Design and synthesis of new nonsteroidal glucocorticoid modulators through application of an "agreement docking" method

Design, synthesis, and exploration of antibacterial activity of 6H-1,2-oxazin-6-ones

This study reports the in silico design of 30 6H-1,2-oxazin-6-ones against DHFR and PTC antimicrobial targets. Docking compounds 1, 3, 4, 6, and 8 with both enzymes was favorable, outperforming Trimethoprim with DHFR. Therefore, 12 6H-1,2-oxazin-6-ones, including the most promising compounds, were synthesized through an aminolysis reaction of β-cyanoketones with hydroxylamine hydrochloride, obtaining moderate to high yields (55-88%). Subsequently, antibacterial studies were conducted against five bacteria: four Gram-positive MRSA (ATCC 43300 and three clinical isolates) and one Gram-negative (E. coli ATCC 25922). Compounds 1, 2, 3, 4, 6, and 8 inhibited bacterial growth with MIC values ranging from 3.125 to 200 μg mL-1. Compound 1 showed better activity against Gram-positive bacteria than Linezolid. Toxicity assays indicated no adverse effects of the active oxazinones in silico and in vitro. This study demonstrated the antibacterial potential of the selected 6H-1,2-oxazin-6-ones against resistant human pathogenic bacteria.

Glucocorticoid receptor modulators CpdX and CpdX-D3 exhibit the same in vivo antiinflammatory activities as synthetic glucocorticoids

We previously reported that the nonsteroidal compound CpdX, which was initially characterized 20 y ago as a possible gestagen and, shortly afterward, as a possible drug for treatments of inflammatory diseases, selectively triggers the NFκB/AP1-mediated tethered indirect transrepression function of the glucocorticoid receptor (GR), and could therefore be a selective glucocorticoid receptor agonistic modulator (SEGRAM). We now demonstrate that, upon administration to the mouse, CpdX and one of its deuterated derivatives, CpdX-D3, repress as efficiently as a synthetic glucocorticoid (e.g., Dexamethasone) an induced skin atopic dermatitis, an induced psoriasis-like inflammation, a house dust mite (HDM)-induced asthma-like allergic lung inflammation, a collagen-induced arthritis, an induced ulcerative colitis, and an ovalbumin-induced allergic conjunctivitis. Interestingly, in the cases of an HDM-induced asthma-like allergic lung inflammation and of a collagen-induced arthritis, the CpdX antiinflammatory activity was selectively exerted by one of the two CpdX enantiomers, namely, CpdX(eA) or CpdX-D3(eA).

Synthesis of novel steroidal agonists, partial agonists, and antagonists for the glucocorticoid receptor

Adverse effects of glucocorticoids could be limited by developing new compounds that selectively modulate anti-inflammatory activity of the glucocorticoid receptor (GR). We have synthesized a novel series of steroidal GR ligands, including potent agonists, partial agonists and antagonists with a wide range of effects on inhibiting secretion of interleukin-6. Some of these new ligands were designed to directly impact conformational stability of helix-12, in the GR ligand-binding domain (LBD). These compounds modulated GR activity and glucocorticoid-induced gene expression in a manner that was inversely correlated to the degree of inflammatory response. In contrast, compounds designed to directly modulate LBD epitopes outside helix-12, led to dissociated levels of GR-mediated gene expression and inflammatory response. Therefore, these new series of compounds and their derivatives will be useful to dissect the ligand-dependent features of GR signaling specificity.

Palladium-catalyzed Csp2–H carbonylation of aromatic oximes: selective access to benzo[d][1,2]oxazin-1-ones and 3-methyleneisoindolin-1-ones

A selective palladium-catalyzed carbonylation of Csp²–H bonds with aromatic oximes for the synthesis of benzo[d][1,2]oxazin-1-ones and 3-methyleneisoindolin-1-ones has been developed.

