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Application of In situ TR Spectroelectrochemical Techniques in Determination of Redox Mechanism of Bioactive Compounds
Sokolová, Romana ; Jiroušková, Eliška ; Degano, I. ; Wantulok, J. ; Nycz, J.
The electron transfer reactions play an important role in many natural processes. Reactions such as \ndissociation, protonation, and reactions with water and other small molecules often occur in \nbiotransformation. The reaction schemes involving these chemical reactions coupled to the \nelectron transfer can be determined by cyclic voltammetry. Additionally, in \nsitu spectroelectrochemistry can efficiently contribute to the determination of oxidation or \nreduction mechanism. This technique provides information about the electroactive chromophore during \nthe redox process allowing to identification the first reaction intermediates. The final reaction \nproducts were identified by chromatographic techniques. This study represents a key role of TR \nspectroelectrochemistry in the determination of reaction intermediates in the case of \n1,10- phenanthroline derivative substituted by bioactive phenothiazine unit and \ndrug 3- fluorophenmetrazine (2-(3-fluorophenyl)-3-methylmorpholine, 3-FPM). Co pound 3-FPM\nhave recently appeared as the new psychoactive substance in the drug market.\n
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Spectroelectrochemistry of 1,10-phenantrolines Substituted by Pyrrolidine and Phenothiazine Redox-active Units
Sokolová, Romana ; Wantulok, J. ; Fiedler, Jan ; Nycz, J. ; Degano, I.
Compounds based on 1,10-phenanthroline (Phen) and their complexes are used in many fields, such as a stabilizing agent in the synthesis of nanoparticles, catalysts in homogeneous catalysis and as a semiconductor in organic light-emitting diodes (OLED) due to their coordination abilities. In this work, 1,10-phenanthrolines functionalized by pyrrolidine and phenothiazine units were studied by electrochemical methods. Cyclic voltammetry resulted in several oxidation and reduction voltammetric peaks. Structure-activity relationship was investigated using in situ spectroeletrochemistry, spectrophotometry, infrared spectroscopy and chromatography.
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UV-Vis and IR Spectroelectrocbemistry of Copper Complexes and Bioactive Compounds
Sokolová, Romana ; Obluková, Michaela ; Sýs, M. ; Mikysek, T. ; Wantulok, J. ; Nycz, J. E. ; Degano, I.
The interpretation of the change of absorption spectrum of an oxidized and reduced molecule\nrecorded during the electron transfer is an efficient tool for the determination of oxidation or\nreduction mechanism. This technique provides the information about the electroactive\nchromophore and is performed in two regimes of electrochemical measurement, cyclic\nvoltammetry and chronoamperometry, respectively. This approach was successfully applied to\nstudy the fundamental electrochemical behavior of recently synthesized copper complexes\nproviding biomimetic activity, ofpolyphenolic bioactive compounds, and also for the reduction\nof halogenated phenanthrolines. The identification of redox products was done by\nchromatographic techniques as HPLC-DAD and HPLC-ESI-MS/MS.
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Looking into the Photo-stability of Eosin by Electrochemical Methods
Sabatini, F. ; Sokolová, Romana ; Degano, I.
Eosin Y is a synthetic organic dye belonging to the xanthene family. Its bright and fluorescent\npink hue attracted and intrigued the painters of the 19th century, who experimented eosin as\npigment lake (often called Geranium lake) in their paintings. Nevertheless, eosin coloration is\nas beautiful as unstable, and examples of work of arts with faded hues have been documented.\nEosin is not only photo-sensitive but also pH sensitive, making its study very complex. In this\nwork, the combination of electrochemical and spectroscopic techniques revealed to be effective\nfor correlating the physical evidence of eosin fading with its chemical degradation.
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Electrochemical properties of triazine herbicides andtheir inclusion complexes with cyclodextrins
Sokolová, Romana
Thesis presents the study of electrochemical properties of s-triazine herbicides atrazine and terbutylazine and their inclusion complexes with cyclodextrins. The mechanism of reduction of atrazine and terbutylazine in aqueous media was suggested based on polarographic properties and identification of reduction products and the value of rate constant of preceding protonation was determined. The part of study was a detailed adsorption study of both s-triazines herbicides. It was found that both triazines are adsorbed on the surface and undergo a phase transition resulting in the formation of a compact layer. The mechanism of the formation and growth of the layer was characterized. The influence of the presence of α-, β-, γ-cyclodextrins on the electrochemical reduction of atrazine was studied. The formation of the inclusion complex of atrazine with cyclodextrins facilitates the reduction also in neutral solution. Na základě elektrochemického chování byly určeny hodnoty konstanty stability inkluzního komplexu atrazinu s cyklodextriny α-, β- a γ- a rychlostní konstanta předřazené chemické reakce. Část výsledků uvedených v této disertační práci bylo publikováno (přílohy č. 1-3), další část je připravována do tisku. Výsledky jsem přednesla také na konferenci "28th Heyrovský Discussion on Electrochemistry...
