Adamantyl carboxamides and acetamides as potent human 11β-hydroxysteroid dehydrogenase type 1 inhibitors

The modulation of 11β-HSD1 activity with selective inhibitors has beneficial effects on various metabolic disorders including insulin resistance, dyslipidemia and obesity. Here we report the discovery of a series of novel adamantyl carboxamide and acetamide derivatives as selective inhibitors of human 11β-HSD1 in HEK-293 cells transfected with the HSD11B1 gene. Optimization based on an initially identified 11β-HSD1 inhibitor (3) led to the discovery of potent inhibitors with IC₅₀ values in the 100 nM range. These compounds are also highly selective 11β-HSD1 inhibitors with no activity against 11β-HSD2 and 17β-HSD1. Compound 15 (IC₅₀ = 114 nM) with weak inhibitory activity against the key human cytochrome P450 enzymes and moderate stability in incubation with human liver microsomes is worthy of further development. Importantly, compound 41 (IC₅₀ = 280 nM) provides a new lead that incorporates an adamantyl group surrogate and should enable further series diversification.     

Design, synthesis, and SAR studies of novel polycyclic acids as potent and selective inhibitors of human 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1)

Starting from high throughput screening hit 2-adamantyl acetic acid 3, a series of polycyclic acids have been designed and synthesized as novel, potent, and selective inhibitors of human 11β-HSD-1. Structure-activity relationships of two different regions of the chemotype (polycyclic ring and substituents on quaternary carbon) are discussed.     

Discovery of cyclicsulfonamide derivatives as 11β-hydroxysteroid dehydrogenase 1 inhibitors

A new series of cyclic sulfonamide derivatives was synthesized and evaluated for their ability to inhibit 11β-HSD1. Cyclic sulfonamides with phenylacetyl substituents at the 2-position showed nanomolar inhibitory activities. Among them, compound 4e exhibited a good in vitro inhibitory activity and selectivity toward human 11β-HSD2.     

Identification of oxazolidinediones and thiazolidinediones as potent 17β-hydroxysteroid dehydrogenase type 3 inhibitors

Novel and potent inhibitors of 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) were identified based on oxazolidinedione and thiazolidinedione derivatives, starting from a high-throughput screening hit, 5-(3-bromo-4-hydroxybenzyl)-3-(4-methoxyphenyl)-1,3-thiazol-2-one. 5-(3-Bromo-4-hydroxybenzylidene)-3-(4-methoxyphenyl)-2-thioxo-1,3-thiazolidin-4-one exhibited a promising activity profile and demonstrated significant selectivity over the related 17β-HSD isoenzymes and nuclear receptors.     

Development of 3-substituted-androsterone derivatives as potent inhibitors of 17β-hydroxysteroid dehydrogenase type 3

17Beta-hydroxysteroid dehydrogenase type 3 (17β-HSD3) is a steroidogenic enzyme that catalyzes the transformation of 4-androstene-3,17-dione (Δ?-dione) into androgen testosterone (T). To provide effective inhibitors of androgen biosynthesis, we synthesized two different series (amines and carbamates) of 3β-substituted-androsterone derivatives and we tested their inhibitory activity on 17β-HSD3. From the results of our structure-activity relationship study, we identified a series of compounds producing a strong inhibition of 17β-HSD3 overexpressed in HEK-293 cells (homogenized cells). The most active compound when tested in intact HEK-293 transfected cells, namely (3α,5α)-3-{[trans-2,5-dimethyl-4-{[2-(trifluoromethyl)phenyl] sulfonyl}piperazin-1-yl]methyl}-3-hydroxyandrostan-17-one (15b), shows an IC?? value of 6 nM, this compound is thus eight times more active than our reference compound D-5-2 (IC??=51 nM). This new improved inhibitor did not stimulate the proliferation of androgen-sensitive Shionogi cells, suggesting a non-androgenic profile. Compound 15b is thus a good candidate for further in vivo studies on rodents.     

