Functional deficit in hippocampal activity during fear extinction recall in the single prolonged-stress model of PTSD in male rats.

To interrogate whether altered function of the hippocampal-mPFC circuit underlies the deficit in fear extinction recall in rats subjected to single-prolonged stress (SPS), changes in brain region-specific metabolic rate were measured in male rats (control and SPS treated). Brain region metabolic rates were quantified using uptake of 14C-2-deoxyglucose (14C-2DG) during fear memory formation, fear memory extinction and extinction recall. Control and SPS rats had similar regional brain activities at baseline. During extinction recall, 14C-2DG uptake decreased in hippocampal regions in control rats, but not in SPS rats. SPS rats also exhibited a significant deficiency in fear extinction recall, replicating a previously reported finding. Reduced hippocampal activity during fear extinction recall in control animals may reflect reduction in fear overgeneralization, thereby enabling discrimination between distinct contexts. In contrast, persistent levels of hippocampal activity in SPS-exposed male animals during fear extinction recall may reflect the dysfunctional persistence of fear overgeneralization. Future studies in females can test gender-specificity of these effects, with appropriate attention to luteal dependent effects on extinction of fear learning. Detailed knowledge of regional brain activities underlying stress-induced deficits in extinction recall may help identify therapeutic targets in PTSD.

Structural determinant for inducing RORgamma specific inverse agonism triggered by a synthetic benzoxazinone ligand.

BACKGROUND: The nuclear hormone receptor RORγ regulates transcriptional genes involved in the production of the pro-inflammatory interleukin IL-17 which has been linked to autoimmune diseases such as rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease. This transcriptional activity of RORγ is modulated through a protein-protein interaction involving the activation function 2 (AF2) helix on the ligand binding domain of RORγ and a conserved LXXLL helix motif on coactivator proteins. Our goal was to develop a RORγ specific inverse agonist that would help down regulate pro-inflammatory gene transcription by disrupting the protein protein interaction with coactivator proteins as a therapeutic agent. RESULTS: We identified a novel series of synthetic benzoxazinone ligands having an agonist (BIO592) and inverse agonist (BIO399) mode of action in a FRET based assay. We show that the AF2 helix of RORγ is proteolytically sensitive when inverse agonist BIO399 binds. Using x-ray crystallography we show how small modifications on the benzoxazinone agonist BIO592 trigger inverse agonism of RORγ. Using an in vivo reporter assay, we show that the inverse agonist BIO399 displayed specificity for RORγ over ROR sub-family members α and ß. CONCLUSION: The synthetic benzoxazinone ligands identified in our FRET assay have an agonist (BIO592) or inverse agonist (BIO399) effect by stabilizing or destabilizing the agonist conformation of RORγ. The proteolytic sensitivity of the AF2 helix of RORγ demonstrates that it destabilizes upon BIO399 inverse agonist binding perturbing the coactivator protein binding site. Our structural investigation of the BIO592 agonist and BIO399 inverse agonist structures identified residue Met358 on RORγ as the trigger for RORγ specific inverse agonism.

Discovery of biaryls as RORγ inverse agonists by using structure-based design.

RORγ plays a critical role in controlling a pro-inflammatory gene expression program in several lymphocyte lineages including T cells, γδ T cells, and innate lymphoid cells. RORγ-mediated inflammation has been linked to susceptibility to Crohn's disease, arthritis, and psoriasis. Thus inverse agonists of RORγ have the potential of modulating inflammation. Our goal was to optimize two RORγ inverse agonists: T0901317 from literature and 1 that we obtained from internal screening. We used information from internal X-ray structures to design two libraries that led to a new biaryl series.

Highly selective 2,4-diaminopyrimidine-5-carboxamide inhibitors of Sky kinase.

We report the SAR around a series of 2,4-diaminopyrimidine-5-carboxamide inhibitors of Sky kinase. 2-Aminophenethyl analogs demonstrate excellent potency but moderate kinase selectivity, while 2-aminobenzyl analogs that fill the Ala571 subpocket exhibit good inhibition activity and excellent kinase selectivity.

Optimization of highly selective 2,4-diaminopyrimidine-5-carboxamide inhibitors of Sky kinase.

Optimization of the ADME properties of a series of 2,4-diaminopyrimidine-5-carboxamide inhibitors of Sky kinase resulted in the identification of highly selective compounds with properties suitable for use as in vitro and in vivo tools to probe the effects of Sky inhibition.

