Michael Kelso

Diarylacylhydrazones: Clostridium-selective antibacterials with activity against stationary-phase cells

Publisher: Elsevier BV

Date: 2014

DOI: 10.1016/J.BMCL.2013.12.015

Tooth development and replacement in the Atlantic Cutlassfish, Trichiurus lepturus, with comparisons to other Scombroidei

Publisher: Wiley

Date: 17-12-2018

DOI: 10.1002/JMOR.20919

Abstract: Atlantic Cutlassfish, Trichiurus lepturus, have large, barbed, premaxillary and dentary fangs, and sharp dagger-shaped teeth in their oral jaws. Functional teeth firmly ankylose to the dentigerous bones. We used dry skeletons, histology, SEM, and micro-CT scanning to study 92 specimens of T. lepturus from the western North Atlantic to describe its dentition and tooth replacement. We identified three modes of intraosseous tooth replacement in T. lepturus depending on the location of the tooth in the jaw. Mode 1 relates to replacement of premaxillary fangs, in which new tooth germs enter the lingual surface of the premaxilla, develop horizontally, and rotate into position. We suggest that growth of large fangs in the premaxilla is accommodated by this horizontal development. Mode 2 occurs for dentary fangs: new tooth germs enter the labial surface of the dentary, develop vertically, and erupt into position. Mode 3 describes replacement of lateral teeth, in which new tooth germs enter a trench along the crest of the dentigerous bone, develop vertically, and erupt into position. Such distinct modes of tooth replacement in a teleostean species are unknown. We compared modes of replacement in T. lepturus to 20 species of scombroids to explore the phylogenetic distribution of these three replacement modes. Alternate tooth replacement (in which new teeth erupt between two functional teeth), ankylosis, and intraosseous tooth development are plesiomorphic to Bluefish + other Scombroidei. Our study highlights the complexity and variability of intraosseous tooth replacement. Within tooth replacement systems, key variables include sites of formation of tooth germs, points of entry of tooth germs into dentigerous bones, coupling of tooth germ migration and bone erosion, whether teeth develop horizontally or immediately beneath the tooth to be replaced, and how tooth eruption and ankylosis occur. Developmentally different tooth replacement processes can yield remarkably similar dentitions.

The first solution stucture of a single α-helical turn. A pentapeptide α-helix stabilized by a metal clip [20]

Publisher: American Chemical Society (ACS)

Date: 10-2000

DOI: 10.1021/JA002416I

Anti-malarial effect of histone deacetylation inhibitors and mammalian tumour cytodifferentiating agents

Publisher: Elsevier BV

Date: 05-2000

DOI: 10.1016/S0020-7519(00)00043-6

Abstract: The histones of Plasmodium falciparum represent a potential new target for anti-malarial compounds. A naturally occurring compound, apicidin, has recently been shown to inhibit the in vitro growth of P. falciparum. Apicidin was shown to hyperacetylate histones, suggesting that its mode of action is through histone deacetylase inhibition. We have tested the ability of known histone deacetylase inhibitors, mammalian tumour suppressor compounds, and cytodifferentiating agents to inhibit the in vitro growth of a drug sensitive and resistant strain of P. falciparum. Seven of the tested compounds had microM IC50 values, and trichostatin A, a histone deacetylation inhibitor and cytodifferentiating agent, was active at low nM concentrations. One compound, suberic acid bisdimethylamide, which selectively arrests tumour cells as opposed to normal mammalian cells, had an in vivo cytostatic effect against the acute murine malaria Plasmodium berghei, and one round of treatment with the compound failed to select for resistant mutations. These results suggest a promising role for histone deacetylase inhibitors and cytodifferentiating agents as antimalarial drug candidates.

Catalytic Enantioselective Conjugate Addition of Carbamates

Publisher: American Chemical Society (ACS)

Date: 09-07-2004

DOI: 10.1021/JA047004E

Abstract: Catalytic, asymmetric conjugate addition of carbamates to enoyl systems has been realized for the first time, providing a two-step access to virtually enantiopure N-protected beta-amino acids.

Novel cylindrical, conical, and macrocyclic peptides from the cyclooligomerization of functionalized thiazole amino acids [2]

Publisher: American Chemical Society (ACS)

Date: 19-12-2001

DOI: 10.1021/JA002666Z

Roles of the Na⁺/H⁺ Exchanger Isoform 1 and Urokinase in Prostate Cancer Cell Migration and Invasion

Publisher: MDPI AG

Date: 09-12-2021

DOI: 10.3390/IJMS222413263

Abstract: Prostate cancer is a leading cause of cancer-associated deaths in men over 60 years of age. Most patients are killed by tumor metastasis. Recent evidence has implicated a role of the tumor microenvironment and urokinase plasminogen activator (uPA) in cancer cell migration, invasion, and metastasis. Here, we examine the role of the Na+/H+ exchanger isoform 1 (NHE1) and uPA in DU 145 prostate cancer cell migration and colony formation. Knockout of NHE1 reduced cell migration. The effects of a series of novel NHE1/uPA hexamethylene-amiloride-based inhibitors with varying efficacy towards NHE1 and uPA were examined on prostate cancer cells. Inhibition of NHE1—alone, or with inhibitors combining NHE1 or uPA inhibition—generally did not prevent prostate cancer cell migration. However, uPA inhibition—but not NHE1 inhibition—prevented anchorage-dependent colony formation. Application of inhibitors at concentrations that only saturate uPA inhibition decreased tumor invasion in vivo. The results suggest that while knockout of NHE1 affects cell migration, these effects are not due to NHE1-dependent proton translocation. Additionally, while neither NHE1 nor uPA activity was critical in cell migration, only uPA activity appeared to be critical in anchorage-dependent colony formation of DU 145 prostate cancer cells and invasion in vivo.

Cephalosporin-NO-donor prodrug PYRRO-C3D shows β-lactam - mediated activity against Streptococcus pneumoniae biofilms

Publisher: Elsevier BV

Date: 05-2017

DOI: 10.1016/J.NIOX.2017.02.006

Abstract: Bacterial biofilms show high tolerance towards antibiotics and are a significant problem in clinical settings where they are a primary cause of chronic infections. Novel therapeutic strategies are needed to improve anti-biofilm efficacy and support reduction in antibiotic use. Treatment with exogenous nitric oxide (NO) has been shown to modulate bacterial signaling and metabolic processes that render biofilms more susceptible to antibiotics. We previously reported on cephalosporin-3'-diazeniumdiolates (C3Ds) as NO-donor prodrugs designed to selectively deliver NO to bacterial infection sites following reaction with β-lactamases. With structures based on cephalosporins, C3Ds could, in principal, also be triggered to release NO following β-lactam cleavage mediated by transpeptidases enicillin-binding proteins (PBPs), the antibacterial target of cephalosporin antibiotics. Transpeptidase-reactive C3Ds could potentially show both NO-mediated anti-biofilm properties and intrinsic (β-lactam-mediated) antibacterial effects. This dual-activity concept was explored using Streptococcus pneumoniae, a species that lacks β-lactamases but relies on transpeptidases for cell-wall synthesis. Treatment with PYRRO-C3D (a representative C3D containing the diazeniumdiolate NO donor PYRRO-NO) was found to significantly reduce viability of planktonic and biofilm pneumococci, demonstrating that C3Ds can elicit direct, cephalosporin-like antibacterial activity in the absence of β-lactamases. While NO release from PYRRO-C3D in the presence of pneumococci was confirmed, the anti-pneumococcal action of the compound was shown to arise exclusively from the β-lactam component and not through NO-mediated effects. The compound showed similar potency to amoxicillin against S. pneumoniae biofilms and greater efficacy than azithromycin, highlighting the potential of C3Ds as new agents for treating pneumococcal infections.

