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1.
Int J Mol Sci ; 23(18)2022 Sep 15.
Article in English | MEDLINE | ID: mdl-36142670

ABSTRACT

ABCB11 is responsible for biliary bile acid secretion at the canalicular membrane of hepatocytes. Variations in the ABCB11 gene cause a spectrum of rare liver diseases. The most severe form is progressive familial intrahepatic cholestasis type 2 (PFIC2). Current medical treatments have limited efficacy. Here, we report the in vitro study of Abcb11 missense variants identified in PFIC2 patients and their functional rescue using cystic fibrosis transmembrane conductance regulator potentiators. Three ABCB11 disease-causing variations identified in PFIC2 patients (i.e., A257V, T463I and G562D) were reproduced in a plasmid encoding an Abcb11-green fluorescent protein. After transfection, the expression and localization of the variants were studied in HepG2 cells. Taurocholate transport activity and the effect of potentiators were studied in Madin-Darby canine kidney (MDCK) clones coexpressing Abcb11 and the sodium taurocholate cotransporting polypeptide (Ntcp/Slc10A1). As predicted using three-dimensional structure analysis, the three variants were expressed at the canalicular membrane but showed a defective function. Ivacaftor, GLP1837, SBC040 and SBC219 potentiators increased the bile acid transport of A257V and T463I and to a lesser extent, of G562D Abcb11 missense variants. In addition, a synergic effect was observed when ivacaftor was combined with SBC040 or SBC219. Such potentiators could represent new pharmacological approaches for improving the condition of patients with ABCB11 deficiency due to missense variations affecting the function of the transporter.


Subject(s)
ATP-Binding Cassette Transporters , Cystic Fibrosis Transmembrane Conductance Regulator , ATP-Binding Cassette Transporters/metabolism , Aminophenols , Animals , Cholestasis, Intrahepatic , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Dogs , Green Fluorescent Proteins/metabolism , Quinolones , Taurocholic Acid/pharmacology
2.
PLoS Biol ; 20(5): e3001610, 2022 05.
Article in English | MEDLINE | ID: mdl-35580139

ABSTRACT

How double-membraned Gram-negative bacteria overcome lipid peroxidation is virtually unknown. Bactericidal antibiotics and superoxide ion stress stimulate the transcription of the Burkholderia cenocepacia bcnA gene that encodes a secreted lipocalin. bcnA gene orthologs are conserved in bacteria and generally linked to a conserved upstream gene encoding a cytochrome b561 membrane protein (herein named lcoA, lipocalin-associated cytochrome oxidase gene). Mutants in bcnA, lcoA, and in a gene encoding a conserved cytoplasmic aldehyde reductase (peroxidative stress-associated aldehyde reductase gene, psrA) display enhanced membrane lipid peroxidation. Compared to wild type, the levels of the peroxidation biomarker malondialdehyde (MDA) increase in the mutants upon exposure to sublethal concentrations of the bactericidal antibiotics polymyxin B and norfloxacin. Microscopy with lipid peroxidation-sensitive fluorescent probes shows that lipid peroxyl radicals accumulate at the bacterial cell poles and septum and peroxidation is associated with a redistribution of anionic phospholipids and reduced antimicrobial resistance in the mutants. We conclude that BcnA, LcoA, and PsrA are components of an evolutionary conserved, hitherto unrecognized peroxidation detoxification system that protects the bacterial cell envelope from lipid peroxyl radicals.


Subject(s)
Aldehyde Reductase , Membrane Lipids , Anti-Bacterial Agents/pharmacology , Gram-Negative Bacteria , Lipocalins
3.
Cell Mol Life Sci ; 78(23): 7813-7829, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34714360

ABSTRACT

Protein misfolding is involved in a large number of diseases, among which cystic fibrosis. Complex intra- and inter-domain folding defects associated with mutations in the cystic fibrosis transmembrane regulator (CFTR) gene, among which p.Phe508del (F508del), have recently become a therapeutical target. Clinically approved correctors such as VX-809, VX-661, and VX-445, rescue mutant protein. However, their binding sites and mechanisms of action are still incompletely understood. Blind docking onto the 3D structures of both the first membrane-spanning domain (MSD1) and the first nucleotide-binding domain (NBD1), followed by molecular dynamics simulations, revealed the presence of two potential VX-809 corrector binding sites which, when mutated, abrogated rescue. Network of amino acids in the lasso helix 2 and the intracellular loops ICL1 and ICL4 allosterically coupled MSD1 and NBD1. Corrector VX-445 also occupied two potential binding sites on MSD1 and NBD1, the latter being shared with VX-809. Binding of both correctors on MSD1 enhanced the allostery between MSD1 and NBD1, hence the increased efficacy of the corrector combination. These correctors improve both intra-domain folding by stabilizing fragile protein-lipid interfaces and inter-domain assembly via distant allosteric couplings. These results provide novel mechanistic insights into the rescue of misfolded proteins by small molecules.


