Discovery and Metabolic Stabilization of Potent and Selective 2-Amino-N-(adamant-2-yl) Acetamide 11β-Hydroxysteroid Dehydrogenase Type 1 Inhibitors

Discovery of C-5 Pyrazole-Substituted Pyrrolopyridine Derivatives as Potent and Selective Inhibitors for Janus Kinase 1

Developing selective inhibitors for Janus kinase 1 (JAK1) is a significant focus for improving the efficacy and alleviating the adverse effects in treating immune-inflammatory diseases. Herein, we report the discovery of a series of C-5 pyrazole-modified pyrrolopyrimidine derivatives as JAK1-selective inhibitors. The potential hydrogen bond between the pyrazole group and E966 in JAK1 is the key point that enhances JAK1 selectivity. These compounds exhibit 10- to 20-fold JAK1 selectivity over JAK2 in enzyme assays. Compound 12b also exhibits excellent JAK1 selectivity in Ba/F3-TEL-JAK cellular assays. Metabolism studies and the results of the hair growth model in mice indicate that compound 12b may be a viable lead compound for the development of highly JAK1-selective inhibitors for immune and inflammatory diseases.

Novel 2-(Adamantan-1-ylamino)Thiazol-4(5H)-One Derivatives and Their Inhibitory Activity towards 11β-HSD1-Synthesis, Molecular Docking and In Vitro Studies

A common mechanism in which glucocorticoids participate is suggested in the pathogenesis of such metabolic diseases as obesity, metabolic syndrome, or Cushing’s syndrome. The enzyme involved in the control of the availability of cortisol, the active form of the glucocorticoid for the glucocorticoid receptor, is 11β-HSD1. Inhibition of 11β-HSD1 activity may bring beneficial results for the alleviation of the course of metabolic diseases such as metabolic syndrome, Cushing’s syndrome or type 2 diabetes. In this work, we obtained 10 novel 2-(adamantan-1-ylamino)thiazol-4(5H)-one derivatives containing different substituents at C-5 of thiazole ring and tested their activity towards inhibition of two 11β-HSD isoforms. For most of them, over 50% inhibition of 11β-HSD1 and less than 45% inhibition of 11β-HSD2 activity at the concentration of 10 µM was observed. The binding energies found during docking simulations for 11β-HSD1 correctly reproduced the experimental IC₅₀ values for analyzed compounds. The most active compound 2-(adamantan-1-ylamino)-1-thia-3-azaspiro[4.5]dec-2-en-4-one (3i) inhibits the activity of isoform 1 by 82.82%. This value is comparable to the known inhibitor-carbenoxolone. The IC₅₀ value is twice the value determined by us for carbenoxolone, however inhibition of the enzyme isoform 2 to a lesser extent makes it an excellent material for further tests.

Mono- and Diamination of 4,6-Dichloropyrimidine, 2,6-Dichloropyrazine and 1,3-Dichloroisoquinoline with Adamantane-Containing Amines

N-heteroaryl substituted adamantane-containing amines are of substantial interest for their perspective antiviral and psychotherapeutic activities. Chlorine atom at alpha-position of N-heterocycles has been substituted by the amino group using convenient nucleophilic substitution reactions with a series of adamantylalkylamines. The prototropic equilibrium in these compounds was studied using NMR spectroscopy. The introduction of the second amino substituent in 4-amino-6-chloropyrimidine, 2-amino-chloropyrazine, and 1-amino-3-chloroisoquinoline was achieved using Pd(0) catalysis.

Metabolic Profiling of a CB2 Agonist, AM9338, Using LC-MS and Microcoil-NMR: Identification of a Novel Dihydroxy Adamantyl Metabolite