Synthesis of an anthracyclinone bearing an unprecedented aromatic ring-fused bridgehead-hydroxylated bicyclo[3.1.1]heptanol

Publisher: Elsevier BV

Date: 10-2007

DOI: 10.1016/J.TETLET.2007.08.080

Linkage isomerism in the binding of pentapeptide Ac-His(Ala) 3His-NH2 to (ethylenediamine)palladium(II): Effect of the binding mode on peptide conformation

Publisher: American Chemical Society (ACS)

Date: 13-09-2008

DOI: 10.1021/IC800970P

Abstract: The reaction of the pentapeptide Ac-His1-Ala2-Ala3-Ala4-His5-NH2 (AcHAAAHNH2) (1) with [Pd(en)(ONO2)2] (en = NH2CH2CH2NH2) in either DMF-d(7) or H2O:D2O (90%:10%) gave three linkage isomers of [Pd(en)(AcHAAAHNH2)](2+) (2), 2a, 2b, and 2c, which differ only in which pair of imidazole nitrogen atoms bind to Pd. In the most abundant isomer, 2a, Pd is bound by N1 from each of the two imidazole rings. In the minor isomers 2b and 2c, Pd is bound by N1(His1) and N3(His5) and by N3(His1) and N1(His5), respectively. The reactions of [Pd(en)(ONO2)2] with the N-methylated peptides Ac-(N3-MeHis)-Ala-Ala-Ala-(N3-MeHis)-NH2 (AcH*AAAH*NH2) (3), Ac-(N3-MeHis)-Ala-Ala-Ala-(N1-MeHis)-NH2 (AcH(*)AAAH(#)NH2) (4), and Ac-(N1-MeHis)-Ala-Ala-Ala-(N3-Me-His)-NH2 (AcH(#)AAAH(*)NH2) (5) each gave a single species [Pd(en)(peptide)](2+) in N,N-dimethylformamide (DMF) or aqueous solution, 7, 8, and 9, respectively, with Pd bound by the two nonmethylated imidazole nitrogen atoms in each case. These complexes were analogous to 2a, 2b, and 2c, respectively. Ac-(N1-MeHis)-Ala-Ala-Ala-(N1-MeHis)-NH2 (AcH(#)AAAH(#)NH2) (6) with [Pd(en)(ONO2)2] in DMF slowly gave a single product, [Pd(en)(AcH(#)AAAH(#)NH2)](2+) (10), in which Pd was bound by the N3 of each imidazole ring. The corresponding linkage isomer of 2 was not observed. Complex 10 was also the major product in aqueous solution, but other species were also present. All compounds were exhaustively characterized in solution by multinuclear 1D ((1)H , (13)C, and, with (15)N-labeled ethylenediamine, (15)N) and 2D (correlation spectroscopy, total correlation spectroscopy, transverse rotating-frame Overhauser effect spectroscopy (T-ROESY), heteronuclear multiple-bond correlation, and heteronuclear single quantum coherence) NMR spectra, circular dichroism (CD) spectra, electrospray mass spectroscopy, and reversed-phase high-performance liquid chromatography. ROESY spectra were used to calculate the structure of 2a, which contained a single turn of a peptide alpha helix in both DMF and water, the helix being better defined in DMF. The Pd(en)(2+) moiety was not used in structure calculations, but its location and coordination by one imidazole N1 from each histidine to form a 22-membered metallocycle were unambiguously established. Convergence of the structures was greatest when calculated with two hydrogen-bond constraints (Ala4 peptide NH...OC acetyl and His5 peptide NH...OC-His1) that were indicated by the low temperature dependence of these NH chemical shifts. Vicinal HN-CHalpha coupling constants and chemical shifts of alpha-H atoms were also consistent with a helical conformation. Similar long-range ROE correlations were observed for [Pd(en)(AcH(*)AAAH(*)NH2)](2+) (7), which displayed a CD spectrum in aqueous solution that suggested the presence of some helicity. Long-range ROE correlations were not observed for 8, 9, or 10, but a combination of NMR data and CD spectroscopy was interpreted in terms of the conformational behavior of the coordinated pentapeptide. Only for the linkage isomer [Pd(en)(AcH(*)AAAH(#)NH2)](2+) (8) was there evidence of a contribution from a helical conformation. The data for 8 were interpreted as interconversion between the helix and random coil conformations. Zn(2+) with peptides gave broad NMR peaks attributed to lability of this metal ion, while reactions of cis-[Pt(NH3)2(ONO2)2] were slow, giving a complex mixture of products rather than the macrochelate ring observed with Pd(en)(2+). In summary, these studies indicate that Pd(en)(2+) coordinates to histidine with similar preference for each of the two imidazole nitrogens, enabling the formation of up to four linkage isomers in its complexes with pentapeptides His-xxx-His. Only the N1-N1 linkage isomer that forms a 22-membered macrochelate ring is able to induce an alpha-helical peptide conformation, whereas the 20- and 21-membered rings of linkage isomers do not. This suggests that linkage isomeric mixtures may compromise histidine coordination to metal ions and reduce alpha-helicity.

Peptides and small molecules targeting the plasminogen activation system: Towards prophylactic anti-metastasis drugs for breast cancer

Publisher: Bentham Science Publishers Ltd.

Date: 2008

DOI: 10.2174/157489208783478711

Abstract: Breast cancer is the most common malignancy afflicting Western women today and is responsible for many deaths due to metastatic disease. Upregulation of the plasminogen-activation system (PAS) has been shown to correlate with poor prognosis in metastatic breast cancer and targeting this system represents an attractive strategy for the development of anti-metastasis prophylactic drugs. Two promising classes of PAS-targeting agents are inhibitors of the serine protease activity of urokinase plasminogen activator (uPA) and antagonists of the interaction of uPA with its cell surface receptor (uPAR). This review begins with a brief overview of the role of PAS in cancer metastasis before describing in detail a subset of the small molecules and peptides from the patent literature that target either uPA activity or uPA/uPAR interactions for use as anti-metastasis drugs.

Raf-kinase inhibitor GW5074 shows antibacterial activity against methicillin-resistant Staphylococcus aureus and potentiates the activity of gentamicin

Publisher: Future Science Ltd

Date: 10-2016

DOI: 10.4155/FMC-2016-0104

Abstract: Aim: Increasing antimicrobial resistance has compromised the effectiveness of many antibiotics, including those used to treat staphylococcal infections like methicillin-resistant Staphylococcus aureus. The development of combination therapies, where antimicrobial agents are used with compounds that inhibit resistance pathways is a promising strategy. Results/methodology: The Raf kinase inhibitor GW5074 exhibited selective in vitro activity against Gram-positive bacteria, including clinical isolates of S. aureus with a minimum inhibitory concentration (MIC) of 2–8 µg/ml. GW5074 was effective in vivo in the Galleria mellonella infection model. The compound showed synergy with gentamicin by lowering MIC by fourfold, compared with gentamicin MIC alone. Conclusion: This work demonstrates the antimicrobial properties of GW5074 and supports further investigation of the kinase inhibitors as antibiotic adjuvants.

