Talanta 2024 Oct 01;278:126513. doi: 10.1016/j.talanta.2024.126513.

Glycosylated flavonoid kaempferitrin: Electroanalytical detection and the proposal of an oxidation mechanism supported by quantum chemical calculations.

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In this work, the electrochemical behavior of the glycosylated flavonoid kaempferitrin was studied, and an electroanalytical methodology was developed for its determination in infusions of Bauhinia forficata using a boron-doped diamond electrode (BDD). The electrochemical behavior of the flavonoid was studied by cyclic voltammetry, and two irreversible oxidation peaks at 0.80 and 1.0 V vs Ag/AgCl were observed. The influence of the pH on the voltammograms was examined, and higher sensitivity was found at pH 7.0. The electrochemical process corresponding to peak 1 at 0.80 V is predominantly diffusion-controlled, as the study shows at varying scan rates. An analytical plot was obtained by square wave voltammetry at optimized experimental conditions (frequency = 100 s-1, amplitude = 90 mV, and step potential = 8 mV) in the concentration range from 3.4 μmol L-1 to 58 μmol L-1, with a linearity of 0.99. The limit of detection and limit of quantification values were 1.0 μmol L-1 and 3.4 μmol L-1, respectively. Three samples of Bauhinia forficata infusions (2 g of sample in 100 mL of water) were analyzed, and the KF values found were 5.0 × 10-4 mol L-1, 3.0 × 10-4 mol L-1, and 7.0 × 10-4 mol L-1, with recovery percentages of 98 %, 106 % and 94 %, respectively. Finally, experiments were performed with two other flavonoids (chrysin and apeginin) to compare and propose an electrochemical oxidation mechanism for kaempferitrin, which was supported by quantum chemical calculations.

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