Design, synthesis, and evaluation of imidazo[4,5-c]pyridin-4-one derivatives with dual activity at angiotensin II type 1 receptor and peroxisome proliferator-activated receptor-γ.

Identification of a series of imidazo[4,5-c]pyridin-4-one derivatives that act as dual angiotensin II type 1 (AT1) receptor antagonists and peroxisome proliferator-activated receptor-γ (PPARγ) partial agonists is described. Starting from a known AT1 antagonist template, conformational restriction was introduced by incorporation of an indane ring that when combined with appropriate substitution at the imidazo[4,5-c]pyridin-4-one provided novel series 5 possessing the desired dual activity. The mode of interaction of this series with PPARγ was corroborated through the X-ray crystal structure of 12b bound to the human PPARγ ligand binding domain. Modulation of activity at both receptors through substitution at the pyridone nitrogen led to the identification of potent dual AT1 antagonists/PPARγ partial agonists. Among them, 21b was identified possessing potent dual pharmacology (AT1 IC(50) = 7 nM; PPARγ EC(50) = 295 nM, 27% max) and good ADME properties.

Novel and selective spiroindoline-based inhibitors of Sky kinase.

We report the discovery of a novel series of spiroindoline-based inhibitors of Sky kinase that bind in the ATP-binding site and exhibit high levels of kinome selectivity through filling the Ala571-subpocket. These inhibitors exhibit moderate oral bioavailability in the rat due to low absorption across the gut wall.

Rational design of 6-(2,4-diaminopyrimidinyl)-1,4-benzoxazin-3-ones as small molecule renin inhibitors.

We report the design and synthesis of a series of 6-(2,4-diaminopyrimidinyl)-1,4-benzoxazin-3-ones as orally bioavailable small molecule inhibitors of renin. Compounds with a 2-methyl-2-aryl substitution pattern exhibit potent renin inhibition and good permeability, solubility, and metabolic stability. Oral bioavailability was found to be dependent on metabolic clearance and cellular permeability, and was optimized through modulation of the sidechain that binds in the S3(sp) subsite.

Discovery of 6-ethyl-2,4-diaminopyrimidine-based small molecule renin inhibitors.

Novel 2,4-diaminopyrimidine-based small molecule renin inhibitors are disclosed. Through high throughput screening, parallel synthesis, X-ray crystallography, and structure based drug design, we have developed the first non-chiral, non-peptidic, small molecular template to possess moderate potency against renin. The designed compounds consist of a novel 6-ethyl-5-(1,2,3,4-tetrahydroquinolin-7-yl)pyrimidine-2,4-diamine ring system that exhibit moderate potency (IC(50): 91-650 nM) against renin while remaining 'Rule-of-five' compliant.

Binding thermodynamics of substituted diaminopyrimidine renin inhibitors.

Renin is an aspartyl protease involved in the production of angiotensin II, a potent vasoconstrictor. Renin inhibitors can prevent blood vessel constriction and therefore could be useful for the treatment of hypertension. High-throughput screening efforts identified a small molecule renin inhibitor with a core substituted diaminopyrimidine ring. Parallel medicinal chemistry efforts based on this lead resulted in compound 1. A complex of 1 bound to renin was crystallized, and structural data were obtained by X-ray diffraction. The structure indicated that there were adjacent unoccupied binding pockets. Synthetic efforts were initiated to extend functionality into these pockets so as to improve affinity and adjust pharmacokinetic parameters. Thermodynamics data for inhibitor binding to renin were also collected using isothermal titration calorimetry. These data were used to help guide inhibitor optimization by suggesting molecular alterations to improve binding affinity from both thermodynamic and structural perspectives. The addition of a methoxypropyl group extending into the S3 subpocket improved inhibitor affinity and resulted in greater binding enthalpy. Initial additions to the pyrimidine ring template that extended into the large hydrophobic S2 pocket did not improve affinity and dramatically altered the thermodynamic driving force for the binding interaction. Binding of the core template was enthalpically driven, whereas binding of initial inhibitors with S2 extensions was both enthalpically and entropically driven but lost significant binding enthalpy. Additional electrostatic interactions were then incorporated into the S2 extension to improve binding enthalpy while taking advantage of the favorable entropy.

