263717-49-3Relevant articles and documents
Synthesis and investigations on the oxidative degradation of C3/C5-Alkyl-1,2,4-triarylpyrroles as ligands for the estrogen receptor
Schaefer, Anja,Wellner, Anja,Gust, Ronald
, p. 794 - 803 (2012/01/06)
In this study, we synthesized 1,2,4-triarylpyrroles as ligands for the estrogen receptor (ER). Two pyrrole series were prepared with either C3-alkyl or C3/C5-dialkyl residues. Compounds from both series were susceptible to oxidative degradation-dialkylated compounds (t1/2=33-66h) to a higher extent than their monoalkylated congeners (t1/2=140-211h). Nevertheless, stability was sufficient for determination of in vitro ER binding affinity. The most active agonist in hormone-dependent, ERα-positive MCF-7/2a and U2-OS/α cells was 1,2,4-tris(4-hydroxyphenyl)-3-propyl-1H-pyrrole (6d) (MCF-7/2a: EC50=70nM; U2-OS/α: EC50=1.6nM). A corresponding inactivity in U2-OS/β cells demonstrated the high ERα selectivity. This trend was confirmed in a competition experiment using estradiol (E2) and purified hERα and hERβ proteins (relative binding affinity (RBA) calculated for 6d: RBA(ERα)=1.85%; RBA(ERβ) 0.01%). Generally, C3/C5-dialkyl substitution led to reduction of activity, possibly due to lower stability. Triarylpyrroles with C3-alkyl or C3/C5-dialkyl residues were synthesized as ligands for the estrogen receptor (ER). The compounds exhibited transcription activation selectively for ERα but only marginally displaced estradiol from its binding site. The compounds were susceptible to oxidative degradation-dialkylated compounds to a higher extent than their monoalkylated congeners. The reasons for instability were elucidated; thus, by changing the substitution pattern, it will be possible to generate stable triarylpyrroles.
Pyrazole ligands: Structure - Affinity/activity relationships and estrogen receptor-α-selective agonists
Stauffer,Coletta,Tedesco,Nishiguchi,Carlson,Sun,Katzenellenbogen,Katzenellenbogen
, p. 4934 - 4947 (2007/10/03)
We have found that certain tetrasubstituted pyrazoles are high-affinity ligands for the estrogen receptor (ER) (Fink et al. Chem. Biol. 1999, 6, 205-219) and that one pyrazole is considerably more potent as an agonist on the ERα than on the ERβ subtype (Sun et al. Endocrinology 1999, 140, 800-804). To investigate what substituent pattern provides optimal ER binding affinity and the greatest enhancement of potency as an ERα-selective agonist, we prepared a number of tetrasubstituted pyrazole analogues with defined variations at certain substituent positions. Analysis of their binding affinity pattern shows that a C(4)-propyl substituent is optimal and that a p-hydroxyl group on the N(1)-phenyl group also enhances affinity and selectivity for ERα. The best compound in this series, a propylpyrazole triol (PPT, compound 4g), binds to ERα with high affinity (ca. 50% that of estradiol), and it has a 410-fold binding affinity preference for ERα. It also activates gene transcription only through ERα. Thus, this compound represents the first ERα-specific agonist. We investigated the molecular basis for the exceptional ERα binding affinity and potency selectivity of pyrazole 4g by a further study of structure-affinity relationships in this series and by molecular modeling. These investigations suggest that the pyrazole triols prefer to bind to ERα with their C(3)-phenol in the estradiol A-ring binding pocket and that binding selectivity results from differences in the interaction of the pyrazole core and C(4)-propyl group with portions of the receptor where ERα has a smaller residue than ERβ. These ER subtype-specific interactions and the ER subtype-selective ligands that can be derived from them should prove useful in defining those biological activities in estrogen target cells that can be selectively activated through ERα.