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Electrochemical properties of triazine herbicides andtheir inclusion complexes with cyclodextrins
Sokolová, Romana
Thesis presents the study of electrochemical properties of s-triazine herbicides atrazine and terbutylazine and their inclusion complexes with cyclodextrins. The mechanism of reduction of atrazine and terbutylazine in aqueous media was suggested based on polarographic properties and identification of reduction products and the value of rate constant of preceding protonation was determined. The part of study was a detailed adsorption study of both s-triazines herbicides. It was found that both triazines are adsorbed on the surface and undergo a phase transition resulting in the formation of a compact layer. The mechanism of the formation and growth of the layer was characterized. The influence of the presence of α-, β-, γ-cyclodextrins on the electrochemical reduction of atrazine was studied. The formation of the inclusion complex of atrazine with cyclodextrins facilitates the reduction also in neutral solution. Na základě elektrochemického chování byly určeny hodnoty konstanty stability inkluzního komplexu atrazinu s cyklodextriny α-, β- a γ- a rychlostní konstanta předřazené chemické reakce. Část výsledků uvedených v této disertační práci bylo publikováno (přílohy č. 1-3), další část je připravována do tisku. Výsledky jsem přednesla také na konferenci "28th Heyrovský Discussion on Electrochemistry...
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Chemical and biochemical transformation of bioactive compounds
Šimášková, Ema ; Sokolová, Romana (advisor) ; Martínková, Markéta (referee)
Xenobiotics, such as pharmaceuticals, food additives, environmental pollutants, and dietary bioactive compounds in organism are metabolized by various enzymes, resulting in their bioactivation or detoxification. Identification of structure of resulting metabolites is important for their detection in bodily fluids and tissues for diagnostic and forensic purposes. This thesis reviews known biochemical processes and enzymes involved in xenobiotic metabolism, including cytochromes 450 (CYP) and flavine monooxygenases (FMO). Given that biochemical reactions are to a major extent composed of electron-transfer reactions (i.e. oxidation and reduction), the thesis includes a section dealing with the practical approaches to determination of the oxidative or reductive mechanism of bioactive compounds.
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Oxidation and Reduction of Selected 1,10-Phenantrolines
Wantulok, J. ; Sokolová, Romana ; Nycz, J. E. ; Degano, I.
Derivatives of 1,10-phenanthroline (Phen) are well-known bident ligands which had a lot of interesting applications thanks to their coordination abilities. Selected 1,10-phenanthroline compounds were studied by electrochemical methods. Depending on their different substituents were observed several oxidation and reduction voltammetric peaks. The study involves also in situ spectroeletrochemistry, infrared spectroscopy and identification of products by HPLC-DAD and HPLC-ESI MS/MS.
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On UV-Vis Spectroelectrochemistry of Luteolin-7-O-Glucoside
Castano, A. ; Sokolová, Romana ; Degano, I.
The UV-Vis spectroelectrochemical cell containing an optically transparent platinum net used as the working electrode was tested in two regimes of electrochemical measurement, cyclic voltammetry and chronoamperometry, respectively. A three electrode setup used silver quasi reference electrode and platinum electrode serving as a counter electrode. The calibration of the spectroelectrochemical cell was performed for one-electron oxidation processes as well as for two-electron oxidations. The spectral changes during the oxidation of luteolin-7-O-Glucoside gave the information about the electroactive chromophores in molecule. Resulted spectra were compared with luteolin. The identification of products of oxidation was done by complementary analytical techniques HPLC-DAD and HPLC-ESI-MS/MS.
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Differences in Oxidation Mechanism of Selected Bioflavonoids, UV-Vis and IR Spectroelectrochemical Study
Sokolová, Romana ; Fiedler, Jan ; Ramešová, Šárka ; Kocábová, Jana ; Degano, I. ; Quinto, A. ; Křen, Vladimír
The oxidation of selected bioflavonoids (quercetin, rhamnazin, fisetin, rhamnetin, taxifolin, luteolin, silybin and 2,3-dehydrosilybin) was studied by electrochemical and spectroscopic methods. The oxidation mechanism and formation of oxidation products depends on the chemical structure. Only small differences in the chemical structure of compounds with flavone, flavanone and flavonol motif result in extremely variable oxidation pathways and products. Products of oxidation and further decomposition were determined by HPLC-ESIMS/MS and HPLC-DAD.
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