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Dive into the research topics where Nadia Touati is active.

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Featured researches published by Nadia Touati.


Angewandte Chemie | 2011

Beyond the silica surface by direct silicon-29 dynamic nuclear polarization

Olivier Lafon; Melanie Rosay; Fabien Aussenac; Xingyu Lu; Julien Trébosc; Odile Cristini; Christophe Kinowski; Nadia Touati; Hervé Vezin; Jean-Paul Amoureux

Buried truth: High-field magic angle spinning dynamic nuclear polarization (MAS DNP) enhances the sensitivity of solid-state NMR spectroscopy, but only for protonated surfaces. Direct 29 Si DNP using the biradical TOTAPOL (see picture) circumvents this limitation by producing a 30-fold enhancement of subsurface 29 Si NMR signals in mesoporous silica, a material with applications in photonics, nanotechnology and catalysis.


Journal of Medicinal Chemistry | 2011

Magnesium Chelating 2-Hydroxyisoquinoline-1,3(2H,4H)-diones, as Inhibitors of HIV-1 Integrase and/or the HIV-1 Reverse Transcriptase Ribonuclease H Domain: Discovery of a Novel Selective Inhibitor of the Ribonuclease H Function

Muriel Billamboz; Fabrice Bailly; Cédric Lion; Nadia Touati; Hervé Vezin; Christina Calmels; Marie-Line Andreola; Frauke Christ; Zeger Debyser; Philippe Cotelle

2-Hydroxyisoquinoline-1,3(2H,4H)-dione was recently discovered as a scaffold for the inhibition of HIV-1 integrase and the ribonuclease H function of HIV-1 reverse transcriptase. First, we investigate its interaction with Mg(2+) and Mn(2+) using different spectroscopic techniques and report that 2-hydroxyisoquinoline-1,3(2H,4H)-dione forms a 1:1 complex with Mg(2+) but a 1:2 complex with Mn(2+). The complex formation requires enolization of the ligand. ESR spectroscopy shows a redox reaction between the ligand and Mn(2+) producing superoxide anions. Second, 2-hydroxyisoquinoline-1,3(2H,4H)-dione, its magnesium complex, and its 4-methyl and 2-hydroxy-4-methoxycarbonylisoquinoline-1,3(2H,4H)-diones were tested as inhibitors of HIV-1 integrase, reverse transcriptase ribonuclease H, and DNA polymerase functions. Their antiviral activities were evaluated and 2-hydroxy-4-methoxycarbonyl-isoquinoline-1,3(2H,4H)-dione was found to inhibit the viral replication of HIV-1 in MT-4 cells. Cross-resistance was measured for this compound on three different viral strains. Experimental data suggest that the antiviral activity of 2-hydroxy-4-methoxycarbonylisoquinoline-1,3(2H,4H)-dione is probably due to the RNase H inhibition.


Molecular Pharmaceutics | 2008

Investigation of the Redox Behavior of Ferroquine, a New Antimalarial

Natascha Chavain; Hervé Vezin; Daniel Dive; Nadia Touati; Jean-François Paul; Eric Buisine; Christophe Biot

Ferroquine (FQ or SR97193) is a unique ferrocene antimalarial drug candidate which just entered phase IIb clinical trials in autumn 2007. FQ is able to overcome the chloroquine (CQ) resistance problem, an important limit to the control of Plasmodium falciparum, the principal causative agent of malaria. However, as for other therapeutic agents such as chloroquine (CQ) and artemisin, its mechanism of action remains partially unknown. Most investigations have so far focused on comparing the activity of FQ to that of CQ in order to understand how the ferrocene core contributes to a stronger antiplasmodial activity. Studies have already shown that the ferrocene altered the shape, volume, lipophilicity, basicity and also electronic profile of the parent molecule and, hence, its pharmacodynamic behavior. However, few investigations have been undertaken to probe the real contribution of redox properties of the ferrocene (iron(II))/ferricinium (iron(III)) system in FQ as reported in this article. In our experimental and theoretical approach, we considered the redox profile of the ferrocene core of FQ in the specific conditions (acidic and oxidizing) of the parasitic digestive vacuole as a possible discriminating property from CQ in the antimalarial activity.


Molecular Microbiology | 2014

Conformational dynamics of protein transporter FhaC: large‐scale motions of plug helix

Jérémy Guérin; Catherine Baud; Nadia Touati; Nathalie Saint; Eve Willery; Camille Locht; Hervé Vezin; Françoise Jacob-Dubuisson

FhaC is an integral outer membrane protein of the whooping cough agent Bordetella pertussis that mediates the transport to the cell surface of a major virulence factor, the filamentous haemagglutinin adhesin FHA. The FHA/FhaC pair is a prototypic TpsA/TpsB system of the widespread ‘Two‐Partner Secretion’ pathway, dedicated to the transport of long extracellular proteins in various pathogenic and environmental Gram‐negative bacteria. FhaC belongs to the ubiquitous Omp85 superfamily of protein transporters. The X‐ray structure of FhaC shows that the transmembrane β‐barrel channel hypothesized to serve as the FHA‐conducting pore is obstructed by two structural elements conserved among TpsB transporters, an N‐terminal α helix and an extracellular loop. Here, we provide evidence for conformational dynamics of FhaC related to the secretion mechanism. Using paramagnetic electron resonance, electrophysiology and in vivo approaches, we showed that FhaC exchanges between open and closed conformations. The interaction with its secretory partner FHA alters this distribution of conformations. The open conformation of FhaC implies a large displacement from the channel of the N‐terminal ‘plug’ helix, which remains in the periplasm during FHA secretion. The membrane environment favours the dynamics of the TpsB transporter.


