Design, synthesis, and biological evaluation of matrix metalloproteinase inhibitors derived from a modified proline scaffold

Regiospecific Alkene Aminofunctionalization via an Electrogenerated Dielectrophile

Modular strategies to rapidly increase molecular complexity have proven immensely synthetically valuable. In principle, transformation of an alkene into a dielectrophile presents an opportunity to deliver two unique nucleophiles across an alkene. Unfortunately, the selectivity profiles of known dielectrophiles have largely precluded this deceptively simple synthetic approach. Herein, we demonstrate that dicationic adducts generated through electrolysis of alkenes and thianthrene possess a unique selectivity profile relative to more conventional dielectrophiles. Specifically, these species undergo a single and perfectly regioselective substitution reaction with phthalimide salts. This observation unlocks an appealing new platform for aminofunctionalization reactions. As an illustrative example, we implement this new reactivity paradigm to address a longstanding synthetic challenge: alkene diamination with two distinct nitrogen nucleophiles. Studies into the mechanism of this process reveal a key alkenyl thianthrenium salt intermediate that controls the exquisite regioselectivity of the process and highlight the importance of proton sources in controlling the reactivity of alkenyl sulfonium salt electrophiles.

Structural and functional role of invariant water molecules in matrix metalloproteinases: a data-mining approach

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases known to degrade extracellular matrix (ECM). Being involved in many biological and physiological processes of tissue remodeling, MMPs play a crucial role in many pathological conditions such as arthritis, cancer, cardiovascular diseases, etc. Typically, MMPs possess a propeptide, a zinc-containing catalytic domain, a hinge region and a hemopexin domain. Based on their structural domain organization and substrates, MMPs are classified into six different classes, viz. collagenases, stromelysins, gelatinases, matrilysins, membrane-type and other MMPs. As per previous studies, a set of invariant water (IW) molecules of MMP-1 (a collagenase) play a significant role in stabilizing their catalytic domain. However, a functional role of IW molecule in other classes of MMPs has not been reported yet. Thus, in this study, IW molecules of MMPs from different classes were located and their plausible role(s) have been assigned. The results suggest that IW molecules anchor the structurally and functionally essential metal ions present in the vicinity of the active site of MMPs. Further, they (in)directly interlink different structural features and bridge the active site metal ions of MMPs. This study provides the key IW molecules that are structurally and functionally relevant to MMPs and hence, in turn, might facilitate the development of potent generalized inhibitor(s) against different classes of MMPs. Communicated by Ramaswamy H. Sarma.

The Critical Role of Passive Permeability in Designing Successful Drugs

Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients.

Matrix metalloproteinase inhibitors based on the 3-mercaptopyrrolidine core

New series of pyrrolidine mercaptosulfide, 2-mercaptocyclopentane arylsulfonamide, and 3-mercapto-4-arylsulfonamidopyrrolidine matrix metalloproteinase inhibitors (MMPIs) were designed, synthesized, and evaluated. Exhibiting unique properties over other MMPIs (e.g., hydroxamates), these newly reported compounds are capable of modulating activities of several MMPs in the low nanomolar range, including MMP-2 (~2 to 50 nM), MMP-13 (~2 to 50 nM), and MMP-14 (~4 to 60 nM). Additionally these compounds are selective to intermediate- and deep-pocket MMPs but not shallow-pocketed MMPs (e.g., MMP-1, ~850 to >50,000 nM; MMP-7, ~4000 to >25,000 nM). Our previous work with the mercaptosulfide functionality attached to both cyclopentane and pyrrolidine frameworks demonstrated that the cis-(3S,4R)-stereochemistry was optimal for all of the MMPs tested. However, in our newest compounds an interesting shift of preference to the trans form of the mercaptosulfonamides was observed with increased oxidative stability and biological compatibility. We also report several kinetic and biological characteristics showing that these compounds may be used to probe the mechanistic activities of MMPs in disease.

