Picking the S1, S1' and S2' pockets of matrix metalloproteinases. A niche for potent acyclic sulfonamide inhibitors

Novel Matrix Metalloproteinase-9 (MMP-9) Inhibitors in Cancer Treatment

Matrix metalloproteinases (MMPs) belong to a family of zinc-dependent proteolytic metalloenzymes. MMP-9, a member of the gelatinase B family, is characterized as one of the most intricate MMPs. The crucial involvement of MMP-9 in extracellular matrix (ECM) remodeling underscores its significant correlation with each stage of cancer pathogenesis and progression. The design and synthesis of MMP-9 inhibitors is a potentially attractive research area. Unfortunately, to date, there is no effective MMP-9 inhibitor that passes the clinical trials and is approved by the FDA. This review primarily focuses on exploring the diverse strategies employed in the design and advancement of MMP-9 inhibitors, along with their anticancer effects and selectivity. To illuminate the essential structural characteristics necessary for the future design of novel MMP-9 inhibitors, the current narrative review highlights several recently discovered MMP-9 inhibitors exhibiting notable selectivity and potency.

Matrix metalloproteinase-9 (MMP-9) and its inhibitors in cancer: A minireview

Matrix metalloproteinases (MMPs) are zinc dependent proteolytic metalloenzyme. MMP-9 is one of the most complex forms of matrix metalloproteinases. MMP-9 has the ability to degrade the extracellular matrix (ECM) components and has important role in the pathophysiological functions. Overexpression and dysregulation of MMP-9 is associated with various diseases. Thus, regulation and inhibition of MMP-9 is an important therapeutic approach for combating various diseases including cancer. Inhibitors of MMP-9 can be used as anticancer agents. Till date no selective MMP-9 inhibitors passed the clinical trials. In this review the structure, activation, function and inhibitors of MMP-9 are mainly focused. Some highly active and/or selective MMP-9 inhibitors have been discussed which may be helpful to explore the structural significance of MMP-9 inhibitors. This study may be useful to design new potent and selective MMP-9 inhibitors against cancer in future.

First insight into structure-activity relationships of selective meprin β inhibitors

The astacin proteases meprin α and β are emerging drug targets for treatment of disorders such as kidney failure, fibrosis or inflammatory bowel disease. However, there are only few inhibitors of both proteases reported to date. Starting from NNGH as lead structure, a detailed elaboration of the structure-activity relationship of meprin β inhibitors was performed, leading to compounds with activities in the lower nanomolar range. Considering the preference of meprin β for acidic residues in the P1' position, the compounds were optimized. Acidic modifications induced potent inhibition and >100-fold selectivity over other structurally related metalloproteases such as MMP-2 or ADAM10.

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.

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.

Compelling P1 substituent affect on metalloprotease binding profile enables the design of a novel cyclohexyl core scaffold with excellent MMP selectivity and HER-2 sheddase inhibition

A serendipitous discovery that the metalloprotease binding profile of a novel class of 2-carboxamide-3-hydroxamic acid piperidines could be significantly attenuated by the modification of the unexplored P1 substituent enabled the design and synthesis of a novel 2-carboxamide-1-hydroxamic acid cyclohexyl scaffold core that exhibited excellent HER-2 potency and unprecedented MMP-selectivity that we believe would not have been possible via conventional P1' perturbations.

Synthesis and evaluation of novel heterocyclic MMP inhibitors

A variety of novel heterocyclic compounds were synthesized and evaluated for MMP inhibition. Broad spectrum inhibition of MMPs 1, 2, 9, and 12 was found with pyridinone-based compounds while N-heterocyclic triazoles and tetrazoles were largely ineffective. A highly selective tetrazole inhibitor for MMP-2 was discovered.

QSAR modeling of matrix metalloproteinase inhibition by N-hydroxy-alpha-phenylsulfonylacetamide derivatives

The main molecular features which determine the selectivity of a set of 80 N-hydroxy-alpha-phenylsulfonylacetamide derivatives (HPSAs) in the inhibition of three matrix metalloproteinases (MMP-1, MMP-9, and MMP-13) have been identified by using linear and nonlinear predictive models. The molecular information has been encoded in 2D autocorrelation descriptors, obtained from different weighting schemes. The linear models were built by multiple linear regression (MLR) combined with genetic algorithm (GA), and a robust QSAR mapping paradigm. The Bayesian-regularized genetic neural network (BRGNN) was employed for nonlinear modeling. In such approaches each model could have its own set of input variables. All models were predictive according to internal and external validation experiments; but the best results correspond to nonlinear ones. The 2D autocorrelation space brings different descriptors for each MMP inhibition, and suggests the atomic properties relevant for the inhibitors to interact with each MMP active site. On the basis of the current results, the reported models have the potential to discover new potent and selective inhibitors and bring useful molecular information about the ligand specificity for MMP S(1)(') and S(2)(') subsites.

