Matrix metalloproteinase inhibitors containing a (carboxyalkyl)amino zinc ligand: modification of the P1 and P2' residues

Polycyclic nitrogen heterocycles as potential thymidine phosphorylase inhibitors: synthesis, biological evaluation, and molecular docking study

New polycyclic heterocycles were synthesised and evaluated as potential inhibitors of thymidine phosphorylase (TP). Inspired by the pharmacophoric pyrimidinedione core of the natural substrate, four series have been designed in order to interact with large empty pockets of the active site: pyrimidoquinoline-2,4-diones (series A), pyrimidinedione linked to a pyrroloquinoline-1,3-diones (series B and C), the polycyclic heterocycle has been replaced by a pyrimidopyridopyrrolidinetetraone (series D). In each series, the tricyclic nitrogen heterocyclic moiety has been synthesised by a one-pot multicomponent reaction. Compared to 7-DX used as control, 2d, 2l, 2p (series A), 28a (series D), and the open intermediate 30 showed modest to good activities. A kinetic study confirmed that the most active compounds 2d, 2p are competitive inhibitors. Molecular docking analysis confirmed the interaction of these new compounds at the active binding site of TP and highlighted a plausible specific interaction in a pocket that had not yet been explored.

Practical access to fluorescent 2,3-naphthalimide derivatives via didehydro-Diels-Alder reaction

A practical and efficient approach for the synthesis of fluorescent 2,3-naphthalimide derivatives has been developed from readily available starting materials via an intramolecular didehydro-Diels-Alder reaction, which proceeded well under room temperature, exhibiting a wide substrate scope and good functional group tolerance. The practicability of this methodology has been verified by one-step synthesis of the environmentally sensitive fluorophore 6-DMN on a gram scale with a shorter time, fewer steps and less waste disposal, and without the utilization of toxic transition metals. The present experimental and computational studies support the crucial role of the propiolimide moiety in the transformation.

Enantioselective Synthesis of a Tricyclic, sp3 -Rich Diazatetradecanedione: an Amino Acid-Based Natural Product-Like Scaffold

6-, 7-, and 8-membered rings are assembled from a linear precursor by successive cyclisation reactions to construct a tricyclic diazatricyclo[6.5.1.04, 9 ]-tetradecanedione scaffold. Advanced building blocks based on d-aspartic acid and l-pyroglutamic acid were combined by a sp3 -sp2 Negishi coupling. A carbamate-guided syn-diastereoselective epoxidation followed by an intramolecular epoxide opening allowed the construction of the piperidine ring. An efficient one-pot hydroxyl-group protection twofold deprotection reaction prepared the ground for the cyclisation to the bicycle. A final deprotection of the orthogonal protecting groups and lactamisation led to the novel, sp3 -rich tricycle. The final compound is a substrate mimic of peptidyl-prolyl cis-trans isomerases featuring a locked trans-amide bond. Cheminformatic analysis of 179 virtual derivatives indicates favourable physicochemical properties and drug-like characteristics. As proof of concept we, show a low micromolar activity in a fluorescence polarisation assay towards the FK506-binding protein 12.

Discovery and Pharmacophore Mapping of a Low-Nanomolar Inhibitor of P. falciparum Growth

The treatment of malaria, the most common parasitic disease worldwide and the third deadliest infection after HIV and tuberculosis, is currently compromised by the dramatic increase and diffusion of drug resistance among the various species of Plasmodium, especially P. falciparum (Pf). In this view, the development of new antiplasmodial agents that are able to act via innovative mechanisms of action, is crucial to ensure efficacious antimalarial treatments. In one of our previous communications, we described a novel class of compounds endowed with high antiplasmodial activity, characterized by a pharmacophore never described before as antiplasmodial and identified by their 4,4'-oxybisbenzoyl amide cores. Here, through a detailed structure-activity relationship (SAR) study, we thoroughly investigated the chemical features of the reported scaffolds and successfully built a novel antiplasmodial agent active on both chloroquine (CQ)-sensitive and CQ-resistant Pf strains in the low nanomolar range, without displaying cross-resistance. Moreover, we conducted an in silico pharmacophore mapping.