A QSAR Study of Matrix Metalloproteinases Type 2 (MMP-2) Inhibitors with Cinnamoyl Pyrrolidine Derivatives

A multivariate PLS-QSAR study with a data set of 31 cinnamoyl pyrrolidine derivatives described as type 2 matrix metalloproteinases (MMP-2) inhibitors is presented in this paper. The variable selection was performed with the Ordered Predictors Selection (OPS) algorithm. The PLS model presented six descriptors and three Latent Variables (LV) that cumulated 71.845% of variance. Leave-N-out (LNO) cross validation and y-randomization tests showed that the model presented robustness and no chance correlation, respectively. The descriptors indicated that MMP-2 inhibition depends mainly on the electronic properties of the compounds. The model obtained can be useful as a support tool in the design of new MMP-2 inhibitors.

Advances in studies on collagenase inhibitors

Matrix metalloproteinases (MMPs) play an important role in many physiological and pathological processes. Development of MMP inhibitors, in particular collagenase inhibitors, for the treatment of arthritis has been more challenging, undoubtedly. Small-molecular-weight collagenase inhibitors may be classified into several different arbitrary structural classes, depending on the catalytic zinc-binding function as well as other structural elements of the inhibitors. This chapter tries to make an attempt in providing the reader with an overall flavor of the type of scaffolds reported in the past few years along with the molecular modeling studies.

THEORETICAL STUDY ON POTENCY AND SELECTIVITY OF NOVEL NONPEPTIDE INHIBITORS OF MATRIX METALLOPROTEINASES MMP-2 AND MMP-9

Two novel matrix metalloproteinase (MMP) inhibitors, myricetin (m) and kaempferol (k), were found and the inhibitory activity is both in decreased order towards MMP-2 and MMP-9. To understand the mechanism during the processes when inhibitors bind to MMP-2 and MMP-9, molecular modeling, docking, and density functional theory (DFT) calculations were performed. The calculated results indicated that the hydroxyls on benzene ring of the inhibitors control the binding modes between inhibitors and MMPs, thus play an important role on the potency and selectivity. Besides coordinating with the N atoms of three His residues, Zn also interacts with a hydroxyl group of inhibitors by O – Zn distances of 2.66–2.78 Å in all of the docked complexes, so that the hydroxyl acts as a weak zinc binding group (ZBG). The DFT calculated results support the above analysis. The binding affinity calculations between inhibitors and MMPs present the total interaction energies in the m-MMP < k-MMP order and the solvation energy of myricetin is less than that of kaempferol, which reflect the experimental inhibitory activity.

Design, synthesis and evaluation of novel sulfonyl pyrrolidine derivatives as matrix metalloproteinase inhibitors

A series of novel sulfonyl pyrrolidine derivatives were designed, synthesized and assayed for their inhibitory activities on matrix metalloproteinase 2 (MMP-2) and aminopeptidase N (AP-N). The results showed that these pyrrolidine derivatives exhibited highly selective inhibition against MMP-2 as compared with AP-N. Compounds 6a-d were more potent MMP-2 inhibitors than the positive control LY52. The structure-activity relationships were also briefly discussed.

Matrix metalloproteinase–inhibitor interaction: the solution structure of the catalytic domain of human matrix metalloproteinase-3 with different inhibitors

We structurally characterized the adducts of the catalytic domain of matrix metalloproteinase-3 (MMP3) with three different nonpeptidic inhibitors by solving the solution structure of one adduct [MMP3-N-isobutyl-N-(4-methoxyphenylsulfonyl)glycyl hydroxamic acid] and then by calculating structural models of the other two adducts using a reduced set of experimental NMR data, following a recently proposed procedure (Bertini et al. in J. Med. Chem. 48:7544-7559, 2005). The inhibitors were selected with the criteria of maintaining in all of them the same zinc-coordinating moiety and of selectively changing the substituents and/or the functional groups. The backbone dynamics on various time scales have been characterized as well. The comparison among these structures and with others previously reported allowed us to elucidate fine details of inhibitor-receptor interactions and to develop some criteria, which could guide in optimizing the design of selective inhibitors.