Non-steroidal Dissociated Glucocorticoid Receptor Agonists

Synthetic glucocorticoids, such as dexamethasone and prednisolone, are amongst the most commonly used drugs due to their potent and efficacious anti-inflammatory and immunosuppressive properties. However, their long-term and/or high-dose administration is limited by a number of deleterious side-effects, including glucocorticoid-induced diabetes and osteoporosis. Glucocorticoids exert their effects through binding to the glucocorticoid receptor. Since the discovery of multiple differentiated down-stream functions of the glucocorticoid-bound receptor, such as gene transrepression and transactivation, researchers in academia and industry have been on a quest to discover novel glucocorticoids that achieve functional selectivity, hence dissociating the desired anti-inflammatory from the undesired side-effects. This review describes the current state of discovery and development of non-steroidal glucocorticoid receptor agonists. Several small-molecule drug candidates have advanced into clinical trials, and have shown promising early biomarker data, as well as beneficial effects in topical applications. However, a clinically efficacious and systemically available glucocorticoid with significantly reduced side-effects as compared to current steroidal drugs, the “Holy Grail” in immunology, is still elusive.

Synthesis and evaluation of 17α-(dimethylphenyl)vinyl estradiols as probes of the estrogen receptor-α ligand binding domain

As part of our program to explore the influence of small structural modifications on the biological response of the estrogen receptor-α (ERα), we prepared and evaluated a series of mono-and di-substituted phenyl vinyl estradiols. The target compounds were prepared in 45-80% yields using the Stille coupling reaction and evaluated using competitive binding analysis with the ERα-ligand binding domain (hERα-LBD) and estrogenic activity (induction of alkaline phosphatase in Ishikawa cells). Results indicated that the 2,4- and 2,5-dimethyl derivatives, 5b and 5c, had the highest relative binding affinity (RBA=20.5 and 37.3%) and relative stimulatory activity (RSA=101.0% and 12.3%) of the di-methyl series.

Non-steroidal dissociated glucocorticoid agonists: indoles as A-ring mimetics and function-regulating pharmacophores

We report a SAR of non-steroidal glucocorticoid mimetics that utilize indoles as A-ring mimetics. Detailed SAR is discussed with a focus on improving PR and MR selectivity, GR agonism, and in vitro dissociation profile. SAR analysis led to compound (R)-33 which showed high PR and MR selectivity, potent agonist activity, and reduced transactivation activity in the MMTV and aromatase assays. The compound is equipotent to prednisolone in the LPS-TNF model of inflammation. In mouse CIA, at 30 mg/kg compound (R)-33 inhibited disease progression with an efficacy similar to the 3 mg/kg dose of prednisolone.

Rational ligand-based virtual screening and structure-activity relationship studies in the ligand-binding domain of the glucocorticoid receptor-α

The interest in developing synthetic glucocorticoids (GCs) arises from the utility of endogenous steroids as potent anti-inflammatory and immunosuppressant agents. The first GCs to be discovered, such as cortisol or dexamethasone, still represent the main treatment for conditions of the inflammatory process, despite the fact that they carry a significant risk of side effects. Hence, there is a continuing need to find drugs that preserve the immune effects of GCs without the side effects, such as those on metabolism (diabetes), bone tissue (osteoporosis), muscles (myopathy), eyes and skin. In this review, we focus on the recent use of ligand-based computational approaches in glucocorticoid receptor (GR) drug-design efforts for the determination of novel GR ligands. We examine a number of ligand-based (similarity searches, pharmacophore screens and quantitative structure-activity relationships) approaches that have been implemented in recent years. A recent virtual high-throughput screening similarity search was successful in developing a novel series of nonsteroidal GR antagonists. Additionally, there has been considerable success in ligand-based structure-analysis relationship generation and lead optimization studies for the GR. Future trends toward integrated GR ligand design incorporating ligand- and structure-based methodologies are inevitable.

