Estrogen receptor beta agonism increases survival in experimentally induced sepsis and ameliorates the genomic sepsis signature: a pharmacogenomic study

BACKGROUND

Nonsteroidal agonists have been developed that selectively bind to and activate estrogen receptor beta (ERbeta) rather than estrogen receptor alpha (ERalpha). ERbeta is expressed equally in both male and female mammals in multiple extragonadal tissues. Work reported elsewhere has demonstrated that ERbeta agonists have beneficial effects in multiple (but not all) models of inflammatory diseases and also increase survival in experimentally induced sepsis.

METHODS

In these experiments, ERbeta agonists (ERB-041 or WAY-202196) were compared with vehicle control in the murine cecal ligation and puncture (CLP) model and in the pneumococcal pneumonia model of sepsis. The effect of WAY-202196 on the gene expression profile in the CLP model was further studied by transcriptome analysis of lung and small intestine tissue samples.

RESULTS

ERbeta agonists provided a significant survival benefit in both experimental models of bacterial sepsis. This survival advantage was accompanied by reduced histologic evidence of tissue damage, reduced transcription of multiple proinflammatory proteins by transcriptome analysis and was not associated with increased bacterial outgrowth.

CONCLUSIONS

ERbeta agonist administration provided a survival advantage in septic animals and appears to be a promising therapeutic modality in sepsis.

ERβ ligands. Part 6: 6H-Chromeno[4,3-b]quinolines as a new series of estrogen receptor β-selective ligands

A new class of estrogen receptor beta (ERbeta) ligands based on the 6H-chromeno[4,3-b]quinoline scaffold has been prepared. Several C7-substituted analogues displayed high affinity and modest selectivity for ERbeta.

Estrogen receptor β ligands: Design and synthesis of new 2-phenyl-isoindole-1,3-diones

The design, synthesis, and biological evaluation of the 2-phenyl-isoindole-1,3-diones will be discussed. Detailed modeling studies with X-ray support were used to understand the ligand binding orientation and observed selectivity.

ERbeta ligands. Part 5: synthesis and structure-activity relationships of a series of 4'-hydroxyphenyl-aryl-carbaldehyde oxime derivatives

A series of 4'-hydroxyphenyl-aryl-carbaldehyde oximes (5b) was prepared and found to have high affinity (4nM) and modest selectivity (39-fold) for estrogen receptor-beta (ERbeta). Substitution of one of the core rings of the scaffold based around these novel ligands further expanded our knowledge in the quest toward achieving high affinity and selectivity for ERbeta. An X-ray co-crystal of structure 11 revealed that the oxime moiety was mimicking the C-ring of genistein, as previously predicted by SAR and docking studies.

Synthesis and biological evaluation of novel compounds within a class of 3-aminochroman derivatives with dual 5-HT1A receptor and serotonin transporter affinity

Compounds containing a 5-carbamoyl-8-fluoro-3-amino-3,4-dihydro-2H-1-benzopyran and a 3-alkylindole moiety linked through a common basic nitrogen were prepared and evaluated for 5-HT1A affinity, serotonin rat transporter affinity, and functional antagonist activity in vitro. 26a was found to be the most potent and selective compound in this series and was shown to possess neurochemical activity in vivo by producing acute and rapid increases in 5-HT in the rat frontal cortex.

Studies toward the discovery of the next generation of antidepressants. Part 5: 3,4-Dihydro-2H-benzo[1,4]oxazine derivatives with dual 5-HT1A receptor and serotonin transporter affinity

The design, synthesis, and structure-activity relationship of two novel classes of benzoxazine derivatives with dual selective serotonin reuptake inhibitors and 5-HT(1A) receptor activities are described.