Homo- and heteronuclear complexes of a new, vicinal dioxime ligand

A new symmetrical vicinal dioxime, N,N′-bis-{4-[[(2-hydroxyphenyl)methylene]hydrazinecarbonyl]phenyl}diaminoglyoxime (LH4), was prepared by reacting anti-dichloroglyoxime with salicylaldehyde 4-aminobenzoylhydrazone. The reaction of ligand with Ni2+ salts gave mono-and homopentanuclear complexes, [Ni(LH3)2] and [Ni5(LH)2X2]. Furthermore, heteropentanuclear complexes of dioxime ligand, [Cu4Ni(LH)2X4], were prepared by the reaction of [Ni(LH3)2)] with Cu2+ salt and a monodentate ligand (X = SCN−, CN−, or N3−). The structures of both the new symmetrical vicinal dioxime and its complexes were identified by elemental analyses, IR, 1H NMR, UV-VIS spectra, and magnetic susceptibility. The elemental analyses and spectral data indicate that the hydrazone side of ligand acts as a O,N,O′ tridentate and the fourth position is occupied with monodentate anion such as SCN−, CN−, N3−.

Synthesis of novel N1-substituted bicyclic pyrazole amino acids and evaluation of their interaction with glutamate receptors

N1-substituted bicyclic pyrazole amino acids (S)-9a-9c and (R)-9a-9c, which are conformationally constrained analogues of glutamic acid, were prepared via a strategy based on a 1,3-dipolar cycloaddition. The new amino acids were tested for activity at ionotropic and metabotropic glutamate receptors. Some of them turned out to be selective for the NMDA receptors, where they behaved as weak antagonists. The biological activity is mainly due to the interaction with the glutamate binding site, and not with the glycine co-agonist site.

Neutralization of the haemorrhagic activities of viperine snake venoms and venom metalloproteinases using synthetic peptide inhibitors and chelators

Envenoming by the West African saw-scaled viper, Echis ocellatus resembles that of most vipers, in that it results in local blistering, necrosis and sometimes life-threatening systemic haemorrhage. While effective against systemic envenoming, current antivenoms have little or no effect against local tissue damage. The major mediators of local venom pathology are the zinc-dependant snake venom metalloproteinases (SVMPs). The high degree of structural and functional homology between SVMPs and their mammalian relatives the matrix metalloproteinases (MMPs) suggests that substrate/inhibitor interactions between these subfamilies are likely to be analogous. In this study, four recently developed MMP inhibitors (MMPIs) (Marimastat, AG-3340, CGS-270 23A and Bay-12 9566) are evaluated in addition to three metal ion chelators (EDTA, TPEN and BAPTA) for their ability to inhibit the haemorrhagic activities of the medically important E. ocellatus venom and one of its haemorrhagic SVMPs, EoVMP2. As expected, the metal ion chelators significantly inhibited the haemorrhagic activities of both whole E. ocellatus venom and EoVMP2, while the synthetic MMPIs show more variation in their efficacies. These variations suggest that individual MMPIs show specificity towards SVMPs and that their application to the neutralization of local haemorrhage may require a synthetic MMPI mixture, ensuring that a close structural component for each SVMP is represented.

Blockade of tumor necrosis factor-alpha-converting enzyme improves experimental small intestinal damage by decreasing matrix metalloproteinase-3 production in rats

OBJECTIVE

Tumor necrosis factor (TNF)-alpha-converting enzyme (TACE), which has been purified, regulates maturity of TNF-alpha. Matrix metalloproteinases (MMPs) play a key role in various inflammatory conditions. The incidence of intestinal damage has increased, but the mechanism and treatment have not been well understood. The purpose of this study was to investigate the roles of TACE and MMP in indomethacin (Indo)-induced intestinal damage as well as the therapeutic effects of TACE inhibitor and selective MMP inhibitor (sMMPi) on this intestinal damage in rats.

MATERIAL AND METHODS

In the first experiment, serial changes in intestinal ulcers and the production of MMP were investigated. In the second experiment, we assessed the effect of three TACE and/or MMP inhibitors and the production of TNF-alpha, TACE, MMP-3, -9 and tissue inhibitor of MMP (TIMP)-1. The rats were divided into five groups: a control group, and four groups that received Indo alone, Indo plus TACE inhibitor (GM6001), Indo plus a selective MMP-3 inhibitor and Indo plus an MMP-9/13 inhibitor, respectively.

