Discovery of Selective Nanomolar Inhibitors for Insulin-Regulated Aminopeptidase Based on α-Hydroxy-β-amino Acid Derivatives of Bestatin.

The oxytocinase subfamily of M1 zinc aminopeptidases comprises emerging drug targets, including the ER-resident aminopeptidases 1 and 2 (ERAP1 and ERAP2) and insulin-regulated aminopeptidase (IRAP); however, reports on clinically relevant inhibitors are limited. Here we report a new synthetic approach of high diastereo- and regioselectivity for functionalization of the α-hydroxy-β-amino acid scaffold of bestatin. Stereochemistry and mechanism of inhibition were investigated by a high-resolution X-ray crystal structure of ERAP1 in complex with a micromolar inhibitor.

Design, Synthesis, and Biological Evaluation of Tubulysin Analogues, Linker-Drugs, and Antibody-Drug Conjugates, Insights into Structure-Activity Relationships, and Tubulysin-Tubulin Binding Derived from X-ray Crystallographic Analysis.

Molecular design, synthesis, and biological evaluation of tubulysin analogues, linker-drugs, and antibody-drug conjugates are described. Among the new discoveries reported is the identification of new potent analogues within the tubulysin family that carry a C11 alkyl ether substituent, rather than the usual ester structural motif at that position, a fact that endows the former with higher plasma stability than that of the latter. Also described herein are X-ray crystallographic analysis studies of two tubulin-tubulysin complexes formed within the α/β interface between two tubulin heterodimers and two highly potent tubulysin analogues, one of which exhibited a different binding mode to the one previously reported for tubulysin M.

Streamlined Symmetrical Total Synthesis of Disorazole B and Design, Synthesis, and Biological Investigation of Disorazole Analogues.

Taking advantage of the -symmetry of the antitumor naturally occurring disorazole B molecule, a symmetrical total synthesis was devised with a monomeric advanced intermediate as the key building block, whose three-step conversion to the natural product allowed for an expeditious entry to this family of compounds. Application of the developed synthetic strategies and methods provided a series of designed analogues of disorazole B, whose biological evaluation led to the identification of a number of potent antitumor agents and the first structure-activity relationships (SARs) within this class of compounds. Specifically, the substitutions of the epoxide units and lactone moieties with cyclopropyl and lactam structural motifs, respectively, were found to be tolerable for biological activities and beneficial with regard to chemical stability.

Exploration of zinc-binding groups for the design of inhibitors for the oxytocinase subfamily of M1 aminopeptidases.

The oxytocinase subfamily of M1 aminopeptidases consists of three members, ERAP1, ERAP2 and IRAP that play several important biological roles, including key functions in the generation of antigenic peptides that drive human immune responses. They represent emerging targets for pharmacological manipulation of the immune system, albeit lack of selective inhibitors is hampering these efforts. Most of the previously explored small-molecule binders target the active site of the enzymes via strong interactions with the catalytic zinc(II) atom and, while achieving increased potency, they suffer in selectivity.

Heterometallic In(III)-Pd(II) Porous Metal-Organic Framework with Square-Octahedron Topology Displaying High CO Uptake and Selectivity toward CH and N.

The targeted synthesis of metal-organic frameworks (MOFs) with open metal sites, following reticular chemistry rules, provides a straightforward methodology toward the development of advanced porous materials especially for gas storage/separation applications. Using a palladated tetracarboxylate metalloligand as a 4-connected node, we succeeded in synthesizing the first heterobimetallic In(III)/Pd(II)-based MOF with square-octahedron (soc) topology. The new MOF, formulated as [InO(L)(HO)Cl]·n(solv) (1), features the oxo-centered trinuclear clusters, [In(μ-O)(-COO)], acting as trigonal-prismatic 6-connected nodes that linked together with the metalloligand trans-[PdCl(PDC)] (L) (PDC: pyridine-3,5-dicarboxylate) to form a 3D network.

Improved Total Synthesis of Tubulysins and Design, Synthesis, and Biological Evaluation of New Tubulysins with Highly Potent Cytotoxicities against Cancer Cells as Potential Payloads for Antibody-Drug Conjugates.

Improved, streamlined total syntheses of natural tubulysins such as V (Tb45) and U (Tb46) and pretubulysin D (PTb-D43), and their application to the synthesis of designed tubulysin analogues (Tb44, PTb-D42, PTb-D47-PTb-D49, and Tb50-Tb120), are described. Cytotoxicity evaluation of the synthesized compounds against certain cancer cell lines revealed a number of novel analogues with exceptional potencies [e.g.

