Design and synthesis of dual inhibitors for matrix metalloproteinase and cathepsin

Rational Multitargeted Drug Design Strategy from the Perspective of a Medicinal Chemist

The development of multitarget-directed ligands (MTDLs) has become a widely focused research topic, but rational design remains as an enormous challenge. This paper reviews and discusses the design strategy of incorporating the second activity into an existing single-active ligand. If the binding sites of both targets share similar endogenous substrates, MTDLs can be designed by merging two lead compounds with similar functional groups. If the binding sites are large or adjacent to the solution, two key pharmacophores can be fused directly. If the binding regions are small and deep inside the proteins, the linked-pharmacophore strategy might be the only way. The added pharmacophores of second targets should not affect the binding mode of the original ones. Moreover, the inhibitory activities of the two targets need to be adjusted to achieve an optimal ratio.

Synthesis and evaluation of 3-hydroxy-3-phenylpropanoate ester–AZT conjugates as potential dual-action HIV-1 Integrase and Reverse Transcriptase inhibitors

Novel 3-hydroxy-3-phenylpropanoate ester-azidothymidine (AZT) conjugates have been prepared using Baylis-Hillman methodology, and their potential as dual-action HIV-1 Integrase and Reverse Transcriptase inhibitors has been explored using enzyme inhibition and computer modelling techniques; their activity and HeLa cell toxicity have been compared with those of their cinnamate ester analogues.

Design and synthesis of potent hydroxamate inhibitors with increased selectivity within the gelatinase family

Triazole-based inhibitors with high potency and selectivity for MMP-2 were obtained through a click chemistry approach.

Novel peptidyl aryl vinyl sulfones as highly potent and selective inhibitors of cathepsins L and B

Herein we present the design, synthesis, and evaluation of a structurally novel library of 20 peptidyl 3-aryl vinyl sulfones as inhibitors of cathepsins L and B. The building blocks, described here for the first time, were synthesized in a highly efficient and enantioselective manner, starting from 3-aryl-substituted allyl alcohols. The corresponding vinyl sulfones were prepared by a new approach, based on a combination of solid-phase peptide synthesis using the Fmoc/tBu strategy, followed by solution-phase coupling to the corresponding (R)-3-amino-3-aryl vinyl sulfones as trifluoroacetate salts. The inhibitory activity of the resulting compounds against cathepsins L and B was evaluated, and the compound exhibiting the best activity was selected for enzymatic characterization. Finally, docking studies were performed in order to identify key structural features of the aryl substituent.

Cathepsin L in metastatic bone disease: therapeutic implications

Cathepsin L is a lysosomal cysteine proteinase primarily devoted to the metabolic turnover of intracellular proteins. However, accumulating evidence suggests that this endopeptidase might also be implicated in the regulation of other important biological functions, including bone resorption in normal and pathological conditions. These findings support the concept that cathepsin L, in concert with other proteolytic enzymes involved in bone remodeling processes, could contribute to facilitate bone metastasis formation. In support of this hypothesis, recent studies indicate that cathepsin L can foster this process by triggering multiple mechanisms which, in part, differ from those of the major cysteine proteinase of osteoclasts, namely cathepsin K. Therefore, cathepsin L can be regarded as an additional target in the treatment of patients with metastatic bone disease. This review discusses the clinical and therapeutic implications related to these findings.

Rationally designed dual inhibitors of HIV reverse transcriptase and integrase

Bifunctional inhibitors were designed and synthesized based on 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT)a1 non-nucleoside reverse transcriptase (RT) inhibitors and diketoacid (DKA) integrase (IN) inhibitors. Biochemical studies revealed activity against RT and IN at low nanomolar and low micromolar concentrations, respectively. Exceptionally low IC50 values from a cell-based assay were achieved along with remarkably high therapeutic indices. Compound 7 was identified as the best compound of the series (IC50: 24 nM against RT, 4.4 microM against IN, and 10 nM against HIV-1).