Automated patch clamp screening of amiloride and 5-N,N-hexamethyleneamiloride (HMA) analogs identifies 6-iodoamiloride as a potent acid-sensing ion channel inhibitor

Publisher: Cold Spring Harbor Laboratory

Date: 14-03-2022

DOI: 10.1101/2022.03.12.484055

Abstract: Acid-sensing ion channels (ASICs) are transmembrane sensors of extracellular acidosis and potential drug targets in several disease indications, including neuropathic pain and cancer metastasis. The K + -sparing diuretic amiloride is a moderate non-specific inhibitor of ASICs and has been widely used as a probe for elucidating ASIC function. In this work, we screened a library of 6-substituted and 5,6-disubstituted amiloride analogs using a custom-developed automated patch-cl protocol and identified 6-iodoamiloride as a more potent ASIC1 inhibitor. Follow-up IC 50 determinations in tsA-201 cells confirmed higher ASIC1 inhibitory potency for 6-iodoamiloride 97 (hASIC1 97 IC 50 88 nM cf. amiloride 11 IC 50 1.7 μM). A similar improvement in activity was observed in ASIC3-mediated currents from rat small diameter dorsal root ganglion neurons (rDRG single-concentration 97 IC 50 230 nM cf. 11 IC 50 2.7 μM). 6-iodoamiloride represents the amiloride analogue of choice for studying the effects of ASIC inhibition on cell physiology.

Determination of ester position in isomeric (O-acyl)-hydroxy fatty acids by ion trap mass spectrometry

Publisher: Wiley

Date: 25-09-2016

DOI: 10.1002/RCM.7715

Abstract: (O-acyl)-hydroxy fatty acids (OAHFAs) are a recently discovered class of endogenous lipids, generating significant interest for their correlation with enhanced glucose tolerance. Structural variants that differ in the position of the ester linkage have been described, including the ω-OAHFA sub-class, that plays a key role in stabilizing the human tear film. Developing analytical tools for rapid and unambiguous structural elucidation of OAHFAs is essential to understanding their erse physiological functions. Commercially available and synthesized OAHFA standards were dissolved in chloroform and subsequently diluted into methanol with 1.5 mM ammonium acetate. Negative ion collision-induced dissociation (CID) MS Major product ions observed during CID of [OAHFA - H] A mechanistic rationale is provided to explain the unimolecular dissociation of [OAHFA - H]

Introduction of a Fixed-Charge, Photolabile Derivative for Enhanced Structural Elucidation of Fatty Acids

Publisher: American Chemical Society (ACS)

Date: 12-07-2019

DOI: 10.1021/ACS.ANALCHEM.9B01566

Abstract: Fatty acids are a structurally erse category of lipids with a myriad of biochemical functions, which includes their role as building blocks of more complex lipids (e.g., glycerophospholipids and triacylglycerols). Increasingly, the analysis of fatty acids is undertaken using liquid chromatography-mass spectrometry (LC-MS), due to its versatility in the detection of lipids across a wide range of concentrations and ersity of molecular structures and masses. Previous work has shown that fixed-charge pyridinium derivatives are effective in enhancing the detection of fatty acids in LC-MS workflows. Herein, we describe the development of two novel pyridinium fixed-charged derivatization reagents that incorporate a photolabile aryl iodide that is selectively activated by laser irradiation inside the mass spectrometer. Photodissociation mass spectra of fatty acids conjugated to 1-(3-(aminomethyl)-4-iodophenyl)pyridin-1-ium (4-I-AMPP

Small molecule antagonists of the urokinase (uPA): urokinase receptor (uPAR) interaction with high reported potencies show only weak effects in cell-based competition assays employing the native uPAR

Publisher: Elsevier BV

Date: 04-2011

DOI: 10.1016/J.BMC.2011.03.016

Abstract: Binding of the urokinase-type plasminogen activator (uPA) to its cell-surface-bound receptor uPAR and upregulation of the plasminogen activation system (PAS) correlates with increased metastasis and poor prognosis in several tumour types. Disruptors of the uPA:uPAR interaction represent promising anti-tumour/metastasis agents and several approaches have been explored for this purpose, including the use of small molecule antagonists. Two highly potent non-peptidic antagonists 1 and 2 (IC(50)1=0.8 nM, IC(50)2=33 nM) from the patent literature were reportedly identified using competition assays employing radiolabelled uPAR-binding uPA fragments and appeared as useful pharmacological tools for studying the PAS. Before proceeding to such studies, confirmation was sought that 1 and 2 retained their potencies in physiologically relevant cell-based competition assays employing uPAR's native binding partner high molecular weight uPA (HMW-uPA). This study describes a new solution phase synthesis of 1, a mixed solid/solution phase synthesis of 2 and reports the activities of 1 and 2 in semi-quantitative competition flow cytometry assays and quantitative cell-based uPA activity assays that employed HMW-uPA as the competing ligand. The flow cytometry experiments revealed that high concentrations of 2 (10-100 μM) are required to compete with HMW-uPA for uPAR binding and that 1 shows no antagonist effects at 100 μM. The cell-based enzyme activity assays similarly revealed that 1 and 2 are poor inhibitors of cell surface-bound HMW-uPA activity (IC(50) >100 μM for 1 and 2). The report highlights the dangers of identifying false-positive lead uPAR antagonists from competition assays employing labelled competing ligands other than the native HMW-uPA.

Synthesis of cephalosporin-3′-diazeniumdiolates: Biofilm dispersing NO-donor prodrugs activated by β-lactamase

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3CC40869H

Abstract: Use of biofilm dispersing NO-donor compounds in combination with antibiotics has emerged as a promising new strategy for treating drug-resistant bacterial biofilm infections. This paper details the synthesis and preliminary evaluation of six cephalosporin-3'-diazeniumdiolates as biofilm-targeted NO-donor prodrugs. Each of the compounds is shown to selectively release NO following reaction with the bacteria-specific enzyme β-lactamase and to trigger dispersion of Pseudomonas aeruginosa biofilms in vitro.

