22 results on '"Z. Barbieriková"'
Search Results
2. Acridin-3,6-dialkyldithiourea hydrochlorides as new photosensitizers for photodynamic therapy of mouse leukemia cells
- Author
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Helena Paulíková, Z. Barbieriková, A. Cisáriková, Ján Imrich, Zuzana Bacova, Ladislav Janovec, and L. Hunáková
- Subjects
0301 basic medicine ,Programmed cell death ,Necrosis ,medicine.medical_treatment ,Clinical Biochemistry ,Pharmaceutical Science ,Photodynamic therapy ,Biochemistry ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Cell Line, Tumor ,Drug Discovery ,medicine ,Animals ,Cytotoxicity ,Molecular Biology ,Leukemia, Experimental ,Photosensitizing Agents ,Chemistry ,Organic Chemistry ,Autophagy ,Electron Spin Resonance Spectroscopy ,Cell cycle ,Molecular biology ,030104 developmental biology ,Photochemotherapy ,Apoptosis ,030220 oncology & carcinogenesis ,Acridines ,Molecular Medicine ,L1210 cells ,medicine.symptom - Abstract
Acridin-3,6-dialkyldithiourea hydrochlorides (AcrDTUs) have been evaluated as a new group of photosensitizers (PSs) for photodynamic antitumor therapy (PDT). Mouse leukemia cells L1210 were used for testing of AcrDTUs as the new PSs. The irradiation (UV-A light (365 nm), 1.05 J/cm(2)) increased cytotoxicity of all derivatives against L1210 cells more than ten times. The highest photocytotoxicity was found for propyl-AcrDTU with IC50=0.48±0.03 μM after 48 h incubation. A generation of the superoxide radical anion upon UV-A irradiation of propyl-AcrDTU was confirmed by in situ photochemical EPR experiments. To explain a mechanism of photocytotoxic action of AcrDTUs, an intracellular distribution of propyl-AcrDTU has been studied. It was found that AcrDTU in non-irradiated cells was not present in their nucleus but in the lysosomes and partly in the mitochondria, and sequestration of propyl-AcrDTU was dependent on pH in lysosomes. After irradiation, the cell death was induced by oxidative damage of lysosomal and mitochondrial membranes. Concerning the cell cycle, flow cytometry after PDT with propyl-AcrDTU showed a significant increase of the cells in the subG0 phase. Observed signs of necrosis, apoptosis, and autophagy indicate that PDT/AcrDTU leads to multiple cell death types (caspase independent apoptosis, necrosis, and autophagy).
- Published
- 2016
3. EPR study of polymeric carbon nitride photocatalysts
- Author
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Z. Barbieriková, D. Dvoranová, M. Mazúr, V. Brezová, G. Marcì, E. García-López, F. R. Pomilla, L. Palmisano, Barbieriková, Z., Dvoranová, D., Mazúr, M., Brezová, V., Marci', G., Garcia Lopez, E., Pomilla, F. R., Palmisano, L., Barbieriková, Z, Dvoranová, D, Mazúr, M, Brezová, V, Marcì, G, García-López, E, Pomilla, F, and Palmisano, L
- Subjects
EPR study, carbon nitride, photocatalysis ,Settore CHIM/07 - Fondamenti Chimici Delle Tecnologie - Abstract
EPR spectrometry servea as a unique tool by characterization of polymeric carbon nitride photocatalysts and evaluation of its photocatalytic performance in suspension.