RESULTS

MMP-3 was overexpressed at 24 h after Indo administration, when intestinal injury was most prominent macroscopically and microscopically. GM6001 significantly decreased ulcer severity and suppressed MMP-3 in a dose-dependent fashion. The selective MMP-3 inhibitor dose-dependently ameliorated intestinal damage to the same degree as GM6001, but the MMP-9 inhibitor had no effect on the injury.

CONCLUSIONS

MMP-3 inhibition ameliorates intestinal damage without apparently affecting either TNF-alpha or TACE production and the dose-response curve suggests that the beneficial effect of the so-called TACE inhibitor is actually mainly mediated via MMP-3 inhibition rather than TNF-alpha inhibition.

Supervised Feature Ranking Using a Genetic Algorithm Optimized Artificial Neural Network

A genetic algorithm optimized artificial neural network GNW has been designed to rank features for two diversified multivariate data sets. The dimensions of these data sets are 85x24 and 62x25 for 24 or 25 molecular descriptors being computed for 85 matrix metalloproteinase-1 inhibitors or 62 hepatitis C virus NS3 protease inhibitors, respectively. Each molecular descriptor computed is treated as a feature and input into an input layer node of the artificial neural network. To optimize the artificial neural network by the genetic algorithm, each interconnected weight between input and hidden or between hidden and output layer nodes is binary encoded as a 16 bits string in a chromosome, and the chromosome is evolved by crossover and mutation operations. Each input layer node and its associated weights of the trained GNW are systematically omitted once (the self-depleted weights), and the corresponding weight adjustments due to the omission are computed to keep the overall network behavior unchanged. The primary feature ranking index defined as the sum of self-depleted weights and the corresponding weight adjustments computed is found capable of separating good from bad features for some artificial data sets of known feature rankings tested. The final feature indexes used to rank the data sets are computed as a sum of the weighted frequency of each feature being ranked in a particular rank for each data set being partitioned into numerous clusters. The two data sets are also clustered by a standard K-means method and trained by a support vector machine (SVM) for feature ranking using the computed F-scores as feature ranking index. It is found that GNW outperforms the SVM method on three artificial as well as the matrix metalloproteinase-1 inhibitor data sets studied. A clear-cut separation of good from bad features is offered by the GNW but not by the SVM method for a feature pool of known feature ranking.

Crystal structures of the catalytic domain of human stromelysin-1 (MMP-3) and collagenase-3 (MMP-13) with a hydroxamic acid inhibitor SM-25453

Crystal structures of the catalytic domain of human stromelysin-1 (MMP-3) and collagenase-3 (MMP-13) with a hydroxamic acid inhibitor SM-25453 have been solved at 2.01 and 2.37A resolutions, respectively. The results revealed that the binding modes for this inhibitor to MMP-3 and -13 were quite similar. However, subtle comparative differences were observed at the bottom of S1' pockets, which were occupied with the guanidinomethyl moiety of the inhibitor. A remarkable feature of the inhibitor was the deep penetration of its long aliphatic chain into the S1' pocket and exposure of the guanidinomethyl moiety to the solvent.

N-Hydroxyurea as zinc binding group in matrix metalloproteinase inhibition: mode of binding in a complex with MMP-8

The first crystallographic structure of an N-hydroxyurea inhibitor bound into the active site of a matrix metalloproteinase is reported. The ligand and three other analogues were prepared and studied as inhibitors of MMP-2, MMP-3, and MMP-8. The crystal structure of the complex with MMP-8 shows that the N-hydroxyurea, contrary to the analogous hydroxamate, binds the catalytic zinc ion in a monodentate rather than bidentate mode and with high out-of-plane distortion of the amide bonds.