Disruption of Water Networks is the Cause of Human/Mouse Species Selectivity in Urokinase Plasminogen Activator (uPA) Inhibitors Derived from Hexamethylene Amiloride (HMA)

Publisher: American Chemical Society (ACS)

Date: 13-12-2021

DOI: 10.1021/ACS.JMEDCHEM.1C01423

Abstract: The urokinase plasminogen activator (uPA) plays a critical role in tumor cell invasion and migration and is a promising antimetastasis target. 6-Substituted analogues of 5-

Bacterial Sliding Clamp Inhibitors that Mimic the Sequential Binding Mechanism of Endogenous Linear Motifs

Publisher: American Chemical Society (ACS)

Date: 28-05-2015

DOI: 10.1021/ACS.JMEDCHEM.5B00232

Abstract: The bacterial DNA replication machinery presents new targets for the development of antibiotics acting via novel mechanisms. One such target is the protein-protein interaction between the DNA sliding cl and the conserved peptide linear motifs in DNA polymerases. We previously established that binding of linear motifs to the Escherichia coli sliding cl occurs via a sequential mechanism that involves two subsites (I and II). Here, we report the development of small-molecule inhibitors that mimic this mechanism. The compounds contain tetrahydrocarbazole moieties as "anchors" to occupy subsite I. Functional groups appended at the tetrahydrocarbazole nitrogen bind to a channel gated by the side chain of M362 and lie at the edge of subsite II. One derivative induced the formation of a new binding pocket, termed subsite III, by rearrangement of a loop adjacent to subsite I. Discovery of the extended binding area will guide further inhibitor development.

Mass spectrometry-directed structure elucidation and total synthesis of ultra-long chain (O-acyl)-ω-hydroxy fatty acids

Publisher: Elsevier BV

Date: 08-2018

DOI: 10.1194/JLR.M086702

Conformationally homogeneous cyclic tetrapeptides: Useful new three-dimensional scaffolds

Publisher: American Chemical Society (ACS)

Date: 18-12-2003

DOI: 10.1021/JA029205T

Abstract: The most commonly recognized motifs in protein-protein interactions are gamma and beta turns, which are defined by three to four contiguous amino acids in a peptide sequence. Cyclic tetrapeptides thus represent minimalist turn mimetics, but their usefulness is compromised by strain in their 12-membered rings, making them difficult to cyclize, unstable to hydrolysis/metabolism, and conformationally heterogeneous in polar solvents. Appropriate placement of a beta amino acid in a tetrapeptide creates a 13-membered ring that is shown to be easier to cyclize, hydrolytically more stable, and conformationally homogeneous in polar solvents such as DMSO and water. Three-dimensional structures reveal that these cyclic tetrapeptides are novel rigid scaffolds, their unique side-chain projections matching a structurally erse range of useful nonpeptidic templates, including sugars and spirocyclic compounds, found as components of natural products. The results provide a potentially useful link between protein architecture and organic natural products. On the basis of protein turn sequences (not protein structures) alone simple cyclic tetrapeptide libraries with a beta amino acid can be rationally designed as conformationally restricted, easily synthesized, and stereochemically controlled screening tools for rapidly identifying pharmacophore space that can then be computer-matched to more complex known natural product templates for drug development.

A cyclic metallopeptide induces α helicity in short peptide fragments of thermolysin

Publisher: Wiley

Date: 27-01-2003

DOI: 10.1002/ANIE.200390128

5′-Substituted Amiloride Derivatives as Allosteric Modulators Binding in the Sodium Ion Pocket of the Adenosine A_2A Receptor

Publisher: American Chemical Society (ACS)

Date: 10-05-2016

DOI: 10.1021/ACS.JMEDCHEM.6B00142

Abstract: The sodium ion site is an allosteric site conserved among many G protein-coupled receptors (GPCRs). Amiloride 1 and 5-(N,N-hexamethylene)amiloride 2 (HMA) supposedly bind in this sodium ion site and can influence orthosteric ligand binding. The availability of a high-resolution X-ray crystal structure of the human adenosine A2A receptor (hA2AAR), in which the allosteric sodium ion site was elucidated, makes it an appropriate model receptor for investigating the allosteric site. In this study, we report the synthesis and evaluation of novel 5'-substituted amiloride derivatives as hA2AAR allosteric antagonists. The potency of the amiloride derivatives was assessed by their ability to displace orthosteric radioligand [(3)H]4-(2-((7-amino-2-(furan-2-yl)-[1,2,4]triazolo[1,5-a]-[1,3,5]triazin-5-yl)amino)ethyl)phenol ([(3)H]ZM-241,385) from both the wild-type and sodium ion site W246A mutant hA2AAR. 4-Ethoxyphenethyl-substituted amiloride 12l was found to be more potent than both amiloride and HMA, and the shift in potency between the wild-type and mutated receptor confirmed its likely binding to the sodium ion site.

Structure-activity relationships of pyrazole-4-carbodithioates as antibacterials against methicillin–resistant Staphylococcus aureus

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.BMCL.2018.09.038

6-Substituted Hexamethylene Amiloride (HMA) Derivatives as Potent and Selective Inhibitors of the Human Urokinase Plasminogen Activator for Use in Cancer

Publisher: American Chemical Society (ACS)

Date: 21-08-2018

DOI: 10.1021/ACS.JMEDCHEM.8B00838

Crystal structures and biochemical characterization of DNA sliding clamps from three Gram-negative bacterial pathogens

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.JSB.2018.10.008

Abstract: Bacterial sliding cl s bind to DNA and act as protein-protein interaction hubs for several proteins involved in DNA replication and repair. The partner proteins all bind to a common pocket on sliding cl s via conserved linear peptide sequence motifs, which suggest the pocket as an attractive target for development of new antibiotics. Herein we report the X-ray crystal structures and biochemical characterization of β sliding cl s from the Gram-negative pathogens Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacter cloacae. The structures reveal close similarity between the pathogen and Escherichia coli cl s and similar patterns of binding to linear cl -binding motif peptides. The results suggest that linear motif-sliding cl interactions are well conserved and an antibiotic targeting the sliding cl should have broad-spectrum activity against Gram-negative pathogens.

Low-Dose Nitric Oxide as Targeted Anti-biofilm Adjunctive Therapy to Treat Chronic Pseudomonas aeruginosa Infection in Cystic Fibrosis

Publisher: Elsevier BV

Date: 09-2017

DOI: 10.1016/J.YMTHE.2017.06.021

Berberine-INF55 (5-nitro-2-phenylindole) hybrid antimicrobials: Effects of varying the relative orientation of the berberine and INF55 components

Publisher: American Society for Microbiology

Date: 08-2010

DOI: 10.1128/AAC.01715-09

Abstract: Hybrid antimicrobials containing an antibacterial linked to a multidrug resistance (MDR) pump inhibitor make up a promising new class of agents for countering efflux-mediated bacterial drug resistance. This study explores the effects of varying the relative orientation of the antibacterial and efflux pump inhibitor components in three isomeric hybrids (SS14, SS14-M, and SS14-P) which link the antibacterial alkaloid and known substrate for the NorA MDR pump berberine to different positions on INF55 (5-nitro-2-phenylindole), an inhibitor of NorA. The MICs for all three hybrids against wild-type, NorA-knockout, and NorA-overexpressing Staphylococcus aureus cells were found to be similar (9.4 to 40.2 μM), indicating that these compounds are not effectively effluxed by NorA. The three hybrids were also found to have similar curing effects in a Caenorhabditis elegans live infection model. Each hybrid was shown to accumulate in S. aureus cells to a greater extent than either berberine or berberine in the presence of INF55, and the uptake kinetics of SS14 were found to differ from those of SS14-M and SS14-P. The effects on the uptake and efflux of the NorA substrate ethidium bromide into S. aureus cells in the presence or absence of the hybrids were used to confirm MDR inhibition by the hybrids. MDR-inhibitory activity was confirmed for SS14-M and SS14-P but not for SS14. Molecular dynamics simulations revealed that SS14 prefers to adopt a conformation that is not prevalent in either SS14-M or SS14-P, which may explain why some properties of SS14 erge from those of its two isomers. In summary, subtle repositioning of the pump-blocking INF55 moiety in berberine-INF55 hybrids was found to have a minimal effect on their antibacterial activities but to significantly alter their effects on MDR pumps.