- Published
- 2018
4. Polymeric C3N4 and O-doped C3N4: Photoelectrochemical and EPR Features for Selective Photocatalytic Oxidation of Alcohols to Aldehydes
- Author
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Marcì, G, García-López, E, Pomilla, F, Palmisano, L, Zaffora, A, Santamaria, M, Kristov, I, Barbieriková, Z, Brezová, V, G. Marcì, E. García-López, F. R. Pomilla, L. Palmisano, A. Zaffora, M. Santamaria, I. Kristov, Z. Barbieriková, V. Brezová, Marcì, G, García-López, E, Pomilla, F, Palmisano, L, Zaffora, A, Santamaria, M, Kristov, I, Barbieriková, Z, Brezová, V, G. Marcì, E. García-López, F. R. Pomilla, L. Palmisano, A. Zaffora, M. Santamaria, I. Kristov, Z. Barbieriková, and V. Brezová
- Abstract
Polymeric C3N4 and O-doped C3N4: Photoelectrochemical and EPR Features for Selective Photocatalytic Oxidation of Alcohols to Aldehydes
- Published
- 2018
5. EPR study of polymeric carbon nitride photocatalysts
- Author
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Barbieriková, Z, Dvoranová, D, Mazúr, M, Brezová, V, Marcì, G, García-López, E, Pomilla, F, Palmisano, L, Z. Barbieriková, D. Dvoranová, M. Mazúr, V. Brezová, G. Marcì, E. García-López, F. R. Pomilla, L. Palmisano, Barbieriková, Z, Dvoranová, D, Mazúr, M, Brezová, V, Marcì, G, García-López, E, Pomilla, F, Palmisano, L, Z. Barbieriková, D. Dvoranová, M. Mazúr, V. Brezová, G. Marcì, E. García-López, F. R. Pomilla, and L. Palmisano
- Abstract
EPR study of polymeric carbon nitride photocatalysts
- Published
- 2018
6. Novel 3,6-bis(imidazolidine)acridines as effective photosensitizers for photodynamic therapy
- Author
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Lýdia Čižeková, Z. Barbieriková, V. Brezová, Z. Ipóthová, A. Grolmusová, Helena Paulíková, Ladislav Janovec, Luba Hunakova, Ima Dovinova, and Ján Imrich
- Subjects
Programmed cell death ,medicine.medical_treatment ,Clinical Biochemistry ,Pharmaceutical Science ,Photodynamic therapy ,Antineoplastic Agents ,medicine.disease_cause ,Imidazolidines ,Biochemistry ,Flow cytometry ,chemistry.chemical_compound ,Mice ,Structure-Activity Relationship ,Drug Discovery ,medicine ,Animals ,Humans ,Molecular Biology ,Cells, Cultured ,Cell Proliferation ,Photosensitizing Agents ,medicine.diagnostic_test ,Cell Death ,Dose-Response Relationship, Drug ,Molecular Structure ,Cell growth ,Chemistry ,Singlet oxygen ,Organic Chemistry ,Cell Cycle ,Cell cycle ,Molecular biology ,Comet assay ,Oxidative Stress ,Photochemotherapy ,NIH 3T3 Cells ,Molecular Medicine ,Acridines ,Drug Screening Assays, Antitumor ,Lysosomes ,Genotoxicity - Abstract
The photoeffect of new proflavine derivatives with DNA-binding and antitumour activities, 3,6-bis((1-alkyl-5-oxo-imidazolidin-2-yliden)imino)acridine hydrochlorides (AcrDIMs), was studied to evaluate them as potential photosensitizers for photodynamic antitumor therapy. EPR measurements showed that superoxide radical anion and singlet oxygen were produced upon irradiation of AcrDIMs with UV-A light (>300 nm) in the presence of molecular oxygen. This indicates that AcrDIMs may act as photosensitizers. The most active pentyl-AcrDIM and hexyl-AcrDIM displayed photocytotoxic effect toward the mouse lymphocytic leukemia cell line L1210 and human ovarian cancer cells A2780. Antitumor activity of pentyl-AcrDIM increased as high as about 12 times (72 h incubation) after irradiation of A2780 cells (365 nm, 1.05 J/cm2). The photocytotoxicity seems to be associated with oxidative stress. Concerning the cell cycle, flow cytometry showed an arrest in the S-phase already 4 h after irradiation. In a comet assay, no genotoxicity of AcrDIMs was found. Typical morphologic changes and formation of DNA-ladders indicated induction of apoptotic cell death, though no activation of caspase-3 was observed. Investigation of intracellular localization of pentyl-AcrDIM confirmed its partial accumulation in mitochondria and lysosomes. After irradiation of the A2780 cells, colocalization of pentyl-AcrDIM with monodansylcadaverine, a lysosomal dye, was proven, suggesting that lysosomes in the irradiated cells may be involved in the cell death.
- Published
- 2014
7. Copper(II) Complexes with Isomeric Morpholine-Substituted 2-Formylpyridine Thiosemicarbazone Hybrids as Potential Anticancer Drugs Inhibiting Both Ribonucleotide Reductase and Tubulin Polymerization: The Morpholine Position Matters.