Dissociated non-steroidal glucocorticoids: tuning out untoward effects

The endogenous glucocorticoid (GC), cortisol, is involved in maintaining homeostatic balance in glucose regulation and immune response while allowing stress adaptation. The glucocorticoid receptor (GR) is required to maintain life and is the target of numerous FDA-approved drugs. Synthetic steroidal GCs are useful in a plethora of conditions characterized by excessive inflammatory or immune responses. Unfortunately, the GCs used at present have potentially dose-limiting and debilitating side effects, some of which derive from the glucose regulatory role of GCs. Consequently, there is a great need to find agents which preserve the potent immune effects without the side effects. This manuscript reviews the existing patent literature on these intensely sought non-steroidal agents that dissociate the therapeutic from metabolic effects, or specifically retain certain GR target effects with attenuated untoward effects. The chemical classes and underlying mechanisms (when known) for these non-steroidal GCs are discussed.

Rational structure-based drug design and optimization in the ligand-binding domain of the glucocorticoid receptor-α

Background: Endogenous glucocorticoids (GCs) are involved in a range of endocrine functions including the metabolism of lipids, carbohydrates and proteins, stress response, fluid and electrolyte balance, as well as the maintenance of immunological, renal and skeletal homeostasis. There is a need to find agents that preserve the immune effects of GCs without side effects such as those affecting metabolism (diabetes), bone tissue (osteoporosis), muscles (myopathy), eyes and skin. Discussion: In this review, we focus on the use of recent computational approaches in glucocorticoid receptor (GR) drug-design efforts for the determination of novel GR ligands. We examine a number of structure-based (e.g., homology modeling and docking) studies that have been implemented and evaluate their success. Conclusion: By the end of 2008, there had been limited achievements utilizing docking studies and no published successes in the area of virtual high-throughput screening. However, the availability of novel crystal structures and the use of induced-fit docking protocols are improving docking success rates and promising to aid the future delivery of nonsteroidal ligands.

Synthesis and Characterization of Nonsteroidal Glucocorticoid Receptor Modulators for Multiple Myeloma

Structure-activity relationship studies centered around 3'-substituted (Z)-5-(2'-(thienylmethylidene))1,2-dihydro-9-hydroxy-10-methoxy-2,2,4-trimethyl-5H-chromeno[3,4-f]quinolines are described. A series of highly potent and efficacious selective glucocorticoid receptor modulators were identified with in vitro activity comparable to dexamethasone. In vivo evaluation of these compounds utilizing a 28 day mouse tumor xenograft model demonstrated efficacy equal to dexamethasone in the reduction of tumor volume.

5(Z)-Benzylidene-1,2-dihydro-9-hydroxy-10-methoxy-2,2,4-trimethyl-5H-1-aza-6-oxa-chrysenes as non-steroidal glucocorticoid receptor modulators

A series of 5-benzylidene-1,2-dihydro-2,2,4-trimethyl-5H-1-aza-6-oxa-chrysenes was synthesized and profiled for their ability to act as selective glucocorticoid receptor modulators (SGRMs). The synthesis and structure-activity relationships for this series of compounds are presented.

Identification of dissociated non-steroidal glucocorticoid receptor agonists

A new series of ligands for the glucocorticoid receptor (GR) is described. SAR development was guided by docking 3 into the GR active site and optimizing an unsubstituted phenyl ring for key interactions found in the steroid A-ring binding pocket. To identify compounds with an improved side effect profile over marketed steroids the functional activity of compounds was evaluated in cell based assays for transactivation (aromatase) and transrepression (IL-6). Through this effort, 36 has been identified as a partial agonist with a dissociated profile in these cell based assays.

Non-steroidal glucocorticoid agonists: the discovery of aryl pyrazoles as A-ring mimetics

Starting from an established series of non-steroidal glucocorticoid receptor (GR) agonists, a large array was designed where a metabolically labile benzoxazinone moiety was replaced. Initial hits bound to GR but lacked agonist activity. Following two further iterations, potent GR agonists were discovered with 20D1E1 having NFkappaB agonism pIC(50) 8.8 (103%). Other analogues such as 23D1E1 display a dissociated profile (NFkappaB pIC(50) 8.1 (103%), MMTV pEC(50) 7.02 (36%)). The tetrahydronaphthalene moiety can also be replaced with substituted aryls such as 24E1 and 25E1.

