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M Karabacak - One of the best experts on this subject based on the ideXlab platform.
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molecular structure vibrational uv and nbo analysis of 4 chloro 7 nitrobenzofurazan by dft calculations
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011Co-Authors: Mustafa Kurt, Chinna P Babu, N Sundaraganesan, Mehmet Cinar, M KarabacakAbstract:Abstract In the present work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of 4-Chloro-7-Nitrobenzofurazan (NBD-Chloride). The FT-IR (400–4000 cm −1 ) and FT-Raman spectra (50–4000 cm −1 ) of NBD-Chloride were recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of NBD-Chloride in the ground-state have been calculated by using the density functional B3LYP method with 6-311++G (d, p) as higher basis set. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) result in DMSO and CDCl 3 solvents complements with each other. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulate infrared and Raman spectra of the title compound which show good agreement with observed spectra.
Elisabeth Davioudcharvet - One of the best experts on this subject based on the ideXlab platform.
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a redox active fluorescent ph indicator for detecting plasmodium falciparum strains with reduced responsiveness to quinoline antimalarial drugs
ACS Infectious Diseases, 2017Co-Authors: Mouhamad Jida, Cecilia P Sanchez, Karene Urgin, Katharina Ehrhardt, Saravanan Mounien, Aurelia Geyer, Mourad Elhabiri, Michael Lanzer, Elisabeth DavioudcharvetAbstract:Mutational changes in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) have been associated with differential responses to a wide spectrum of biologically active compounds including current and former quinoline and quinoline-like antimalarial drugs. PfCRT confers altered drug responsiveness by acting as a transport system, expelling drugs from the parasite’s digestive vacuole where these drugs exert, at least part of, their antiplasmodial activity. To preserve the efficacy of these invaluable drugs, novel functional tools are required for epidemiological surveys of parasite strains carrying mutant PfCRT variants and for drug development programs aimed at inhibiting or circumventing the action of PfCRT. Here we report the synthesis and characterization of a pH-sensitive fluorescent chloroquine analogue consisting of 7-chloro-N-{2-[(propan-2-yl)amino]ethyl}quinolin-4-amine functionalized with the fluorochrome 7-nitrobenzofurazan (NBD) (henceforth termed Fluo-CQ). In the parasite, Fluo-CQ...
Mustafa Kurt - One of the best experts on this subject based on the ideXlab platform.
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molecular structure vibrational uv and nbo analysis of 4 chloro 7 nitrobenzofurazan by dft calculations
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011Co-Authors: Mustafa Kurt, Chinna P Babu, N Sundaraganesan, Mehmet Cinar, M KarabacakAbstract:Abstract In the present work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of 4-Chloro-7-Nitrobenzofurazan (NBD-Chloride). The FT-IR (400–4000 cm −1 ) and FT-Raman spectra (50–4000 cm −1 ) of NBD-Chloride were recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of NBD-Chloride in the ground-state have been calculated by using the density functional B3LYP method with 6-311++G (d, p) as higher basis set. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) result in DMSO and CDCl 3 solvents complements with each other. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulate infrared and Raman spectra of the title compound which show good agreement with observed spectra.
Mouhamad Jida - One of the best experts on this subject based on the ideXlab platform.
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a redox active fluorescent ph indicator for detecting plasmodium falciparum strains with reduced responsiveness to quinoline antimalarial drugs
ACS Infectious Diseases, 2017Co-Authors: Mouhamad Jida, Cecilia P Sanchez, Karene Urgin, Katharina Ehrhardt, Saravanan Mounien, Aurelia Geyer, Mourad Elhabiri, Michael Lanzer, Elisabeth DavioudcharvetAbstract:Mutational changes in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) have been associated with differential responses to a wide spectrum of biologically active compounds including current and former quinoline and quinoline-like antimalarial drugs. PfCRT confers altered drug responsiveness by acting as a transport system, expelling drugs from the parasite’s digestive vacuole where these drugs exert, at least part of, their antiplasmodial activity. To preserve the efficacy of these invaluable drugs, novel functional tools are required for epidemiological surveys of parasite strains carrying mutant PfCRT variants and for drug development programs aimed at inhibiting or circumventing the action of PfCRT. Here we report the synthesis and characterization of a pH-sensitive fluorescent chloroquine analogue consisting of 7-chloro-N-{2-[(propan-2-yl)amino]ethyl}quinolin-4-amine functionalized with the fluorochrome 7-nitrobenzofurazan (NBD) (henceforth termed Fluo-CQ). In the parasite, Fluo-CQ...
