Acetylenic TACE inhibitors. Part 1. SAR of the acyclic sulfonamide hydroxamates

Targeting Metalloenzymes for Therapeutic Intervention

Metalloenzymes are central to a wide range of essential biological activities, including nucleic acid modification, protein degradation, and many others. The role of metalloenzymes in these processes also makes them central for the progression of many diseases and, as such, makes metalloenzymes attractive targets for therapeutic intervention. Increasing awareness of the role metalloenzymes play in disease and their importance as a class of targets has amplified interest in the development of new strategies to develop inhibitors and ultimately useful drugs. In this Review, we provide a broad overview of several drug discovery efforts focused on metalloenzymes and attempt to map out the current landscape of high-value metalloenzyme targets.

Multiple target-centric strategy to tame inflammation

Single-target inhibition is an unsatisfactory therapeutic option to treat multifactorial pathologies, brought into limelight 'paradox of inflammation' beside dearth of innovation, rationalizes a shift toward 'multiple-target' design concept in anti-inflammatory research field. To improvise, two platform strategies, drugs mixture or multitarget drugs, are plausible. Dual cyclooxygenase/lipoxygenase inhibitor 'licofelone' developed after the backfire of rofecoxib due to safety concerns has fetched first light of triumph of the latter strategy. As hitting multiple targets in restraint is perhaps more viable strategy rather than single target, this review, outlines the most germane multiple target agents of synthetic and natural origin placing clear advantage in favors of multitarget strategy as real therapeutic solution for inflammation.

Discovery and process development of a novel TACE inhibitor for the topical treatment of psoriasis

Targeting the TNFα pathway is a validated approach to the treatment of psoriasis. In this pathway, TACE stands out as a druggable target and has been the focus of in-house research programs. In this article, we present the discovery of clinical candidate 26a. Starting from hits plagued with poor solubility or genotoxicity, 26a was identified through thorough multiparameter optimisation. Showing robust in vivo activity in an oxazolone-mediated inflammation model, the compound was selected for development. Following a polymorph screen, the hydrochloride salt was selected and the synthesis was efficiently developed to yield the API in 47% overall yield.

Protective effects of gingerol on streptozotocin-induced sporadic Alzheimer's disease: emphasis on inhibition of β-amyloid, COX-2, alpha-, beta - secretases and APH1a

Gingerol is a major dietary compound that occurs in several plants belonging to the Zingiberaceae family. In the current study, the protective effect of gingerol on STZ-induced sporadic Alzheimer's disease (SAD) was determined. Gingerol was isolated from the seeds of Aframomum melegueta K. Schum and tested at doses of 10 and 20 mg/kgbwt for its possible effect on the SAD model in mice, using celecoxib (30 mg/kg bwt) as a reference standard. The curative effects of gingerol were assessed through measurement of β-amyloid (Aβ-42), α-, β- secretases, APH1a and COX-2 levels. In addition, improvement in the cognitive deficit in mice after treatment was confirmed using the water maze and Y-maze with intra-maze cues. Gingerol improved the cognitive and behavioral impairment and AD-like pathology in streptozotocin model mice. These beneficial effects occurred with an increase in α-secretase activity and a decrease in cerebral Aβ-42, β- secretase, APH1a activity and COX-2-linked neuro-inflammation.

Discovery of potent inhibitor for matrix metalloproteinase-9 by pharmacophore based modeling and dynamics simulation studies

Matrix metalloproteinase-9 (MMP-9) is an attractive target for anticancer therapy. In the present study ligand based pharmacophore modeling was performed to elucidate the structural elements for a diverse class of MMP-9 inhibitors. The pharmacophore model was validated through Güner-Henry (GH) scoring method. The final pharmacophore model consisted of three hydrogen bond acceptors (HBA), and two ring aromatic regions (RA). This model was utilized to screen the natural compound database to seek novel compounds as MMP-9 inhibitors. The identified hits were validated using molecular docking and molecular dynamics simulation studies. Finally, one compound named Hinokiflavone from Juniperus communis had high binding free energy of -26.54kJ/mol compared with the known inhibitors of MMP-9. Cytotoxicity for hinokiflavone was evaluated by MTT assay. Inhibition of MMP-9 in the presence of hinokiflavone was detected by gelatin zymography and gelatinolytic inhibition assay. Results revealed that the natural compounds derived based on the developed pharmacophore model would be useful for further design and development of MMP-9 inhibitors.