Antibacterial Properties of Four Novel Hit Compounds from a Methicillin-ResistantStaphylococcus aureus–Caenorhabditis elegansHigh-Throughput Screen

Publisher: Mary Ann Liebert Inc

Date: 06-2018

DOI: 10.1089/MDR.2017.0250

Activity of a novel protonophore against methicillin-resistant Staphylococcus aureus

Publisher: Future Science Ltd

Date: 08-2017

DOI: 10.4155/FMC-2017-0047

Abstract: Aim: Compound 1-(4-chlorophenyl)-4,4,4-trifluoro-3-hydroxy-2-buten-1-one (compound 1) was identified as a hit against methicillin-resistant Staphylococcus aureus (MRSA) strain MW2. Methods & results: The MIC of compound 1 against MRSA was 4 μg/ml. The compound showed enhanced activity at acidic pH by lowering bacterial intracellular pH and exhibited no lysis of human red blood cells at up to 64 μg/ml and its IC 50 against HepG2 cells was 32 μg/ml. The compound reduced 1-log 10 colony forming units of intracellular MRSA in macrophages and prolonged the survival of MRSA-infected Caenorhabditis elegans (p = 0.0015) and Galleria mellonella (p = 0.0002). Conclusion: Compound 1 is a protonophore with potent in vitro and in vivo activity against MRSA and no toxicity in mammalian cells up to 8 μg/ml that warrants further investigation as a novel antibacterial.

DNA Replication Is the Target for the Antibacterial Effects of Nonsteroidal Anti-Inflammatory Drugs

Publisher: Elsevier BV

Date: 04-2014

DOI: 10.1016/J.CHEMBIOL.2014.02.009

Abstract: Evidence suggests that some nonsteroidal anti-inflammatory drugs (NSAIDs) possess antibacterial properties with an unknown mechanism. We describe the in vitro antibacterial properties of the NSAIDs carprofen, bromfenac, and vedaprofen, and show that these NSAIDs inhibit the Escherichia coli DNA polymerase III β subunit, an essential interaction hub that acts as a mobile tether on DNA for many essential partner proteins in DNA replication and repair. Crystal structures show that the three NSAIDs bind to the sliding cl at a common binding site required for partner binding. Inhibition of interaction of the cl loader and/or the replicative polymerase α subunit with the sliding cl is demonstrated using an in vitro DNA replication assay. NSAIDs thus present promising lead scaffolds for novel antibacterial agents targeting the sliding cl .

A mass spectrometric investigation of novel quadruplex DNA-selective berberine derivatives

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/C0CC01933J

Abstract: ESI mass spectrometry was used to assess the binding of 13-substituted, 5-nitro-2-phenylindolyl- and 2-naphthalenyl-based berberine derivatives to inter- and intramolecular G-quadruplex DNA molecules. In contrast with the parent berberine, the compounds showed selectivity for quadruplex over duplex DNA and stabilised the quadruplex structure. They represent a new class of quadruplex DNA-selective ligands.

Synthesis and preliminary evaluation of 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones as angiogenesis inhibitors.

Publisher: Elsevier BV

Date: 04-2016

DOI: 10.1016/J.BMCL.2016.02.033

Abstract: Sunitinib (Sutent®) is a receptor tyrosine kinase (RTK) and angiogenesis inhibitor approved for the treatment of renal cell carcinomas, gastrointestinal stromal tumours and pancreatic neuroendocrine tumours. A key structural motif retained throughout medicinal chemistry efforts during sunitinib's development was the indoline-2-one group. In the search for new anti-angiogenic scaffolds, we previously reported that non-indoline-2-one-based derivatives of semaxanib (SU5416, a structurally simpler sunitinib predecessor that underwent Phase III trials) are active as angiogenesis inhibitors, indicating that the group is not essential for activity. This Letter describes the synthesis and structure-activity relationships of another class of non-indoline-2-one angiogenesis inhibitors related to sunitinib/semaxanib the 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones. A focussed library of 19 analogues was prepared using a simple novel process, wherein commercially available substituted arylacetic acids activated with an amide coupling reagent (HBTU) were reacted with the potassium salt of 3,5-dimethyl-1H-pyrrole-2-carbaldehyde in one-pot. Screening of the library using a cell-based endothelial tube formation assay identified 6 compounds with anti-angiogenesis activity. Two of the compounds were advanced to the more physiologically relevant rat aortic ring assay, where they showed similar inhibitory effects to semaxanib at 10μg/mL, confirming that 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones represent a new class of angiogenesis inhibitors.

Synthesis of berberineefflux pump inhibitor hybrid antibacterials

Publisher: Informa UK Limited

Date: 03-11-2010

DOI: 10.1080/00397910903457415

Anti-tumour/metastasis effects of the potassium-sparing diuretic amiloride: An orally active anti-cancer drug waiting for its call-of-duty?

Publisher: Wiley

Date: 08-2011

DOI: 10.1002/IJC.26156

Abstract: Amiloride.HCl is clinically used as an oral potassium-sparing diuretic, but multiple studies in biochemical, cellular and animal models have shown that the drug also possesses anti-tumour and anti-metastasis activities. The additional effects appear to arise through inhibition of two discrete targets: (i) the sodium-hydrogen exchanger 1 (NHE1), a membrane protein responsible for the characteristically low extracellular pH of tumours and (ii) the urokinase-type plasminogen activator (uPA), a serine protease mediator of cell migration, invasion and metastasis and well-known marker of poor prognosis in cancer. This mini-review summarises for the first time the reported anti-tumour/metastasis effects of amiloride in experimental models, discusses the putative molecular mechanisms responsible for these effects and concludes by commenting on the pros and cons of trialling amiloride or one of its structural analogues as potential new anti-tumour/metastasis drugs.

Antibacterial properties of 3-(phenylsulfonyl)-2-pyrazinecarbonitrile

Publisher: Elsevier BV

Date: 11-2015

DOI: 10.1016/J.BMCL.2015.09.066

Oxidative coupling of indoles using thallium(III) trifluoroacetate

Publisher: Elsevier BV

Date: 08-2008

DOI: 10.1016/J.TET.2008.05.133

Synthesis and preliminary evaluation of amiloride analogs as inhibitors of the urokinase-type plasminogen activator (uPA)

Publisher: Elsevier BV

Date: 11-2011

DOI: 10.1016/J.BMCL.2011.09.044

Abstract: A known side-activity of the oral potassium-sparing diuretic drug amiloride is inhibition of the enzyme urokinase-type plasminogen activator (uPA, K(i)=7 μM), a promising anticancer target. Several studies have demonstrated significant antitumor/metastasis properties for amiloride in animal cancer models and it would appear that these arise, at least in part, through inhibition of uPA. Selective optimization of amiloride's structure for more potent inhibition of uPA and loss of diuretic effects would thus appear as an attractive strategy towards novel anticancer agents. The following report is a preliminary structure-activity exploration of amiloride analogs as inhibitors of uPA. A key finding was that the well-studied 5-substituted analogs ethylisopropyl amiloride (EIPA) and hexamethylene amiloride (HMA) are approximately twofold more potent than amiloride as uPA inhibitors.

