National Repository of Grey Literature 9 records found  Search took 0.01 seconds. 
Oxidation of Bioflavonoids in Respect to their Chemical Structure
Sokolová, Romana ; Ramešová, Šárka ; Kocábová, Jana ; Degano, I.
The electrochemical oxidation of flavone luteolin, flavanone taxifolin and flavonols derived from quercetin was studied by cyclic voltammetry. Only small differences in the chemical structure of bioflavonoids resulted in extremely variable oxidation pathways and products. Products of oxidation and further decomposition were determined by HPLC-ESI-MS/MS and HPLC-DAD.
Oxidation Mechanism of Rhamnetin, a Bioflavonoid Compound
Ramešová, Šárka ; Sokolová, Romana ; Degano, I.
The natural flavonoid rhamnetin (2-(3,4-dihydroxyfenyl)-3,5-dihydroxy-7-methoxychromen-4-one) is important bioactive compound. Rhamnetin was studied in aqueous solution by electrochemical methods. The oxidation mechanism proceeds in sequential steps, which correspond to the hydroxyl oxidation of groups in the three aromatic rings. The study is based on in situ spectroelectrochemistry and identification of products by HPLC-DAD and HPLC–ESI MS/MS.
Reduction and Oxidation of Hydroxyquinolines in Acetonitrile and Dimethylsulfoxide
Sokolová, Romana ; Ramešová, Šárka ; Fiedler, Jan ; Kolivoška, Viliam ; Degano, I. ; Gál, M. ; Szala, M. ; Nycz, J. E.
This study is focused on investigation of oxidation and reduction pathways of selected hydroxyquinoline compounds in nonaqueous solutions. The experimentally obtained reduction potentials are reported to well correlate with calculated values of LUMO energies as well as the obtained oxidation potentials are in a good agreement with theoretical HOMO energies. The cyclic voltammetry, in situ UV/Vis spectroelectrochemistry and in situ IR spectroelectrochemistry confirmed that the oxidation mechanism is complicated. Oxidation unexpectedly proceeds together with protonation of the starting compound. This behaviour was found for all studied compounds, hydroxyquinoline carboxylic acids and also for compounds, where a methyl group is present instead of carboxylic group.
Electrochemistry of Flavonolignans in Acetonitrile and Dimethylsulfoxide
Sokolová, Romana ; Kocábová, Jana ; Fiedler, Jan ; Vacek, J. ; Marhol, Petr ; Vavříková, Eva ; Křen, Vladimír
This study is focused on investigation of oxidation pathways of silybin and 2,3-dehydrosilybin in nonaqueous solutions. The oxidation mechanism of both flavonolignans differs and depends strongly on their chemical structure. The cyclic voltammetry, UV/Vis and IR spectroelectrochemistry were used for identification of electrooxidation (semiquinone) intermediates. HPLC with diode array detection was applied for identification of oxidation and degradation products. Molecular orbital calculations supported the experimental findings.
Oxidation Mechanisms of Diflunisal on Glassy Carbon Electrode
Tiribilli, Ch. ; Giannarelli, S. ; Sokolová, Romana ; Valášek, M.
The electrochemical oxidation of diflunisal in acetonitrile was studied on a glassy carbon electrode. Diflunisal yields one irreversible oxidation wave at 1.6 V (vs. Ag/AgCl/1M LiCl electrode). The oxidation mechanism depends on the basicity of the solvent. The study is based on cyclic voltammetry, electroanalytical methods and UV-Vis spectroelectrochemistry. The degradation products were determined by separation techniques (HPLC-DAD, GC-MS).
Electrochemical Study of Rhamnazin
Ramešová, Šárka ; Sokolová, Romana ; Degano, I.
The natural flavonoid compound rhamanzin (3,5,4’-trihydroxy-7,3’-dimethoxyflavone) is important bioactive compound with antioxidative, anti-allergic, and anti-inflammatory properties. The cyclic voltammetry is used for the electrochemistry behavior of rhamnazin. The determination of oxidation pathways is supported by the identification of degradation products using separation technique.
Adsorption of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine on Au(111) and HOPG
Kocábová, Jana ; Sokolová, Romana
Atomic force microscopy (AFM) was used to study the formation of layers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) on Au(111) and highly oriented pyrolytic graphite (HOPG) in microscopic level. Both substrates were found to support the DPPC layers. The nanoshaving technique was applied to determine the layer thickness. In addition, the influence of deionized water on the DPPC ordering at the substrates was studied by ex-situ and in-situ AFM intermittent contact mode measurements.
The Adsorption of Phospholipids at the Interface
Sokolová, Romana ; Kocábová, Jana ; Parisová, Martina ; Navrátil, Tomáš ; Gál, Miroslav
The adsorption of phospholipids on different types of substrate was studied. The adsorbate-surface interactions play an important role in the formation of supported phospholipid bilayer. The deposition of phospholipids on atomically flat surfaces as mica, gold(111), highly oriented graphite and rough surface of polycarbonate membrane is compared. The supported phospholipids bilayer covers some small defects (5 – 30 nm deep) present in rough polycarbonate membrane.
Spectroelectrochemistry of Flavonolignans and their DNA-binding Copper Complexes
Sokolová, Romana ; Kubala, M. ; Vavříková, E. ; Ulrichová, J. ; Křen, Vladimír ; Vacek, J.
The oxidation of flavonolagnan silybin and its selected derivatives was studied on glassy carbon electrode in aqueous environment by means of cyclic voltammetry, in situ UV/VIS spectroelectrochemistry and absorption spectrometry. The oxidation mechanism of flavonolignans and their complexion with copper was investigated under anaerobic conditions. The acquired results were interpreted in context of protective (antioxidant) and DNA-binding (prooxidant) properties of flavonolignans and their transition metal complexes.

Interested in being notified about new results for this query?
Subscribe to the RSS feed.