ADAM17-mediated shedding of FcγRIIIA on human NK cells: identification of the cleavage site and relationship with activation

FcγRIIIA/CD16A, the low-affinity receptor for the IgG Fc portion expressed on human CD56(dim) NK cells and involved in Ab-dependent cell cytotoxicity, is shed upon NK cell activation. We found that recombinant a disintegrin and metalloprotease (ADAM) 17 cleaved the ectodomain of FcγRIIIA/CD16A and a peptide for which the sequence encompasses aa 191-201 of the FcγRIIIA/CD16A stalk region but not ADAM10. MALDI-TOF analysis revealed that the peptide was cleaved between Ala(195) and Val(196) (i.e., 1 aa upstream of the expected position). This location of the cleavage site was confirmed by the finding that ADAM17 failed to cleave a peptide in which Ala and Val were reversed. ADAM17 was found to be expressed on NK cells, and stimulation with PMA or N-ethyl-maleimide resulted in the shedding of FcγRIIIA/CD16A and CD62L, a specific substrate of ADAM17. Selective inhibition of ADAM17 prevented the shedding of both molecules. Moreover, the shedding of FcγRIIIA/CD16A was strongly correlated with degranulation when a wide range of CD56(dim) NK cell activating receptors were stimulated, whereas both ADAM17-dependent shedding and internalization were involved in FcγRIIIA/CD16A downmodulation when the latter was engaged. Finally, the shedding of FcγRIIIA/CD16A was restricted to activated cells, suggesting that ADAM17 acts mainly, if not exclusively, in cis. Taken together, our results demonstrated for the first time, to our knowledge, at the molecular level that ADAM17 cleaves the stalk region of FcγRIIIA/CD16A and identified its cleavage site. The shedding of FcγRIIIA/CD16A was at least partially ADAM17 dependent, and it may be considered as a marker of FcγRIIIA/CD16A-independent NK cell activation highly correlated with degranulation.

Quantitative structure-activity relationship studies on sulfonamide-based MMP inhibitors

Matrix metalloproteinases (MMPs) regulate a wide range of biological functions, but their overactivation leads to a wide array of disease processes such as rheumatoid arthritis, ostereoarthritis, tumor metastatis, multiple sclerosis, congestive heart failure, and a host of others. Therefore, the study of MMP inhibitors has evoked a great interest among scientists. As a result, different groups of compounds have been synthesized and studied for MMP inhibitions. Among them, a large number of structurally novel sulfonamide derivatives have been reported to be potential MMP inhibitors, but only a few have reached to the final stage of clinical trial. Many authors have made quantitative structure-activity relationship (QSAR) studies on them to provide the guidelines to design more potent MMP inhibitors. This article presents a comprehensive review on all such QSARs reported with critical assessment in order to provide a deeper insight into the structure-activity relationship of sulfonamides which can be used to synthesize highly potential drugs of pharmaceutical importance.

Exploring the functional space of thiiranes as gelatinase inhibitors using click chemistry

A series of 4-[(triazolyl)methoxy]phenyl analogs of the phenoxyphenyl-substituted thiirane SB-3CT 1 was evaluated for its ability to inhibit gelatinases, members of the matrix metalloproteinase family of enzymes. The triazole segment of these inhibitors was assembled using the Meldal-Sharpless copper-catalyzed Huisgen dipolar cycloaddition of an azide and a terminal alkyne. While these triazole derivatives possessed fair activity as gelatinase inhibitors, an intermediate used in the dipolar cycloaddition, 4-(propargyloxy)phenyl derivative 2, showed very good activity (>50% inhibitory activity following a 3 h pre-incubation of 2 at a concentration of 3 μM) as an inhibitor of human matrix metalloproteinase-2.

Synthesis and activity of tryptophan sulfonamide derivatives as novel non-hydroxamate TNF-alpha converting enzyme (TACE) inhibitors

A novel series of non-hydroxamate tryptophan sulfonamide derivatives containing a butynyloxy P1' moiety was identified as inhibitors of TNF-alpha converting enzyme (TACE). The structure-activity relationship of the series was examined via substitution on the tryptophan indole ring. Of the compounds investigated, 2-(4-(but-2-ynyloxy)phenylsulfonamido)-3-(1-(4-methoxybenzyl)-1H-indol-3-yl)propanoic acid (12p) has the best in vitro potency against isolated TACE enzyme with an IC(50) of 80 nM. Compound 12p also shows good selectivity over MMP-1, -13, -14.

Dual inhibitors of matrix metalloproteinases and carbonic anhydrases: iminodiacetyl-based hydroxamate-benzenesulfonamide conjugates

Matrix metalloproteinases (MMPs) and carbonic anhydrases (CAs) are two classes of zinc enzymes with different roles and catalytic targets, such as the degradation of most of the extracellular matrix (ECM) proteins and the regulation of the CO(2)/HCO(3)(-) equilibrium in the cells, respectively. Both families have isoforms which were proved to be involved in several stages of carcinogenic processes, and so the selective inhibition of these enzymes might be of interest in cancer therapy. We report herein the design, synthesis, and in vitro evaluation of a series of compounds possessing the iminodiacetic acid as the main backbone and two functional groups attached, namely, the hydroxamic acid and the arylsulfonamide (ArSO(2)NH(2)) moieties, to enable the inhibition of MMPs and CAs, respectively. These compounds were demonstrated to strongly inhibit both MMPs and CAs, some of them from the nanomolar to subnanomolar range. Furthermore, a docking study for MMPs was reported for the most promising compound in order to investigate its binding interactions with the different MMPs.