ERβ ligands. Part 4: Synthesis and structure–activity relationships of a series of 2-phenylquinoline derivatives

A new class of estrogen receptor beta (ERbeta) ligands based on the 2-phenylquinoline scaffold was prepared. Several analogues with C4 substitution displayed high affinity (3-5 nM) and significant selectivity (up to 83-fold) for ERbeta. The best compound, 13b, was profiled as a selective partial agonist for ERbeta at 1 muM in a cell-based transcriptional assay. Uterine weight bioassay of 13b indicated no activation of ERalpha in vivo.

ERbeta ligands. 3. Exploiting two binding orientations of the 2-phenylnaphthalene scaffold to achieve ERbeta selectivity

The 2-phenylnaphthalene scaffold was explored as a simplified version of genistein in order to identify ER selective ligands. With the aid of docking studies, positions 1, 4, and 8 of the 2-phenylnaphthalene template were predicted to be the most potentially influential positions to enhance ER selectivity using two different binding orientations. Both orientations have the phenol moiety mimicking the A-ring of genistein. Several compounds predicted to adopt orientations similar to that of genistein when bound to ERbeta were observed to have slightly higher ER affinity and selectivity than genistein. The second orientation we exploited, which was different from that of genistein when bound to ERbeta, resulted in the discovery of several compounds that had superior ER selectivity and affinity versus genistein. X-ray structures of two ER selective compounds (i.e., 15 and 47) confirmed the alternate binding mode and suggested that substituents at positions 1 and 8 were responsible for inducing selectivity. One compound (i.e., 47, WAY-202196) was further examined and found to be effective in two models of inflammation, suggesting that targeting ER may be therapeutically useful in treating certain chronic inflammatory diseases.

Studies towards the next generation of antidepressants. Part 4: derivatives of 4-(5-fluoro-1H-indol-3-yl)cyclohexylamine with affinity for the serotonin transporter and the 5-HT1A receptor

Derivatives of the serotonin reuptake inhibitor 4-(5-fluoro-1H-indol-3-yl)cyclohexylamine, in which serotonin 1A (5-HT(1A)) receptor pharmacophoric elements are incorporated, are reported. Analogs exhibiting affinity for both the serotonin transporter and the 5-HT(1A) receptor are described. Compounds containing 1-(4-indolyl)piperazine and 2-(1H-indol-4-yloxy)ethylamine are promising leads for further SAR studies.

Novel aryloxy-8-azabicyclo[3.2.1]oct-3-enes with 5-HT transporter and 5-HT1A affinity

Joining aryl 8-azabicyclo[3.2.1]oct-3-enes with aryloxyethanes and aryloxypropanes produces novel series of compounds 11 and 12 with potent 5-HT-T affinity and moderately potent 5-HT(1A) affinity. Moreover, several of these compounds possess functional 5-HT(1A) antagonism. Optimal compounds are, 4-indolyloxyethane 21, 4-indolyloxypropanes 25, and 27, which possess potent 5-HT-T affinity (5-HT-T K(i): 21: 1.2nM, 25: 0.54nM, 27: 0.38nM) and good 5-HT(1A) affinity/antagonism (5-HT(1A)K(i), [(35)S]GTPgammaS: E(max) (%): 21: 111.1nM, 0%; 25: 173.2nM, 0%; 27: 107nM, 0%).

ERbeta ligands. Part 2: Synthesis and structure-activity relationships of a series of 4-hydroxy-biphenyl-carbaldehyde oxime derivatives

A series of biphenyl carbaldehyde oximes (6) was prepared and shown to have significant selectivity for the estrogen receptor-beta (ERbeta). The exploitation of the oxime moiety as a hydrogen bond donating group, which mimicked the C-ring of genistein makes these compounds unique. Molecular modeling studies showed the oxime moiety hydrogen bonding to the histidine residue, which was supported by the structure-activity relationships. The most potent compounds in this study had IC50 values in a radioligand binding assay of between 8-35 nM. Among the most selective compounds were 6i and 6s (49- and 31-fold ERbeta selective, respectively).