- Author
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Milunovic MNM, Ohui K, Besleaga I, Petrasheuskaya TV, Dömötör O, Enyedy ÉA, Darvasiova D, Rapta P, Barbieriková Z, Vegh D, Tóth S, Tóth J, Kucsma N, Szakács G, Popović-Bijelić A, Zafar A, Reynisson J, Shutalev AD, Bai R, Hamel E, and Arion VB
- Subjects
- Humans, Animals, Mice, Cell Line, Tumor, Cell Proliferation drug effects, Structure-Activity Relationship, Polymerization drug effects, Coordination Complexes pharmacology, Coordination Complexes chemistry, Coordination Complexes chemical synthesis, Pyridines pharmacology, Pyridines chemistry, Pyridines chemical synthesis, Tubulin Modulators pharmacology, Tubulin Modulators chemical synthesis, Tubulin Modulators chemistry, Drug Screening Assays, Antitumor, Models, Molecular, Thiosemicarbazones chemistry, Thiosemicarbazones pharmacology, Thiosemicarbazones chemical synthesis, Antineoplastic Agents pharmacology, Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Ribonucleotide Reductases antagonists & inhibitors, Ribonucleotide Reductases metabolism, Tubulin metabolism, Morpholines pharmacology, Morpholines chemistry, Morpholines chemical synthesis, Copper chemistry
- Abstract
The development of copper(II) thiosemicarbazone complexes as potential anticancer agents, possessing dual functionality as inhibitors of R2 ribonucleotide reductase (RNR) and tubulin polymerization by binding at the colchicine site, presents a promising avenue for enhancing therapeutic effectiveness. Herein, we describe the syntheses and physicochemical characterization of four isomeric proligands H
2 L3 - H2 L6 , with the methylmorpholine substituent at pertinent positions of the pyridine ring, along with their corresponding Cu(II) complexes 3 - 6 . Evidently, the position of the morpholine moiety and the copper(II) complex formation have marked effects on the in vitro antiproliferative activity in human uterine sarcoma MES-SA cells and the multidrug-resistant derivative MES-SA/Dx5 cells. Activity correlated strongly with quenching of the tyrosyl radical (Y• ) of mouse R2 RNR protein, inhibition of RNR activity in the cancer cells, and inhibition of tubulin polymerization. Insights into the mechanism of antiproliferative activity, supported by experimental results and molecular modeling calculations, are presented.- Published
- 2024
- Full Text
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8. Environmental risk of nanomaterials and nanoparticles and EPR technique as an effective tool to study them-a review.
- Author
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Bimová P, Barbieriková Z, Grenčíková A, Šípoš R, Škulcová AB, Krivjanská A, and Mackuľak T
- Subjects
- Nanotechnology, Nanoparticles, Nanostructures
- Abstract
Nanotechnologies and different types of nanomaterials belong in present day to intensively studied materials due to their unique properties and diverse potential applications in, e.g., electronics, medicine, or display technologies. Together with the investigation of their desired beneficial properties, a need to investigate and evaluate their influence on the environment and possible harmful effects towards living organisms is growing. This review summarizes possible toxic effects of nanomaterials on environment and living organisms, focusing on the possible bioaccumulation in organisms, toxicity, and its mechanisms. The main goal of this review is to refer to potential environmental risks rising from the use of nanomaterials and the necessity to deal with the possible toxic effects considering the growing interest in the wide-scale utilization of these materials. Electron paramagnetic resonance spectroscopy as the only analytical technique capable of detecting radical species enables detection, quantification, and monitoring of the generation of short-lived radicals often coupled with toxic effects of nanomaterials, which makes it an important method in the process of nanotoxicity mechanism determination.
- Published
- 2021
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9. Hydration and bactericidal activity of nanometer- and micrometer-sized particles of rock salt-type Mg 1-x Cu x O oxides.
- Author
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Clavier B, Baptiste T, Barbieriková Z, Hajdu T, Guiet A, Boucher F, Brezová V, Roques C, and Corbel G
- Subjects
- Escherichia coli, Magnesium, Oxides, Staphylococcus aureus, Metal Nanoparticles, Nanoparticles
- Abstract
Copper substitution together with nano-structuring are applied with the aim to increase the bactericidal performances of the rocksalt-type MgO oxide. The partial substitution of magnesium ions with Cu
2+ has been successfully achieved in both micrometer- and nanometer-sized particles of MgO up to 20 mol% in increments of 5 mol%. Microstructural analyses using the Integral Breadth method revealed that the thermal decomposition of the single source precursor Mg1-x Cux (OH)2-2y (CO3 )y .zH2 O at 400 °C creates numerous defects in 10-20 nm-sized particles of Mg1-x Cux O thus obtained. These defects make the surface of nanoparticles highly reactive towards the sorption of water molecules, to the extent that the cubic cell a parameter in as-prepared Mg1-x Cux O expands by +0.24% as soon as the nanoparticles are exposed to ambient air (60% RH). The hydration of Mg1-x Cux O particles in liquid water is based on a conventional dissolution-precipitation mechanism. Particles of a few microns in size dissolve all the more slowly the higher the copper content and only Mg(OH)2 starts precipitating after 3 h. In contrast, the dissolution of all 10-20 nm-sized Mg1-x Cux O particles is complete over a 3 h period and water suspension only contains 4-12 nm-sized Mg1-x Cux (OH)2 particles after 3 h. Thereby, the bactericidal activity reported for water suspension of Mg1-x Cux O nanoparticles depends on the speed at which these nanoparticles dissolve and Mg1-x Cux (OH)2 nanoparticles precipitate in the first 3 h. Only 10 mol% of cupric ions in MgO nanoparticles are sufficient to kill both E. coli and S. aureus with a bactericidal kinetics faster and reductions in viability at 3 h (6.5 Log10 and 2.7 Log10 , respectively) higher than the conventional antibacterial agent CuO (4.7 Log10 and 2 Log10 under the same conditions). EPR spin trapping study reveals that "hydroxylated" Mg0.9 Cu0.1 O as well as Mg0.9 Cu0.1 (OH)2 nanoparticles produce more spin-adducts with highly toxic hydroxyl radicals than their copper-free counterparts. The rapid mass adsorption of Mg0.9 Cu0.1 (OH)2 nanoparticles onto the cell envelopes following their precipitation together with their ability to produce Reactive Oxygen Species are responsible for the exceptionally high bactericidal activity measured in the course of the hydroxylation of Mg0.9 Cu0.1 O nanoparticles., (Copyright © 2021 Elsevier B.V. All rights reserved.)- Published
- 2021
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10. Graphitic Carbon Nitride for Photocatalytic Air Treatment.