Adamantyl groups are key structural subunit commonly used in many marketed drugs targeting diseases ranging from viral infections to neurological disorders. The metabolic disposition of adamantyl compounds has been mostly studied using LC-MS based approaches. However, metabolite quantities isolated from biological preparations are often insufficient for unambiguous structural characterization by NMR. In this work, we utilized microcoil NMR in conjunction with LC-MS to characterize liver microsomal metabolites of an adamantyl based CB2 agonist AM9338, 1-(3-(1H-1,2,3-triazol-1-yl) propyl)-N-(adamantan-1-yl)-1H-indazole-3-carboxamide, a candidate compound for potential multiple sclerosis treatment. We have identified a total of 9 oxidative metabolites of AM9338 whereas mono- or di-hydroxylation of the adamantyl moiety is the primary metabolic pathway. While it is generally believed that the tertiary adamantyl carbons are the preferred sites of CYP450 oxidation, both the mono- and di-hydroxyl metabolites of AM9338 show that the primary oxidative sites are located on the secondary adamantyl carbons. To our knowledge this di-hydroxylated metabolite is a novel adamantyl metabolite that has not been reported before. Further, the stereochemistry of both mono- and di-hydroxyl adamantyl metabolites has been determined using NOE correlations. Furthermore, docking of AM9338 into the CYP3A4 metabolic enzyme corroborates with our experimental findings, and the modelling results also provide a possible mechanism for the unusual susceptibility of adamantyl secondary carbons to metabolic oxidations. The novel dihydroxylated AM9338 metabolite identified in this study, along with the previously known adamantyl metabolites, gives a more complete picture of the metabolic disposition for adamantyl compounds.

Synthesis of Sterically Congested 2,2'-Bi(Adamantyl)-Based Alcohol and Amines

Sterically congested chiral alcohol and amines have gained tremendous attention in the design of asymmetric catalysts. Herein, the synthesis of a sterically congested bis-adamantane framework-based chiral alcohol, (1R,2S,3S,4R)-4-(2-adamantyl)adamantan-2-ol, and amine, (1R,2S,3S,4R)-4-(2-adamantyl)adamantan-2-amine, is described. Access to these sterically encumbered compounds is found via the preparation of an enantioenriched 4-adamantyladamantan-2-one intermediate, which was synthesized in 6 steps from adamantan-2-one. The key step involved enzyme-catalyzed ester hydrolysis in giving unsaturated alcohol with an enantiomeric excess of >95%. This adamantylidene adamantanol was subjected to an acid-catalyzed intramolecular [1,4] shift to give the key chiral intermediate without racemization. This ketone intermediate was transformed into the target compounds via reduction and reductive amination protocols.

Discovery of Clinical Candidate 2-((2S,6S)-2-Phenyl-6-hydroxyadamantan-2-yl)-1-(3'-hydroxyazetidin-1-yl)ethanone [BMS-816336], an Orally Active Novel Selective 11β-Hydroxysteroid Dehydrogenase Type 1 Inhibitor

BMS-816336 (6n-2), a hydroxy-substituted adamantyl acetamide, has been identified as a novel, potent inhibitor against human 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) enzyme (IC₅₀ 3.0 nM) with >10000-fold selectivity over human 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2). 6n-2 exhibits a robust acute pharmacodynamic effect in cynomolgus monkeys (ED₅₀ 0.12 mg/kg) and in DIO mice. It is orally bioavailable (%F ranges from 20 to 72% in preclinical species) and has a predicted pharmacokinetic profile of a high peak to trough ratio and short half-life in humans. This ADME profile met our selection criteria for once daily administration, targeting robust inhibition of 11β-HSD1 enzyme for the first 12 h period after dosing followed by an "inhibition holiday" so that the potential for hypothalamic-pituitary-adrenal (HPA) axis activation might be mitigated. 6n-2 was found to be well-tolerated in phase 1 clinical studies and represents a potential new treatment for type 2 diabetes, metabolic syndrome, and other human diseases modulated by glucocorticoid control.

Triflic Acid Promoted Decarboxylation of Adamantane-oxazolidine-2-one: Access to Chiral Amines and Heterocycles

We have developed a one-step procedure to a variety of chiral lipophilic and conformationally rigid amines and heterocycles by decarboxylation of adamantane-oxazolidine-2-one. Triflic acid or aluminum triflate promote the addition of diverse nucleophiles to the oxazolidine-2-one moiety accompanied by the release of carbon dioxide. The resulting amine or heterocycle is then protonated/metalated by the catalyst (promotor). Additionally, the starting racemic material, adamantane-oxazolidine-2-one, was resolved into single enantiomers using a chiral auxiliary to access enantio-enriched products and to study the racemization pathway of chiral 1,2-disubstituted adamantane derivatives.