Novel enzymological profiles of human 11β-hydroxysteroid dehydrogenase type 1

The human enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD) catalyzes the reversible oxidoreduction of 11β-OH/11-oxo groups of glucocorticoid hormones. Besides this important endocrinological property, the type 1 isozyme (11β-HSD1) mediates reductive phase I reactions of several carbonyl group bearing xenobiotics, including drugs, insecticides and carcinogens. The aim of this study was to explore novel substrate specificities of human 11β-HSD1, using heterologously expressed protein in the yeast system Pichia pastoris. In addition to established phase I xenobiotic substrates, it is now demonstrated that transformed yeast strains catalyze the reduction of ketoprofen to its hydroxy metabolite, and the oxidation of the prodrug DFU-lactol to the pharmacologically active lactone compound. Purified recombinant 11β-HSD1 mediated oxidative reactions, however, the labile reductive activity component could not be maintained. In conclusion, evidence is provided that human 11β-HSD1 in vitro is involved in phase I reactions of anti-inflammatory non-steroidal drugs like ketoprofen and DFU-lactol.     

Mono-carbonyl curcumin analogues as 11β-hydroxysteroid dehydrogenase 1 inhibitors

A series of structurally novel mono-carbonyl curcumin analogues have been synthesized and biologically evaluated to test their inhibitory potencies and the structure–activity relationship (SAR) on human and rat 11β-hydroxysteroid dehydrogenase isoform (11β-HSD1) activities. 11β-HSD1 selective inhibitors have been discovered and compound A10 is discovered as a very potent with an IC₅₀ value of 97 nM without inhibiting 11β-HSD2.     

Structural assessment and identification of 11β-hydroxysteroid dehydrogenase type 1 inhibitors

Communicated by Ramaswamy H. Sarma     

Synthesis and optimization of arylsulfonylpiperazines as a novel class of inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1)

The synthesis and SAR of a series of arylsulfonylpiperazine inhibitors of 11β-HSD1 are described. Optimization rapidly led to potent, selective, and orally bioavailable inhibitors demonstrating efficacy in a cynomolgus monkey ex vivo enzyme inhibition model.     

Hydroxybenzothiazoles as new nonsteroidal inhibitors of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1)

17β-estradiol (E2), the most potent estrogen in humans, known to be involved in the development and progession of estrogen-dependent diseases (EDD) like breast cancer and endometriosis. 17β-HSD1, which catalyses the reduction of the weak estrogen estrone (E1) to E2, is often overexpressed in breast cancer and endometriotic tissues. An inhibition of 17β-HSD1 could selectively reduce the local E2-level thus allowing for a novel, targeted approach in the treatment of EDD. Continuing our search for new nonsteroidal 17β-HSD1 inhibitors, a novel pharmacophore model was derived from crystallographic data and used for the virtual screening of a small library of compounds. Subsequent experimental verification of the virtual hits led to the identification of the moderately active compound 5. Rigidification and further structure modifications resulted in the discovery of a novel class of 17β-HSD1 inhibitors bearing a benzothiazole-scaffold linked to a phenyl ring via keto- or amide-bridge. Their putative binding modes were investigated by correlating their biological data with features of the pharmacophore model. The most active keto-derivative 6 shows IC₅₀-values in the nanomolar range for the transformation of E1 to E2 by 17β-HSD1, reasonable selectivity against 17β-HSD2 but pronounced affinity to the estrogen receptors (ERs). On the other hand, the best amide-derivative 21 shows only medium 17β-HSD1 inhibitory activity at the target enzyme as well as fair selectivity against 17β-HSD2 and ERs. The compounds 6 and 21 can be regarded as first benzothiazole-type 17β-HSD1 inhibitors for the development of potential therapeutics.     

