N-hydroxy-2-(naphthalene-2-ylsulfanyl)-acetamide, a novel hydroxamic acid-based inhibitor of aminopeptidase N and its anti-angiogenic activity

Synthesis, structural characterization, and DFT studies of anti-cancer drug N-(2-Aminophenyl)-2-(4-bromophenoxy)acetamide

Drug design is an integrated and developing system that portends an era of a novel and safe tailored drugs. It involves studying the effects of biologically active synthetic, semi-synthetic, and natural compounds based on molecular interactions in terms of molecular structure with activated functional groups or its unique physicochemical properties involved. The title compound, N-(2-aminophenyl)-2-(4-bromophenoxy) acetamide (c), was synthesized in a good yield and characterized by different spectroscopic techniques (1H, 13CNMR, and LC-MS) and finally, the structure was confirmed by X-ray diffraction (XRD) studies. The XRD data confirms that the cryatal structure is orthorhombic with space group of Pca2 1 . The intermolecular interactions (N-H … O and N-H … Cg) inside the molecule stabilizes the crystal structure. The existence of this intermolecular interactions are computed by the Hirshfeld surfaces (HS) and two-dimensional (2D) fingerprints plot analysis. In addition to this, Energy frame work analysis is performed to quantify the interaction energies between the molecular pairs in a crystal by incorporating new version of CrystalExplorer17 using the energy model of HF/3-21G. Also to calculate the HOMO and LUMO energies, DFT calculations were carried out.

Aminobenzosuberone Scaffold as a Modular Chemical Tool for the Inhibition of Therapeutically Relevant M1 Aminopeptidases

The synthesis of racemic substituted 7-amino-5,7,8,9-tetrahydrobenzocyclohepten-6-one hydrochlorides was optimized to enhance reproducibility and increase the overall yield. In order to investigate their specificity, series of enzyme inhibition assays were carried out against a diversity of proteases, covering representative members of aspartic, cysteine, metallo and serine endopeptidases and including eight members of the monometallic M1 family of aminopeptidases as well as two members of the bimetallic M17 and M28 aminopeptidase families. This aminobenzosuberone scaffold indeed demonstrated selective inhibition of M1 aminopeptidases to the exclusion of other tested protease families; it was particularly potent against mammalian APN and its bacterial/parasitic orthologues EcPepN and PfAM1.

Establishment of a screening protocol for identification of aminopeptidase N inhibitors

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Two pharmacophore models have been developed.

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Virtual screening was performed by the pharmacophore models and docking.

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Six selected hits were discovered to have inhibitory activities.

Inhibitors of aminopeptidase N (APN) have been thought as potential drugs for the treatment of tumor angiogenesis, invasion and metastasis and a considerable number of APN inhibitors have been reported recently. To clarify the essential structure–activity relationship for the APN inhibitors as well as identify new potent leads against APN, pharmacophore models were established using structure- and common feature-based approaches and validated with a database of active and inactive compounds. These validated pharmacophores were then used in database screening for novel virtual leads. The hit compounds were further subjected to molecular docking studies to refine the retrieved hits. Finally, six structurally diverse compounds that showed strong interactions with the key amino acids and the zinc ion were selected for biological evaluation, where two hits showed more than 70% inhibition against APN at 60 μM concentration. The evaluation results show the potential of our screening approach in identifying APN inhibitors.

The sphingosine-1-phosphate derivative NHOBTD inhibits angiogenesis both in vitro and in vivo

Sphingosine-1-phosphate (S1P) plays an important role in angiogenesis by stimulating DNA synthesis, chemotactic motility, and early blood vessel formation. Accordingly, the S1P signaling pathway is an attractive target for novel anti-angiogenic therapeutics. Here, we describe a small synthetic derivative of S1P that acts as an anti-angiogenic agent. We found that the S1P derivative NHOBTD [N-((2S,3R)-3-hydroxy-1-morpholino-4-(3-octylphenyl)butan-2-yl)tetradecanamide] suppressed S1P-induced invasion and tube formation by human umbilical vein endothelial cells. NHOBTD also suppressed S1P signaling, as seen by destabilization of hypoxia inducible factor-1 alpha (HIF-1α) and secretion of VEGF, a transcriptional target of HIF-1α. Moreover, NHOBTD profoundly blocked endogenous neovascularization of the chick embryo chorioallantoic membrane, without rupturing any existing vessels. Together, these results demonstrate that NHOBTD is a new anti-angiogenic molecule that is capable of perturbing S1P signaling, and provides the basis for developing new anti-angiogenic drugs.