Crystal Structures of ERAP2 Complexed with Inhibitors Reveal Pharmacophore Requirements for Optimizing Inhibitor Potency.

Endoplasmic reticulum aminopeptidase 2 assists with the generation of antigenic peptides for presentation onto Major Histocompatibility Class I molecules in humans. Recent evidence has suggested that the activity of ERAP2 may contribute to the generation of autoimmunity, thus making ERAP2 a possible pharmacological target for the regulation of adaptive immune responses. To better understand the structural elements of inhibitors that govern their binding affinity to the ERAP2 active site, we cocrystallized ERAP2 with a medium activity 3,4-diaminobenzoic acid inhibitor and a poorly active hydroxamic acid derivative.

Exceptional gravimetric and volumetric CO2 uptake in a palladated NbO-type MOF utilizing cooperative acidic and basic, metal-CO2 interactions.

A novel NbO-type MOF is reported based on a palladated organic linker, showing a remarkable gravimetric and volumetric CO2 uptake, reaching 201.8 cm(3) g(-1) (9.0 mmol g(-1), 39.

Total Synthesis and Biological Evaluation of Natural and Designed Tubulysins.

A streamlined total synthesis of N(14)-desacetoxytubulysin H (Tb1) based on a C-H activation strategy and a short total synthesis of pretubulysin D (PTb-D43) are described. Applications of the developed synthetic strategies and technologies to the synthesis of a series of tubulysin analogues (Tb2-Tb41 and PTb-D42) are also reported. Biological evaluation of the synthesized compounds against an array of cancer cells revealed a number of novel analogues (e.

Synthesis and Biopharmaceutical Evaluation of Imatinib Analogues Featuring Unusual Structural Motifs.

A convenient synthesis of imatinib, a potent inhibitor of ABL1 kinase and widely prescribed drug for the treatment of a variety of leukemias, was devised and applied to the construction of a series of novel imatinib analogues featuring a number of non-aromatic structural motifs in place of the parent molecule's phenyl moiety. These analogues were subsequently evaluated for their biopharmaceutical properties (e.g.

3,4-diaminobenzoic acid derivatives as inhibitors of the oxytocinase subfamily of M1 aminopeptidases with immune-regulating properties.

Members of the oxytocinase subfamily of M1 aminopeptidases (ERAP1, ERAP2, and IRAP) play important roles in both the adaptive and innate human immune responses. Their enzymatic activity can contribute to the pathogenesis of several major human diseases ranging from viral and parasitic infections to autoimmunity and cancer. We have previously demonstrated that diaminobenzoic acid derivatives show promise as selective inhibitors for this group of aminopeptidases.

A zebrafish in vivo phenotypic assay to identify 3-aminothiophene-2-carboxylic acid-based angiogenesis inhibitors.

Abstract Small molecules that inhibit angiogenesis are attractive drug candidates for cancer, retinopathies, and age-related macular degeneration. In vivo, phenotypic screening in zebrafish (Danio rerio) emerges as a powerful methodology to identify and optimize novel compounds with pharmacological activity. Zebrafish provides several advantages for in vivo phenotypic screens especially for angiogenesis, since it develops rapidly, externally, and does not rely on a functional cardiovascular system to survive for several days during development.

Rigid spiroethers targeting the decoding center of the bacterial ribosome.

Continuing our efforts towards understanding the principles governing ribosomal recognition and function, we have synthesized and evaluated a series of diversely functionalized 5,6-, 6,6- and 7,6-spiroethers. These compounds successfully mimic natural aminoglycosides regarding their binding to the decoding center of the bacterial ribosome. Their potential to inhibit prokaryotic protein production in vitro along with their antibacterial potencies have also been examined.

Synthesis of triazole-functionalized 2-DOS analogues and their evaluation as A-site binders.

Aminoglycoside-antibiotics represent important tools for studying the biological functions of RNA. An orthogonal protection strategy applied on 2-deoxystreptamine (2-DOS) revealed a series of key intermediates that enable its regioselective functionalization. Our approach allowed the construction of selected representatives of triazole-containing analogues with diverse molecular frameworks for biological evaluation regarding their binding and antibacterial potencies.

Novel selective inhibitors of aminopeptidases that generate antigenic peptides.