Structure-based design of 7-azaindole-pyrrolidine amides as inhibitors of 11β-hydroxysteroid dehydrogenase type I

Indole-pyrrolidines were identified as inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) by high-throughput screening. Optimisation of the initial hit through structure-based design led to 7-azaindole-derivatives, with the best analogues displaying single digit nanomolar IC(50) potency. The modeling hypotheses were confirmed by solving the X-ray co-crystal structure of one of the lead compounds. These compounds were selective against 11β-hydroxysteroid dehydrogenase type 2 (selectivity ratio >200) and exhibited good inhibition of 11β-HSD1 (IC(50)<1μM) in a cellular model (3T3L1 adipocytes).     

Discovery of potent and orally bioavailable 17β-hydroxysteroid dehydrogenase type 3 inhibitors

We have previously reported the discovery of a new class of potent inhibitors of 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) derived from benzylidene oxazolidinedione and thiazolidinedione scaffolds. In this study, these analogs were designed, synthesized, and evaluated in a human cell-based assay. The detailed structure-activity relationship (SAR) surrounding this pharmacophore were developed, and consequently a number of compounds from this series demonstrated single-digit nanomolar 17β-HDS3 inhibitory activity in vitro. Subsequent optimization work in pursuit of the improvement of oral bioavailability demonstrated in vivo proof-of-concept by prodrug strategy based on phosphate esters for these 17β-HSD3 inhibitors. When a phosphate ester 16 was administered orally at a high dose of 100mg/kg, 16 showed approximately two times more potent testosterone (T)-lowering effect against a positive control in the luteinizing hormone-releasing hormone (LH-RH)-induced T production assay. The T-lowering effect continued at ca 10% level of control over 4h after administration. The nonsteroidal molecules based on this series have the potential to provide unique and effective clinical opportunities for treatment of prostate cancer.     

Pyrrolidine-pyrazole ureas as potent and selective inhibitors of 11β-hydroxysteroid-dehydrogenase type 1

A High Throughput Screening campaign allowed the identification of a novel class of ureas as 11β-HSD1 inhibitors. Rational chemical optimization provided potent and selective inhibitors of both human and murine 11β-HSD1 with an appropriate ADME profile and ex vivo activity in target tissues.     

Discovery of highly potent, nonsteroidal 17β-hydroxysteroid dehydrogenase type 1 inhibitors by virtual high-throughput screening

17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) catalyzes the formation of the potent proliferation-stimulating hormone estradiol, and it is thus involved in the development of hormone-dependent breast cancer. Due to its high substrate specificity and the known relationships between its overexpression and disease incidence, 17β-HSD1 is considered an attractive target for drug development. Here, we have used structure-based virtual high-throughput screening to successfully identify potent nonsteroidal 17β-HSD1 inhibitors. Computational screening of a drug-like database containing 13 million compounds identified hits with a 2-benzylidenebenzofuran-3(2H)-one scaffold that we show to be highly potent 17β-HSD1 inhibitors. The most potent in the series, compound 1, showed an IC(50) of 45nM in our 17β-HSD1 inhibition assay, and also showed good selectivity for 17β-HSD1 over 17β-HSD2.     

N-(Pyridin-2-yl) arylsulfonamide inhibitors of 11β-hydroxysteroid dehydrogenase type 1: Discovery of PF-915275

N-(Pyridin-2-yl) arylsulfonamides are identified as inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), an enzyme that catalyzes the reduction of the glucocorticoid cortisone to cortisol. Dysregulation of glucocorticoids has been implicated in the pathogenesis of diabetes and the metabolic syndrome. In this Letter, we present the development of an initial lead to an efficient ligand with improved physiochemical properties using a deletion strategy. This strategy allowed for further optimization of potency leading to the discovery of the clinical candidate PF-915275.     