Structural and Spectroscopic Study of Reactions between Chelating Zinc-Binding Groups and Mimics of the Matrix Metalloproteinase and Disintegrin Metalloprotease Catalytic Sites: The Coordination Chemistry of Metalloprotease Inhibition

To understand the coordination chemistry of zinc-binding groups (ZBGs) with catalytic zinc centers in matrix metalloproteinases (MMPs) and disintegrin metalloproteases (ADAMs), we have undertaken a model compound study centered around tris(3,5-methylphenypyrazolyl)hydroboratozinc(II) hydroxide and aqua complexes ([Tp(Ph,Me)ZnOH] and [Tp(Ph,Me)Zn(OH2)]+, respectively, wherein (Tp(Ph,Me))- = hydrotris(3,5-methylphenylpyrazolyl)borate) and the products of their reactions with a class of chelating Schiff's base ligands. The results show that the protic ligands, HL (HL = N-propyl-1-(5-methyl-2-imidazolyl)methanimine (5-Me-4-ImHPr), N-propyl-1-(4-imidazolyl)methanimine (4-ImHPr), and N-propyl-1-(2-imidazolyl)methanimine (2-ImHPr)), react with [Tp(Ph,Me)ZnOH] and give products with the general formula [Tp(Ph,Me)ZnL], whereas reactions with neutral aprotic ligands, L' (L' = N-propyl-1-(1-methyl-2-imidazolyl)methanimine (1-Me-2-ImPr) and N-propyl-1-(2-thiazolyl)methanimine (2-TaPr)), yield the corresponding [Tp(Ph,Me)ZnL]+ complexes. Although the phenol group of N-propyl-1-(2-hydroxyphenyl)methanimine (2-HOPhPr) is protic, this ligand forms a cationic four-coordinate complex containing an intraligand hydrogen bond. The solid-state structures of these complexes were determined by single-crystal X-ray diffraction, and the results showed that the protic ligands form five-membered chelates of the Zn2+ ion. All ligands displace the aqua ligand in [Tp(Ph,Me)Zn(OH2)]+ to yield complexes having 1H NMR spectra consistent with the formation of five membered chelates. The 1H resonance frequencies of the chelating ligands typically shift upfield upon coordination to the zinc center, due to ring current effects from the pendant phenyl groups of the (Tp(Ph,Me))- ligand. Thus, the 1H NMR spectra provide a convenient and sensitive means of tracking the solution reactions by titration. The resulting series of spectra showed that the stabilities of the chelates in solution depend on the propensity of the ligands to deprotonate upon chelation of the zinc center. The behaviors of these bidentate ZBGs provide insight into the structural and electronic factors that contribute to the stabilities of inhibited MMPs and ADAMs and suggest that the proton acidity of the coordinated ZBG may be a crucial criterion for inhibitor design.

Future challenges facing the development of specific active-site-directed synthetic inhibitors of MMPs

Despite a deep knowledge on the 3D-structure of several catalytic domains of MMPs, the development of highly specific synthetic active-site-directed inhibitors of MMPs, able to differentiate the different members of this protease family, remains a strong challenge. Due to the flexible nature of MMP active-site, the development of specific MMP inhibitors will need to combine sophisticated theoretical and experimental approaches to decipher in each MMP the specific structural and dynamic features that can be exploited to obtain the desired selectivity.

A Ligand-Based Molecular Modeling Study on Some Matrix Metalloproteinase-1 Inhibitors Using Several 3D QSAR Techniques