Ketopiperazine-based renin inhibitors: optimization of the "C" ring.

A systematic investigation of the S3 sub-pocket activity requirements was conducted. It was observed that linear and sterically small side chain substituents are preferred in the S3 sub-pocket for optimal renin inhibition. Polar groups in the S3-sub-pocket were not well tolerated and caused a reduction in renin inhibitory activity. Further, compounds with clog P's < or = 3 demonstrated a dramatic reduction in CYP3A4 inhibitory activity.

Benzyl ether structure-activity relationships in a series of ketopiperazine-based renin inhibitors.

Inhibition of renin enzymatic activity by a series of ketopiperazine-based compounds containing a C6 benzyloxymethyl substituent correlated with a +(pi+sigma) effect. A 3-pyridinyloxymethyl substituent was also found to be equipotent as higher molecular weight analogs, and exhibited decreased CYP3A4 inhibition levels and improved pharmacokinetic properties.

Equipotent activity in both enantiomers of a series of ketopiperazine-based renin inhibitors.

We have found that both enantiomeric configurations of the 6-alkoxymethyl-1-aryl-2-piperazinone scaffold display equipotent renin inhibition activity and similar SAR patterns. This enantiomeric flexibility is in contrast to a previously reported 3-alkoxymethyl-4-arylpiperidine scaffold.

Discovery of novel non-peptidic ketopiperazine-based renin inhibitors.

Ketopiperazine 2 was designed from a previously published analog. Compound 2 was shown to be a novel, potent inhibitor of renin that, when administered orally, lowered blood pressure in a hypertensive double transgenic (human renin and angiotensinogen) mouse model. Compound 2 was further optimized to sub-nanomolar potency by designing an analog that addressed the S3 sub-pocket of the renin enzyme (16).

The discovery and preparation of disubstituted novel amino-aryl-piperidine-based renin inhibitors.

Recently, trans-disubstituted oxo-aryl-piperidines have been identified as small molecule nonpeptide renin inhibitors for the modulation of hypertension. Herein, we report on the discovery and preparation of a new class of novel cis-disubstituted amino-aryl-piperidines as a mixture of enantiomers that are potent in vitro renin inhibitors and also, possess in vivo antihypertensive activity in a double transgenic mouse model.

Practical synthesis of 1-aryl-6-(hydroxymethyl)-2-ketopiperazines via a 6-exo amide-epoxide cyclization.

[reaction: see text] Chiral 1-aryl-6-(hydroxymethyl)-2-ketopiperazines can be prepared via an operationally simple, 6-exo epoxide ring-opening cyclization to form the ketopiperazine C6-N1 bond in high yields and with excellent enantiomeric purity.

Total synthesis of formamicin.

The enantioselective total synthesis of the cytotoxic plecomacrolide natural product formamicin (1) is described. Key aspects of this synthesis include the efficient transacetalation reactions of MOM ethers 28 and 38 to form the seven-membered formyl acetals 29 and 39, a late-stage Suzuki cross-coupling reaction of the highly functionalized vinyl boronic acid 6 and vinyl iodide 7, a highly beta-selective glycosidation reaction of beta-hydroxy ketone 4 with 2,6-dideoxy-2-iodoglucopyranosyl fluoride 3, and the global desilylation of penultimate intermediate 77 mediated by in situ generated Et(3)N.2HF.

Anti-1,3-diols by Addition of Dialkylzinc Reagents to 4-Acetoxy-1,3-dioxanes.

Dialkylzincs couple with 4-acetoxy-6-alkyl-1,3-dioxanes in the presence of trimethylsilyl triflate (TMSOTf) to form trans-4,6-dialkyl-1,3-dioxanes with excellent diastereoselectivities. These dioxanes could be deprotected to yield anti-1,3-diols. A variety of functional groups are tolerated in the dialkylzinc, although silyl and benzyl ethers led to diminished diastereoselectivities. Substituents at the C5-position of the dioxane ring have little effect on the selectivity, while small C2 (acetal) substituents led to slightly reduced diastereoselectivity. These couplings work best with cyclic acetals, which can be difficult to hydrolyze. The 4-(benzyloxy)butanal (BOB) acetal has been developed as a new cyclic acetal protecting group that is compatible with dialkylzinc coupling reactions. BOB protecting groups are easily removed by catalytic hydrogenation followed by mild acid hydrolysis.