Synthesis, Antimicrobial and Hypoglycemic Activities of Novel N-(1-Adamantyl)carbothioamide Derivatives

The reaction of 1-adamantyl isothiocyanate 4 with the various cyclic secondary amines yielded the corresponding N-(1-adamantyl)carbothioamides 5a–e, 6, 7, 8a–c and 9. Similarly, the reaction of 4 with piperazine and trans-2,5-dimethylpiperazine in 2:1 molar ratio yielded the corresponding N,N'-bis(1-adamantyl)piperazine-1,4-dicarbothioamides 10a and 10b, respectively. The reaction of N-(1-adamantyl)-4-ethoxycarbonylpiperidine-1-carbothioamide 8c with excess hydrazine hydrate yielded the target carbohydrazide 11, in addition to 4-(1-adamantyl)thiosemicarbazide 12 as a minor product. The reaction of the carbohydrazide 11 with methyl or phenyl isothiocyanate followed by heating in aqueous sodium hydroxide yielded the 1,2,4-triazole analogues 14a and 14b. The reaction of the carbohydrazide 11 with various aromatic aldehydes yielded the corresponding N'-arylideneamino derivatives 15a–g. The compounds 5a–e, 6, 7, 8a–c, 9, 10a, 10b, 14a, 14b and 15a–g were tested for in vitro antimicrobial activity against certain strains of pathogenic Gram-positive and Gram-negative bacteria and the yeast-like fungus Candida albicans. The compounds 5c, 5d, 5e, 6, 7, 10a, 10b, 15a, 15f and 15g showed potent antibacterial activity against one or more of the tested microorganisms. The oral hypoglycemic activity of compounds 5c, 6, 8b, 9, 14a and 15b was determined in streptozotocin (STZ)-induced diabetic rats. Compound 5c produced significant reduction of serum glucose levels, compared to gliclazide.

Synthesis and Docking Studies of the NovelN-(2,2-Di(1H-pyrrol-2-yl)ethyl)adamantane-1-carboxamide, a Potential 11β-HSD1 Inhibitor

The synthesis of the novel 1-adamantyl-(N-meso-dipyrrolylmethylene)-carboxamide is described, providing a three-step, two-pot reaction. Docking studies with 11β-HSD1 revealed favorable binding interactions with the enzyme.

Synthesis of analogs of the radiation mitigator JP4-039 and visualization of BODIPY derivatives in mitochondria

JP4-039 is a lead structure in a series of nitroxide conjugates that are capable of accumulating in mitochondria and scavenging reactive oxygen species (ROS). To explore structure-activity relationships (SAR), new analogs with variable nitroxide moieties were prepared. Furthermore, fluorophore-tagged analogs were synthesized and provided the opportunity for visualization in mitochondria. All analogs were tested for radioprotective and radiomitigative effects in 32Dcl3 cells.

11β-Hydroxysteroid dehydrogenase 1: translational and therapeutic aspects

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) interconverts the inactive glucocorticoid cortisone and its active form cortisol. It is widely expressed and, although bidirectional, in vivo it functions predominantly as an oxoreductase, generating active glucocorticoid. This allows glucocorticoid receptor activation to be regulated at a prereceptor level in a tissue-specific manner. In this review, we will discuss the enzymology and molecular biology of 11β-HSD1 and the molecular basis of cortisone reductase deficiencies. We will also address how altered 11β-HSD1 activity has been implicated in a number of disease states, and we will explore its role in the physiology and pathologies of different tissues. Finally, we will address the current status of selective 11β-HSD1 inhibitors that are in development and being tested in phase II trials for patients with the metabolic syndrome. Although the data are preliminary, therapeutic inhibition of 11β-HSD1 is also an exciting prospect for the treatment of a variety of other disorders such as osteoporosis, glaucoma, intracranial hypertension, and cognitive decline.