- Author
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Baudys M, Paušová Š, Praus P, Brezová V, Dvoranová D, Barbieriková Z, and Krýsa J
- Abstract
Graphitic carbon nitride (g-C
3 N4 ) is a conjugated polymer, which recently drew a lot of attention as a metal-free and UV and visible light responsive photocatalyst in the field of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability and earth-abundant nature. In the present work, bulk g-C3 N4 was synthesized by thermal decomposition of melamine. This material was further exfoliated by thermal treatment. S-doped samples were prepared from thiourea or further treatment of exfoliated g-C3 N4 by mesylchloride. Synthesized materials were applied for photocatalytic removal of air pollutants (acetaldehyde and NOx ) according to the ISO 22197 and ISO 22197-1 methodology. The efficiency of acetaldehyde removal under UV irradiation was negligible for all g-C3 N4 samples. This can be explained by the fact that g-C3 N4 under irradiation does not directly form hydroxyl radicals, which are the primary oxidation species in acetaldehyde oxidation. It was proved by electron paramagnetic resonance (EPR) spectroscopy that the dominant species formed on the irradiated surface of g-C3 N4 was the superoxide radical. Its production was responsible for a very high NOx removal efficiency not only under UV irradiation (which was comparable with that of TiO2 ), but also under visible irradiation.- Published
- 2020
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11. Polyradical PROXYL/TEMPO-Derived Amides: Synthesis, Physicochemical Studies, DFT Calculations, and Antimicrobial Activity.
- Author
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Poprac P, Poliak P, Kavala M, Barbieriková Z, Zalibera M, Fronc M, Švorc Ľ, Vihonská Z, Olejníková P, Lušpai K, Lukeš V, Brezová V, and Szolcsányi P
- Abstract
A series of polynitroxide amides possessing 2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PROXYL) and/or 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) units connected through various bridges were synthesized and their properties were analyzed. EPR spectroscopy provided detailed insight into their paramagnetic character and related properties. A thorough examination of the EPR spectra of dinitroxides in organic solvents provided valuable information on the intramolecular motions, thermodynamics, and spin-exchange mechanisms. Analysis of low-temperature X- and Q-band EPR spectra of the dissolved dinitroxides provided spin-spin distances that were comparable with the theoretical values obtained by DFT. Cyclic voltammetry investigations revealed (quasi)reversible electrochemical behavior for PROXYL-derived biradicals, whereas significant loss of the reversibility was found for TEMPO-containing bi- and polyradicals. The inhibitory activities of the nitroxides against model bacteria, yeasts, and filamentous fungi were assessed., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2017
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12. Protonation and electronic structure of 2,6-dichlorophenolindophenolate during reduction. A theoretical study including explicit solvent.
- Author
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Malček M, Bučinský L, Barbieriková Z, Dorotíková S, Dvoranová D, Brezová V, Rapta P, and Biskupič S
- Abstract
Protonation in the two-electron/two-proton reduction processes of 2,6-dichlorophenolindophenolate (DCIP) is investigated combining density functional theory (DFT) and molecular dynamics (MD) methods. DCIP (anion), DCIP
•- (radical anion), and DCIP2- (dianion) are considered, including the electronic structure analysis from the prospective of quantum theory of atoms and molecules (QTAIM). It is shown that oxygen on the indophenolate moiety and nitrogen are the first and/or the second proton acceptor sites and their energetic order depends on the total charge of the system. MD simulations of differently charged species interacting with the solvent molecules have been performed for methanol, water, and oxonium cation (H3 O+ ). Methanol and water molecules are found to form only hydrogen bonds with the solute irrespective of its charge. The calculated pKa values show that the imino group of DCIPH- is a weaker acid than water. While in the case of DCIP (and DCIP•- ) plus oxonium cation, proton transfer from the solvent to the solute was evidenced for both aforementioned acceptor sites. In addition, MD simulations of bulks containing 15 and 43 molecules of water around the DCIP molecule have been performed, revealing the formation of 2-4 hydrogen bonds. Graphical Abstract 2,6-Dichlorophenolindophenolate interacts with solvent molecules (water, oxonium cation and methanol). Hydrogen transfer and electronic structure are studied by DFT and molecular dynamics methods.- Published
- 2016
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13. Acridin-3,6-dialkyldithiourea hydrochlorides as new photosensitizers for photodynamic therapy of mouse leukemia cells.