Subject(s)
Aminopyridines/pharmacology , Benzodioxoles/pharmacology , Cystic Fibrosis Transmembrane Conductance Regulator/chemistry , Cystic Fibrosis/drug therapy , Mutation , Protein Folding/drug effects , Pyrazoles/pharmacology , Pyridines/pharmacology , Pyrrolidines/pharmacology , Binding Sites , Chloride Channel Agonists/pharmacology , Cystic Fibrosis/genetics , Cystic Fibrosis/metabolism , Cystic Fibrosis/pathology , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Drug Therapy, Combination , HEK293 Cells , Humans , Protein Domains , Protein Structure, Tertiary
4.
Int J Mol Sci ; 22(16)2021 Aug 13.
Article in English | MEDLINE | ID: mdl-34445410

ABSTRACT

Development of novel therapeutics to treat antibiotic-resistant infections, especially those caused by ESKAPE pathogens, is urgent. One of the most critical pathogens is P. aeruginosa, which is able to develop a large number of factors associated with antibiotic resistance, including high level of impermeability. Gram-negative bacteria are protected from the environment by an asymmetric Outer Membrane primarily composed of lipopolysaccharides (LPS) at the outer leaflet and phospholipids in the inner leaflet. Based on a large hemi-synthesis program focusing on amphiphilic aminoglycoside derivatives, we extend the antimicrobial activity of 3',6-dinonyl neamine and its branched isomer, 3',6-di(dimethyloctyl) neamine on clinical P. aeruginosa, ESBL, and carbapenemase strains. We also investigated the capacity of 3',6-homodialkyl neamine derivatives carrying different alkyl chains (C7-C11) to interact with LPS and alter membrane permeability. 3',6-Dinonyl neamine and its branched isomer, 3',6-di(dimethyloctyl) neamine showed low MICs on clinical P. aeruginosa, ESBL, and carbapenemase strains with no MIC increase for long-duration incubation. In contrast from what was observed for membrane permeability, length of alkyl chains was critical for the capacity of 3',6-homodialkyl neamine derivatives to bind to LPS. We demonstrated the high antibacterial potential of the amphiphilic neamine derivatives in the fight against ESKAPE pathogens and pointed out some particular characteristics making the 3',6-dinonyl- and 3',6-di(dimethyloctyl)-neamine derivatives the best candidates for further development.


Subject(s)
Allyl Compounds/pharmacology , Anti-Bacterial Agents/pharmacology , Framycetin/chemistry , Gram-Negative Bacteria/growth & development , Lipopolysaccharides/metabolism , Allyl Compounds/chemical synthesis , Allyl Compounds/chemistry , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Cell Membrane/drug effects , Cell Membrane/metabolism , Cell Membrane Permeability/drug effects , Drug Resistance, Bacterial/drug effects , Escherichia coli/drug effects , Escherichia coli/growth & development , Escherichia coli/metabolism , Gram-Negative Bacteria/drug effects , Gram-Negative Bacteria/metabolism , Microbial Sensitivity Tests , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/growth & development , Pseudomonas aeruginosa/metabolism
6.
Int J Mol Sci ; 21(19)2020 Oct 08.
Article in English | MEDLINE | ID: mdl-33049963