Design and synthesis of 3,3-piperidine hydroxamate analogs as selective TACE inhibitors

Structure-based methods were used to design beta-sulfone 3,3-piperidine hydroxamates as TACE inhibitors with the aim of improving selectivity for TACE versus MMP-13. Several compounds in this series were synthesized and evaluated in enzymatic and cell-based assays. These analogs exhibit excellent in vitro potency against isolated TACE enzyme and show good selectivity for TACE over the related metalloproteases MMP-2, -13, and -14.

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.

Matrix metalloproteinases (MMPs): chemical-biological functions and (Q)SARs

Matrix metalloproteinases (MMPs) are a large family of calcium-dependent zinc-containing endopeptidases, which are responsible for the tissue remodeling and degradation of the extracellular matrix (ECM), including collagens, elastins, gelatin, matrix glycoproteins, and proteoglycan. They are regulated by hormones, growth factors, and cytokines, and are involved in ovarian functions. MMPs are excreted by a variety of connective tissue and pro-inflammatory cells including fibroblasts, osteoblasts, endothelial cells, macrophages, neutrophils, and lymphocytes. These enzymes are expressed as zymogens, which are subsequently processed by other proteolytic enzymes (such as serine proteases, furin, plasmin, and others) to generate the active forms. Matrix metalloproteinases are considered as promising targets for the treatment of cancer due to their strong involvement in malignant pathologies. Clinical/preclinical studies on MMP inhibition in tumor models brought positive results raising the idea that the development of strategies to inhibit MMPs may be proved to be a powerful tool to fight against cancer. However, the presence of an inherent flexibility in the MMP active-site limits dramatically the accurate modeling of MMP-inhibitor complexes. The interest in the application of quantitative structure-activity relationships (QSARs) has steadily increased in recent decades and we hope it may be useful in elucidating the mechanisms of chemical-biological interactions for this enzyme. In the present review, an attempt has been made to explore the in-depth knowledge from the classification of this enzyme to the clinical trials of their inhibitors. A total number of 92 QSAR models (44 published and 48 new formulated QSAR models) have also been presented to understand the chemical-biological interactions. QSAR results on the inhibition of various compound series against MMP-1, -2, -3, -7, -8, -9, -12, -13, and -14 reveal a number of interesting points. The most important of these are hydrophobicity and molar refractivity, which are the most important determinants of the activity.

Identification of potent and selective TACE inhibitors via the S1 pocket

By focusing on the P1 portion of the piperidine beta-sulfone ligands we identified a motif that induces selectivity and resulted in a series of TACE inhibitors that demonstrated excellent in vitro potency against isolated TACE enzyme and excellent selectivity over MMPs 1, 2, 9, 13, and 14.

Design and synthesis of butynyloxyphenyl β-sulfone piperidine hydroxamates as TACE inhibitors

A series of butynyloxyphenyl beta-sulfone piperidine hydroxamate TACE inhibitors was designed and synthesized. The resulting structure-activity relationship and MMP selectivity of the series were examined. Of the compounds investigated, 17s has excellent in vitro potency against isolated TACE enzyme, shows good selectivity over MMP-1, -2, -7, -8, -9, -13, and -14, and oral activity in an in vivo mouse model of TNF-alpha production.

Synthesis and structure–activity relationship of a novel, achiral series of TNF-α converting enzyme inhibitors

A novel series of achiral TNF-alpha converting enzyme (TACE) inhibitors has been discovered. These compounds exhibited activities from 0.35 to 11nM in a porcine TACE assay and inhibited TNF-alpha production in an LPS-stimulated whole blood assay with an IC(50) value of 23nM for the most potent one. They also have excellent selectivities over related metalloproteases including aggrecanases.

Acetylenic TACE inhibitors. Part 2: SAR of six-membered cyclic sulfonamide hydroxamates

The SAR of a series of potent sulfonamide hydroxamate TACE inhibitors bearing a butynyloxy P1' group was explored. In particular, compound 5k has excellent in vitro potency against TACE enzyme and in cells, and oral activity in an in vivo model of TNF-alpha production and a collagen-induced arthritis model.

