Prediction of the skin permeability of topical drugs using in silico and in vitro models.

The main challenge of topically applied drugs is to overcome the skin barrier to reach the site of action at the concentration needed for efficacy. In the research of new topical drugs, design of molecules with optimized properties for skin penetration is a key factor and assays for its characterization are needed. A group of 20 representative topical molecules of clinical use were studied in two in silico models (Potts & Guy and Barratt), and an in vitro assay with artificial membrane (Skin-PAMPA).

Structure-activity relationships (SAR) and structure-kinetic relationships (SKR) of sulphone-based CRTh2 antagonists.

Monocyclic and bicyclic ring systems were investigated as the "core" section of a series of diphenylsulphone-containing acetic acid CRTh2 receptor antagonists. A range of potencies were observed and single-digit nanomolar potencies were obtained in both the monocyclic and bicyclic cores. Residence times for the monocyclic compounds were very short.

A novel inhaled Syk inhibitor blocks mast cell degranulation and early asthmatic response.

Spleen tyrosine kinase (Syk) is essential for signal transduction of immunoreceptors. Inhibition of Syk abrogates mast cell degranulation and B cell responses. We hypothesized that Syk inhibition in the lung by inhaled route could block airway mast cells degranulation and the early asthmatic response without the need of systemic exposure.

Discovery of 7-azaindole derivatives as potent Orai inhibitors showing efficacy in a preclinical model of asthma.

Synthesis and SAR of a series of 7-azaindoles as Orai channel inhibitors showing good potency inhibiting IL-2 production in Jurkat cells is described. Compound 14d displaying best pharmacokinetic properties was further characterized in a model of allergen induced asthma showing inhibition in the number of eosinophils in BALF. High lipophilicity remains as one of the main challenges for this class of compounds.

Structure-activity relationships (SAR) and structure-kinetic relationships (SKR) of bicyclic heteroaromatic acetic acids as potent CRTh2 antagonists III: the role of a hydrogen-bond acceptor in long receptor residence times.

The correct positioning and orientation of an hydrogen bond acceptor (HBA) in the tail portion of the biaryl series of CRTh2 antagonists is a requirement for long receptor residence time. The HBA in combination with a small steric substituent in the core section (R(core) ≠ H) gives access to compounds with dissociation half-lives of ⩾ 24h.

Structure-activity relationships (SAR) and structure-kinetic relationships (SKR) of bicyclic heteroaromatic acetic acids as potent CRTh2 antagonists II: lead optimization.

Extensive structure-activity relationship (SAR) and structure-kinetic relationship (SKR) studies in the bicyclic heteroaromatic series of CRTh2 antagonists led to the identification of several molecules that possessed both excellent binding and cellular potencies along with long receptor residence times. A small substituent in the bicyclic core provided an order of magnitude jump in dissociation half-lives. Selected optimized compounds demonstrated suitable pharmacokinetic profiles.

Structure-activity relationships (SAR) and structure-kinetic relationships (SKR) of bicyclic heteroaromatic acetic acids as potent CRTh2 antagonists I.

A knowledge-based design strategy led to the discovery of several new series of potent and orally bioavailable CRTh2 antagonists where a bicyclic heteroaromatic ring serves as the central core. Structure-kinetic relationships (SKR) opened up the possibility of long receptor residence times.

Highly potent aminopyridines as Syk kinase inhibitors.

A novel class of potent Syk inhibitors has been developed from rational design. Highly potent aminopyridine derivatives bearing a 4-trifluoromethyl-2-pyridyl motif and represented by compound 13b IC(50): 0.6 nM were identified.

Novel triazolopyridylbenzamides as potent and selective p38α inhibitors.

A new class of p38α inhibitors based on a biaryl-triazolopyridine scaffold was investigated. X-ray crystallographic data of the initial lead compound cocrystallised with p38α was crucial in order to uncover a unique binding mode of the inhibitor to the hinge region via a pair of water molecules. Synthesis and SAR was directed towards the improvement of binding affinity, as well as ADME properties for this new class of p38α inhibitors and ultimately afforded compounds showing good in vivo efficacy.

Pyrazine-based Syk kinase inhibitors.