Strategies to Potentiate Antimicrobial Photoinactivation by Overcoming Resistant Phenotypes^†

Publisher: Wiley

Date: 13-02-2012

DOI: 10.1111/J.1751-1097.2012.01087.X

Synthesis of thioridazine-VLA-4 antagonist hybrids usingN-propargyl northioridazine enantiomers

Publisher: Informa UK Limited

Date: 02-07-2020

DOI: 10.1080/00397911.2020.1785503

Discovery of Cephalosporin-3′-Diazeniumdiolates That Show Dual Antibacterial and Antibiofilm Effects against Pseudomonas aeruginosa Clinical Cystic Fibrosis Isolates and Efficacy in a Murine Re

Publisher: American Chemical Society (ACS)

Date: 24-04-2020

DOI: 10.1021/ACSINFECDIS.0C00070

An amiloride derivative is active against the F1Fo-ATP synthase and cytochrome bd oxidase of Mycobacterium tuberculosis

Publisher: Springer Science and Business Media LLC

Date: 24-02-2022

DOI: 10.1038/S42003-022-03110-8

Abstract: Increasing antimicrobial resistance compels the search for next-generation inhibitors with differing or multiple molecular targets. In this regard, energy conservation in Mycobacterium tuberculosis has been clinically validated as a promising new drug target for combatting drug-resistant strains of M. tuberculosis . Here, we show that HM2-16F, a 6-substituted derivative of the FDA-approved drug amiloride, is an anti-tubercular inhibitor with bactericidal properties comparable to the FDA-approved drug bedaquiline (BDQ Sirturo ® ) and inhibits the growth of bedaquiline-resistant mutants. We show that HM2-16F weakly inhibits the F 1 F o -ATP synthase, depletes ATP, and affects the entry of acetyl-CoA into the Krebs cycle. HM2-16F synergizes with the cytochrome bcc-aa 3 oxidase inhibitor Q203 (Telacebec) and co-administration with Q203 sterilizes in vitro cultures in 14 days. Synergy with Q203 occurs via direct inhibition of the cytochrome bd oxidase by HM2-16F. This study shows that amiloride derivatives represent a promising discovery platform for targeting energy generation in drug-resistant tuberculosis.

Unexpected synthesis of 3-imino-2-(pyrrol-2-yl) isatogen derivatives affords facile access to a 2-pyrrolyl isatogen

Publisher: Informa UK Limited

Date: 02-12-2017

DOI: 10.1080/00397911.2016.1249290

Structure-activity relationships of 2-aryl-1H-indole inhibitors of the NorA efflux pump in Staphylococcus aureus

Publisher: Elsevier BV

Date: 08-2008

DOI: 10.1016/J.BMCL.2008.06.093

Anti-tumour activity in vitro and in vivo of selective differentiating agents containing hydroxamate

Publisher: Springer Science and Business Media LLC

Date: 28-05-1999

DOI: 10.1038/SJ.BJC.6690493

Helical cyclic pentapeptides constrain HIV-1 Rev peptide for enhanced RNA binding

Publisher: Elsevier BV

Date: 10-2014

DOI: 10.1016/J.TET.2014.06.059

A comparison of patient matched meibum and tear lipidomes

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 11-11-2013

DOI: 10.1167/IOVS.13-12916

Abstract: To quantify the molecular lipid composition of patient-matched tear and meibum s les and compare tear and meibum lipid molecular profiles. Lipids were extracted from tears and meibum by bi-phasic methods using 10:3 tert-butyl methyl ether:methanol, washed with aqueous ammonium acetate, and analyzed by chip-based nanoelectrospray ionization tandem mass spectrometry. Targeted precursor ion and neutral loss scans identified in idual molecular lipids and quantification was obtained by comparison to internal standards in each lipid class. Two hundred and thirty-six lipid species were identified and quantified from nine lipid classes comprised of cholesterol esters, wax esters, (O-acyl)-ω-hydroxy fatty acids, triacylglycerols, phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and phosphatidylserine. With the exception of phospholipids, lipid molecular profiles were strikingly similar between tears and meibum. Comparisons between tears and meibum indicate that meibum is likely to supply the majority of lipids in the tear film lipid layer. However, the observed higher mole ratio of phospholipid in tears shows that analysis of meibum alone does not provide a complete understanding of the tear film lipid composition.

Clostridium difficileinfection: molecular pathogenesis and novel therapeutics

Publisher: Informa UK Limited

Date: 2014

DOI: 10.1586/14787210.2014.866515

Conformationally Constrained Macrocycles That Mimic Tripeptide β-Strands in Water and Aprotic Solvents

Publisher: American Chemical Society (ACS)

Date: 24-04-2002

DOI: 10.1021/JA0256461

Abstract: The beta-strand conformation is unknown for short peptides in aqueous solution, yet it is a fundamental building block in proteins and the crucial recognition motif for proteolytic enzymes that enable formation and turnover of all proteins. To create a generalized scaffold as a peptidomimetic that is pre-organized in a beta-strand, we in idually synthesized a series of 15-22-membered macrocyclic analogues of tripeptides and analyzed their structures. Each cycle is highly constrained by two trans amide bonds and a planar aromatic ring with a short nonpeptidic linker between them. A measure of this ring strain is the restricted rotation of the component tyrosinyl aromatic ring (DeltaG(rot) 76.7 kJ mol(-1) (16-membered ring), 46.1 kJ mol(-1) (17-membered ring)) evidenced by variable temperature proton NMR spectra (DMF-d(7), 200-400 K). Unusually large amide coupling constants ((3)J(NH-CHalpha) 9-10 Hz) corresponding to large dihedral angles were detected in both protic and aprotic solvents for these macrocycles, consistent with a high degree of structure in solution. The temperature dependence of all amide NH chemical shifts (Deltadelta/T 7-12 ppb/deg) precluded the presence of transannular hydrogen bonds that define alternative turn structures. Whereas similar sized conventional cyclic peptides usually exist in solution as an equilibrium mixture of multiple conformers, these macrocycles adopt a well-defined beta-strand structure even in water as revealed by 2-D NMR spectral data and by a structure calculation for the smallest (15-membered) and most constrained macrocycle. Macrocycles that are sufficiently constrained to exclusively adopt a beta-strand-mimicking structure in water may be useful pre-organized and generic templates for the design of compounds that interfere with beta-strand recognition in biology.