- Author
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Cisáriková A, Barbieriková Z, Janovec L, Imrich J, Hunáková L, Bačová Z, and Paulíková H
- Subjects
- Acridines chemistry, Animals, Cell Line, Tumor, Electron Spin Resonance Spectroscopy, Mice, Acridines therapeutic use, Leukemia, Experimental drug therapy, Photochemotherapy, Photosensitizing Agents pharmacology
- Abstract
Acridin-3,6-dialkyldithiourea hydrochlorides (AcrDTUs) have been evaluated as a new group of photosensitizers (PSs) for photodynamic antitumor therapy (PDT). Mouse leukemia cells L1210 were used for testing of AcrDTUs as the new PSs. The irradiation (UV-A light (365 nm), 1.05 J/cm(2)) increased cytotoxicity of all derivatives against L1210 cells more than ten times. The highest photocytotoxicity was found for propyl-AcrDTU with IC50=0.48±0.03 μM after 48 h incubation. A generation of the superoxide radical anion upon UV-A irradiation of propyl-AcrDTU was confirmed by in situ photochemical EPR experiments. To explain a mechanism of photocytotoxic action of AcrDTUs, an intracellular distribution of propyl-AcrDTU has been studied. It was found that AcrDTU in non-irradiated cells was not present in their nucleus but in the lysosomes and partly in the mitochondria, and sequestration of propyl-AcrDTU was dependent on pH in lysosomes. After irradiation, the cell death was induced by oxidative damage of lysosomal and mitochondrial membranes. Concerning the cell cycle, flow cytometry after PDT with propyl-AcrDTU showed a significant increase of the cells in the subG0 phase. Observed signs of necrosis, apoptosis, and autophagy indicate that PDT/AcrDTU leads to multiple cell death types (caspase independent apoptosis, necrosis, and autophagy)., (Copyright © 2016. Published by Elsevier Ltd.)
- Published
- 2016
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14. UVA-induced effects of 2,6-disubstituted 4-anilinoquinazolines on cancer cell lines.
- Author
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Jantová S, Melušová M, Pánik M, Brezová V, and Barbieriková Z
- Subjects
- Animals, Apoptosis radiation effects, Caspase 3 metabolism, Caspase 9 metabolism, Cell Line, Tumor, Cell Proliferation drug effects, Cell Proliferation radiation effects, Comet Assay, DNA Damage drug effects, DNA Damage radiation effects, Electron Spin Resonance Spectroscopy, HT29 Cells, HeLa Cells, Humans, Mice, Mitochondria drug effects, Mitochondria metabolism, Mitochondria radiation effects, Oxidation-Reduction, Photosensitizing Agents chemistry, Quinazolines chemistry, Singlet Oxygen metabolism, Superoxides metabolism, Apoptosis drug effects, Photosensitizing Agents pharmacology, Quinazolines pharmacology, Ultraviolet Rays
- Abstract
Five 2,6-substituted 4-anilinoquinazolines were evaluated for their ability to generate superoxide radical anion and singlet oxygen upon UVA irradiation and to induce cytotoxic/phototoxic effects on cancer cell lines L1210, HeLa and HT-29. The formation of radical intermediates, especially reactive oxygen species, upon UVA photoexcitation of the studied derivatives was monitored by indirect techniques of EPR spectroscopy. For all 4-anilinoquinazolines the photoinduced generation of superoxide radical anion was evidenced using spin trapping agent 5,5-dimethyl-1-pyrroline N-oxide, and the presence of (1)O2 was detected by the oxidation of 4-hydroxy-2,2,6,6-tetramethylpiperidine to the paramagnetic species 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl. The confirmed photoinduced activation of molecular oxygen via both Type I and Type II photooxidation mechanisms indicates potential phototoxic responses in cells. Biological results showed that derivatives I-V initiated different cytotoxic/phototoxic effects dependent on their concentration, time of treatment and the character of the cell line. UVA irradiation increased the cytotoxic activity of all tested 4-anilinoquinazoline derivatives. The highest cytotoxicity/phototoxicity on all tested cancer cells was induced by N,2-diphenyl-quinazolin-4-amine (derivative III). This most effective derivative emerged as the potent photosensitizer, which possesses a significant antiproliferative activity and DNA damage in L1210 cells increased by UVA irradiation. In addition derivative III induced programmed cell death in leukemia cells through mitochondrial/caspase 9/caspase 3-dependent pathway., (Copyright © 2015 Elsevier B.V. All rights reserved.)