Linear and nonlinear QSAR study of N-hydroxy-2-[(phenylsulfonyl)amino]acetamide derivatives as matrix metalloproteinase inhibitors

The inhibitory activity (IC50) toward matrix metalloproteinases (MMP-1, MMP-2, MMP-3, MMP-9, and MMP-13) of N-hydroxy-2-[(phenylsulfonyl)amino]acetamide derivatives (HPSAAs) has been successfully modeled using 2D autocorrelation descriptors. The relevant molecular descriptors were selected by linear and nonlinear genetic algorithm (GA) feature selection using multiple linear regression (MLR) and Bayesian-regularized neural network (BRANN) approaches, respectively. The quality of the models was evaluated by means of cross-validation experiments and the best results correspond to nonlinear ones (Q2>0.7 for all models). Despite the high correlation between the studied compound IC50 values, the 2D autocorrelation space brings different descriptors for each MMP inhibition. On the basis of these results, these models contain useful molecular information about the ligand specificity for MMP S'1, S1, and S'2 pockets.

Synthesis and evaluation of novel oxazoline MMP inhibitors

MMP inhibitors with novel oxazoline zinc binding groups have been synthesized and evaluated. Selectivity for the inhibition of MMP-9 over MMP-1, MMP-2, and MMP-12 has been achieved in several cases.

Protease inhibitors of the sulfonamide type: anticancer, antiinflammatory, and antiviral agents

The sulfonamides constitute an important class of drugs, with several types of pharmacological agents possessing antibacterial, anticarbonic anhydrase, diuretic, hypoglycemic, and antithyroid activity among others. A large number of structurally novel sulfonamide derivatives have ultimately been reported to show substantial protease inhibitory properties. Of particular interest are some metalloprotease inhibitors belonging to this class, which by inhibiting several matrix metalloproteases (MMPs) show interesting antitumor properties. Some of these compounds are currently being evaluated in clinical trials. The large number of sulfonamide MMP inhibitors ultimately reported also lead to the design of effective tumor necrosis factor-alpha converting enzyme (TACE) inhibitors, potentially useful in the treatment of inflammatory states of various types. Since both MMPs and TACE contribute synergistically to the pathophysiology of many diseases, such as arthritis, bacterial meningitis, tumor invasion; the dual inhibition of these enzymes emerged as an interesting target for the drug design of anticancer/antiinflammatory drugs, and many such sulfonamide derivatives were recently reported. Human neutrophyl elastase (HNE) inhibitors of the sulfonamide type may also be useful in the treatment of inflammatory conditions, such as emphysema, cystic fibrosis, chronic bronchitis, ischemia reperfusion injury, and acute respiratory distress syndrome. Inhibition of some cysteine proteases, such as several caspase and cathepsin isozymes, may lead to the development of pharmacological agents effective for the management of several diseases, such as rheumatoid arthritis, inflammatory bowel disease, brain damage, and stroke. Another research line that progressed much in the last time regards different sulfonamides with remarkable antiviral activity. Some clinically used HIV protease inhibitors (such as amprenavir) possess sulfonamide moieties in their molecules, which are critical for the potency of these drugs, as shown by means of X-ray crystallography, whereas a very large number of other derivatives are constantly being synthesized and evaluated in order to obtain compounds with lower toxicity or augmented activity against viruses resistant to the such first generation drugs. Other viral proteases, such as those isolated from several types of herpes viruses may be inhibited by sulfonamide derivatives, leading thus to more effective classes of antiviral drugs.

A quantitative structure-activity relationship study on Clostridium histolyticum collagenase inhibitors: roles of electrotopological state indices

A quantitative structure-activity relationship (QSAR) study has been made on eight different series of Clostridium histolyticum collegenase (ChC) inhibitors. These series are comprised of four different groups of sulfonylated amino acids and their corresponding hydroxamates. In each series, the inhibition potency of the compounds has been found to be significantly correlated with the electrotopological state (E-state) indices of nitrogen and sulfur atoms of the sulfonylated amino group in the molecules, showing the importance of the electronic characterstics of these atoms in controlling the inhibition potency of the compounds.