Endoplasmic reticulum aminopeptidases, ERAP1 and ERAP2, as well as Insulin regulated aminopeptidase (IRAP) play key roles in antigen processing, and have recently emerged as biologically important targets for manipulation of antigen presentation. Taking advantage of the available structural and substrate-selectivity data for these enzymes, we have rationally designed a new series of inhibitors that display low micromolar activity. The selectivity profile for these three highly homologous aminopeptidases provides a promising avenue for modulating intracellular antigen processing.

Comparative CYP1A1 and CYP1B1 substrate and inhibitor profile of dietary flavonoids.

CYP1A1 and CYP1B1 are two extrahepatic enzymes that have been implicated in carcinogenesis and cancer progression. Selective inhibition of CYP1A1 and CYP1B1 by dietary constituents, notably the class of flavonoids, is a widely accepted paradigm that supports the concept of dietary chemoprevention. In parallel, recent studies have documented the ability of CYP1 enzymes to selectively metabolize dietary flavonoids to conversion products that inhibit cancer cell proliferation.

Probing the S1 specificity pocket of the aminopeptidases that generate antigenic peptides.

ERAP1 (endoplasmic reticulum aminopeptidase 1), ERAP2 and IRAP (insulin-regulated aminopeptidase) are three homologous enzymes that play critical roles in the generation of antigenic peptides. These aminopeptidases excise amino acids from N-terminally extended precursors of antigenic peptides in order to generate the correct length epitopes for binding on to MHC class I molecules. The specificity of these peptidases can affect antigenic peptide selection, but has not yet been investigated in detail.

A Homo sapiens cytoplasmic ribosomal decoding A-site affinity screen evaluating aminoglycoside and analogue binding.

The potential of aminoglycoside antibiotics to induce premature stop codon read-through in eukaryotic systems has been reported recently, inspiring the evaluation of structural alterations within the Homo sapiens cytoplasmic decoding center on ligand binding. Here we report the employment of an affinity screen capable of monitoring conformational changes of adenines 1492 and 1493 in solution. Thus, changes induced by the presence of a ligand can be directly translated to binding affinities for the eukaryotic decoding center.

Designed spiro-bicyclic analogues targeting the ribosomal decoding center.

The bacterial ribosome represents the confirmed biological target for many known antibiotics that interfere with bacterial protein synthesis. Aminoglycosides represent a lead paradigm in RNA molecular recognition and constitute ideal starting points for the design and synthesis of novel RNA binders. Previous rational design approaches of RNA-targeting small molecules have been mainly concentrated on direct functionalization of aminoglycosidic substructures.

Second generation analogs of rigid 6,7-spiro scaffolds targeting the bacterial ribosome.

Previous work from our group described the synthesis and biological evaluation of new rigid, 6,6- and 6,7-spiro aminoglycosidic scaffolds targeting the bacterial ribosome. Herein we describe an improved synthetic protocol for their construction, and extend our study by further amino-functionalization of their 6,7-spiro analogs. The synthetic strategy, preparation and evaluation of some representative examples are reported.

Dietary flavonoids in cancer therapy and prevention: substrates and inhibitors of cytochrome P450 CYP1 enzymes.

Flavonoids are polyphenolic compounds that have attracted the attention of the scientific community as the hallmark molecules responsible for cancer prevention by a plethora of different mechanisms. One of their most important characteristics, responsible for their cancer preventive properties, is their interaction with cytochrome P450 CYP1 enzymes. Flavonoids have traditionally been described as CYP1 inhibitors due to the inhibition of carcinogenic product formation and consequent blockage of the initiation stage of carcinogenesis.

Discovery of potent vascular endothelial growth factor receptor-2 inhibitors.

Substantial evidence over the last decades has implicated uncontrolled angiogenesis with various pathological states, including cancer. Vascular endothelial growth factor (VEGF) plays a critical role in its regulation. Because the tyrosine kinase VEGF receptor-2 (VEGFR-2) is the major mediator of the mitogenic, angiogenic, and permeability-enhancing effects of VEGF, it has become one of the most profound anti-angiogenesis targets.

Conformational dynamics of the EGFR kinase domain reveals structural features involved in activation.

The epidermal growth factor receptor (EGFR) has been the focus of intensive studies because of its importance in cancer research. Thus, a broader understanding of the molecular mechanism of activation of the EGFR kinase will have profound significance for the development of novel therapeutics. Numerous crystal structures of EGFR kinase, including the structure of the activating-kinase dimer, have provided snapshots of the specific pathway.