- Published
- 2016
- Full Text
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15. Radical intermediates in photoinduced reactions on TiO2 (an EPR spin trapping study).
- Author
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Dvoranová D, Barbieriková Z, and Brezová V
- Subjects
- Acetonitriles chemistry, Carbon chemistry, Dimethyl Sulfoxide chemistry, Electrons, Ethanol chemistry, Methanol chemistry, Oxides chemistry, Oxygen chemistry, Solubility, Solvents chemistry, Spin Trapping methods, Hydroxyl Radical chemistry, Superoxides chemistry, Titanium chemistry
- Abstract
The radical intermediates formed upon UVA irradiation of titanium dioxide suspensions in aqueous and non-aqueous environments were investigated applying the EPR spin trapping technique. The results showed that the generation of reactive species and their consecutive reactions are influenced by the solvent properties (e.g., polarity, solubility of molecular oxygen, rate constant for the reaction of hydroxyl radicals with the solvent). The formation of hydroxyl radicals, evidenced as the corresponding spin-adducts, dominated in the irradiated TiO2 aqueous suspensions. The addition of 17O-enriched water caused changes in the EPR spectra reflecting the interaction of an unpaired electron with the 17O nucleus. The photoexcitation of TiO2 in non-aqueous solvents (dimethylsulfoxide, acetonitrile, methanol and ethanol) in the presence of 5,5-dimethyl-1-pyrroline N-oxide spin trap displayed a stabilization of the superoxide radical anions generated via electron transfer reaction to molecular oxygen, and various oxygen- and carbon-centered radicals from the solvents were generated. The character and origin of the carbon-centered spin-adducts was confirmed using nitroso spin trapping agents.
- Published
- 2014
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16. Novel 3,6-bis(imidazolidine)acridines as effective photosensitizers for photodynamic therapy.
- Author
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Cižeková L, Grolmusová A, Ipóthová Z, Barbieriková Z, Brezová V, Hunáková L, Imrich J, Janovec L, Dovinová I, and Paulíková H
- Subjects
- Acridines chemical synthesis, Acridines chemistry, Animals, Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Cell Cycle drug effects, Cell Death drug effects, Cell Proliferation drug effects, Cells, Cultured, Dose-Response Relationship, Drug, Drug Screening Assays, Antitumor, Humans, Imidazolidines chemical synthesis, Imidazolidines chemistry, Lysosomes drug effects, Lysosomes metabolism, Mice, Molecular Structure, NIH 3T3 Cells, Oxidative Stress drug effects, Photosensitizing Agents chemical synthesis, Photosensitizing Agents chemistry, Structure-Activity Relationship, Acridines pharmacology, Antineoplastic Agents pharmacology, Imidazolidines pharmacology, Photochemotherapy, Photosensitizing Agents pharmacology
- Abstract
The photoeffect of new proflavine derivatives with DNA-binding and antitumour activities, 3,6-bis((1-alkyl-5-oxo-imidazolidin-2-yliden)imino)acridine hydrochlorides (AcrDIMs), was studied to evaluate them as potential photosensitizers for photodynamic antitumor therapy. EPR measurements showed that superoxide radical anion and singlet oxygen were produced upon irradiation of AcrDIMs with UV-A light (>300nm) in the presence of molecular oxygen. This indicates that AcrDIMs may act as photosensitizers. The most active pentyl-AcrDIM and hexyl-AcrDIM displayed photocytotoxic effect toward the mouse lymphocytic leukemia cell line L1210 and human ovarian cancer cells A2780. Antitumor activity of pentyl-AcrDIM increased as high as about 12 times (72h incubation) after irradiation of A2780 cells (365nm, 1.05J/cm(2)). The photocytotoxicity seems to be associated with oxidative stress. Concerning the cell cycle, flow cytometry showed an arrest in the S-phase already 4h after irradiation. In a comet assay, no genotoxicity of AcrDIMs was found. Typical morphologic changes and formation of DNA-ladders indicated induction of apoptotic cell death, though no activation of caspase-3 was observed. Investigation of intracellular localization of pentyl-AcrDIM confirmed its partial accumulation in mitochondria and lysosomes. After irradiation of the A2780 cells, colocalization of pentyl-AcrDIM with monodansylcadaverine, a lysosomal dye, was proven, suggesting that lysosomes in the irradiated cells may be involved in the cell death., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2014
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17. Fused-ring derivatives of quinoxalines: spectroscopic characterization and photoinduced processes investigated by EPR spin trapping technique.