ABSTRACT

The conjugation of hydrophobic group(s) to the polycationic hydrophilic core of the antibiotic drugs aminoglycosides (AGs), targeting ribosomal RNA, has led to the development of amphiphilic aminoglycosides (AAGs). These drugs exhibit numerous biological effects, including good antibacterial effects against susceptible and multidrug-resistant bacteria due to the targeting of bacterial membranes. In the first part of this review, we summarize our work in identifying and developing broad-spectrum antibacterial AAGs that constitute a new class of antibiotic agents acting on bacterial membranes. The target-shift strongly improves antibiotic activity against bacterial strains that are resistant to the parent AG drugs and to antibiotic drugs of other classes, and renders the emergence of resistant Pseudomonas aeruginosa strains highly difficult. Structure-activity and structure-eukaryotic cytotoxicity relationships, specificity and barriers that need to be crossed in their development as antibacterial agents are delineated, with a focus on their targets in membranes, lipopolysaccharides (LPS) and cardiolipin (CL), and the corresponding mode of action against Gram-negative bacteria. At the end of the first part, we summarize the other recent advances in the field of antibacterial AAGs, mainly published since 2016, with an emphasis on the emerging AAGs which are made of an AG core conjugated to an adjuvant or an antibiotic drug of another class (antibiotic hybrids). In the second part, we briefly illustrate other biological and biochemical effects of AAGs, i.e., their antifungal activity, their use as delivery vehicles of nucleic acids, of short peptide (polyamide) nucleic acids (PNAs) and of drugs, as well as their ability to cleave DNA at abasic sites and to inhibit the functioning of connexin hemichannels. Finally, we discuss some aspects of structure-activity relationships in order to explain and improve the target selectivity of AAGs.


Subject(s)
Aminoglycosides/chemistry , Aminoglycosides/pharmacology , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Antifungal Agents/chemistry , Antifungal Agents/pharmacology , Aminoglycosides/metabolism , Anti-Bacterial Agents/metabolism , Antifungal Agents/metabolism , Bacterial Outer Membrane/drug effects , Bacterial Outer Membrane/metabolism , Cardiolipins/metabolism , Drug Carriers , Drug Resistance, Multiple, Bacterial/drug effects , Hydrophobic and Hydrophilic Interactions , Lipopolysaccharides/metabolism , Microbial Sensitivity Tests , Pseudomonas aeruginosa/drug effects , Solubility , Structure-Activity Relationship
7.
ChemMedChem ; 15(8): 716-725, 2020 04 20.
Article in English | MEDLINE | ID: mdl-32073756

ABSTRACT

2-aminothiophene derivatives (2AT) in which the thiophene ring is fused with a cycloalkyl or a N-acylated piperidine ring by positions 5 and 6 and carrying a 3-carbethoxy group were synthesized and their bacterial growth and enzyme inhibitory effects against efflux proteins of Staphylococcus aureus leading to resistance to fluoroquinolones and erythromycin (ERY) were investigated. Compounds that most effectively decreases the minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP) were assayed for their dose and time effects on the accumulation and efflux of ethidium bromide (EtBr) in the SA-1 strain. None of the compounds displayed antibacterial activity however, three derivatives carrying 2-amino, 2-aminoacetyl and 2-aminotrifluoroacetyl group enhanced the activity of CIP and ERY by 8- and 16-fold, respectively, and were able to restore the sensitivity of resistant strains, acting as typical efflux pump inhibitors (EPIs). The 2-aminoacetyl and 2-aminotrifluoroacetyl derivatives and two other piperidinyl 2-aminotrifluoroacetyl derivatives increased EtBr accumulation in a dose- and time-dependent manner, and one of them was also able to inhibit the EtBr efflux. Taken together, these results represent an important advance in the development of new EPIs, and demonstrate that 2AT represent a good scaffold for developing new antibiotic adjuvants.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/antagonists & inhibitors , Multidrug Resistance-Associated Proteins/antagonists & inhibitors , Staphylococcus aureus/drug effects , Thiophenes/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Bacterial Proteins/metabolism , Drug Resistance, Bacterial/drug effects , Microbial Sensitivity Tests , Molecular Structure , Multidrug Resistance-Associated Proteins/metabolism , Thiophenes/chemical synthesis , Thiophenes/chemistry
8.
Eur J Med Chem ; 190: 112116, 2020 Mar 15.
Article in English | MEDLINE | ID: mdl-32078860

ABSTRACT

Recent evidence shows that combination of correctors and potentiators, such as the drug ivacaftor (VX-770), can significantly restore the functional expression of mutated Cystic Fibrosis Transmembrane conductance Regulator (CFTR), an anion channel which is mutated in cystic fibrosis (CF). The success of these combinatorial therapies highlights the necessity of identifying a broad panel of specific binding mode modulators, occupying several distinct binding sites at structural level. Here, we identified two small molecules, SBC040 and SBC219, which are two efficient cAMP-independent potentiators, acting at low concentration of forskolin with EC50 close to 1 µM and in a synergic way with the drug VX-770 on several CFTR mutants of classes II and III. Molecular dynamics simulations suggested potential SBC binding sites at the vicinity of ATP-binding sites, distinct from those currently proposed for VX-770, outlining SBC molecules as members of a new family of potentiators.


