beta-N-Biaryl ether sulfonamide hydroxamates as potent gelatinase inhibitors: part 1. Design, synthesis, and lead identification

A new series of beta-N-biaryl ether sulfonamide hydroxamates as novel gelatinase inhibitors is described. These compounds exhibit good potency for MMP-2 and MMP-9 without inhibiting MMP-1. The structure-activity relationships (SAR) reveal the biaryl ether type P1' moiety together with methanesulfonamide is the optimal combination that provides inhibitory activity of MMP-9 in the single-digit nanomolar range.     

Acetylenic TACE inhibitors. Part 3: Thiomorpholine sulfonamide hydroxamates

A series of thiomorpholine sulfonamide hydroxamate TACE inhibitors, all bearing propargylic ether P1' groups, was explored. In particular, compound 5h has excellent in vitro potency against isolated TACE enzyme and in cells, oral activity in a model of TNF-alpha production and a collagen-induced arthritis model, was selected as a clinical candidate for the treatment of RA.     

beta-N-Biaryl ether sulfonamide hydroxamates as potent gelatinase inhibitors: part 2. Optimization of alpha-amino substituents

The introduction and the optimization of an alpha-amino substituent based on a series of alpha-hydroxy-beta-N-biaryl ether sulfonamide hydroxamates is described. The modification leads to a new series of MMP-2/MMP-9 inhibitors with enhanced inhibitory activities and improved ADME properties. An efficacy study on reducing the ischemia-induced brain edema in the rat transient middle cerebral artery occlusion (tMCAo) model is also demonstrated.     

Non-nucleoside inhibitors of HCV polymerase NS5B. Part 4: Structure-based design,synthesis, and biological evaluation of benzo[d]isothiazole-1,1-dioxides

A series of benzo[d]isothiazole-1,1-dioxides were designed and evaluated as inhibitors of HCV polymerase NS5B. Structure-based design led to the incorporation of a high affinity methyl sulfonamide group. Structure–activity relationship (SAR) studies of this series revealed analogues with submicromolar potencies in the HCV replicon assay and moderate pharmacokinetic properties. SAR studies combined with structure based drug design focused on the sulfonamide region led to a novel and potent cyclic analogue.     

Discovery of novel and potent aryl diamines as leukotriene A4 hydrolase inhibitors

The synthesis and biological evaluation of a series of aryl diamines as inhibitors of LTA₄-h inhibitors are described. The optimization which led to the identification of the optimal para-substitution on the diphenyl ether moiety and diamine spacer is discussed. The resulting compounds such as 3l have excellent enzyme and cellular potency as well as desirable pharmacokinetic properties.     

Exploration of acyl sulfonamides as carboxylic acid replacements in protease inhibitors of the hepatitis C virus full-length NS3

The hepatitis C virus (HCV) NS3 protease has emerged as a promising anti-HCV drug target. Herein, we present an investigation of NS3 inhibitors comprising the acyl sulfonamide functionality. A series of tetra- and tripeptide based acyl sulfonamide inhibitors and their structure-activity relationships from both enzymatic and cell-based in vitro assays are presented. In summary, the acidity of the acyl sulfonamide functionality, the character of the P1 side chain, and the acyl sulfonamide substituent were found to be important for the inhibitory potencies.     

Synthesis and biological activity of selective pipecolic acid-based TNF-alpha converting enzyme (TACE) inhibitors

A series of novel, selective TNF-alpha converting enzyme inhibitors based on 4-hydroxy and 5-hydroxy pipecolate hydroxamic acid scaffolds is described. The potency and selectivity of TACE inhibition is dramatically influenced by the nature of the sulfonamide group which interacts with the S1' site of the enzyme. Substituted 4-benzyloxybenzenesulfonamides exhibit excellent TACE potency with >100x selectivity over inhibition of matrix metalloprotease-1 (MMP-1). Alkyl substituents on the ortho position of the benzyl ether moiety give the most potent inhibition of TNF-alpha release in LPS-treated human whole blood.     

Discovery and pharmacological characterization of aryl piperazine and piperidine ethers as dual acting norepinephrine reuptake inhibitors and 5-HT1A partial agonists

Compounds that are both norepinephrine reuptake inhibitors (NRI) and 5-HT1_A partial agonists may have the potential to treat neuropsychiatric disorders including attention deficit hyperactivity disorder (ADHD) and depression. Targeted screening of NRI-active compounds for binding to the 5-HT_1A receptor provided a series of thiomorpholinone hits with this dual activity profile. Several iterations of design, synthesis, and testing led to substituted piperidine diphenyl ethers which are potent NRIs with 5-HT1_A partial agonist properties. In addition, optimization of these molecules provided compounds which exhibit selectivity for NRI over the dopamine (DAT) and serotonin (SERT) reuptake transporters. Monoamine and 5-HT_1A in vitro functional activities for select compounds from the developed piperidine diphenyl ether series are also presented.     