Studies toward the discovery of the next generation of antidepressants. 3. Dual 5-HT1A and serotonin transporter affinity within a class of N-aryloxyethylindolylalkylamines

N-aryloxylethylindolealkylamines (5) having dual 5-HT transporter and 5-HT(1A) affinity are described. These compounds represent truncated analogues of our previously reported piperidinyl derivatives (3). Compounds in this investigation were found to have more similar affinities and functional activities for the 5-HT(1A) receptor and 5-HT transporter. Though 5-HT(1A) antagonism is not consistently observed throughout series 5, several molecular features were found to be essential to obtain high and balanced activities. The proper placement of a heteroatom in the aryl ring and the length of the linkage used to tether the indole moiety had significant influence on 5-HT(1A) and 5-HT transporter affinities. Introduction of a halogen into the aryl ring usually lowered intrinsic activity and in some cases led to full 5-HT(1A) antagonists. Compounds 33 and 34 were observed to be full 5-HT(1A) antagonists with K(i) values of approximately 30 nM for the 5-HT(1A) receptor and K(i) values of 5 and 0.5 nM for the 5-HT transporter, respectively. Unfortunately, similar to our previous series (3), compounds in this report also had high affinity for the alpha(1) receptor.

Evaluation of an estrogen receptor-beta agonist in animal models of human disease

The discovery of a second estrogen receptor (ER), called ERbeta, in 1996 sparked intense interest within the scientific community to discover its role in mediating estrogen action. However, despite more than 6 yr of research into the function of this receptor, its physiological role in mediating estrogen action remains unclear and controversial. We have developed a series of highly selective agonists for ERbeta and have characterized their activity in several clinically relevant rodent models of human disease. The activity of one such compound, ERB-041, is reported here. We conclude from these studies that ERbeta does not mediate the bone-sparing activity of estrogen on the rat skeleton and that it does not affect ovulation or ovariectomy-induced weight gain. In addition, these compounds are nonuterotrophic and nonmammotrophic. However, ERB-041 has a dramatic beneficial effect in the HLA-B27 transgenic rat model of inflammatory bowel disease and the Lewis rat adjuvant-induced arthritis model. Daily oral doses as low as 1 mg/kg reverse the chronic diarrhea of HLA-B27 transgenic rats and dramatically improve histological disease scores in the colon. The same dosing regimen in the therapeutic adjuvant-induced arthritis model reduces joint scores from 12 (maximal inflammation) to 1 over a period of 10 d. Synovitis and Mankin (articular cartilage) histological scores are also significantly lowered (50-75%). These data suggest that one function of ERbeta may be to modulate the immune response, and that ERbeta-selective ligands may be therapeutically useful agents to treat chronic intestinal and joint inflammation.

ERbeta ligands. Part 1: the discovery of ERbeta selective ligands which embrace the 4-hydroxy-biphenyl template

The synthesis and structure-activity relationships of a series of simple biphenyls is described. Optimization of the 4-hydroxy-biphenyl template led to compounds with ERbeta selectivity on the order of 20-70-fold.

Studies toward the discovery of the next generation of antidepressants. Part 2: incorporating a 5-HT(1A) antagonist component into a class of serotonin reuptake inhibitors

The design and synthesis of a novel series of indole derivatives (9) having dual 5-HT transporter reuptake and 5-HT(1A) antagonist activity are described.

New generation dopaminergic agents. Part 8: heterocyclic bioisosteres that exploit the 7-OH-2-(aminomethyl)chroman D(2) template

Based on the 7-OH-2-(aminomethyl)chroman dopamine D(2) template (2) is described the preparation and resolution of two bioisosteric analogues. The benzimidazol-2-one derivative (6) had similar affinity to the known indolone derivative (4).

Studies towards the next generation of antidepressants. Part 1: Indolylcyclohexylamines as potent serotonin reuptake inhibitors

A series of indolylcyclohexylamines possessing potent and selective serotonin reuptake inhibition is reported. The most interesting compounds proved to have subnanomolar 5-HT transporter activity, and exhibited moderate 5-HT(1A) affinity.