Subject(s)
Benzamides/pharmacology , Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Purines/pharmacology , Aminophenols/pharmacology , Benzamides/chemical synthesis , Benzamides/metabolism , Binding Sites , Cystic Fibrosis Transmembrane Conductance Regulator/chemistry , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Drug Synergism , HeLa Cells , Humans , Molecular Docking Simulation , Mutation , Protein Binding , Purines/chemical synthesis , Purines/metabolism , Quinolones/pharmacology
9.
Molecules ; 24(16)2019 Aug 20.
Article in English | MEDLINE | ID: mdl-31434312

ABSTRACT

Alternative splicing of tau pre-mRNA is regulated by a 5' splice site (5'ss) hairpin present at the exon 10-intron 10 junction. Single mutations within the hairpin sequence alter hairpin structural stability and/or the binding of splicing factors, resulting in disease-causing aberrant splicing of exon 10. The hairpin structure contains about seven stably formed base pairs and thus may be suitable for targeting through antisense strands. Here, we used antisense peptide nucleic acids (asPNAs) to probe and target the tau pre-mRNA exon 10 5'ss hairpin structure through strand invasion. We characterized by electrophoretic mobility shift assay the binding of the designed asPNAs to model tau splice site hairpins. The relatively short (10-15 mer) asPNAs showed nanomolar binding to wild-type hairpins as well as a disease-causing mutant hairpin C+19G, albeit with reduced binding strength. Thus, the structural stabilizing effect of C+19G mutation could be revealed by asPNA binding. In addition, our cell culture minigene splicing assay data revealed that application of an asPNA targeting the 3' arm of the hairpin resulted in an increased exon 10 inclusion level for the disease-associated mutant C+19G, probably by exposing the 5'ss as well as inhibiting the binding of protein factors to the intronic spicing silencer. On the contrary, the application of asPNAs targeting the 5' arm of the hairpin caused an increased exon 10 exclusion for a disease-associated mutant C+14U, mainly by blocking the 5'ss. PNAs could enter cells through conjugation with amino sugar neamine or by cotransfection with minigene plasmids using a commercially available transfection reagent.


Subject(s)
Alternative Splicing , Oligonucleotides, Antisense/genetics , Peptide Nucleic Acids/genetics , tau Proteins/genetics , Exons , HEK293 Cells , Humans , Molecular Conformation , RNA Precursors , RNA Splice Sites , RNA, Messenger/genetics
10.
Biochim Biophys Acta Biomembr ; 1861(10): 182998, 2019 10 01.
Article in English | MEDLINE | ID: mdl-31153908

ABSTRACT

Amphiphilic aminoglycoside derivatives are potential new antimicrobial agents mostly developed to fight resistant bacteria. The mechanism of action of the 3',6-dinonyl neamine, one of the most promising derivative, has been investigated on Gram-negative bacteria, including P. aeruginosa. In this study, we have assessed its mechanism of action against Gram-positive bacteria, S. aureus and B. subtilis. By conducting time killing experiments, we assessed the bactericidal effect induced by 3',6-dinonyl neamine on S. aureus MSSA and MRSA. By measuring the displacement of BODIPY™-TR cadaverine bound to lipoteichoic acids (LTA), we showed that 3',6-dinonyl neamine interacts with these bacterial surface components. We also highlighted the ability of 3',6-dinonyl neamine to enhance membrane depolarization and induce membrane permeability, by using fluorescent probes, DiSC3C(5) and propidium iodide, respectively. These effects are observed for both MSSA and MRSA S. aureus as well as for B. subtilis. By electronic microscopy, we imaged the disruption of membrane integrity of the bacterial cell wall and by fluorescence microscopy, we demonstrated changes in the localization of lipids from the enriched-septum region and the impairment of the formation of septum. At a glance, we demonstrated that 3',6-dinonyl neamine interferes with multiple targets suggesting a low ability of bacteria to acquire resistance to this agent. In turn, the amphiphilic neamine derivatives are promising candidates for development as novel multitarget therapeutic antibiotics.


