Mechanistic Pathways and Identification of the Electrochemically Generated Oxidation Products of Flavonoid Eriodictyol in the Presence of Glutathione

Newair, Emad F.; Nafady, Ayman; Abdel-Hamid, Refat; Al-Enizi, Abdullah M.; Garcia, François

doi:10.1002/elan.201800071

Cited by 5 publications

(3 citation statements)

References 44 publications

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“…The behavior of KC in the oxidation process was similar to what was observed previously in procyanidin B2 [27]. A previous study reported that the hydroxyl groups of the catechol B ring are more easily oxidized than those of the resorcinol A ring [29,30]. When the potential scan is switched at +0.9 V, the anodic peak at +0.59 V indicates a reversible reaction (inset in Figure 2, blue voltammogram).…”

Section: Voltammetric Behavior Of Kc On Gcesupporting

confidence: 83%

Electrochemical Oxidation Profile of Anthocyanin Keracyanin on Glassy and Screen-Printed Carbon Electrodes

Newair,

Shehata,

Essam

2023

Electrochem

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A study of keracyanin chloride (KC) electrochemical behavior in an aqueous buffer solution using screen-printed carbon electrodes (SPCEs) and glassy carbon electrodes (GCEs) was performed. Cyclic voltammetry (CV) and square-wave voltammetry (SWV) were used to analyze the electrochemical response of KC under studied conditions. A clear redox wave was observed for KC, primarily due to the oxidation of the catechol 3′,4′-dihydroxyl group of its ring B, with a minor redox wave from oxidation of the hydroxyl groups in ring A. Compared to GCEs, using modified SPCEs resulted in two-fold amplification in the electrochemical oxidation signal of KC. Using SPCEs as a working electrode could provide high sensitivity in the quantification of KC and the ability to gauge KC quantification to significantly lower detection limits.

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Section: Voltammetric Behavior Of Kc On Gcesupporting

confidence: 83%

Electrochemical Oxidation Profile of Anthocyanin Keracyanin on Glassy and Screen-Printed Carbon Electrodes

Newair,

Shehata,

Essam

2023

Electrochem

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“…Secondly, the objective was to use the polyphenol solution when GSH is present in excess (1.0 mM) and then flow it through the cell of electrolysis (method 2). This approach ensured that there was an ample amount of GSH available to react with the polyphenols, facilitating the desired reactions within the electrolysis cell [51]. By employing these two distinct methods, it aimed to explore different approaches for handling oxidized polyphenols and GSH in the electrochemical cell.…”

Section: Bulk-electrolysis Flow-cell System For the Oxidation Of Poly...mentioning

confidence: 99%

Oxidation of Wine Polyphenols by Electrochemical Means in the Presence of Glutathione

Newair,

Al-Anazi,

Garcia

2023

Antioxidants

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The oxidation of wine may be beneficial or harmful to its quality. On the one hand, controlled oxidation can lead to the development of desirable sensory characteristics for red wine, such as enhanced color stability. Alternatively, oxidation can lead to white wine browning and a decrease in fruity aromas, and the development of an off flavor and wine polyphenols are also involved. The presence of glutathione (GSH) can help mitigate the negative effects of oxidation by acting as a protective antioxidant. In order to better understand the antioxidant role played by GSH, wine polyphenols oxidation experiments by electrochemical means in the presence of GSH were carried out. The oxidation behavior of polyphenols representing different phenolic classes commonly found in wines, including protocatechuic acid (PCA), caffeic acid (CAF), epicatechin (EC), and rutin (Ru), was investigated using cyclic voltammetry and bulk electrolysis. We identified the oxidation products and reaction pathways of these polyphenols using ultra-high-performance liquid chromatography coupled with mass spectrometry (UPLC-MS), in both the absence and the presence of glutathione (GSH). UPLC-MS was utilized to demonstrate that, in the presence of glutathione (GSH), the four molecules were subjected to electrochemical oxidation, resulting in the formation of mono- and bi-glutathione conjugates. A two-electron oxidation process combined with the removal of two protons is the first step in transforming polyphenol molecules. As a result, the corresponding quinone is formed. The quinone can then be reduced back to its original form by glutathione (GSH), or it can interact further with GSH to produce mono- and bi-glutathione conjugates. These results contribute to understanding and predicting the oxidative degradation pathway of polyphenols in wine. Understanding this process seems important for winemakers to control and optimize the sensory characteristics of their wines.

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“…PAs become more hydrophobic in an acidic medium due to their nonionizing OH groups, which migrate on the hydrophobic surface of a GCE and adsorb there. By becoming more ionizable in the basic medium, the OH groups make the PAs molecule more hydrophilic and migrate away from the surface of the GCE to the bulk solution [57]. As a result, the electroactive species of PAs (i.e., nonionizable forms) are more concentrated at acidic pH levels than at basic pH levels.…”

Section: Effect Of Ph On the Cyclic Voltammetric Behavior Of Proantho...mentioning

confidence: 99%

Square-Wave and Cyclic Voltammetry of Native Proanthocyanidins Extracted from Grapevine (Vitis vinifera) on the Glassy Carbon Electrode

Adam

Newair

2022

Chemosensors

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Condensed tannins are short polymers of flavan-3-ols found in grapes (also known as proanthocyanidins). An investigation on the electrochemical oxidation of grapevine proanthocyanidins (PAs) on glassy carbon electrodes under various conditions was conducted for the first time. To study how the proanthocyanidins were oxidized, square-wave and cyclic voltammetry were used. There is a predominant oxidation peak associated with the extract of proanthocyanidins, and this can be attributed to the oxidation of catechol 3′,4′-dihydroxyl groups, which can form their oxidation peak. There are two electrons and two protons involved in the oxidation of the catechol group, which must be kept in mind when considering the oxidation of the catechol group. On the glassy carbon electrode (GCE), the PAs extracted from grapevine are oxidized by an adsorption-dependent mechanism as they interact with the GCE surface. As a result, it was found that the anodic peak current varied linearly with PAs’ concentrations in the range of 4 to 50 ppm, with a detection limit of 3.07 ppm (S/N = 3). There was a development in the surface concentration of the oxidation products at the GC electrode; as the scans progressed, the surface concentration of oxidation products at the electrode remained at 4.83 × 10−11 mol cm−2, indicating that they were immobilized on the GCE as oxidation products adsorbed on the electrode.

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Mechanistic Pathways and Identification of the Electrochemically Generated Oxidation Products of Flavonoid Eriodictyol in the Presence of Glutathione

Cited by 5 publications

References 44 publications

Electrochemical Oxidation Profile of Anthocyanin Keracyanin on Glassy and Screen-Printed Carbon Electrodes

Electrochemical Oxidation Profile of Anthocyanin Keracyanin on Glassy and Screen-Printed Carbon Electrodes

Oxidation of Wine Polyphenols by Electrochemical Means in the Presence of Glutathione

Square-Wave and Cyclic Voltammetry of Native Proanthocyanidins Extracted from Grapevine (Vitis vinifera) on the Glassy Carbon Electrode

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