Novel glucocorticoids containing a 6,5-bicyclic core fused to a pyrazole ring: Synthesis, in vitro profile, molecular modeling studies, and in vivo experiments

Chemistry was developed to synthesize the title series of compounds. The ability of these novel ligands to bind to the glucocorticoid receptor was investigated. These compounds were also tested in a series of functional assays and some were found to display the profile of a dissociated glucocorticoid. The SAR of the 6,5-bicyclic series differed markedly from the previously reported 6,6-series. Molecular modeling studies were employed to understand the conformational differences between the two series of compounds, which may explain their divergent activity. Two compounds were profiled in vivo and shown to reduce inflammation in a mouse model. An active metabolite is suspected in one case.

Dissociated nonsteroidal glucocorticoid receptor modulators; discovery of the agonist trigger in a tetrahydronaphthalene-benzoxazine series

The tetrahydronaphthalene-benzoxazine glucocorticoid receptor (GR) partial agonist 4b was optimized to produce potent full agonists of GR. Aromatic ring substitution of the tetrahydronaphthalene leads to weak GR antagonists. Discovery of an "agonist trigger" substituent on the saturated ring of the tetrahydronaphthalene leads to increased potency and efficacious GR agonism. These compounds are efficacy selective in an NFkB GR agonist assay (representing transrepression effects) over an MMTV GR agonist assay (representing transactivation effects). 52 and 60 have NFkB pIC(50) = 8.92 (105%) and 8.69 (92%) and MMTV pEC(50) = 8.20 (47%) and 7.75 (39%), respectively. The impact of the trigger substituent on agonism is modeled within GR and discussed. 36, 52, and 60 have anti-inflammatory activity in a mouse model of inflammation after topical dosing with 52 and 60, having an effect similar to that of dexamethasone. The original lead was discovered by a manual agreement docking method, and automation of this method is also described.

Update on glucocorticoid action and resistance

Extensive development of inhaled and oral glucocorticoids has resulted in highly potent molecules that have been optimized to target activity to the lung and minimize systemic exposure. These have proved highly effective for most asthmatic subjects, but despite these developments, there are a number of subjects with asthma who fail to respond to even high doses of inhaled or even oral glucocorticoids. Advances in delineating the fundamental mechanisms of glucocorticoid pharmacology, especially the concepts of transactivation and transrepression and cofactor recruitment, have resulted in better understanding of the molecular mechanisms whereby glucocorticoids suppress inflammation. The existence of multiple mechanisms underlying glucocorticoid insensitivity raises the possibility that this might indeed reflect different diseases with a common phenotype, and studies examining the efficacy of potential new agents should be targeted toward subgroups of patients with severe corticosteroid-resistant asthma who clearly require effective new drugs and other approaches to improved asthma control.

Trifluoromethyl group as a pharmacophore: Effect of replacing a CF3 group on binding and agonist activity of a glucocorticoid receptor ligand

Compound 1, a potent glucocorticoid receptor ligand, contains a quaternary carbon bearing trifluoromethyl and hydroxyl groups. This paper describes the effect of replacing the trifluoromethyl group on binding and agonist activity of the GR ligand 1. The results illustrate that replacing the CF3 group with a cyclohexylmethyl or benzyl group maintains the GR binding potency. These substitutions alter the functional behavior of the GR ligands from agonists to antagonists. Docking studies suggest that the benzyl analog 19 binds in a similar fashion as the GR antagonist, RU486. The central benzyl group of 19 and the C-11 dimethylaniline moiety of RU486 overlay. Binding of compound 19 is believed to force helix 12 to adopt an open conformation and this leads to the antagonist properties of the non-CF3 ligands carrying a large group at the center of the molecule.