Aminopeptidase N (EC 3.4.11.2) inhibitors (2006 - 2010): a patent review

INTRODUCTION

Aminopeptidase N (APN/CD13) acts as an exopeptidase and has been studied for decades. In recent years, it has been seen not only as a tumor-related target but also as a potential functional protein in various other physiological or pathological processes, such as analgesia, virus infection and inflammation.

AREAS COVERED

In this review, APN inhibitors in the patents publicized during 2006 - 2010 are introduced. Readers will gain information on the patent inhibitors, including chemical structures, original sources or synthetic methods, biological assays and application potential.

EXPERT OPINION

It is difficult to identify compounds that interact with the function not relevant with peptide-hydrolysis of APN in the enzyme activity assay, and such compounds have not been reported in the patents during the past 5 years. The progress of protein-small molecule interaction detecting means, such as surface plasmon resonance, will possibly help develop such compounds for the treatment of relevant diseases or new molecular probes in mechanism investigation.

Metallo-aminopeptidase inhibitors

Aminopeptidases are enzymes that selectively hydrolyze an amino acid residue from the N-terminus of proteins and peptides. They are important for the proper functioning of prokaryotic and eukaryotic cells, but very often are central players in the devastating human diseases like cancer, malaria and diabetes. The largest aminopeptidase group include enzymes containing metal ion(s) in their active centers, which often determines the type of inhibitors that are the most suitable for them. Effective ligands mostly bind in a non-covalent mode by forming complexes with the metal ion(s). Here, we present several approaches for the design of inhibitors for metallo-aminopeptidases. The optimized structures should be considered as potential leads in the drug discovery process against endogenous and infectious diseases.

Aminopeptidase-N/CD13 (EC 3.4.11.2) inhibitors: chemistry, biological evaluations, and therapeutic prospects

Aminopeptidase N (APN)/CD13 (EC 3.4.11.2) is a transmembrane protease present in a wide variety of human tissues and cell types (endothelial, epithelial, fibroblast, leukocyte). APN/CD13 expression is dysregulated in inflammatory diseases and in cancers (solid and hematologic tumors). APN/CD13 serves as a receptor for coronaviruses. Natural and synthetic inhibitors of APN activity have been characterized. These inhibitors have revealed that APN is able to modulate bioactive peptide responses (pain management, vasopressin release) and to influence immune functions and major biological events (cell proliferation, secretion, invasion, angiogenesis). Therefore, inhibition of APN/CD13 may lead to the development of anti-cancer and anti-inflammatory drugs. This review provides an update on the biological and pharmacological profiles of known natural and synthetic APN inhibitors. Current status on their potential use as therapeutic agents is discussed with regard to toxicity and specificity.

Discovery of a Dual-Function Peptide That Combines Aminopeptidase N Inhibition and Kinin B1Receptor Antagonism

Previous analyses support that aminopeptidase N is a major inactivation pathway for high-affinity peptide ligands of the human and rabbit forms of the kinin B(1) receptor (agonists or antagonists). In this study, we found that the high-affinity antagonist B-9958 (Lys-Lys-[Hyp(3), CpG(5), D-Tic(7), CpG(8)]des-Arg(9)-BK; des-Arg(9)-BK, des-arginine(9)-bradykinin) is an aminopeptidase N substrate based on its capacity to compete for the hydrolysis of the chromogenic substrate L-Ala-p-nitroanilide by membranes isolated from human or rabbit arterial smooth muscle cells, its inactivation in the presence of these membranes (radioreceptor assay) and on its intense potentiation by the aminopeptidase N inhibitor amastatin in the rabbit aorta contractility assay (gain of 0.84 units in the pA(2) scale). Analogs of B-9958 in which the N-terminal Lys residue was substituted by D-Lys or D-Arg (B-10352 and B-10356, respectively) showed reduced affinity at the human or rabbit B(1) receptors (1.2-2.8-fold), as estimated by the displacement of [(3)H]Lys-des-Arg(9)-BK binding, but were more potent antagonists of des-Arg(9)-BK-induced contraction of the rabbit aorta than B-9958 in the absence of amastatin; they were not potentiated by the latter inhibitor. Unexpectedly, B-10356 inhibited L-Ala- p-nitroanilide hydrolysis without being inactivated, suggesting that it is an aminopeptidase N inhibitor. This was verified because B-10356 (but not B-10352) potentiated peptides unrelated to kinins but susceptible to aminopeptidase N inactivation (angiotensin III, thrombin receptor hexapeptide agonist). B-10356 inhibits dual molecular targets (aminopeptidase N enzyme K(i), 0.9-2.2 microM; kinin B(1) receptor binding K(i), 0.5-1.5 nM), and this may be an advantage for specific therapeutic applications (e.g., inhibition of angiogenesis).