Subject(s)
Cell Membrane Permeability/drug effects , Framycetin/metabolism , Framycetin/pharmacology , Anti-Bacterial Agents/pharmacology , Bacillus subtilis/drug effects , Cell Membrane/metabolism , Gram-Positive Bacteria/drug effects , Gram-Positive Bacteria/metabolism , Lipopolysaccharides , Microbial Sensitivity Tests , Staphylococcus aureus/drug effects , Structure-Activity Relationship , Surface-Active Agents/pharmacology , Teichoic Acids
11.
Bioconjug Chem ; 30(3): 931-943, 2019 03 20.
Article in English | MEDLINE | ID: mdl-30721034

ABSTRACT

RNAs play critical roles in diverse catalytic and regulatory biological processes and are emerging as important disease biomarkers and therapeutic targets. Thus, developing chemical compounds for targeting any desired RNA structures has great potential in biomedical applications. The viral and cellular RNA sequence and structure databases lay the groundwork for developing RNA-binding chemical ligands through the recognition of both RNA sequence and RNA structure. Influenza A virion consists of eight segments of negative-strand viral RNA (vRNA), all of which contain a highly conserved panhandle duplex structure formed between the first 13 nucleotides at the 5' end and the last 12 nucleotides at the 3' end. Here, we report our binding and cell culture anti-influenza assays of a short 10-mer chemically modified double-stranded RNA (dsRNA)-binding peptide nucleic acid (PNA) designed to bind to the panhandle duplex structure through novel major-groove PNA·RNA2 triplex formation. We demonstrated that incorporation of chemically modified PNA residues thio-pseudoisocytosine (L) and guanidine-modified 5-methyl cytosine (Q) previously developed by us facilitates the sequence-specific recognition of Watson-Crick G-C and C-G pairs, respectively, at physiologically relevant conditions. Significantly, the chemically modified dsRNA-binding PNA (dbPNA) shows selective binding to the dsRNA region in panhandle structure over a single-stranded RNA (ssRNA) and a dsDNA containing the same sequence. The panhandle structure is not accessible to traditional antisense DNA or RNA with a similar length. Conjugation of the dbPNA with an aminosugar neamine enhances the cellular uptake. We observed that 2-5 µM dbPNA-neamine conjugate results in a significant reduction of viral replication. In addition, the 10-mer dbPNA inhibits innate immune receptor RIG-I binding to panhandle structure and thus RIG-I ATPase activity. These findings would provide the foundation for developing novel dbPNAs for the detection of influenza viral RNAs and therapeutics with optimal antiviral and immunomodulatory activities.


Subject(s)
Orthomyxoviridae/drug effects , Peptide Nucleic Acids/chemistry , Peptide Nucleic Acids/pharmacology , RNA, Double-Stranded/metabolism , RNA, Viral/drug effects , Virus Replication/drug effects , Animals , Circular Dichroism , Dogs , Madin Darby Canine Kidney Cells , Native Polyacrylamide Gel Electrophoresis , Nucleic Acid Conformation , Orthomyxoviridae/genetics , Orthomyxoviridae/physiology , RNA, Double-Stranded/chemistry
12.
Eur J Med Chem ; 157: 1512-1525, 2018 Sep 05.
Article in English | MEDLINE | ID: mdl-30282323

ABSTRACT

Amphiphilic aminoglycosides (AAGs) constitute a new class of antibacterial compounds targeting the bacterial membranes. We have identified the 3',6-dinonyl neamine 9 as a broad spectrum antibacterial AAG. Here, we report on the synthesis, antibacterial activity and eukaryotic cytotoxicity of new 3',6-dialkyl neamines designed in order to finely delineate the structure-activity relationships relating their activity to a lipophilicity window. New broad-spectrum antibacterial derivatives were obtained carrying two identical linear or branched alkyl groups or two different linear alkyl groups. Two fluorescent antibacterial 3',6-heterodialkyl neamines carrying a pyrenylbutyl fluorophore were also identified as potential tools for mechanistic study. Homodialkyl and heterodialkyl neamines appeared to be more active on Gram-negative bacteria than dinaphthylalkyl neamines. However, branched dialkyl neamines or heterodialkyl derivatives were found to be more cytotoxic on mammalian cells than 9. The exposure of P. aeruginosa over one month to half-MIC of one of the most active derivatives 9 demonstrated the high difficulty of resistance emergence to AAGs.


Subject(s)
Aminoglycosides/pharmacology , Anti-Bacterial Agents/pharmacology , Eukaryotic Cells/drug effects , Framycetin/pharmacology , Pseudomonas aeruginosa/drug effects , Surface-Active Agents/pharmacology , Aminoglycosides/chemical synthesis , Aminoglycosides/chemistry , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Cell Survival/drug effects , Dose-Response Relationship, Drug , Framycetin/chemical synthesis , Framycetin/chemistry , Humans , Microbial Sensitivity Tests , Molecular Structure , Pseudomonas aeruginosa/growth & development , Structure-Activity Relationship , Surface-Active Agents/chemical synthesis , Surface-Active Agents/chemistry
13.
Curr Protoc Nucleic Acid Chem ; 74(1): e57, 2018 09.
Article in English | MEDLINE | ID: mdl-30102466