Piperazine sulfonamide BACE1 inhibitors: Design,synthesis, and in vivo characterization

With collaboration between chemistry, X-ray crystallography, and molecular modeling, we designed and synthesized a series of novel piperazine sulfonamide BACE1 inhibitors. Iterative exploration of the non-prime side and S2′ sub-pocket of the enzyme culminated in identification of an analog that potently lowers peripheral Aβ₄₀ in transgenic mice with a single subcutaneous dose.     

Novel thiol-based TACE inhibitors: rational design, synthesis, and SAR of thiol-containing aryl sulfonamides

A series of potent thiol-containing aryl sulfonamide TACE inhibitors was designed and synthesized. The SAR and MMP selectivity of the series were investigated. In particular, compound 4b has shown excellent in vitro potency against the isolated TACE enzyme and good selectivity over MMP-2, -7, -8, -9, and -13. The X-ray structure of 4b bound to TACE was obtained.     

Synthesis and antitubercular activity of heterocycle substituted diphenyl ether derivatives

Despite being an ancient disease, tuberculosis (TB) remains the leading single-agent infectious disease killer in the world. The emerging serious problem of TB control and clinical management prompted us to synthesize a novel series of heterocyclic substituted diphenyl ether derivatives and determine their activity against the H37Rv strain of Mycobacterium. All ten compounds inhibited the growth of the H37Rv strain of Mycobacterium at concentrations of 1 μg/mL. This activity was found to be comparable to the reference drugs rifampicin and isoniazid at the same concentration. While the antimicrobial activity of other diphenyl ether analogues, such as triclosan, is associated with the inhibition of enoyl-ACP reductase (ENR), the synthesised substituted diphenyl ether derivatives did not affect this enzyme activity in spite of their structural similarity with triclosan. Therefore, these compounds appear to have a novel mechanism of action against M. tuberculosis, and their structural features should be studied further for their potential as new antitubercular drugs.     

Synthesis and evaluation of novel 1-(2-acylhydrazinocarbonyl)-cycloalkyl carboxamides as interleukin-1beta converting enzyme (ICE) inhibitors

Novel 1-(2-acylhydrazinocarbonyl)cycloalkyl carboxamides were designed as peptidomimetic inhibitors of interleukin-1beta converting enzyme (ICE). A short synthesis was developed and moderately potent ICE inhibitors were identified (IC(50) values <100 nM). Most of the synthesized examples were selective for ICE versus the related cysteine proteases caspase-3 and caspase-8, although several dual-acting inhibitors of ICE and caspase-8 were identified. Several of the more potent ICE inhibitors were also shown to inhibit IL-1beta production in a whole cell assay (IC(50) < 500 nM).     

Structure-based design of nonpeptide inhibitors of interleukin-1beta converting enzyme (ICE, caspase-1).

A novel class of reversible inhibitors of Interleukin-1beta-converting enzyme (ICE, caspase-1) were discovered by iterative structure-based design. Guided by the X-ray crystal structure of analogues 1, 7 and 10 bound to ICE, we have designed a nonpeptide series of small molecule inhibitors. These compounds incorporate an arylsulfonamide moiety which replaces Val-His unit (P3-P2 residues) amino acids of the native substrate. The synthesis of the core structure, structure-activity relationships (SARs), and proposed binding orientation based on molecular modeling studies for this series of ICE inhibitors are described.     

Synthesis and in vitro antimycobacterial activity of B-ring modified diaryl ether InhA inhibitors

Previous structure-based design studies resulted in the discovery of alkyl substituted diphenyl ether inhibitors of InhA, the enoyl reductase from Mycobacterium tuberculosis. Compounds such as 5-hexyl-2-phenoxyphenol 19 are nM inhibitors of InhA and inhibit the growth of both sensitive and isoniazid-resistant strains of Mycobacterium tuberculosis with MIC(90) values of 1-2 microg/mL. However, despite their promising in vitro activity, these compounds have ClogP values of over 5. In efforts to reduce the lipophilicity of the compounds, and potentially enhance compound bioavailability, a series of B ring analogues of 19 were synthesized that contained either heterocylic nitrogen rings or phenyl rings having amino, nitro, amide, or piperazine functionalities. Compounds 3c, 3e, and 14a show comparable MIC(90) values to that of 19, but have improved ClogP values.     

Arylsulfonamides: a study of the relationship between activity and conformational preferences for a series of factor Xa inhibitors

Torsional scans of sulfonamide S-C bonds in small model systems of a series of arylsulfonamide factor Xa inhibitors were performed in order to investigate if conformational effects can help to rationalise the observed SAR. Computational results were in good agreement with the experimental data indicating that the sulfonamide conformation plays an important role in determining the activity in this particular series of factor Xa inhibitors.     