Bioorganic & Medicinal Chemistry | 2010

New 2-arylnaphthalenediols and triol inhibitors of HIV-1 integrase—Discovery of a new polyhydroxylated antiviral agent

Cédric Maurin; Cédric Lion; Fabrice Bailly; Nadia Touati; Hervé Vezin; Gladys Mbemba; Jean François Mouscadet; Zeger Debyser; Myriam Witvrouw; Philippe Cotelle

A series of 13 hydroxylated 2-arylnaphthalenes have been synthesized and evaluated as HIV-1 integrase inhibitors. 7-(3,4,5-trihydroxyphenyl)naphthalene-1,2,3-triol 1c revealed chemical instability upon storage, leading to the isolation of a dimer 5c which was also tested. In the 2-arylnaphthalene series, all compounds were active against HIV-1 IN with IC50s within the 1-10 microM range, except for 1c and 5c which displayed submicromolar activity. Antiviral activity against HIV-1 replication was measured on 1b-c and 5c. Amongst the tested molecules, only 5c was found to present antiviral properties with a low cytotoxicity on two different cell lines.


Bioorganic & Medicinal Chemistry Letters | 2008

New NSAIDs-NO hybrid molecules with antiproliferative properties on human prostatic cancer cell lines.

Nicolas Bézière; Laurence Goossens; Jean Pommery; Hervé Vezin; Nadia Touati; Jean-Pierre Hénichart; Nicole Pommery

The design of profen hybrids containing a NO donor moiety connected to an aliphatic spacer led to compounds with a similar cyclooxygenase inhibition compared to their parent profen and with significant antiproliferative activities on PC3 cells. However, inhibition of COX-2 pathway alone did not seem sufficient to inhibit cancer cell proliferation, and NO-release in a time-dependent manner strongly contributes to this activity.


Journal of Magnetic Resonance | 2014

New chemometric approach MCR-ALS to unmix EPR spectroscopic data from complex mixtures.

Maya Abou Fadel; Anna de Juan; Nadia Touati; Hervé Vezin; Ludovic Duponchel

Electron paramagnetic resonance (EPR) spectra of mixtures are often difficult to interpret due to the superposition of spectral contribution of various species present in the complex materials. It is challenging to accurately identify the number of pure compounds present and to extract their pure spectra. In this study, the powerful chemometric method, multivariate curve resolution-alternating least squares (MCR-ALS), is applied to identify different paramagnetic centers. This method is used to simultaneously extract, with no prior knowledge, the pure spectra and the corresponding concentration profiles of all the compounds in the unknown and unresolved mixtures. The goal of our work is to apply, for the first time, this new chemometrics methodology, MCR-ALS, on EPR spectroscopic data in order to characterize a series of distinct but strongly overlapping spectra of various paramagnetic species.


Angewandte Chemie | 2014

Two-Orbital Three-Electron Stabilizing Interaction for Direct Co2+As3+ Bonds involving Square-Planar CoO4 in BaCoAs2O5†

Rénald David; Houria Kabbour; Alain Pautrat; Nadia Touati; Myung-Hwan Whangbo; Olivier Mentré

The quest for new oxides with cations containing active lone-pair electrons (E) covers a broad field of targeted specificities owing to asymmetric electronic distribution and their particular band structure. Herein, we show that the novel compound BaCoAs2 O5, with lone-pair As(3+) ions, is built from rare square-planar Co(2+) O4 involved in direct bonding between As(3+) E and Co(2+) dz2 orbitals (Co-As=2.51 Å). By means of DFT and Hückel calculations, we show that this σ-type overlapping is stabilized by a two-orbital three-electron interaction allowed by the high-spin character of the Co(2+) ions. The negligible experimental spin-orbit coupling is expected from the resulting molecular orbital scheme in O3 AsE-CoO4 clusters.


Applied Catalysis B-environmental | 2014

Highly productive iron molybdate mixed oxides and their relevant catalytic properties for direct synthesis of 1,1-dimethoxymethane from methanol

Kaew-arpha Thavornprasert; Mickaël Capron; Louise Jalowiecki-Duhamel; Olivier Gardoll; Martine Trentesaux; Anne-Sophie Mamede; Ge Fang; Jérémy Faye; Nadia Touati; Hervé Vezin; Jean-Luc Dubois; Jean-Luc Couturier; Franck Dumeignil


Catalysis Communications | 2012

Ethanol transformation into higher hydrocarbons over HZSM-5 zeolite: Direct detection of radical species by in situ EPR spectroscopy

Karima Ben Tayeb; L. Pinard; Nadia Touati; Hervé Vezin; Sylvie Maury; O. Delpoux

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L. Pinard

University of Poitiers

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Zeger Debyser

Katholieke Universiteit Leuven

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Gaëlle Fontaine

École nationale supérieure de chimie de Lille

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