| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1274431 | Bioelectrochemistry | 2012 | 6 Pages |
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).
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Electrochemical oxidation of the isoquinoline alkaloid berberine in aqueous medium has been studied. ► In this study cyclic and differential pulse voltammetry at a glassy carbon and platinum electrode was used. ► The main water soluble product of berberine oxidation (OP1) was identified as demethyleneberberine cation. ► The electrochemical approaches presented here could be useful for the study of oxidation of berberine and its derivatives.