Some three-dimensional quantitative structure-activity relationship (3D-QSAR) models have been constructed using the comparative molecular field analysis (CoMFA) and comparative molecular similarity indices (CoMSIA) for a series of 84 proline-based plus 12 structurally more diversified nonproline matrix metalloproteinase inhibitors. The structures of these inhibitors were built from a structure template extracted from the crystal structure of stromelysin. The structures built were divided into the training and test sets for both the CoMFA and CoMSIA analyses for each being composed of 60 and 24 inhibitors, respectively. The structures in the training set were aligned using some alignment rules derived from the analysis of the Ligplot program on a recent crystal structure of ligand-collagenase-1 complex. Some stepwise CoMSIA's were performed on the aligned training set on which the best CoMFA result was obtained. The best CoMSIA model was identified from the stepwise results, and the corresponding pharmacophore features were used for the construction of a pharmacophore hypothesis by the Catalyst 4.9 program. The training set was extended to include 11 structurally more diversified and nonproline inhibitors. To construct a pharmacophore hypothesis, the conformation of 60 structurally aligned proline-based inhibitors was fixed, while that of the 11 structurally more diversified nonproline inhibitors was allowed to vary during the hypothesis construction process. It was found that the predicted activities by the top hypothesis constructed for both the training and test sets were as good in statistics as those predicted by the best CoMSIA model from which the hypothesis was derived. The top hypothesis was mapped onto the structures of several highly active inhibitors selected from both the training and test sets. The goodness of mapping on each inhibitor was found to be correlated well with the activity of each inhibitor.

Azasugar-Based MMP/ADAM Inhibitors as Antipsoriatic Agents

As a part of synthetic studies on MMP (matrix metalloproteinase)/ADAM (a disintegrin and metalloproteinase) inhibitors, we have preliminarily communicated that azasugar-based compound 1a exhibited a potential inhibitory activity on some metalloprotease-catalyzed proteolytic reactions. To find promising candidates for the topical treatment of psoriasis, we investigated stability in aqueous solution of compound 1a and its derivative 1b and then optimized the P1' substuent (2-5). In the present study, we synthesized novel derivatives of compound 1a and evaluated their inhibitory activity toward MMP-1, -3, and -9, TACE, and HB-EGF shedding, from a viewpoint of versatility of azasugars as a functional scaffold. As a result, it was found that compound 1b demonstrated desirable inhibitory activity as an antipsoriatic agent, and some of the derivatives showed selective inhibitory activity. In addition, it was found that compound 1b exhibited a significant therapeutic effect on a mouse TPA-induced epidermal hyperplasia model. Therefore, compound 1b could become a promising candidate as a practical antipsoriatic agent.

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.

Synthesis and preliminary biological evaluation of MMP inhibitor radiotracers [11C]methyl-halo-CGS 27023A analogs, new potential PET breast cancer imaging agents

A series of [11C]methyl-halo-CGS 27023A analogs (2-F, 1a; 4-F, 1b; 2-Cl, 1c; 3-Cl, 1d; 4-Cl, 1e; 2-Br, 1f; 3-Br, 1g; 4-Br, 1h; 4-I, 1i), novel radiolabeled matrix metalloproteinase (MMP) inhibitors, have been synthesized for evaluation as new potential positron emission tomography (PET) breast cancer imaging agents. The precursors halo-CGS 27023A analogs (2-F, 6a; 4-F, 6b; 2-Cl, 6c; 3-Cl, 6d; 4-Cl, 6e; 2-Br, 6f; 3-Br, 6g; 4-Br, 6h; 4-I, 6i) for radiolabeling were obtained in four steps from starting material amino acid D-valine with moderate to excellent chemical yields. Precursors were labeled by [11C]methyl triflate through 11C-O-methylation method at the aminohydroxyl position under basic conditions and isolated by solid-phase extraction (SPE) purification to produce pure target compounds in 40-60% radiochemical yields (decay corrected to end of bombardment), in 20-25 min synthesis time.

Structure-based design and synthesis of potent matrix metalloproteinase inhibitors derived from a 6H-1,3,4-thiadiazine scaffold