Application of comparative molecular field analysis to dopamine D2 partial agonists

Comparative molecular field analysis (CoMFA) has been applied to novel D2 partial agonists. Due to the predictability of the CoMFA model across different series of D2 partial agonists, we believe these compounds are binding to the D2 agonist receptor in the conformation and alignment described herein.

New generation dopaminergic agents. 7. Heterocyclic bioisosteres that exploit the 3-OH-phenoxyethylamine D2 template

The synthesis of several bioisosteric analogs based on the 3-OH-phenoxyethylamine dopamine D2 agonist template (i.e., 3) is described. The benzimidazol-2-ones and benzthioimidazol-2-ones (7-10) and 2-trifluoromethyl-benzimidazole (13) were observed to have excellent affinity for the D2 receptor.

New generation dopaminergic agents. 6. Structure-activity relationship studies of a series of 4-(aminoethoxy)indole and 4-(aminoethoxy)indolone derivatives based on the newly discovered 3-hydroxyphenoxyethylamine D2 template

A series of 4-(aminoethoxy)indoles 7 and a related series of 4-(aminoethoxy)indolones 8 were synthesized and evaluated for their affinity for both the high- and low-affinity agonist states (D2High and D2Low, respectively) of the dopamine (DA) D2 receptor. The 4-aminoethoxy derivatives (i.e., 7 and 8) were designed as bioisosteric analogues based on the phenol prototype 4. The indolones 8 were observed to have high affinity for the D2High receptor. Comparison of their previously reported chroman analogues with the more flexible 4-(aminoethoxy)indoles revealed the chroman analogues to be more potent, whereas little loss in D2High affinity was observed when comparing the 4-(aminoethoxy)indolones with their respective chroman analogues. Several regions of the phenoxyethylamine framework were modified and recognized as potential sites to modulate the level of intrinsic activity. A conformational analysis was performed and a putative bioactive conformation was proposed which fulfilled the D2 agonist pharmacophore criteria based on the McDermed model. Structure-activity relationships gained from these studies have aided in the synthesis of D2 partial agonists of varying intrinsic activity levels. These agents should be of therapeutic value in treating disorders resulting from hypo- and hyperdopaminergic activity, without the side effects associated with complete D2 agonism or antagonism.

New generation dopaminergic agents. 5. Heterocyclic bioisosteres that exploit the 3-OH-N1-phenylpiperazine dopaminergic template

The synthesis of several bioisosteric analogs based on the 3-OH-N1-phenylpiperazine dopamine D2 agonist template (i.e., 4) is described. The indolone (5) and 2-CF3-benzimidazole (13) were observed to have excellent affinity for the D2 receptor. Several D4 selective compounds were also identified. Molecular modeling studies and a putative bioactive conformation are discussed.

New generation dopaminergic agents. 2. Discovery of 3-OH-phenoxyethylamine and 3-OH-N1-phenylpiperazine dopaminergic templates

Described in this report is a systematic study which led to the identification of two new dopamine D2 partial agonists (5 and 17). Phenols 5 and 17 represent prototypes of two new classes of D2 partial agonists as well as templates for the future design of novel dopaminergic agents.

New generation dopaminergic agents. 1. Discovery of a novel scaffold which embraces the D2 agonist pharmacophore. Structure-activity relationships of a series of 2-(aminomethyl)chromans