A series of aminopyrazines as inhibitors of Syk kinase activity and showing inhibition of LAD2 cells degranulation is described. Optimization of the carboxamide motif with aminomethylpiperidines provided high potency inhibiting Syk but low cellular activity. Amides of cis and trans adamantanol showed good inhibitory activity against Syk as well as remarkable activity in LAD2 cells degranulation assay.

1,7-Naphthyridine 1-oxides as novel potent and selective inhibitors of p38 mitogen activated protein kinase.

The design, synthesis, and ability to inhibit p38α MAP kinase by a novel series of naphthyridine N-oxides will be described. Some of these compounds showed a significant reduction in the LPS-induced TNFα production in human whole blood. Structure-activity relationship studies revealed that N-oxide oxygen was essential for activity and was probably a determinant factor for its marked selectivity against other related kinases.

Indolin-2-one p38α inhibitors I: design, profiling and crystallographic binding mode.

The use of structure-based design and molecular modeling led to the discovery of indolin-2-one derivatives as potent and selective p38α inhibitors. The predicted binding mode was confirmed by X-ray crystallography.

Discovery of LAS101057: A Potent, Selective, and Orally Efficacious A2B Adenosine Receptor Antagonist.

The structure-activity relationships for a series of pyrazine-based A2B adenosine receptor antagonists are described. From this work, LAS101057 (17), a potent, selective, and orally efficacious A2B receptor antagonist, was identified as a clinical development candidate. LAS101057 inhibits agonist-induced IL-6 production in human fibroblasts and is active in an ovalbumin (OVA)-sensitized mouse model after oral administration, reducing airway hyperresponsiveness to methacholine, Th2 cytokine production, and OVA-specific IgE levels.

Synthesis and pharmacological evaluation of novel substituted 9-deazaxanthines as A2B receptor antagonists.

A new series of 9-deazaxanthine derivatives with various substituents at the heterocyclic system were synthesized and evaluated for their binding affinities for the four human recombinant adenosine receptors, A(1)-A(3) subtypes. A number of the 9-deazaxanthines derivatives 3a-m showed moderate-to-high affinity for hA(2B) receptors, with compound 3f showing a 32-fold selectivity for A(2B) over A(1) and a 2750-fold selectivity for A(2B) over A(2A).

Discovery of potent and selective bicyclic A(2B) adenosine receptor antagonists via bioisosteric amide replacement.

Several new potent and selective A(2B) adenosine receptor antagonists have been prepared in which the aryl-amide moiety of the lead series, exemplified by 1a, has been replaced by bioisosteric bicyclic moieties. Although the majority of compounds had generally improved microsomal stability as compared to 1a, this was not translated into overall improvements in the pharmacokinetic profiles of a representative set of compounds.

Discovery of N-(5,6-diarylpyridin-2-yl)amide derivatives as potent and selective A(2B) adenosine receptor antagonists.

The synthesis and SAR of a series of N-(5,6-diarylpyridin-2-yl)amide derivatives as potent A(2B) adenosine receptor antagonists is described. Several compounds showed good selectivity versus other adenosine receptors. The potent and selective analogue 9 was shown to have good oral bioavailability in the rat.

Design, synthesis, and structure-activity relationships of aminopyridine N-oxides, a novel scaffold for the potent and selective inhibition of p38 mitogen activated protein kinase.

A novel series of aminopyridine N-oxides were designed, synthesized, and tested for their ability to inhibit p38alpha MAP kinase. Some of these compounds showed a significant reduction in the LPS-induced TNFalpha production in human whole blood. Structure-activity relationship studies revealed that N-oxide oxygen was essential for activity and was probably a determinant factor for a marked selectivity against other related kinases.

1,3-dialkyl-8-N-substituted benzyloxycarbonylamino-9-deazaxanthines as potent adenosine receptor ligands: Design, synthesis, structure-affinity and structure-selectivity relationships.

A number of 1,3-dialkyl-9-deazaxanthines (9-dAXs), bearing a variety of N-substituted benzyloxycarbonylamino substituents at position 8, were prepared and evaluated for their binding affinity to the recombinant human adenosine receptors (hARs), chiefly to the hA(2B) and hA(2A) AR subtypes. Several ligands endowed with excellent binding affinity to the hA(2B) receptors, but low selectivity versus hA(2A) and hA(1) were identified. Among these, 1,3-dimethyl-N-3'-thienyl carbamate 15 resulted as the most potent ligand at hA(2B) (K(i)=0.