- Author
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Barbieriková Z, Dvoranová D, Bella M, Milata V, Czímerová A, and Brezová V
- Subjects
- Electron Spin Resonance Spectroscopy, Oxygen chemistry, Spectroscopy, Fourier Transform Infrared, Spin Labels, Spin Trapping, Ultraviolet Rays, Quinoxalines chemistry, Reactive Oxygen Species chemistry, Superoxides chemistry
- Abstract
10-Ethyl-7-oxo-7,10-dihydropyrido[2,3-f]quinoxaline derivatives, synthesized as promising biologically/photobiologically active compounds were characterized by UV/vis, FT-IR and fluorescent spectroscopy. Photoinduced processes of these derivatives were studied by EPR spectroscopy, monitoring in situ the generation of reactive intermediates upon UVA (λmax=365 nm) irradiation. The formation of reactive oxygen species and further oxygen- and carbon-centered radical intermediates was detected and possible reaction routes were suggested. To quantify the investigated processes, the quantum yields of the superoxide radical anion spin-adduct and 4-oxo-2,2,6,6-tetramethylpiperidine N-oxyl generation were determined, reflecting the activation of molecular oxygen by the excited state of the quinoxaline derivative.
- Published
- 2014
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18. Oxidation of quinolones with peracids (an in situ EPR study).
- Author
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Staško A, Milata V, Barbieriková Z, and Brezová V
- Subjects
- Oxidation-Reduction, Aniline Compounds chemistry, Chlorobenzoates chemistry, Electron Spin Resonance Spectroscopy methods, Oxygen chemistry, Quinolones chemistry
- Abstract
4-Oxoquinoline derivatives (quinolones) represent heterocyclic compounds with a variety of biological activities, along with interesting chemical reactivity. The quinolone derivatives possessing secondary amino hydrogen at the nitrogen of the enaminone system are oxidized with 3-chloroperbenzoic acid to nitroxide radicals in the primary step while maintaining their 4-pyridone ring. Otherwise, N-methyl substituted quinolones also form nitroxide radicals coupled with the opening of the 4-pyridone ring in a gradual oxidation of the methyl group via the nitrone-nitroxide spin-adduct cycle. This was confirmed in an analogous oxidation using N,N-dimethylaniline as a model compound. N-Ethyl quinolones in contrast to its N-methyl analog form only one nitroxide radical without a further degradation., (Copyright © 2013 John Wiley & Sons, Ltd.)
- Published
- 2014
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19. Photoinduced oxidation of sterically hindered amines in acetonitrile solutions and titania suspensions (an EPR study).
- Author
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Barbieriková Z, Mihalíková M, and Brezová V
- Abstract
The reactions of sterically hindered amines (SHA) were investigated in acetonitrile solutions and TiO(2) suspensions upon exposure to monochromatic radiation, λ=365 nm, by means of in situ EPR spectroscopy. The formation of singlet oxygen, as one of the possible oxidation agents for SHA, in these systems is affected significantly by solvent used and the experimental conditions. Experiments in homogeneous media evidenced alternative pathways for the SHA oxidation with a variety reactive oxygen species involved. In anhydrous acetonitrile solutions containing KO(2), the SHA oxidation was negligible not only in the dark but also on continuous exposure. However, the presence of water, even at low concentrations, led to the transformation of O(2)(•-) to singlet oxygen and hydrogen peroxide, which served as a source of hydroxyl radicals. These species participated in oxidation of SHA resulting in the generation of nitroxide radicals. To investigate the influence of different competitive reactions of SHA with other ROS formed upon TiO(2) photoexcitation, a series of experiments using different additives (e.g. KO(2), H(2)O(2), NaN(3), dimethylsulfoxide, methanol as organic cosolvents) under air or argon were performed. The detailed analysis of paramagnetic intermediates formed upon the irradiation of the studied systems was accomplished using EPR spin trapping technique., (© 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.)
- Published
- 2012
- Full Text
- View/download PDF
20. Stable radical trianions from reversibly formed sigma-dimers of selenadiazoloquinolones studied by in situ EPR/UV-vis spectroelectrochemistry and quantum chemical calculations.