A comparison of the binding sites of matrix metalloproteinases and tumor necrosis factor-alpha converting enzyme: implications for selectivity

MMPs and TACE (ADAM-17) assume independent, parallel, or opposite pathological roles in cancer, arthritis, and several other diseases. For therapeutic purposes, selective inhibition of individual MMPs and TACE is required in most cases due to distinct roles in diseases and the need to preserve activities in normal states. Toward this goal, we compared force-field interaction energies of five ubiquitous inhibitor atoms with flexible binding sites of 24 known human MMPs and TACE. The results indicate that MMPs 1-3, 10, 11, 13, 16, and 17 have at least one subsite very similar to TACE. S3 subsite is the best target for development of specific TACE inhibitors. Specific binding to TACE compared to most MMPs is promoted by placing a negatively charged ligand part at the bottom of S2 subsite, at the entrance of S1' subsite, or the part of S3' subsite that is close to catalytic zinc. Numerous other clues, consistent with available experimental data, are provided for design of selective inhibitors.

Characterization of (2R, 3S)-2-([[4-(2-butynyloxy)phenyl]sulfonyl]amino)-N,3-dihydroxybutanamide, a potent and selective inhibitor of TNF-alpha converting enzyme

TNF-alpha converting enzyme (TACE) is a validated therapeutic target for the development of oral tumor necrosis factor-alpha (TNF-alpha) inhibitors. Here we report the pre-clinical results and characterization of a selective and potent TACE inhibitor, (2R, 3S)-2-([[4-(2-butynyloxy)phenyl]sulfonyl]amino)-N,3-dihydroxybutanamide (TMI-2), in various in vitro and in vivo assays. TMI-2 is a potent TACE inhibitor in an enzymatic FRET assay (IC50=2 nM). It is more than 250-fold selective over MMP-1, -7, -9, -14, and ADAM-10 in vitro. In cell-based assays and human whole blood, TMI-2 inhibits lipopolysaccharide (LPS)-induced TNF secretion with IC50s<1 uM. Importantly, TMI-2 inhibits the spontaneous release of TNF-alpha in human synovium tissue explants of rheumatoid arthritis patients with an IC50 of 0.8 microM. In vivo, TMI-2 potently inhibits LPS-induced TNF-alpha production in mice (ED50=3 mg/kg). In the adjuvant-induced arthritis (AIA) model in rats, treatment with TMI-2 at 30 mg/kg and 100 mg/kg p.o. b.i.d. was highly effective in reducing joint arthritis scores. In a semi-therapeutic collagen-induced arthritis (CIA) model in mice, TMI-2 is highly effective in reducing disease severity scores after oral treatment at 100 mg/kg twice per day. In summary, TMI-2 is a potent and selective TACE inhibitor that inhibits TNF-alpha production and reduces the arthritis scores in pre-clinical models. TMI-2 represents a novel class of TACE inhibitors that may be effective and beneficial in the treatment of rheumatoid arthritis as well as other TNF-mediated inflammatory autoimmune diseases.

Synthesis and Structure−Activity Relationships of 4-alkynyloxy Phenyl Sulfanyl, Sulfinyl, and Sulfonyl Alkyl Hydroxamates as Tumor Necrosis Factor-α Converting Enzyme and Matrix Metalloproteinase Inhibitors

A series of 4-alkynyloxy phenyl sulfanyl, sulfinyl and sulfony alkyl and piperidine-4-carboxylic acid hydroxamides were synthesized. Their structure-activity relationships, against tumor necrosis factor-alpha (TACE) and matrix metalloproteinase (MMP) inhibitor activities, are presented by investigating the oxidation state on sulfur and altering the P1' substituent. The sulfonyl derivatives 20-24 carrying a 4-butynyloxy moiety were selective TACE inhibitors over the MMPs tested. The sulfinyl derivatives showed a preference for a specific oxidation on sulfur as in compounds 25-28. The selectivity over MMPs was also demonstrated in the sulfonyl series. The enhanced cellular activity was achieved upon incorporating a butynyloxy substituent in the piperidene series. Compounds 64 and 65 were potent inhibitors of TNF-alpha release in the mouse at 100 mg/kg po.

Benzodiazepine inhibitors of the MMPs and TACE. Part 2

A series of benzodiazepine MMP/TACE inhibitors bearing polar moieties has been synthesized in an effort to optimize inhibitory activity against LPS-stimulated TNF production in human monocytes and oral activity in a murine LPS model.

Reverse hydroxamate-based selective TACE inhibitors

Reverse hydroxamate-based selective TACE inhibitors are described. They have potent TACE inhibitory activities and excellent selectivities against MMP-1, 2, 3, 8, 9, 13, 14, and 17. One representative compound, 18 has demonstrated an excellent oral inhibitory activity of the lipopolysaccharide (LPS)-stimulated TNF-alpha production in rats.