Transformation of diphenyl ethers by Trametes versicolor and characterization of ring cleavage products

The white-rot fungi Trametes versicolor SBUG 1050, DSM 11269 and DSM 11309 are able to oxidize diphenyl ether and its halogenated derivatives 4-bromo- and 4-chlorodiphenyl ether. The products formed from diphenyl ether were 2- and 4-hydroxydiphenyl ether. Both 4-bromo- and 4-chlorodiphenyl ether were transformed to the corresponding products hydroxylated at the non-halogenated ring. Additionally, ring-cleavage products were detected by high perfomance liquid chromatography and characterized by gas chromatography/mass spectrometry and proton nuclear magnetic resonance spectroscopy. Unhalogenated diphenyl ether was degraded to 2-hydroxy-4-phenoxymuconic acid and 6-carboxy-4-phenoxy-2-pyrone. Brominated derivatives of both these compounds were formed from 4-bromodiphenyl ether, and 4-chlorodiphenyl ether was transformed in the same way to the analogous chlorinated ring cleavage products. Additionally, 4-bromo- and 4-chlorophenol were detected as intermediates from 4-bromo- and 4-chlorodiphenyl ether, respectively. In the presence of the cytochrome-P450 inhibitor 1-aminobenzotriazole, no metabolites were formed by cells of Trametes versicolor from the diphenyl ethers investigated. Cell-free supernatants of whole cultures with high laccase and manganese peroxidase activities were not able to transform the unhydroxylated diphenyl ethers used.     

A novel series of highly selective inhibitors of MMP-3

The design and synthesis of a series of highly selective hydroxamate inhibitors of stromelysin-1 (MMP-3) is described. Substitution of a 4-biaryl piperidine sulfonamide core, which binds at the S1′ subsite of MMP-3, was optimised to give potent inhibitors of MMP-3, with greater than 300-fold selectivity over MMP-1, MMP-2, MMP-9 and MMP-14. Compounds 26 and 27 were identified as having the best balance of pharmacology and properties required for topical drug delivery.     

Prediction of caspase-3 inhibitory activity of 1,3-dioxo-4-methyl-2,3-dihydro-1h-pyrrolo[3,4-c] quinolines: QSAR study

Neurodegenerative disorders are consequences of progressive and irreversible loss of neurons due to unwanted apoptosis which involves caspases, a group of cysteine proteases that cleave other proteins and inactivate them. Among several different groups of caspase enzymes, caspases-3 plays a key role in apoptosis and are a therapeutic target for their inhibition. In pursuit of better caspase-3 inhibitors, a quantitative structure-activity relationship (QSAR) analysis was performed on a series of 1,3-dioxo-4-methyl-2,3-dihydro-1H-pyrrolo[3,4-c] quinolines as caspase-3 inhibitors using WIN CAChe 6.1 and Medicinal Chemistry Regression Machine. The best QSAR model was selected and validated by internal and external validation method. The values of statistical data are r = 0.955, F = 72.95, SEE = 0.397, q² = 0.885, S_PRESS = 0.44. The present study reveals that when the conformational minimum energy is increased, and lowest unoccupied molecular orbital energy and highest occupied molecular orbital energy are decreased the biological activity can be increased. On the basis of a selected QSAR model, we designed a new series of 1,3-dioxo-4-methyl-2,3-dihydro-1H-pyrrolo[3,4-c]quinolines compounds, calculated their caspases inhibitory activity and found that the designed compounds were more potent than the existing compounds.     

Prediction of caspase-3 inhibitory activity of 1,3-dioxo-4-methyl-2,3-dihydro-1h-pyrrolo[3,4-c] quinolines: QSAR study

Neurodegenerative disorders are consequences of progressive and irreversible loss of neurons due to unwanted apoptosis which involves caspases, a group of cysteine proteases that cleave other proteins and inactivate them. Among several different groups of caspase enzymes, caspases-3 plays a key role in apoptosis and are a therapeutic target for their inhibition. In pursuit of better caspase-3 inhibitors, a quantitative structure-activity relationship (QSAR) analysis was performed on a series of 1,3-dioxo-4-methyl-2,3-dihydro-1H-pyrrolo[3,4-c] quinolines as caspase-3 inhibitors using WIN CAChe 6.1 and Medicinal Chemistry Regression Machine. The best QSAR model was selected and validated by internal and external validation method. The values of statistical data are r = 0.955, F = 72.95, SEE = 0.397, q(2) = 0.885, S(PRESS) = 0.44. The present study reveals that when the conformational minimum energy is increased, and lowest unoccupied molecular orbital energy and highest occupied molecular orbital energy are decreased the biological activity can be increased. On the basis of a selected QSAR model, we designed a new series of 1,3-dioxo-4-methyl-2,3-dihydro-1H-pyrrolo[3,4-c]quinolines compounds, calculated their caspases inhibitory activity and found that the designed compounds were more potent than the existing compounds.     

Carbonic anhydrase II-induced selection of inhibitors from a dynamic combinatorial library of Schiff’s bases

A dynamic combinatorial library (DCL) has been generated under thermodynamic control by using the aminocarbonyl/imine interconversion as reversible chemistry, combined with non-covalent binding within the active site of the metalloenzyme human carbonic anhydrase II (hCA II, EC 4.2.1.1). The high affinity of hCA II isozyme towards some sulfonamide inhibitors obtained here was used to select from the dynamic library specific inhibitors of this isoform. These results point out to the possibility of identifying sulfonamide amplified compounds presenting potent inhibition and high yield of formation in the presence of the isoform(s) towards which the inhibitors were designed.