1,1-Dioxo-5,6-dihydro-[4,1,2]oxathiazines, a novel class of 11ß-HSD1 inhibitors for the treatment of diabetes

Racemic cis-1,1-dioxo-5,6-dihydro-[4,1,2]oxathiazine derivative 4a was isolated as an impurity in a sample of a hit from a HTS campaign on 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). After separation by chiral chromatography the 4a-S, 8a-R enantiomer of compound 4a was identified as the true, potent enzyme inhibitor. The cocrystal structure of 4a with human and murine 11ß-HSD1 revealed the unique binding mode of the oxathiazine series. SAR elucidation and optimization in regard to metabolic stability led to monocyclic tetramethyloxathiazines as exemplified by compound 21g.

Crystal structures of 11β-hydroxysteroid dehydrogenase type 1 and their use in drug discovery

Cortisol is synthesized by 11β-hydroxysteroid dehydrogenase type 1, inhibitors of which may treat disease associated with excessive cortisol levels. The crystal structures of 11β-hydroxysteroid dehydrogenase type 1 that have been released may aid drug discovery. The crystal structures have been analyzed in terms of the interactions between the protein and the ligands. Despite a variety of structurally different inhibitors the crystal structures of the proteins are quite similar. However, the differences are significant for drug discovery. The crystal structures can be of use in drug discovery, but care needs to be taken when selecting structures for use in virtual screening and ligand docking.

1-(1-acetyl-piperidin-4-yl)-3-adamantan-1-yl-urea (AR9281) as a potent, selective, and orally available soluble epoxide hydrolase inhibitor with efficacy in rodent models of hypertension and dysglycemia

1-(1-Acetyl-piperidin-4-yl)-3-adamantan-1-yl-urea 14a (AR9281), a potent and selective soluble epoxide hydrolase inhibitor, was recently tested in a phase 2a clinical setting for its effectiveness in reducing blood pressure and improving insulin resistance in pre-diabetic patients. In a mouse model of diet induced obesity, AR9281 attenuated the enhanced glucose excursion following an intraperitoneal glucose tolerance test. AR9281 also attenuated the increase in blood pressure in angiotensin-II-induced hypertension in rats. These effects were dose-dependent and well correlated with inhibition of the sEH activity in whole blood, consistent with a role of sEH in the observed pharmacology in rodents.

Inhibitors of 11β-hydroxysteroid dehydrogenase type 1 in antidiabetic therapy

Glucocorticoid action is mediated by glucocorticoid receptor (GR), which upon cortisol binding is activated and regulates the transcriptional expression of target genes and downstream physiological functions. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyzes the conversion of inactive cortisone to active cortisol. Since cortisol is also produced through biosynthesis in the adrenal glands, the total cortisol level in a given tissue is determined by both the circulating cortisol concentration and the local 11β-HSD1 activity. 11β-HSD1 is expressed in liver, adipose, brain, and placenta. Since it contributes to the local cortisol levels in these tissues, 11β-HSD1 plays a critical role in glucocorticoid action. The metabolic symptoms caused by glucocorticoid excess in Cushing's syndrome overlap with the characteristics of the metabolic syndrome, suggesting that increased glucocorticoid activity may play a role in the etiology of the metabolic syndrome. Consistent with this notion, elevated adipose expression of 11β-HSD1 induced metabolic syndrome-like phenotypes in mice. Thus, 11β-HSD1 is a proposed therapeutic target to normalize glucocorticoid excess in a tissue-specific manner and mitigate obesity and insulin resistance. Selective inhibitors of 11β-HSD1 are under development for the treatment of type 2 diabetes and other components of the metabolic syndrome.

Structure-activity relationships of a small-molecule inhibitor of the PDZ domain of PICK1

Recently, we described the first small-molecule inhibitor, (E)-ethyl 2-cyano-3-(3,4-dichlorophenyl)acryloylcarbamate (1), of the PDZ domain of protein interacting with Calpha-kinase 1 (PICK1), a potential drug target against brain ischemia, pain and cocaine addiction. Herein, we explore structure-activity relationships of 1 by introducing subtle modifications of the acryloylcarbamate scaffold and variations of the substituents on this scaffold. The configuration around the double bond of 1 and analogues was settled by a combination of X-ray crystallography, NMR and density functional theory calculations. Thereby, docking studies were used to correlate biological affinities with structural considerations for ligand-protein interactions. The most potent analogue obtained in this study showed an improvement in affinity compared to 1 and is currently a lead in further studies of PICK1 inhibition.