On the mechanism of berberine-INF55 (5-Nitro-2-phenylindole) hybrid antibacterials

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/CH14426

Abstract: Berberine–INF55 hybrids are a promising class of antibacterials that combine berberine and the NorA multidrug resistance pump inhibitor INF55 (5-nitro-2-phenylindole) together in one molecule via a chemically stable linkage. Previous studies demonstrated the potential of these compounds for countering efflux-mediated antibacterial drug resistance but they didn’t establish whether the compounds function as originally intended, i.e. with the berberine moiety providing antibacterial activity and the attached INF55 component independently blocking multidrug resistance pumps, thereby enhancing the activity of berberine by reducing its efflux. We hypothesised that if the proposed mechanism is correct, then hybrids carrying more potent INF55 pump inhibitor structures should show enhanced antibacterial effects relative to those bearing weaker inhibitors. Two INF55 analogues showing graded reductions in NorA inhibitory activity compared with INF55 were identified and their corresponding berberine–INF55 hybrids carrying equivalent INF55 inhibitor structures synthesised. Multiple assays comparing the antibacterial effects of the hybrids and their corresponding berberine–INF55 analogue combinations showed that the three hybrids all show very similar activities, leading us to conclude that the antibacterial mechanism(s) of berberine–INF55 hybrids is different from berberine–INF55 combinations.

Propyl-5-hydroxy-3-methyl-1-phenyl-1H-pyrazole-4-carbodithioate (HMPC): a new bacteriostatic agent against methicillin—resistant Staphylococcus aureus

Publisher: Springer Science and Business Media LLC

Date: 04-05-2018

DOI: 10.1038/S41598-018-25571-W

Abstract: The emergence of Staphylococcus aureus strains resistant to ‘last resort’ antibiotics compels the development of new antimicrobials against this important human pathogen. We found that propyl 5-hydroxy-3-methyl-1-phenyl-1 H -pyrazole-4-carbodithioate (HMPC) shows bacteriostatic activity against S. aureus (MIC = 4 μg/ml) and rescues Caenorhabditis elegans from S. aureus infection. Whole-genome sequencing of S. aureus mutants resistant to the compound, along with screening of a S. aureus promoter- lux reporter array, were used to explore possible mechanisms of action. All mutants resistant to HMPC acquired missense mutations at distinct codon positions in the global transcriptional regulator mgrA , followed by secondary mutations in the phosphatidylglycerol lysyltransferase fmtC/mprF . The S. aureus promoter- lux array treated with HMPC displayed a luminescence profile that was unique but showed similarity to DNA-damaging agents and/or DNA replication inhibitors. Overall, HMPC is a new anti-staphylococcal compound that appears to act via an unknown mechanism linked to the global transcriptional regulator MgrA.

On the stability of a single-turn α-helix: The single versus multiconformation problem

Publisher: American Chemical Society (ACS)

Date: 24-12-2003

DOI: 10.1021/JA0278279

Abstract: The pentapeptide Ac-HAAAH-NH2, cyclized through its imidazoles by PdII to give [Pd(en)(peptide)]2+, has recently been evaluated by 2-D NMR and simulated annealing as a single alpha-helix conformation in solution. In the present work, we have questioned this assumption by developing Pd2+ parameters for AMBER*, performing an extensive conformational search for the [Pd(en)(peptide)]2+, and deconvoluting the averaged NMR data into eight rapidly equilibrating conformations with populations ranging from 2 to 55%. None of the latter correspond to the alpha-helix, although a 3% form possesses a related structure. As a critical component of interpreting an averaged NMR spectrum in terms of a single conformation, we advise testing this assumption with a method that permits conformational deconvolution.

Synthesis, Structural Characterisation, and Preliminary Evaluation of Non-Indolin-2-one-based Angiogenesis Inhibitors Related to Sunitinib (Sutent®)

Publisher: CSIRO Publishing

Date: 2013

DOI: 10.1071/CH13219

Abstract: The indolin-2-one fused-ring system and the 2,4-dimethylpyrrole unit represent key structural motifs in the anticancer drug sunitinib (Sutent®) and predecessor angiogenesis inhibitors that have undergone anticancer clinical trials (e.g. semaxanib, SU5416). In pursuit of novel anti-angiogenic scaffolds, we were interested in identifying whether the indolin-2-one group in these structures could be modified without losing activity. This paper describes novel condensation chemistry used to prepare a test series of (E)- and (Z)-alkenes related to SU5416 that retain the 2,4-dimethylpyrrole unit while incorporating ring-opened indolin-2-ones. Unique structural characteristics were identified in the compounds, such as intramolecular hydrogen bonds in the (Z)-alkenes, and several ex les were shown to possess significant anti-angiogenic activity in a rat aorta in vitro model of angiogenesis. The work demonstrates that the indolin-2-one moiety is not an absolute requirement for angiogenesis inhibition in the sunitinib/SU5416 class.

Characterization of Five Novel Anti-MRSA Compounds Identified Using a Whole-Animal Caenorhabditis elegans/Galleria mellonella Sequential-Screening Approach

Publisher: MDPI AG

Date: 27-07-2020

DOI: 10.3390/ANTIBIOTICS9080449

Abstract: There is a significant need to combat the growing challenge of antibacterial drug resistance. We have previously developed a whole-animal dual-screening platform that first used the nematode Caenorhabditis elegans, to identify low-toxicity antibacterial hits in a high-throughput format. The hits were then evaluated in the wax moth caterpillar Galleria mellonella infection model to confirm efficacy and low toxicity at a whole animal level. This multi-host approach is a powerful tool for revealing compounds that show antibacterial effects and relatively low toxicity at the whole organism level. This paper reports the use of the multi-host approach to identify and validate five new anti-staphylococcal compounds: (1) 4,4′,4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol(PPT), (2) (1S,2S)-2-[2-[[3-(1H-benzimidazol-2-yl)propyl]methylamino]ethyl]-6-fluoro-1,2,3,4-tetrahydro-1-(1-methylethyl)-2-naphthalenyl cyclopropanecarboxylate dihydrochloride(NNC), (3) 4,5,6,7-tetrabromobenzotriazole (TBB), (4) 3-[2-[2-chloro-4-[3-(2,6-dichlorophenyl)-5-(1-methylethyl)-4-isoxazolyl]methoxy]phenyl]ethenyl] benzoic acid(GW4064), and (5) N-(cyclopropylmethoxy)-3,4,5-trifluoro-2-[(4-iodo-2-methylphenyl)amino] benzamide(PD198306). The compounds reduced the severity of methicillin-resistant Staphylococcus aureus (MRSA, strain MW2) infections in both C. elegans and G. mellonella and showed minimal inhibitory concentrations (MICs) in the range of 2–8 µg/mL. Compounds NNC, PPT, and TBB permeabilized MRSA-MW2 cells to SYTOX green, suggesting that they target bacterial membranes. Compound TBB showed synergistic activity with doxycycline and oxacillin against MRSA-MW2, and compounds PPT, NNC, GW4064, and PD198306 synergized with doxycycline, polymyxin-B, gentamicin, and erythromycin, respectively. The study demonstrates the utility of the multi-host approach with follow-up hit characterization for prioritizing anti-MRSA compounds for further evaluation.

Cephalosporin-3'-diazeniumdiolates: targeted NO-donor prodrugs for dispersing bacterial biofilms.