ABSTRACT

A one-pot glycosylation and cyclization procedure is described for the synthesis of 6-chloropurine ribonucleosides from chloropyrimidines. From such a procedure and modification of the obtained chloropurine ribonucleosides, many drug candidates or molecular tools for biological study designed from their similarity to naturally occurring nucleosides could be obtained. The synthesis begins by preparation of several amidinoaminochloropyrimidines as precursors for the one-pot procedure. Then, by adding trimethylsilyl trifluoromethanesulfonate (TMSOTf) to a mixture of a pyrimidine and 1-O-acetyl-2,3,5-tri-O-benzoyl-ß-D-ribose, different 6-chloropurine ribonucleosides are obtained. This methodology allows the straightforward introduction of an alkyl substituent at position 8 of purine ribonucleosides, which then can be functionalized at positions 2 and 6. © 2018 by John Wiley & Sons, Inc.


Subject(s)
Purines/chemistry , Pyrimidines/chemistry , Ribonucleosides/chemical synthesis , Ribonucleosides/chemistry
14.
PLoS One ; 13(8): e0201752, 2018.
Article in English | MEDLINE | ID: mdl-30125281

ABSTRACT

Amphiphilic aminoglycoside derivatives are promising new antibacterials active against Gram-negative bacteria such as Pseudomonas aeruginosa, including colistin resistant strains. In this study, we demonstrated that addition of cardiolipin to the culture medium delayed growth of P. aeruginosa, favored asymmetrical growth and enhanced the efficiency of a new amphiphilic aminoglycoside derivative, the 3',6-dinonylneamine. By using membrane models mimicking P. aeruginosa plasma membrane composition (POPE:POPG:CL), we demonstrated the ability of 3'6-dinonylneamine to induce changes in the biophysical properties of membrane model lipid systems in a cardiolipin dependent manner. These changes include an increased membrane permeability associated with a reduced hydration and a decreased ability of membrane to mix and fuse as shown by monitoring calcein release, Generalized Polarization of Laurdan and fluorescence dequenching of octadecyl rhodamine B, respectively. Altogether, results shed light on how cardiolipin may be critical for improving antibacterial action of new amphiphilic aminoglycoside derivatives.


Subject(s)
Aminoglycosides/pharmacology , Anti-Bacterial Agents/pharmacology , Cardiolipins/metabolism , Pseudomonas aeruginosa/drug effects , 2-Naphthylamine/analogs & derivatives , 2-Naphthylamine/chemistry , Aminoglycosides/chemistry , Anti-Bacterial Agents/chemistry , Cardiolipins/chemistry , Cell Membrane Permeability/drug effects , Cell Membrane Permeability/physiology , Dose-Response Relationship, Drug , Fluoresceins/chemistry , Fluoresceins/metabolism , Laurates/chemistry , Membrane Fusion/physiology , Phosphatidylethanolamines/chemistry , Phosphatidylglycerols/chemistry , Pseudomonas aeruginosa/growth & development , Pseudomonas aeruginosa/metabolism , Pseudomonas aeruginosa/ultrastructure , Unilamellar Liposomes/chemistry
15.
Cell Mol Life Sci ; 75(20): 3829-3855, 2018 Oct.
Article in English | MEDLINE | ID: mdl-29779042

ABSTRACT

Cryo-electron microscopy (cryo-EM) has recently provided invaluable experimental data about the full-length cystic fibrosis transmembrane conductance regulator (CFTR) 3D structure. However, this experimental information deals with inactive states of the channel, either in an apo, quiescent conformation, in which nucleotide-binding domains (NBDs) are widely separated or in an ATP-bound, yet closed conformation. Here, we show that 3D structure models of the open and closed forms of the channel, now further supported by metadynamics simulations and by comparison with the cryo-EM data, could be used to gain some insights into critical features of the conformational transition toward active CFTR forms. These critical elements lie within membrane-spanning domains but also within NBD1 and the N-terminal extension, in which conformational plasticity is predicted to occur to help the interaction with filamin, one of the CFTR cellular partners.


Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/chemistry , Models, Molecular , Amino Acid Sequence , Animals , Cryoelectron Microscopy , Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Humans , Protein Domains , Protein Structure, Tertiary , Sequence Alignment
16.
Org Lett ; 19(23): 6360-6363, 2017 12 01.
Article in English | MEDLINE | ID: mdl-29125774

ABSTRACT

Highly substituted purines were synthesized in good to high yields through a one-pot straightforward metal-free scalable method, using the Traube synthesis adapted to Vilsmeier-type reagents. From 5-amino-4-chloropyrimidines, new 9-aryl-substituted chloropurines and intermediates for peptide nucleic acid synthesis were prepared. Variant procedures allowing a rapid synthesis of ribonucleosides and 7-benzylpurine from 5-amidino-6-aminopyrimidines are also reported to illustrate the high potential of this versatile toolbox. This route appears to be particularly interesting in the field of nucleic acids for a direct and rapid access to various new 8-alkylpurine nucleosides.

17.
Sci Rep ; 7(1): 10697, 2017 09 06.
Article in English | MEDLINE | ID: mdl-28878347

ABSTRACT

Some bacterial proteins involved in cell division and oxidative phosphorylation are tightly bound to cardiolipin. Cardiolipin is a non-bilayer anionic phospholipid found in bacterial inner membrane. It forms lipid microdomains located at the cell poles and division plane. Mechanisms by which microdomains are affected by membrane-acting antibiotics and the impact of these alterations on membrane properties and protein functions remain unclear. In this study, we demonstrated cardiolipin relocation and clustering as a result of exposure to a cardiolipin-acting amphiphilic aminoglycoside antibiotic, the 3',6-dinonyl neamine. Changes in the biophysical properties of the bacterial membrane of P. aeruginosa, including decreased fluidity and increased permeability, were observed. Cardiolipin-interacting proteins and functions regulated by cardiolipin were impacted by the amphiphilic aminoglycoside as we demonstrated an inhibition of respiratory chain and changes in bacterial shape. The latter effect was characterized by the loss of bacterial rod shape through a decrease in length and increase in curvature. It resulted from the effect on MreB, a cardiolipin dependent cytoskeleton protein as well as a direct effect of 3',6-dinonyl neamine on cardiolipin. These results shed light on how targeting cardiolipin microdomains may be of great interest for developing new antibacterial therapies.


Subject(s)
Aminoglycosides/pharmacology , Anti-Bacterial Agents/pharmacology , Antigens, Bacterial/metabolism , Cardiolipins/metabolism , Membrane Microdomains/drug effects , Surface-Active Agents/pharmacology , Aminoglycosides/chemistry , Anti-Bacterial Agents/chemistry , Antigens, Bacterial/chemistry , Cardiolipins/chemistry , Cell Membrane/chemistry , Cell Membrane/drug effects , Cell Membrane/metabolism , Cell Membrane Permeability , Mitochondria/drug effects , Mitochondria/metabolism , Models, Molecular , Molecular Conformation , Protein Synthesis Inhibitors/pharmacology , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/metabolism , Quantitative Structure-Activity Relationship , Static Electricity , Surface-Active Agents/chemistry
18.
Bioorg Med Chem ; 25(13): 3259-3277, 2017 07 01.
Article in English | MEDLINE | ID: mdl-28495384

ABSTRACT

Neglected tropical diseases (NTDs) are a group of diseases that, besides prevailing in poverty conditions, contribute to the maintenance of social inequality, being a strong barrier to a country development. Schistosomiasis, a NTD, is a tropical and subtropical disease caused by the trematode Schistosoma mansoni (Africa, Middle East, Caribbean, Brazil, Venezuela, Suriname), japonicum (China, Indonesia, the Philippines), mekongi (several districts of Cambodia and the Lao People's Democratic Republic), intercalatum and guianensis (areas of tropical rainforests in Central Africa) and hematobium (Middle East Africa, Corsica, France) whose adult forms inhabit the mesenteric vessels of the host, while the intermediate forms are found in the aquatic gastropod snails of the genus Biomphalaria. Currently, praziquantel (PZQ) is the first line drug chosen for the treatment of schistosomiasis according to the World Health Organization (WHO) Model List of Essential Medicines, 2015. PZQ chemotherapy is considered to be the most important development for decades in the treatment of schistosomiasis. Beside the PZQ, oxamniquine (OXA) has been first described in 1969 and launched in Brazil by Pfizer under the name of Mansil® for oral administration. It has a lower cost when compared to PZQ, being active in the intestinal and hepatosplenic infections caused exclusively by S. mansoni, single species in Brazil. Both PZQ and OXA have limitations, as low efficacy in the treatment of acute schistosomiasis, low activity against S. mansoni in immature stages and resistance or tolerance, which is the reason why further research are still necessary for the development of a second generation of antischistosomal drugs. For the development of new PZQ analogs, three main strategies can be adopted: (a) synthesis and evaluation of PZQ analogues; (b) rational design of new pharmacophores; (c) discovery of new active compounds from screening programs on a large scale. Such (b) approach is difficult as the target of PZQ still unknown, the synthesis of new active analogues is possible from delineation of structure-activity relationships for PZQ. Thus, we proposed for a review article an accurate analysis of PZQ and OXA medicinal properties and uses, focusing on the pharmacochemical aspects of both drugs through 178 bibliographic references. The mechanisms of action will be discussed, with the latest information available in the literature (for the first time in the case of the oxamniquine). Cases of resistance are also discussed. As both drugs are available as a racemic mixture the biological impact of their stereochemistry to activity and side effects are reviewed. The results obtained for the combination of PZQ and artemisinin derivatives against immature worms are also introduced in the discussion. Using the information about more than 200 PZQ new derivatives synthetized during almost 35years since its discovery, a deep structure-activity relationship (SAR) is also proposed in this study.