Protease inhibitors: synthesis of bacterial collagenase and matrix metalloproteinase inhibitors incorporating arylsulfonylureido and 5-dibenzo-suberenyl/suberyl moieties

Novel matrix metalloproteinase (MMP)/bacterial collagenase inhibitors are reported, considering the sulfonylated amino acid hydroxamates as lead molecules. A series of compounds was prepared by reaction of arylsulfonyl isocyanates with N-(5H-dibenzo[a,d]cyclohepten-5-yl)- and N-(10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-yl) methyl glycocolate, respectively, followed by the conversion of the COOMe to the carboxylate/hydroxamate moieties. The corresponding derivatives with methylene and ethylene spacers between the polycyclic moiety and the amino acid functionality were also obtained by related synthetic strategies. These new compounds were assayed as inhibitors of MMP-1, MMP-2, MMP-8 and MMP-9, and of the collagenase isolated from Clostridium histolyticum (ChC). Some of the new derivatives reported here proved to be powerful inhibitors of the four MMPs mentioned above and of ChC, with activities in the low nanomolar range for some of the target enzymes, depending on the substitution pattern at the sulfonylureido moiety and on the length of the spacer through which the dibenzosuberenyl/suberyl group is connected with the rest of the molecule. Several of these inhibitors also showed selectivity for the deep pocket enzymes (MMP-2, MMP-8 and MMP-9) over the shallow pocket ones MMP-1 and ChC.

Protease inhibitors: synthesis of matrix metalloproteinase and bacterial collagenase inhibitors incorporating 5-amino-2-mercapto-1,3,4-thiadiazole zinc binding functions

Matrix metalloproteinase (MMP)/bacterial collagenase inhibitors incorporating 5-amino-2-mercapto-1,3,4-thiadiazole zinc binding functions are reported. A series of compounds was prepared by reaction of arylsulfonyl isocyanates or arylsulfonyl halides with phenylalanyl-alanine, followed by coupling with 5-amino-2-mercapto-1,3,4-thiadiazole in the presence of carbodiimides. These new compounds were assayed as inhibitors of human MMP-1, MMP-2, MMP-8 and MMP-9, and of the collagenase isolated from the anaerobe Clostridium histolyticum (ChC). The new derivatives proved to be powerful inhibitors of these metalloproteases, with activities in the low micromolar range for some of the target enzymes, depending on the substitution pattern at the arylsulfonyl(ureido) moieties.

A comparative docking study and the design of potentially selective MMP inhibitors

As part of a program aimed at the design and synthesis of constrained MMP inhibitors, a survey of the reported X-ray and NMR structures of MMP/inhibitor complexes was performed, revealing mutations of key amino acids at different subsites between MMPs. A comparative study of fully automated docking programs AutoDock and DOCK in closely approximating the X-ray crystal structures of ten selected MMP inhibitors was performed. AutoDock proved to be highly reliable, efficient and predictive for a set of inhibitors with less than six atom types.

Small ring constrained peptidomimetics. Synthesis of epoxy peptidomimetics, inhibitors of cysteine proteases

Different dipeptide analogues containing an oxirane ring in the place of the peptidic bond were prepared starting from naturally occurring amino acids. N-Fmoc-amino aldehydes were transformed into the corresponding methoxyvinyl derivatives through a Wittig reaction, and the addition of PhSeCl gave a series of different alpha-phenylselenyl aldehydes. Mukajiama reaction with silylketene acetals gave an intermediate product that was finally transformed into the desired oxiranyl peptidomimetics. Following this strategy we were able to control three new contiguous stereocenters starting from the enantiomerically pure amino acid. The dipeptide analogues could be used in SPPS on a SASRIN resin as the final epoxides were relatively unstable under acidic conditions. Moreover the synthesis of the single dipeptide mimetics was carried out on solid phase to generate a small library of epoxy peptidomimetics. Some of the products prepared in this work resulted as time-dependent reversible inhibitors of cysteine protease.