11beta-hydroxysteroid dehydrogenase type 1 inhibitors: a review of recent patents

BACKGROUND

The main components of metabolic syndrome (obesity, insulin resistance, hypertension and dyslipidemia) have become prevalent worldwide, and excess glucocorticoid levels have been implicated in patients with these symptoms. 11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is an enzyme involved in glucocorticoid regulation through catalysis of the conversion of inactive cortisone to its active form cortisol. Numerous rodent studies have demonstrated the potential use of 11beta-HSD1 inhibitors as treatment for the components of metabolic syndrome and limited clinical data in humans have shown 11beta-HSD1 inhibition to improve glucose levels, insulin sensitivity and lipid profiles. Many organizations have been active in the 11beta-HSD1 academic and patent literature, and two previous articles from this journal have reviewed disclosures through August 2007.

OBJECTIVE

To summarize the recent patent literature and progress in defining the utility of small molecule 11beta-HSD1 inhibitors.

METHODS

This review covers the recent 11beta-HSD1 patent literature and clinical activity ranging from late 2007 through the end of 2008.

RESULTS/CONCLUSION

The exploration of 11beta-HSD1 inhibitors continues, as a number of structural classes have been reported by several pharmaceutical companies over the past 16 months. Current clinical trials will ultimately shed light on the feasibility of 11beta-HSD1 inhibitors as pharmaceutical agents for the various components of metabolic syndrome.

Unsymmetrical non-adamantyl N,N'-diaryl urea and amide inhibitors of soluble expoxide hydrolase

Incorporation of an adamantyl group in prototypical soluble expoxide hydrolase (sEH) inhibitors afforded improved enzyme potency. We explored replacement of the adamantyl group in unsymmetrical ureas and amides with substituted aryl rings to identify equipotent and metabolically stable sEH inhibitors. We found that aryl rings, especially those substituted in the para position with a strongly electron withdrawing substituent, afforded enzyme IC(50) values comparable to the adamantyl compounds in an ether substituted, unsymmetrical N,N'-diaryl urea or amide scaffold.

Discovery and optimization of piperidyl benzamide derivatives as a novel class of 11beta-HSD1 inhibitors

Discovery and optimization of a piperidyl benzamide series of 11beta-HSD1 inhibitors is described. This series was derived from a cyclohexyl benzamide lead structures to address PXR selectivity, high non-specific protein binding, poor solubility, limited in vivo exposure, and in vitro cytotoxicity issues observed with the cyclohexyl benzamide structures. These efforts led to the discovery of piperidyl benzamide 15 which features improved properties over the cyclohexyl benzamide derivatives.

Quantitative measurements of corticosteroids in ex vivo samples using on-line SPE-LC/MS/MS

Abnormal elevation of 11beta-HSD1 activities in tissues, such as fat and brain, may contribute to the development of the abdominal obesity and Alzheimer disease, and the inhibition of 11beta-HSD1 might be beneficial to the management of these diseases. To assess the effects of pharmacologic inhibitors of 11beta-HSD1, we developed a fast LC/MS/MS method to quantify corticosteroids in minced tissue samples in the presence of 11beta-HSD substrates. The novel on-line SPE-LC/MS/MS method was developed with dual binary gradient and a throughput of 4.5 min/sample. A total of six corticosteroids (cortisol, cortisone, corticosterone, dehydrocorticosterone, dexamethasone, and dehydrodexamethasone) were studied. The lower limit of quantitation from 0.40 to 11.4 fmol and 4.5 orders magnitude of dynamic range were obtained for these six compounds. Three novel enzymatic bi-products, all isomers of cortisol, were observed in the liver or fat samples. Two of them were identified by matching the HPLC retention times and MS/MS spectra with authentic compounds. The potential interferences of these isomers and their removal are discussed.