. "Electrochemical oxidation of berberine and mass spectrometric identification of its oxidation products"@en . "133875" . "[CA6184CBFDEC]" . "Jirovsk\u00FD, David" . "Papou\u0161kov\u00E1, Barbora" . . . "6"^^ . . . "5"^^ . "Bioelectrochemistry" . . . . . "15310" . . "Electrochemical oxidation of the isoquinoline alkaloid berberine in aqueous medium was studied by cyclic and differential pulse voltammetry at a glassy carbon electrode (GCE). Two anodic peaks of the quaternary form of berberine were observed at +1.2 V and +1.4 V (vs. SCE) in acidic and neutral solutions. When the anodic polarization exceeded the value of +1.1 V. the redox active film is formed on the GCE surface. The formation of adsorbed film was well-documented by quasireversible redox couple at +0.25 V which was studied in redox cycling experiments. In alkaline medium, a new anodic peak at +0.5 V appeared due to oxidation of berberine pseudobase to 8-oxoberberine. Solutions of berberine at different pH were subjected to controlled potential electrolysis on platinum gauze electrode and analyzed using liquid chromatography (HPLC) equipped with electrospray ionization/quadrupole time-of-flight mass spectrometry. The main water soluble monomeric product of berberine oxidation under physiological-near experimental conditions, OP1, was identified as demethyleneberberine cation (2,3-dihydroxy-9,10-dimethoxy-5,6-dihydroisoquinolino[3,2-a]isoquinolin-7-ium)."@en . . "6"^^ . . "000309033000004" . "Electrochemical oxidation of the isoquinoline alkaloid berberine in aqueous medium was studied by cyclic and differential pulse voltammetry at a glassy carbon electrode (GCE). Two anodic peaks of the quaternary form of berberine were observed at +1.2 V and +1.4 V (vs. SCE) in acidic and neutral solutions. When the anodic polarization exceeded the value of +1.1 V. the redox active film is formed on the GCE surface. The formation of adsorbed film was well-documented by quasireversible redox couple at +0.25 V which was studied in redox cycling experiments. In alkaline medium, a new anodic peak at +0.5 V appeared due to oxidation of berberine pseudobase to 8-oxoberberine. Solutions of berberine at different pH were subjected to controlled potential electrolysis on platinum gauze electrode and analyzed using liquid chromatography (HPLC) equipped with electrospray ionization/quadrupole time-of-flight mass spectrometry. The main water soluble monomeric product of berberine oxidation under physiological-near experimental conditions, OP1, was identified as demethyleneberberine cation (2,3-dihydroxy-9,10-dimethoxy-5,6-dihydroisoquinolino[3,2-a]isoquinolin-7-ium)." . . . . "Electrochemical oxidation of berberine and mass spectrometric identification of its oxidation products" . . . "P(ED2.1.00/03.0058), P(GPP503/11/P312), Z(MSM6198959216)" . "RIV/61989592:15310/12:33142149" . "Skopalov\u00E1, Jana" . "Electrochemical oxidation of berberine and mass spectrometric identification of its oxidation products"@en . "RIV/61989592:15310/12:33142149!RIV13-MSM-15310___" . "87" . . . "SI" . "Maier, V\u00EDt\u011Bzslav" . "Vacek, Jan" . "Mass spectrometry; Hydroxylation; Demethylenation; Oxidation; Berberine"@en . "1567-5394" . . "Electrochemical oxidation of berberine and mass spectrometric identification of its oxidation products" . . "Ranc, V\u00E1clav" . . . . . "10.1016/j.bioelechem.2011.09.002" . "CH - \u0160v\u00FDcarsk\u00E1 konfederace" .