A series of 2-(aminomethyl)chromans (2-AMCs) was synthesized and evaluated for their affinity and selectivity for both the high- and low-affinity agonist states (D2High and D2Low, respectively) of the dopamine (DA) D2 receptor. The 7-hydroxy-2-(aminomethyl)chroman moiety was observed to be the primary D2 agonist pharmacophore. The 2-methylchroman moiety was discovered to be an entirely novel scaffold which could be used to access the D2 agonist pharmacophore. Attaching various simple alkyl and arylalkyl side chains to the 7-hydroxy 2-AMC nucleus had significant effects on selectivity for the D2High receptor vs the 5HT1A and alpha 1 receptors. A novel DA partial agonist, (R)-(-)-2-(benzylamino)methyl)chroman-7-ol [R-(-)-35c], was identified as having the highest affinity and best selectivity for the D2High receptor vs the alpha 1 and 5HT1A receptors. Several regions of the 2-AMC nucleus were modified and recognized as potential sites to modulate the level of intrinsic activity. The global minimum conformer of the 7-hydroxy-2-AMC moiety was identified as fulfilling the McDermed model D2 agonist pharmacophoric criteria and was proposed as the D2 receptor-bound conformation. Structure-activity relationships gained from these studies have aided in the synthesis of D2 partial agonists of varying intrinsic activity levels. These agents should be of therapeutic value in treating disorders resulting from hypo- and hyperdopaminergic activity, without the side effects associated with complete D2 agonism or antagonism.

Novel anti-inflammatory compounds prevent CD11b/CD18, alpha M beta 2 (Mac-1)-dependent neutrophil adhesion without blocking activation-induced changes in Mac-1

Leumedins are small organic molecules with anti-inflammatory properties in vivo. We report here that leumedins inhibit the CD11b/CD18 alpha M beta 2 (Mac-1)-dependent adherence of neutrophils to serum proteins. The activation of neutrophils leading to adherence via Mac-1 is associated with an increase in cell surface Mac-1 level, and with an increased affinity of Mac-1 for adhesion partners. Inhibition of neutrophil adherence by leumedins does not require blocking the recruitment of Mac-1 from intracellular granules to the cell surface. Furthermore, leumedins do not block the expression on Mac-1 of the epitope for an "activation-specific" antibody (CBRM1/5). Time course studies show that leumedins inhibit adherence by targeting an event which occurs concurrently with changes in Mac-1 level and induction of the CBRM1/5 epitope. Therefore, leumedins block an unknown process which is permissive for Mac-1-dependent adherence.

Fluorenylalkanoic and benzoic acids as novel inhibitors of cell adhesion processes in leukocytes

A series of fluoren-9-ylalkanoic and alkylbenzoic acids was prepared as simplified analogues of a previously reported series of antiinflammatory agents which act to inhibit neutrophil recruitment into inflamed tissue. The previous compounds ("leumedins") contained (alkoxycarbonyl)amino or benzoic acid moieties tethered to a fluorene ring. This functionality was replaced with simple structural elements. The new compounds were, in general, found to be more potent than the earlier series at inhibiting adherence of neutrophils to serum-coated wells or endothelial cells in vitro. Compound 9 was approximately 10-fold more potent than the previously reported FMOC-phenylalanine, of which it is an analogue. Similarly, compound 19 was superior in potency to its first generation progenitor, NPC 16570. The new compounds were shown to inhibit neutrophil adherence under conditions in which adherence is mediated by Mac-1 (CD11b/CD18) and LFA-1 (CD11a/CD18); they thus appear to target beta 2-integrins in their antiadhesion activity. These compounds provide a departure point for the further development of new cell adhesion inhibitors which should exhibit enhanced potency and a more selective mode of action.

Examination of the D2/5-HT2 affinity ratios of resolved 5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indoles: an enantioselective approach toward the design of potential atypical antipsychotics

Enantiomers of several N-substituted 5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indoles were obtained by the resolution of 2-fluoro-5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indole and 5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indole followed by N-alkylation. These, as well as the racemates, were evaluated for their affinity for the 5-HT2 and D2 receptors. Those compounds possessing the 7S,10R stereochemistry were consistently recognized by the 5-HT2 and D2 receptors as the eutomer. 2-Fluoro-11-[4-(4-fluorophenyl)-4-oxobutyl]-5,6,7,8,9,10-hexahydro-7S,10 R- iminocyclohept[b]indole [(7S,10R)-8] had the highest affinity for the 5-HT2 receptor (Ki = 0.80 nM), while its distomer (7R,10S)-8 was the most selective member of this class of bridged gamma-carbolines (D2/5-HT2 = 562). Incorporation of a benzoyl or isosteric benzisoxazole moiety tethered by a four-carbon spacer to a bridged gamma-carboline nucleus, possessing the 7S,10R absolute configuration, produced high affinity ligands for the 5-HT2 and D2 receptors.

