding assays showed that most of these imines demonstrated high affinity for ERs (in some cases exceeding estradiol) and showing modest selectivity for ER? (up to5.2fold). The highest RBA for ERa is96.7%, and for ER? is138.7%. The position and size of substituents had a major impact on binding affinity. In cell-based assays, these imines profiled as full agonists on ERa, but as antagonists on ER?, they can promote the transcription mediated by AF-1, while no effect on transcription mediated by AF-2. X-ray crystallographic analysis reveals that the tri-aryl imines distort the ligand-binding pocket in a new way, by controlling the separation of helices3and11to activate the ER pathway. This work illustrates the ease with which high affinity ER ligands having altered core structures can be prepared, and illustrates the unusual ER conformations can be obtained by altering the ligand core. It also suggests that C=N for C=C substitution might be more widely considered as a general strategy for preparing drug analogs.2) During the experiments, we found a new strategy to get1,4-disubstituted phthalazine derivaitves using the products of Sonogashira coupling reaciton as starting materials, and these compounds showed detectable ER binding affinities. So, base on the ER non-selective and ER?-selective pharmacophore model, we examed the possibilities using phthalzine and phthalazin-1(2H)-one core structure as ER ligands. We got34phthalazin-1(2H)-one derivatives, relative binding assays showed that they had low affinities for ERs but with good ER? selectivity (up to18fold). The highest RBA for ERa is0.062%(0.32?M), and for ER? is0.184%(0.27?M). The position and size of various substituents had a major impact on binding affinity. Primary celluar experiments showed that some compounds are ERa agonists and ER? antagonists, and have some antiproliferation activities. Molecular modeling reveals that they have a similar pattern as E2, the4-phenol group can form a hydrogen bond with Arg394and Glu353, and the1-carbonyl group can form a hydrogen bond with His524, in a agonistic conformation. This work demonstrated that different core sturtures and substituents can affect the binding affinities vastly.3) In order to investigate the influence of small changing of the core sturcture on ER affinities, based on previous works in our lab, we used OBHS and SOBHS as leads, and synthesized21of bicyclo[2.2.1]hept-2-ene derivatives,9of tricyclo[2.2.1.02,6]heptan-1-yl compounds and1of7-carbonylbicyclo[2.2.1]hept-2-ene analogue. Relative binding assays showed that they have much lower affinities for ERs than OBHS and SOBHS. The highest RBA for ERa is0.041%(0.49?M), and for ER? is0.064%(0.78?M). The position and size of various substituents had a major impact on binding affinity. Molecular modeling reveals that they have a similar pattern as OBHS (SOBHS), the5,6-diphenol group can form a hydron bond with Arg394/Glu353and Thr347, respectively, while the2-ester groups show different orientation and position in the pocket, so they can interact with different residues and generate the agonistic or antagonistic conformations. This work certified that small changes in the core sturcture can influence the RBAs greatly, and it provided a example for modification of OBHS.Over all, in order to get some potential useful leads, we have synthesized three different core sturture compounds, evaluated their biological activities and analysised the molecular modeling. The results proved that small changes in the core sturcture can interfere the interaction of ligands with different residues, so that presented diverse RBAs and ER subtype selctivity. These works contributed to the discovery of new SERMs and provided important significant guidence for further researches.