Protease inhibitors. Part 12. Synthesis of potent matrix metalloproteinase and bacterial collagenase inhibitors incorporating sulfonylated N-4-nitrobenzyl-beta-alanine hydroxamate moieties

N-4-Nitrobenzyl-beta-alanine was reacted with alkyl/arylsulfonyl halides, followed by conversion of the COOH to the CONHOH group. Structurally related compounds were obtained by reaction of N-4-nitrobenzyl-beta-alanine with aryl isocyanates, arylsulfonyl isocyanates or benzoyl isothiocyanate, followed by similar conversion of the COOH into the CONHOH moiety. Another subseries of derivatives was prepared from sulfanilyl- or metanilyl-4-nitrobenzyl-beta-alanine by reaction with arylsulfonyl isocyanates, followed by the introduction of the hydroxamate moiety. The new compounds were assayed as inhibitors of four matrix metalloproteinases (MMPs), MMP-1, MMP-2, MMP-8 and MMP-9, and of the Clostridium histolyticum collagenase (ChC). Some of the prepared hydroxamate derivatives proved to be very effective collagenase/gelatinase inhibitors, depending on the substitution pattern at the sulfonamido moiety. Substitutions leading to the best inhibitors of MMP-1, a short-pocket enzyme, were those involving pentafluorophenylsulfonyl or 3-trifluoromethyl-phenylsulfonyl at P(1') (K(I) of 3-5 nM). For MMP-2, MMP-8 and MMP-9 (deep-pocket enzymes), the best inhibitors were those containing perfluoroalkylsulfonyl- and substituted-arylsulfonyl moieties, such as pentafluorophenylsulfonyl, 3- and 4-protected-aminophenylsulfonyl-, 3- and 4-carboxy-phenylsulfonyl-, arylsulfonylureido- or arylsulfonylureido-sulfanilyl-/metanilyl moieties at P(1'). Bulkier groups in this position, such as 1- and 2-naphthyl-, substituted-naphthyl or quinoline-8-yl- moieties, among others, led to less effective MMP/ChC inhibitors. The best ChC inhibitors were again those containing pentafluorophenylsulfonyl, 3- and 4-protected-aminophenylsulfonyl P(1') groups. This study demonstrates that the 4-nitrobenzyl moiety, investigated here for the first time, is an efficient P(2') anchoring moiety, whereas the beta-alanyl scaffold can successfully replace the alpha-amino acyl one, for obtaining potent MMP/ChC inhibitors.

Protease inhibitors: synthesis of clostridium histolyticum collagenase inhibitors incorporating sulfonyl-L-alanine hydroxamate moieties

A series of hydroxamates was obtained by the reaction of N-(4-nitrobenzyl)-L-alanine with alkyl/arylsulfonyl halides, followed by conversion of the COOH group into CONHOH. Structurally-related compounds were prepared similarly by using arylsulfonyl isocyanates, aryl isocyanates or arylsulfenyl halides instead of the sulfonyl halides. Many of the new compounds showed nanomolar affinity for the bacterial collagenase isolated from the pathogen Clostridium histolyticum.

Protease inhibitors. Part 8: synthesis of potent Clostridium histolyticum collagenase inhibitors incorporating sulfonylated L-alanine hydroxamate moieties

A series of hydroxamates was prepared by reaction of alkyl/arylsulfonyl halides with N-2-chlorobenzyl-L-alanine, followed by conversion of the COOH moiety to the CONHOH group, with hydroxylamine in the presence of carbodiimides. Other structurally related compounds were obtained by reaction of N-2-chlorobenzyl-L-alanine with aryl isocyanates, arylsulfonyl isocyanates or benzoyl isothiocyanate, followed by the similar conversion of the COOH into the CONHOH moiety. The new compounds were assayed as inhibitors of the Clostridium histolyticum collagenase, ChC (EC 3.4.24.3), a bacterial zinc metallo-peptidase which degrades triple helical collagen as well as a large number of synthetic peptides. The prepared hydroxamate derivatives proved to be 100-500 times more active collagenase inhibitors than the corresponding carboxylates. Substitution patterns leading to best ChC inhibitors (both for carboxylates as well as for the hydroxamates) were those involving perfluoroalkylsulfonyl- and substituted-arylsulfonyl moieties, such as pentafluorophenylsulfonyl; 3- and 4-protected-aminophenylsulfonyl-; 3- and 4-carboxyphenylsulfonyl-; 3-trifluoromethyl-phenylsulfonyl; as well as 1- and 2-naphthyl-, quinoline-8-yl- or substituted-arylsulfonylamidocarboxyl moieties among others. Similarly to the matrix metalloproteinase (MMP) hydroxamate inhibitors, ChC inhibitors of the type reported here must incorporate hydrophobic moieties at the P2' and P3' sites, in order to achieve tight binding to the enzyme. This study also proves that the 2-chlorobenzyl moiety, investigated here for the first time, is an efficient P2' anchoring moiety for obtaining potent ChC inhibitors.