Stereoselective synthesis of unsaturated and functionalized L-NHBoc amino acids, using Wittig reaction under mild phase-transfer conditions

The stereoselective synthesis of a new amino acid phosphonium salt was described by quaternization of melting triphenylphosphine with the γ-iodo NHBoc-amino ester, derived from L-aspartic acid. The deprotection of the carboxylic acid function to afford the phosphonium salt with a free carboxylic acid group was achieved by a palladium-catalyzed desallylation reaction. This phosphonium salt was used in the Wittig reaction with aromatic or aliphatic aldehydes and trifluoroacetophenone, under solid-liquid phase-transfer conditions in chlorobenzene and in the presence of K(3)PO(4) as weak base, to afford the corresponding unsaturated amino acids without racemization. Thus, the reaction with substituted aldehydes allows to graft various functionalized groups on the lateral chain of the amino acid, such as trifluoromethyl, cyano, nitro, ferrocenyl, boronato, or azido. In addition, the reaction of the amino acid Wittig reagent with α,β-unsaturated aldehydes leads to amino acids bearing a diene on the lateral chain. Finally, this amino acid phosphonium salt appears to be a new powerful tool for the preparation of unsaturated and non-proteinogenic α-amino acids, directly usable for the synthesis of customized peptides.

"Clicktophycin-52": a bioactive cryptophycin-52 triazole analogue

An endocyclic trans-amide linkage within the macrocyclic antitumor agent cryptophycin-52 was replaced by a 1,4-disubstituted 1H-1,2,3-triazole ring. Macrocyclisation of the triazole analogue was accomplished by macrolactamization as well as by Cu(I)-mediated "click"-cyclization. Compared to cryptophycin-52, in vitro cytotoxicity of "clicktophycin-52" against the multidrug resistant human cancer cell line KB-V1 is only slightly reduced.

Design and synthesis of novel P2 substituents in diol-based HIV protease inhibitors

The synthesis and SAR of HIV-1 protease inhibitors containing novel P2 structural elements are presented. The inhibitors were designed having hydrogen bond accepting P2 substituents to probe potential favorable interactions to Asp-29/Asp-30 of the HIV-1 protease backbone utilizing inhibitor 3 as a model template. Several inhibitors were synthesized from an L-Val methyl amide P2 motif by appending hydrogen bonding moieties from either the isopropyl side-chain or from the methyl amide portion. The most promising inhibitors 4a and 4e displayed Ki values of 1.0 nM and 0.7 nM respectively and EC50 values in the MT4 cell-based assay of 0.17 microM and 0.33 microM respectively, a slight loss in potency compared to lead inhibitor 3. These inhibitors were also tested against an HIV protease inhibitor resistant strain carrying the M46I, V82F, and I84V mutations. Inhibitors 4a and 4e displayed a 3 and 4 fold change respectively compared with HIV wild type, whereas lead inhibitor 3 showed a higher 9 fold change. This study further demonstrate the chemical tractability of the approach where various P2 substituents can be introduced in just one chemical step from lactone 21 enabling facile modifications of the overall properties in this inhibitor class.

Efficient and Versatile Stereoselective Synthesis of Cryptophycins

The cryptophycins are a family of cyclic depsipeptides with four retrosynthetic units A to D which correspond to the respective amino acids and hydroxy acids. A new synthetic route to unit A allows the selective generation of all four stereogenic centres by introducing two of them in a catalytic asymmetric dihydroxylation, followed by substrate-controlled diastereoselective reactions. The diol also serves as the epoxide precursor. This approach provides selective access to stereoisomers of unit A (enantiomers, epimers) for structure-activity relationship studies. The unit A derivatives were incorporated into cryptophycin-1, cryptophycin-52 and a novel epimer of cryptophycin-52.

4-Anilino-3-cyanobenzo[g]quinolines as kinase inhibitors

A series of 4-anilino-3-cyanobenzo[g]quinolines was prepared as potent kinase inhibitors. Compared with their bicyclic 4-anilino-3-cyanoquinoline analogues, the tricyclic 4-anilino-3-cyanobenzo[g]quinolines are less active against EGF-R kinase, equally active against MAPK kinase (MEK), and more active against Src kinase. For Src kinase inhibition, the best activity is obtained when both the 7- and 8-positions are substituted with alkoxy groups. Several of these kinase inhibitors show potent growth inhibitory activity in tumor cells.

General synthesis of alpha-substituted 3-bisaryloxy propionic acid derivatives as specific MMP inhibitors

Modulations of alpha and aryl substitutions on 3-aryloxy propionic acid hydroxamates led to novel and potent inhibitors of MMP-2,3,9 and 13, and selectivity versus MMP-1.