Chemogenomics in drug discovery

Chemogenomics is a new strategy in drug discovery which, in principle, searches for all molecules that are capable of interacting with any biological target. Because of the almost infinite number of drug-like organic molecules, this is an impossible task. Therefore chemogenomics has been defined as the investigation of classes of compounds (libraries) against families of functionally related proteins. In this definition, chemogenomics deals with the systematic analysis of chemical-biological interactions. Congeneric series of chemical analogs are probes to investigate their action on specific target classes, e.g., GPCRs, kinases, phosphodiesterases, ion channels, serine proteases, and others. Whereas such a strategy developed in pharmaceutical industry almost 20 years ago, it is now more systematically applied in the search for target- and subtype-specific ligands. The term "privileged structures" has been defined for scaffolds, such as the benzodiazepines, which very often produce biologically active analogs in a target family, in this case in the class of G-protein-coupled receptors. The SOSA approach is a strategy to modify the selectivity of biologically active compounds, generating new drug candidates from the side activities of therapeutically used drugs.

Pharmacological Effects of ATI22-107 [2-(2-{2-[2-Chloro-4-(6-oxo-1,4,5,6-tetrahydro-pyridazin-3-yl)-phenoxy]-acetylamino}-ethoxymethyl)-4-(2-chloro-phenyl)-6-methyl-1,4-dihydro-pyridine-3,5-dicarboxylic Acid Dimethyl Ester)], a Novel Dual Pharmacophore, on Myocyte Calcium Cycling and Contractility

Historically, inhibitors of type III phosphodiesterases (PDE-III) have been effective inotropes in mammalian myocardium, but their clinical utility has been limited by adverse events, including arrhythmias that are considered to be due to Ca(2+) overload. ATI22-107 [2-(2-{2-[2-chloro-4-(6-oxo-1,4,5,6-tetrahydro-pyridazin-3-yl)-phenoxy]-acetylamino}-ethoxymethyl)-4-(2-chlorophenyl)-6-methyl-1,4-dihydro-pyridine-3,5-dicarboxylic acid dimethyl ester)], a novel, dual pharmacophore compound, was designed to simultaneously inhibit the cardiac phosphodiesterase (PDE-III) and produce inotropic effects, whereas inhibiting the L-type calcium channel (LTCC) was designed to minimize increases in diastolic Ca(2+). We compared the effects of ATI22-107 and enoximone, a pure PDE-III inhibitor, on the Fluo-3 calcium transient in normal feline ventricular myocytes and trabeculae. Enoximone-induced dose-dependent increases in peak [Ca(2+)](i), diastolic [Ca(2+)](i), T50, and T75. ATI22-107 demonstrated similar dose-dependent increases in peak [Ca(2+)](i) at 300 nM and 1.0 microM doses, with no further increases at higher doses. Throughout the dosing range, ATI22-107 induced much smaller, if any, increases in diastolic [Ca(2+)](i), T(25), and T(75). Current measurement of LTCC via patch-clamp techniques revealed dose-dependent decreases in LTCC current with an increasing dose of ATI22-107, thereby validating the dual functionality of the drug that has been proposed in this study. Studies in isolated trabeculae demonstrated that enoximone-induced a dose-dependent augmentation of the entire force-frequency relation in normal myocardium, whereas augmentation of contractility was only observed at lower stimulation frequencies with ATI22-107. These results demonstrate the effects of the LTCC-antagonizing moiety of ATI22-107 and suggest that the novel simultaneous combination of PDE-III and LTCC inhibition by one molecule may produce a favorable profile of limited inotropy without detrimental effects of increased diastolic [Ca(2+)](i).

From magic bullets to designed multiple ligands

Increasingly, it is being recognised that a balanced modulation of several targets can provide a superior therapeutic effect and side effect profile compared to the action of a selective ligand. Rational approaches in which structural features from selective ligands are combined have produced designed multiple ligands that span a wide variety of targets and target classes. A key challenge in the design of multiple ligands is attaining a balanced activity at each target of interest while simultaneously achieving a wider selectivity and a suitable pharmacokinetic profile. An analysis of literature examples reveals trends and insights that might help medicinal chemists discover the next generation of these types of compounds.

Recent advances in the synthesis, design and selection of cysteine protease inhibitors

Inhibition of cysteine proteases is emerging as an important strategy for the treatment of a variety of human diseases. Intense efforts involving structure-based inhibitor design have been directed toward several cysteine proteases, including cathepsin K, calpain, human rhinovirus 3C protease and several parasitic cysteine protease targets. Other successful recent efforts have involved combinatorial synthesis and screening for identification of new inhibitor templates.