Cell-based assay for screening 11β-hydroxysteroid dehydrogenase 1 inhibitors

11β-Hydroxysteroid dehydrogenase 1 (11β-HSD1) is primarily responsible for intracellular biosynthesis of active glucocorticoid, and its tissue-specific dysregulation has been implicated in the development of metabolic syndromes. We have developed a cell-based assay for measuring 11β-HSD1 activities using murine skeletal muscle cell line C2C12. We found that the messenger RNA (mRNA) expression of 11β-HSD1 increased on differentiation with enhanced enzyme activity as determined by homogeneous time-resolved fluorescence (HTRF) assay. Carbenoxolone, a well-known 11β-HSD1 inhibitor, exhibited an IC₅₀ value similar to that in in vitro microsomal assay (IC₅₀ = 0.3 μM). Unlike in vitro microsomal assay, cosubstrate NADPH was not required in the cell-based assay, indicating that viable cells might provide a sufficient amount of endogenous NADPH to catalyze the enzymatic conversion of inactive cortisone to active cortisol. Treatment of C2C12 myotubes with cortisone concentration dependently transactivated and transrepressed glutamine synthase and interleukin-6, respectively, which were abrogated by carbenoxolone or RU-486 (mifepristone), a glucocorticoid receptor antagonist. Accordingly, a newly designed cell-based assay using differentiated skeletal muscle cells would be useful for high-throughput screening of 11β-HSD1 inhibitors as well as for understanding the molecular mechanisms of glucocorticoid action.     

Discovery of substituted 3-(phenylamino)benzoic acids as potent and selective inhibitors of type 5 17β-hydroxysteroid dehydrogenase (AKR1C3)

Aldo-keto reductase 1C3 (AKR1C3) also known as type 5 17β-hydroxysteroid dehydrogenase has been implicated as one of the key enzymes driving the elevated intratumoral androgen levels observed in castrate resistant prostate cancer (CRPC). AKR1C3 inhibition therefore presents a rational approach to managing CRPC. Inhibitors should be selective for AKR1C3 over other AKR1C enzymes involved in androgen metabolism. We have synthesized 2-, 3-, and 4-(phenylamino)benzoic acids and identified 3-(phenylamino)benzoic acids that have nanomolar affinity and exhibit over 200-fold selectivity for AKR1C3 versus other AKR1C isoforms. The AKR1C3 inhibitory potency of the 4′-substituted 3-(phenylamino)benzoic acids shows a linear correlation with both electronic effects of substituents and the pK_a of the carboxylic acid and secondary amine groups, which are interdependent. These compounds may be useful in treatment and/or prevention of CRPC as well as understanding the role of AKR1C3 in endocrinology.     

Synthesis of 3-spiromorpholinone androsterone derivatives as inhibitors of 17β-hydroxysteroid dehydrogenase type 3

Spiromorpholinone derivatives were synthesized from androsterone or cyclohexanone in 6 or 3 steps, respectively, and these scaffolds were used for the introduction of a hydrophobic group via a nucleophilic substitution. Non-steroidal spiromorpholinones are not active as inhibitors of 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3), but steroidal morpholinones are very potent inhibitors. In fact, those with (S) stereochemistry are more active than their (R) homologues, whereas N-benzylated compounds are more active than their non substituted precursors. The target compounds exhibited strong inhibition of 17β-HSD3 in rat testis homogenate (87–92% inhibition at 1 μM).     

Azabicyclic sulfonamides as potent 11β-HSD1 inhibitors

Inhibition of 11β-HSD1 has demonstrated potential in the treatment of various components of metabolic syndrome. We wish to report herein the discovery of novel azabicyclic sulfonamide based 11β-HSD1 inhibitors. Highly potent compounds exhibiting inhibitory activities at both human and mouse 11β-HSD1 were identified. Several compounds demonstrated significant in vivo activity in the mouse cortisone challenge assay.     

Synthesis and biological analysis of benzazol-2-yl piperazine sulfonamides as 11β-hydroxysteroid dehydrogenase 1 inhibitors

In the last decade the inhibition of the enzyme 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) emerged as a promising new strategy to treat diabetes and several metabolic syndrome phenotypes. Using a molecular modeling approach and classical bioisosteric studies, we discovered a new class of 11β-HSD1 inhibitors bearing an arylsulfonylpiperazine scaffold. Optimization of the initial lead resulted in compound 11 that selectively inhibits 11β-HSD1 (IC₅₀ = 0.7 μM).