Publisher: Wiley

Date: 13-08-2012

DOI: 10.1002/ANIE.201202414

Attaching NorA efflux pump inhibitors to methylene blue enhances antimicrobial photodynamic inactivation of Escherichia coli and Acinetobacter baumannii in vitro and in vivo

Publisher: Elsevier BV

Date: 09-2018

DOI: 10.1016/J.BMCL.2018.02.041

Automated Patch Clamp Screening of Amiloride and 5-N,N-Hexamethyleneamiloride Analogs Identifies 6-Iodoamiloride as a Potent Acid-Sensing Ion Channel Inhibitor

Publisher: American Chemical Society (ACS)

Date: 06-2023

DOI: 10.1021/ACS.MOLPHARMACEUT.2C01083

α-Turn Mimetics: Short Peptide α-Helices Composed of Cyclic Metallopentapeptide Modules

Publisher: American Chemical Society (ACS)

Date: 26-03-2004

DOI: 10.1021/JA037980I

Abstract: Alpha-Helices are key structural components of proteins and important recognition motifs in biology. Short peptides (<or=15 residues) corresponding to these helical sequences are rarely helical away from their stabilizing protein environments. New techniques for stabilizing short peptide helices could be valuable for studying protein folding, modeling proteins, creating artificial proteins, and may aid the design of inhibitors or mimics of protein function. This study reports the facile incorporation of 3- and 4-alpha turns in 10-15 residue peptides through formation in situ of multiple cyclic metallopeptide modules [Pd(en)(H*XXXH*)](2+). The nonhelical peptides Ac-H*ELTH*H*VTDH*-NH(2) (1), Ac-H*ELTH*AVTDYH*ELTH*-NH(2) (2), and Ac-H*AAAH*HELTH*H*VTDH*-NH(2) (3) (H is histidine-methylated at imidazole-N3) react in N,N-dimethylformamide (DMF) or water with 2, 2, and 3 molar equivalents, respectively, of [Pd(en)(NO(3))(2)] to form exclusively [Pd(2)(en)(2)(Ac-H*ELTH*H*VTDH*-NH(2))](4+) (4), [Pd(2)(en)(2)(Ac-H*ELTH*AVTDYH*ELTH*-NH(2))](4+) (5), and [Pd(3)(en)(3)(Ac-H*AAAH*HELTH*H*VTDH*-NH(2))](6+) (6), characterized by mass spectrometry, 1D and 2D (1)H- and 1D (15)N-NMR spectroscopy. Despite the presence of multiple histidines and other possible metal-binding residues in these peptides, 2D (1)H NMR spectra reveal that Pd(en)(2+) is remarkably specific in coordinating to imidazole-N1 of only (i, i + 4) pairs of histidines (i.e., only those separated by three amino acids), resulting in 4-6 made up of cyclic metallopentapeptide modules ([Pd(en)(H*XXXH*)](2+))(n), n = 2, 2, 3, respectively, each cycle being a 22-membered ring. We have previously shown that a single metallopentapeptide can nucleate alpha-helicity (Kelso et al., Angew. Chem., Int. Ed. 2003, 42, 421-424.). We now demonstrate its use as an alpha-turn-mimicking module for the facile conversion of unstructured short peptides into helices of macrocycles and provide 1D and 2D NMR spectroscopic data, structure calculations via XPLOR and NMR analysis of molecular flexibility in solution (NAMFIS), and CD spectra in support of the alpha-helical nature of these monomeric metallopeptides in solution.

6-Furopyridine Hexamethylene Amiloride Is a Non-Selective P2X7 Receptor Antagonist

Publisher: MDPI AG

Date: 16-09-2022

DOI: 10.3390/BIOM12091309

Abstract: P2X7 is an extracellular adenosine 5′-triphopshate (ATP)-gated cation channel present on leukocytes, where its activation induces pro-inflammatory cytokine release and ectodomain shedding of cell surface molecules. Human P2X7 can be partially inhibited by amiloride and its derivatives at micromolar concentrations. This study aimed to screen a library of compounds derived from amiloride or its derivative 5-(N,N-hexamethylene) amiloride (HMA) to identify a potential P2X7 antagonist. 6-Furopyridine HMA (6-FPHMA) was identified as a novel P2X7 antagonist and was characterized further. 6-FPHMA impaired ATP-induced dye uptake into human RPMI8226 multiple myeloma cells and human P2X7-HEK293 cells, in a concentration-dependent, non-competitive manner. Likewise, 6-FPHMA blocked ATP-induced Ca2+ fluxes in human P2X7-HEK293 cells in a concentration-dependent, non-competitive manner. 6-FPHMA inhibited ATP-induced dye uptake into human T cells, and interleukin-1β release within human blood and CD23 shedding from RPMI8226 cells. 6-FPHMA also impaired ATP-induced dye uptake into murine P2X7- and canine P2X7-HEK293 cells. However, 6-FPHMA impaired ATP-induced Ca2+ fluxes in human P2X4-HEK293 cells and non-transfected HEK293 cells, which express native P2Y1, P2Y2 and P2Y4. In conclusion, 6-FPHMA inhibits P2X7 from multiple species. Its poor selectivity excludes its use as a specific P2X7 antagonist, but further study of amiloride derivatives as P2 receptor antagonists is warranted.

Cephalosporin-3'-Diazeniumdiolate NO Donor Prodrug PYRRO-C3D Enhances Azithromycin Susceptibility of Nontypeable Haemophilus influenzae Biofilms.

Publisher: American Society for Microbiology

Date: 02-2017

DOI: 10.1128/AAC.02086-16

Abstract: PYRRO-C3D is a cephalosporin-3-diazeniumdiolate nitric oxide (NO) donor prodrug designed to selectively deliver NO to bacterial infection sites. The objective of this study was to assess the activity of PYRRO-C3D against nontypeable Haemophilus influenzae (NTHi) biofilms and examine the role of NO in reducing biofilm-associated antibiotic tolerance. The activity of PYRRO-C3D on in vitro NTHi biofilms was assessed through CFU enumeration and confocal microscopy. NO release measurements were performed using an ISO-NO probe. NTHi biofilms grown on primary ciliated respiratory epithelia at an air-liquid interface were used to investigate the effects of PYRRO-C3D in the presence of host tissue. Label-free liquid chromatography-mass spectrometry (LC/MS) proteomic analyses were performed to identify differentially expressed proteins following NO treatment. PYRRO-C3D specifically released NO in the presence of NTHi, while no evidence of spontaneous NO release was observed when the compound was exposed to primary epithelial cells. NTHi lacking β-lactamase activity failed to trigger NO release. Treatment significantly increased the susceptibility of in vitro NTHi biofilms to azithromycin, causing a log fold reduction (10-fold reduction or 1-log-unit reduction) in viability ( P 0.05) relative to azithromycin alone. The response was more pronounced for biofilms grown on primary respiratory epithelia, where a 2-log-unit reduction was observed ( P 0.01). Label-free proteomics showed that NO increased expression of 16 proteins involved in metabolic and transcriptional/translational functions. NO release from PYRRO-C3D enhances the efficacy of azithromycin against NTHi biofilms, putatively via modulation of NTHi metabolic activity. Adjunctive therapy with NO mediated through PYRRO-C3D represents a promising approach for reducing biofilm-associated antibiotic tolerance.