We describe a new generation of heterocyclic nonpeptide matrix metalloproteinase (MMP) inhibitors derived from a 6H-1,3,4-thiadiazine scaffold. A screening effort was utilized to identify some chiral 6-methyl-1,3,4-thiadiazines that are weak inhibitors of the catalytic domain of human neutrophil collagenase (cdMMP-8). Further optimization of the lead compounds revealed general design principles that involve the placement of a phenyl or thienyl group at position 5 of the thiadiazine ring, to improve unprimed side affinity; the incorporation of an amino group at position 2 of the thiadiazine ring as the chelating agent for the catalytic zinc; the placement of a N-sulfonamide-substituted amino acid residue at the amino group, to improve primed side affinity; and the attachment of diverse functional groups at position 4 or 5 of the phenyl or thienyl group at the unprimed side, to improve selectivity. The new compounds were assayed against eight different matrix metalloproteinases, MMP-1, cdMMP-2, cdMMP-8, MMP-9, cdMMP-12, cdMMP-13, cdMMP-14, and the ectodomain of MMP-14, respectively. A unique combination of the above-described modifications produced the selective inhibitor (2R)-N-[5-(4-bromophenyl)-6H-1,3,4-thiadiazin-2-yl]-2-[(phenylsulfonyl)amino]propanamide with high affinity for MMP-9 (K(i) = 40 nM). X-ray crystallographic data obtained for cdMMP-8 cocrystallized with N-allyl-5-(4-chlorophenyl)-6H-1,3,4-thiadiazin-2-amine hydrobromide gave detailed design information on binding interactions for thiadiazine-based MMP inhibitors.

Arylsulphonyl hydroxamic acids: potent and selective matrix metalloproteinase inhibitors

A series of novel matrix metalloproteinase inhibitors is described in which selectivity between MMP and 'sheddase' activity has been achieved and which demonstrate potent in vivo activity in models of arthritis and cancer.

Chemoenzymatic synthesis of functionalized cyclohexylglycines and alpha-methylcyclohexylglycines via Kazmaier-Claisen rearrangement

The synthesis of homochiral functionalized cyclohexylglycines and alpha-methylcyclohexylglycines via chelated Kazmaier-Claisen rearrangement is described. These were shown to be potent scaffolds for the development of MMP inhibitors.

Recent advances in structure-based rational drug design

Two approaches to structure-based drug design, that is, the docking of known compounds into a target protein and molecular assembly in situ, are seen to be merging technologies. The need for structural information about drug-protein complexes is now fundamental for drug discovery.

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 potent bacterial collagenase and matrix metalloproteinase inhibitors incorporating N-4-nitrobenzylsulfonylglycine hydroxamate moieties

A series of compounds was prepared by reaction of alkyl/arylsulfonyl halides with N-4-nitrobenzylglycine, followed by conversion of the COOH to the CONHOH group, with hydroxylamine in the presence of carbodiimides. Other structurally related compounds were obtained by reaction of N-4-nitrobenzylglycine with aryl isocyanates, arylsulfonyl isocyanates, or benzoyl isothiocyanate, followed by the similar conversion of the COOH into the CONHOH moiety. Another subseries of derivatives was prepared from sulfanilyl- or metanilyl-4-nitrobenzylglycine by reaction with arylsulfonyl isocyanates, followed by conversion of the COOH to 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 best inhibitors of MMP-1, a short pocket enzyme, were those involving pentafluorophenylsulfonyl or 3-trifluoromethylphenylsulfonyl moieties at P(1') (K(I)'s of 3-5 nM). For MMP-2, MMP-8, and MMP-9 (deep-pocket enzymes), best inhibitors were especially those containing long perfluoroalkylsulfonyl and substituted-arylsulfonyl moieties, such as pentafluorophenylsulfonyl, 3- and 4-protected-aminophenylsulfonyl, 3- and 4-carboxyphenylsulfonyl, arylsulfonylureido, or arylsulfonylureidosulfanilyl/metanilyl moieties, at P(1'). Bulkier groups in this position, such as 1- and 2-naphthyl, substituted-naphthyl, or quinolin-8-yl moieties among others, led to less effective MMP/ChC inhibitors. Best ChC inhibitors were again those containing pentafluorophenylsulfonyl or 3- and 4-protected-aminophenylsulfonyl P(1') anchoring groups, suggesting that this protease is also a short-pocket wider-neck one (more similar to MMP-1). This study also proves that the 4-nitrobenzyl moiety is an efficient P(2') anchoring moiety and that sulfonylureido, ureido, or carboxythioureido substitutions at P(1') are also tolerated for obtaining potent sulfonylated amino acid hydroxamate-like MMP/ChC inhibitors.