A new chemical tool (C0036E08) supports the role of adenosine A(2B) receptors in mediating human mast cell activation.

Asthma is a chronic inflammatory disease of the airways that involves many cell types, amongst which mast cells are known to be important. Adenosine, a potent bronchoconstricting agent, exerts its ability to modulate adenosine receptors of mast cells thereby potentiating derived mediator release, histamine being one of the first mediators to be released. The heterogeneity of sources of mast cells and the lack of highly potent ligands selective for the different adenosine receptor subtypes have been important hurdles in this area of research.

Synthesis, adenosine receptor binding and 3D-QSAR of 4-substituted 2-(2'-furyl)-1,2,4-triazolo[1,5-a]quinoxalines.

A collection of 25 2-(2'-furyl)-1,2,4-triazolo[1,5-a]quinoxalines incorporating different substitution patterns at position 4 have been synthesized and their binding affinity towards human adenosine receptors (hA(1), hA(2A), hA(2B) and hA(3)) was determined. The biological data show that several potent at hA(1), but lightly selective, adenosine ligands were identified. Moreover, these results confirmed the hypothesis that the structural modifications carried out on the 4-position of the tricyclic system produces a remarkable modification of the adenosine receptorial profile.

1-, 3- and 8-substituted-9-deazaxanthines as potent and selective antagonists at the human A2B adenosine receptor.

A large series of piperazin-, piperidin- and tetrahydroisoquinolinamides of 4-(1,3-dialkyl-9-deazaxanthin-8-yl)phenoxyacetic acid were prepared through conventional or multiple parallel syntheses and evaluated for their binding affinity at the recombinant human adenosine receptors, chiefly at the hA(2B) and hA(2A) receptor subtypes. Several ligands endowed with high binding affinity at hA(2B) receptors, excellent selectivity over hA(2A) and hA(3) and a significant, but lower, selectivity over hA(1) were identified. Among them, piperazinamide derivatives 23 and 52, and piperidinamide derivative 69 proved highly potent at hA(2B) (K(i)=11, 2 and 5.

Discovery and characterization of 4'-(2-furyl)-N-pyridin-3-yl-4,5'-bipyrimidin-2'-amine (LAS38096), a potent, selective, and efficacious A2B adenosine receptor antagonist.

A novel series of N-heteroaryl 4'-(2-furyl)-4,5'-bipyrimidin-2'-amines has been identified as potent and selective A(2B) adenosine receptor antagonists. In particular, compound 5 showed high affinity for the A(2B) receptor (Ki = 17 nM), good selectivity (IC(50): A(1) > 1000 nM, A(2A) > 2500 nM, A3 > 1000 nM), displayed a favorable pharmacokinetic profile in preclinical species, and showed efficacy in functional in vitro models.

New pyrrolopyrimidin-6-yl benzenesulfonamides: potent A2B adenosine receptor antagonists.

A new series of 4-(1,3-dialkyl-2,4-dioxo-2,3,4,5-tetrahydro-1H-pyrrolo[3,2-d]pyrimidin-6-yl)benzenesulfonamides has been identified as potent A2B adenosine receptor antagonists. The products have been evaluated for their binding affinities for the human A2B, A1 and A3 adenosine receptors. 6-(4-{[4-(4-Bromobenzyl)piperazin-1-yl]sulfonyl}phenyl)-1,3-dimethyl-1H-pyrrolo[3,2-d]pyrimidine-2,4(3H,5H)-dione (16) showed a high affinity for the A2B adenosine receptor (IC50=1 nM) and selectivity (A1: 183x; A3: 12660x).

Design, synthesis, and structure-activity relationships of 1-,3-,8-, and 9-substituted-9-deazaxanthines at the human A2B adenosine receptor.

Over two hundred 1-, 3-, 8-, and 9-substituted-9-deazaxanthines were prepared and evaluated for their binding affinity at the recombinant human adenosine receptors, in particular at the hA(2B) and hA(2A) subtypes. Several ligands endowed with sub-micromolar to low nanomolar binding affinity at hA(2B) receptors, good selectivity over hA(2A) and hA(3), but a relatively poor selectivity over hA(1) were obtained. Good antagonistic potencies and efficacies, with pA(2) values close to the corresponding pK(i)s, were observed in functional assays in vitro performed on a selected series of compounds.