Matrix metalloproteinase inhibitors

The matrix metalloproteinases (MMPs) are a family of at least fifteen secreted and membrane-bound zinc-endopeptidases. Collectively, these enzymes can degrade all of the components of the extracellular matrix, including fibrallar and non-fibrallar collagens, fibronectin, laminin and basement membrane glycoproteins. MMPs are thought to be essential for the diverse invasive processes of angiogenesis and tumor metastasis. Numerous studies have shown that there is a close association between expression of various members of the MMP family by tumors and their proliferative and invasive behavior and metastatic potential. In some of human cancers a positive correlation has also been demonstrated between the intensity of new blood vessel growth (angiogenesis) and the likelihood of developing metastases. Thus, control of MMP activity in these two different contexts has generated considerable interest as a possible therapeutic target. The tissue inhibitors of metalloproteinases (TIMPs) are naturally occurring proteins that specifically inhibit matrix metalloproteinases, thus maintaining balance between matrix destruction and formation. An imbalance between MMPs and the associated TIMPs may play a significant role in the invasive phenotype of malignant tumors. TIMP-1 has been shown to inhibit tumor-induced angiogenesis in experimental systems. These findings raised the possibility of using an agent that affects expression or activity of MMPs as an anti-cancer therapy. TIMPs are probably not suitable for pharmacologic applications due to their short half-life in vivo. Batimastat (BB-94) and marimastat (BB-2516) are synthetic, low-molecular weight MMP inhibitors. They have a collagen-mimicking hydroxamate structure, which facilitates chelation of the zinc ion in the active site of the MMPs. These compounds inhibit MMPs potently and specifically. Batimastat was the first synthetic MMP inhibitor studied in humans with advanced malignancies, but its usefulness has been limited by extremely poor water solubility, which required intraperitoneal administration of the drug as a detergent emulsion. Marimastat belongs to a second generation of MMP inhibitors. In contrast to batimastat, marimastat is orally available. Both of these agents are currently in Phase I/II trials in US, Europe and Canada. Some other new agents, currently in clinical trials, have been shown to inhibit MMP production. Bryostatins, naturally occurring macrocyclic lactones, have both in vitro and in vivo activity in numerous murine and human tumors. In culture, bryostatin-1 has been shown to induce differentiation and halt the growth of several malignant cell lines. While the exact mechanism responsible for anti-tumor activity is unclear, an initial event in the action of bryostatin-1 is activation of protein kinase C (PKC), followed by its down regulation. Bryostatin-1 does not directly affect the activity of MMPs, but it can inhibit the production of MMP-1, 3, 9, 10 and 11 by inhibiting PKC. TIMP-1 levels could also be modulated by bryostatin-1, as it is encoded by a PKC responsive gene.

Structure of the catalytic domain of fibroblast collagenase complexed with an inhibitor

Collagenase is a zinc-dependent endoproteinase and is a member of the matrix metalloproteinase (MMP) family of enzymes. The MMPs participate in connective tissue remodeling events and aberrant regulation has been associated with several pathologies. The 2.4 angstrom resolution structure of the inhibited enzyme revealed that, in addition to the catalytic zinc, there is a second zinc ion and a calcium ion which play a major role in stabilizing the tertiary structure of collagenase. Despite scant sequence homology, collagenase shares structural homology with two other endoproteinases, bacterial thermolysin and crayfish astacin. The detailed description of protein-inhibitor interactions present in the structure will aid in the design of compounds that selectively inhibit individual members of the MMP family. Such inhibitors will be useful in examining the function of MMPs in pathological processes.

Protease inhibitors: role and potential therapeutic use in human cancer

Proteases and protease inhibitors have been increasingly recognised as important factors in the physiopathology of human diseases, and our understanding of their role in cancer has dramatically increased over the last decade. We have obtained causal evidence linking proteases to tumour invasion and metastasis, and have become aware of genuine mechanisms used by tumour cells to optimise the use of proteases in the pericellular matrix. Many synthetic and natural inhibitors of these proteases have also been characterised, and their mechanisms of interaction with their corresponding enzymes are progressively unveiled as the X-ray crystal structures of these enzymes and their inhibitors are now reported. It has also become evident that many of these inhibitors, in addition to preventing the dissemination of cancer cells, have an inhibitory effect on tumour growth. Thus protease inhibitors are emerging as potentially therapeutic tools to treat cancer. In this article, recent studies on the role of proteases and their inhibitors in cancer are reviewed, and current ideas on their potential use as therapeutic agents are discussed.