- Author
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Staško A, Lušpai K, Barbieriková Z, Rimarčík J, Vagánek A, Lukeš V, Bella M, Milata V, Zalibera M, Rapta P, and Brezová V
- Subjects
- Anions chemistry, Dimerization, Electron Spin Resonance Spectroscopy, Free Radicals chemistry, Molecular Structure, Spectrophotometry, Ultraviolet, Organoselenium Compounds chemistry, Quantum Theory, Quinolones chemistry
- Abstract
The redox behavior of the series of 7-substituted 6-oxo-6,9-dihydro[1,2,5]selenadiazolo[3,4-h]quinolines and 8-substituted 9-oxo-6,9-dihydro[1,2,5]selenadiazolo[3,4-f]quinolines with R(7), R(8) = H, COOC(2)H(5), COOCH(3), COOH, COCH(3), and CN has been studied by in situ EPR and EPR/UV-vis spectroelectrochemistry in dimethylsulfoxide. All selenadiazoloquinolones undergo a one-electron reduction process to form the corresponding radical anions. Their stability strongly depends on substitution at the nitrogen atom of the 4-pyridone ring. The primary generated radical anions from N-ethyl-substituted quinolones are stable, whereas for the quinolones with imino hydrogen, the initial radical anions rapidly dimerize to produce unusually stable sigma-dimer (σ-dimer) dianions. These are reversibly oxidized to the initial compounds at potentials considerably less negative than the original reduction process in the back voltammetric scan. The dimer dianion can be further reduced to the stable paramagnetic dimer radical trianion in the region of the second reversible reduction step. The proposed complex reaction mechanism was confirmed by in situ EPR/UV-vis cyclovoltammetric experiments. The site of the dimerization in the σ-dimer and the mapping of the unpaired spin density both for radical anions and σ-dimer radical trianions with unusual unpaired spin distribution have been assigned by means of density functional theory calculations.
- Published
- 2012
- Full Text
- View/download PDF
21. Anodic oxidation of selenadiazoloquinolones in alkaline media.
- Author
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Staško A, Zalibera M, Barbieriková Z, Rimarčík J, Lukeš V, Bella M, Milata V, and Brezová V
- Subjects
- Electrodes, Electron Spin Resonance Spectroscopy, Hydrogen-Ion Concentration, Molecular Structure, Organometallic Compounds chemistry, Oxidation-Reduction, Quantum Theory, Solutions, Organometallic Compounds chemical synthesis, Quinolines chemistry, Selenium chemistry, Sodium Hydroxide chemistry
- Abstract
Newly synthesized derivatives of 6-oxo-6,9-dihydro[1,2,5]selenadiazolo[3,4-h]quinoline variously substituted at position 7 (R = H, COOH, COCH(3), CN, COOC(2)H(5) and COOCH(3)) are established in strongly alkaline aqueous solutions (0.1 M NaOH; pH ∼ 13) as N(9)-deprotonated structures, but in less alkaline solutions (0.001 M NaOH; pH ∼ 11) the N(9)-protonated oxo tautomeric forms dominate. Upon their anodic oxidation in alkaline solutions, the selenadiazole ring is replaced, forming instead the paramagnetic species analogous to the ortho semiquinone radical anions as monitored by in situ EPR spectroscopy. The quantum chemical calculations for two representative selenadiazoloquinolones (R = H and COOH) and their anodic oxidation products presented are in agreement with experiments., (Copyright © 2011 John Wiley & Sons, Ltd.)
- Published
- 2011
- Full Text
- View/download PDF
22. Photoinduced superoxide radical anion and singlet oxygen generation in the presence of novel selenadiazoloquinolones (an EPR Study).
- Author
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Barbieriková Z, Bella M, Kučerák J, Milata V, Jantová S, Dvoranová D, Veselá M, Staško A, and Brezová V
- Subjects
- Animals, Cell Line, Tumor, Electron Spin Resonance Spectroscopy, Humans, Mice, Spectrophotometry, Ultraviolet, Ultraviolet Rays, Quinolones chemistry, Singlet Oxygen chemistry, Superoxides chemistry
- Abstract
Novel 7-substituted 6-oxo-6,9-dihydro[1,2,5]selenadiazolo[3,4-h]quinoline (SeQ(1-6)) and 8-substituted 9-oxo-6,9-dihydro[1,2,5]selenadiazolo[3,4-f ]quinoline derivatives (SeQN(1-5)) with R(7), R(8) =H, COOC(2) H(5), COOCH(3), COOH, COCH(3) or CN were synthesized and their spectral characteristics were obtained by UV/Vis spectroscopy. Ultraviolet A photoexcitation of the selenadiazoloquinolones in dimethylsulfoxide or acetonitrile resulted in the formation of paramagnetic species coupled with molecular oxygen activation generating the superoxide radical anion or singlet oxygen, evidenced by electron paramagnetic resonance spectroscopy. The cytotoxic/photocytotoxic impact of selenadiazoloquinolones on murine and human cancer cell lines was demonstrated using the derivative SeQ5 (with R(7)=COCH(3))., (© 2010 The Authors. Photochemistry and Photobiology © 2010 The American Society of Photobiology.)
- Published
- 2011
- Full Text
- View/download PDF
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