Bridged gamma-carbolines and derivatives possessing selective and combined affinity for 5-HT2 and D2 receptors

A series of 5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indoles and 6,7,8,9,10,11-hexahydro-7,11-imino-5H-cyclooct[b]indoles was prepared. Structural modifications of the lead compound, 11-[4-(4-fluorobenzoyl)propyl]-5,6,7,8,9,10-hexahydro-7,10- iminocyclohept[b]indole (5, Ki = 0.82 nM vs [3H]ketanserin) enabled the identification of the functionality necessary for high affinity at serotonin 5-HT2 and dopamine D2 receptors in ligand binding studies. The indole ring, as well as the benzoyl or isosteric benzisoxazole moiety, were essential for high affinity. Variations of the length of the side chains resulted in ligands having either selective affinity for the 5-HT2 receptor or a combination of 5-HT2 and D2 affinity. In vivo binding studies were performed on selected members in this series. The most potent member, 2-fluoro-11-[4-(4-fluorobenzoyl)butyl]-5,6,7,8,9,10-hexahydro-7,10- iminocyclohept[b]indole (36) had an ED50 of < 1 mg/kg at the 5-HT2 and D2 receptors following oral administration.

Synthesis and in vitro evaluation of 5,6,7,8,9,10-hexahydro-7,10-iminocyclohept[b]indoles: high-affinity ligands for the N,N'-di-o-tolylguanidine-labeled sigma binding site

A series of 5,6,7,8,9,10-hexahydro-7,10-iminocyclo[b]indoles substituted at the 5 and/or 11 positions was synthesized from tropinone. Affinity for sigma binding sites was determined using [3H]-N,N'-di-o-tolylguanidine ([3H]DTG) and [3H]-(+)-3-(3-hydroxyphenyl)-N-1-propylpiperidine ([3H]-(+)-3-PPP) and for the dopamine D2 receptor labeled with [3H]sulpiride. Nearly all compounds studied in this series possessed a higher affinity for [3H]DTG than [3H]-(+)-PPP-labeled sigma sites, suggesting that [3H]DTG and [3H]-(+)-3-PPP radioligands label pharmacologically distinct sigma binding sites, as reported previously. Substitution at the 11 position with side chains containing a four-carbon tether resulted in compounds having the highest affinity for the [3H]DTG-labeled sigma site. The most potent and selective member of this series was 11-[4-(2-furanyl)butyl]-5,6,7,8,9,10-hexahydro-7,10-iminocyclohept [b] indole (40). Enantioselectivity was investigated by preparing the (+)- and (-)-isomers of 40. These studies revealed that (+)-40 was more potent at the [3H]-DTG-labeled sigma site whereas (-)-40 had a higher affinity at sigma sites labeled with [3H]-(+)-PPP. Racemic 40 was observed to possess a higher affinity than either of its respective enantiomers at both the [3H]DTG- and [3H]-(+)-3-PPP-labeled sites, suggesting an allosteric interaction.

Synthesis of arylnaphthalenyl derivatives: inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme a reductase

Trans-tetrahydro-4-hydroxy-6-[1-aryl-7-naphthalenyl]-2H-pyran-2-ones of general structure 4 were prepared and tested for inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase in vitro. In contrast to previously described biphenyl lactones (2) containing an ethenyl linkage, linkage of the pyranone ring to the aryl moiety in these compounds is via a rigid aromatic ring system, which still allows free rotation of the aryl rings. The imposed conformational constraint is compatible with activity, since members of the series had activity in range 1-20 microM (IC50 values).