Subject(s)
Neglected Diseases/drug therapy , Oxamniquine/pharmacology , Praziquantel/pharmacology , Schistosoma mansoni/drug effects , Animals , Chemistry, Pharmaceutical , Dose-Response Relationship, Drug , Humans , Molecular Structure , Oxamniquine/chemistry , Praziquantel/chemistry , Structure-Activity Relationship
19.
J Med Chem ; 59(20): 9350-9369, 2016 Oct 27.
Article in English | MEDLINE | ID: mdl-27690420

ABSTRACT

Aminoglycosides (AGs) constitute a major family of potent and broad-spectrum antibiotics disturbing protein synthesis through binding to the A site of 16S rRNA. Decades of widespread clinical use of AGs strongly reduced their clinical efficacy through the selection of resistant bacteria. Recently, conjugation of lipophilic groups to AGs generated a novel class of potent antibacterial amphiphilic aminoglycosides (AAGs) with significant improved activities against various sensitive and resistant bacterial strains. We have identified amphiphilic 3',6-dialkyl derivatives of the small aminoglycoside neamine as broad spectrum antibacterial agents targeting bacterial membranes. Here, we report on the synthesis and the activity against sensitive and resistant Gram-negative and/or Gram-positive bacteria of new amphiphilic 3',4'-dialkyl neamine derivatives and of their smaller analogues in the 6-aminoglucosamine (neosamine) series prepared from N-acetylglucosamine.


Subject(s)
Aminoglycosides/pharmacology , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial/drug effects , Framycetin/chemistry , Framycetin/pharmacology , Glucosamine/analogs & derivatives , Surface-Active Agents/pharmacology , Aminoglycosides/chemical synthesis , Aminoglycosides/chemistry , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Dose-Response Relationship, Drug , Framycetin/chemical synthesis , Glucosamine/chemical synthesis , Glucosamine/chemistry , Glucosamine/pharmacology , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , Surface-Active Agents/chemical synthesis , Surface-Active Agents/chemistry
20.
J Biol Chem ; 291(26): 13864-74, 2016 Jun 24.
Article in English | MEDLINE | ID: mdl-27189936

ABSTRACT

Bacterial membranes are highly organized, containing specific microdomains that facilitate distinct protein and lipid assemblies. Evidence suggests that cardiolipin molecules segregate into such microdomains, probably conferring a negative curvature to the inner plasma membrane during membrane fission upon cell division. 3',6-Dinonyl neamine is an amphiphilic aminoglycoside derivative active against Pseudomonas aeruginosa, including strains resistant to colistin. The mechanisms involved at the molecular level were identified using lipid models (large unilamellar vesicles, giant unilamelllar vesicles, and lipid monolayers) that mimic the inner membrane of P. aeruginosa The study demonstrated the interaction of 3',6-dinonyl neamine with cardiolipin and phosphatidylglycerol, two negatively charged lipids from inner bacterial membranes. This interaction induced membrane permeabilization and depolarization. Lateral segregation of cardiolipin and membrane hemifusion would be critical for explaining the effects induced on lipid membranes by amphiphilic aminoglycoside antibiotics. The findings contribute to an improved understanding of how amphiphilic aminoglycoside antibiotics that bind to negatively charged lipids like cardiolipin could be promising antibacterial compounds.


Subject(s)
Cardiolipins/chemistry , Framycetin/chemistry , Phosphatidylglycerols/chemistry , Pseudomonas aeruginosa/chemistry
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