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A Redox-Active Fluorescent pH Indicator for Detecting Plasmodium falciparum Strains with Reduced Responsiveness to Quinoline Antimalarial Drugs
2016Co-Authors: Mouhamad Jida, Cecilia P Sanchez, Karene Urgin, Katharina Ehrhardt, Saravanan Mounien, Aurelia Geyer, Mourad Elhabiri, Michael Lanzer, Elisabeth Davioud-charvetAbstract:Mutational changes in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) have been associated with differential responses to a wide spectrum of biologically active compounds including current and former quinoline and quinoline-like antimalarial drugs. PfCRT confers altered drug responsiveness by acting as a transport system, expelling drugs from the parasite’s digestive vacuole where these drugs exert, at least part of, their antiplasmodial activity. To preserve the efficacy of these invaluable drugs, novel functional tools are required for epidemiological surveys of parasite strains carrying mutant PfCRT variants and for drug development programs aimed at inhibiting or circumventing the action of PfCRT. Here we report the synthesis and characterization of a pH-sensitive fluorescent chloroquine analogue consisting of 7-chloro-N-{2-[(propan-2-yl)amino]ethyl}quinolin-4-amine functionalized with the fluorochrome 7-nitrobenzofurazan (NBD) (henceforth termed Fluo-CQ). In the parasite, Fluo-CQ accumulates in the digestive vacuole, giving rise to a strong fluorescence signal but only in parasites carrying the wild type PfCRT. In parasites carrying the mutant PfCRT, Fluo-CQ does not accumulate. The differential handling of the fluorescent probe, combined with live cell imaging, provides a diagnostic tool for quick detection of those P. falciparum strains that carry a PfCRT variant associated with altered responsiveness to quinoline and quinoline-like antimalarial drugs. In contrast to the accumulation studies, chloroquine (CQ)-resistant parasites were observed cross-resistant to Fluo-CQ when the chemical probe was tested in various CQ-sensitive and -resistant parasite strains. NBD derivatives were found to act as redox cyclers of two essential targets, using a coupled assay based on methemoglobin and the NADPH-dependent glutathione reductase (GRs) from P. falciparum. This redox activity is proposed to contribute to the dual action of Fluo-CQ on redox equilibrium and methemoglobin reduction via PfCRT-mediated drug efflux in the cytosol and then continuous redox-dependent shuttling between food vacuole and cytosol. Taking into account these physicochemical characteristics, a model was proposed to explain Fluo-CQ antimalarial effects involving the contribution of PfCRT-mediated transport, methemoglobin reduction, hematin binding, and NBD reduction activity catalyzed by PfGR in CQ-resistant versus CQ-sensitive parasites. Therefore, introduction of NBD fluorophore in drugs is not inert and should be taken into account in drug transport and imaging studies
Armagan Onal - One of the best experts on this subject based on the ideXlab platform.
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spectrofluorimetric methods for the determination of gemifloxacin in tablets and spiked plasma samples
Journal of Fluorescence, 2011Co-Authors: Serife Evrim Kepekci Tekkeli, Armagan OnalAbstract:Two new, sensitive and selective spectrofluorimetric methods have been developed for the determination of gemifloxacin (GFX) in tablets and spiked plasma samples. Gemifloxacin, as a primary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl) (for method A) and fluorescamine (for method B) which are a highly sensitive fluorogenic reagents used in many investigations. For method A, the reaction product was measured spectrofluorimetrically at 516 nm with excitation at 451 nm. The reaction proceeded quantitatively at pH 8.5, 80 °C in 7 min. For method B, the method was based on the reaction between GFX and fluorescamine in borate buffer solution of pH 8.5 to give highly fluorescent derivatives that were measured at 481 nm using an excitation wavelength of 351 nm. The fluorescence intensity was directly proportional to the concentration over the range 40–200 ng mL−1 and 100–1,200 ng mL−1 for method A and B, respectively. Successful applications of the developed methods, for the drug determination in pharmaceutical preparations and spiked plasma samples, were performed.
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spectrophotometric and spectrofluorimetric methods for the determination of pregabalin in bulk and pharmaceutical preparation
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2009Co-Authors: Armagan Onal, Olcay SagirliAbstract:Abstract Two new, sensitive and selective spectrofluorimetric and spectrophotometric methods have been developed for the determination of the γ-amino-n-butyric acid derivative pregabalin (PGB) in bulk drug and capsule. Pregabalin, as a primary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl) which is a highly sensitive fluorogenic and chromogenic reagent used in many investigations. According to this fact, spectrophotometric and spectrofluorimetric methods for the determination of pregabalin in capsules were developed for the first time. The relation between the absorbance at 460 nm and the concentration is rectilinear over the range 0.5–7.0 μg mL−1. The reaction product was also measured spectrofluorimetrically at 558 nm after excitation at 460 nm. The fluorescence intensity was directly proportional to the concentration over the range 40–400 ng mL−1. The method was applied successfully to the determination of this drug in pharmaceutical dosage form. The mean recovery for the commercial capsules was 99.93% and 99.96% for spectrophotometric and spectrofluorimetric study, respectively. The suggested procedures could be used for the determination of PGB in pure and capsules being sensitive, simple and selective.
