Antioxidant and Antiradical Properties of Some Examples of Flavonoids and Coumarins—Potentiometric Studies

Abstract

A comprehensive study of a range of flavonoids and coumarins is presented in this article. The work uses an approach that evaluates the activity of these compounds by various mechanisms: the electron transfer (ET), the hydrogen atom transfer (HAT), and the mechanism of metal chelation. The studies were carried out using the methods of the cyclic voltammetry and the potentiometry. The electrochemical behavior of these compounds was studied by the method of cyclic voltammetry; the main types of voltammograms, depending on the oxidation mechanisms, were identified. Various versions of potentiometric sensor systems have been used to detect analytical signal in approaches implemented in ET, HAT and metal chelation mechanisms. The antioxidant capacity was studied by the electron-transfer mechanism. Compounds with antioxidant properties were selected; half-reaction periods for these compounds have been determined. It has been shown that electron-donating and complexing properties directly depend on the mutual arrangement of hydroxyl groups in the molecule. The antiradical ability of the compounds has been studied. It was shown that all studied compounds inhibit peroxyl radicals. Series on the change in antioxidant and antiradical properties of compounds have been compiled. There is no correlation between the results of the study of antioxidant properties obtained using sensory systems that reveal various antioxidant mechanisms. The need to use an integrated approach in the study of antioxidant properties is shown.

Design and Antioxidant Properties of Bifunctional 2H-Imidazole-Derived Phenolic Compounds—A New Family of Effective Inhibitors for Oxidative Stress-Associated Destructive Processes

“…The value of the antiradical capacity was found to reflect the antioxidant properties based on the hydrogen atom transfer mechanism [40,41,56,57]. A number of valuable patterns were also observed herein.…”

“…Determination of antioxidant capacity (AOC) was carried out by the potentiometric method using the oxidizing agent K 3 [Fe(CN) 6 ]. The use of potassium hexacyanoferrate (III) as an oxidizing agent is justified both from a thermodynamic point of view and from the point of view of obtaining an optimal analytical signal [40,41,[54][55][56]. An analytical signal, in this case, is the shift of the potential of the platinum electrode in the K 3 [Fe(CN) 6 ]/K 4 [Fe(CN) 6 ] system, which is observed when the analyzed sample is introduced (Figure S22).…”

“…The basis for the definition of total antiradical capacity (ARC) is a regular change in the redox potential of the reaction of antioxidants with peroxyl radicals generated during the thermal decomposition of 2,2 -azobis (2-amidinopropane) dihydrochloride (Figure S23) [40,41,56,57].…”

“…This fact does confirm the inadequacy of using one approach. The antioxidant capacity is known to be an integral value reflecting the contribution of antioxidant activity through both the electron transfer and the chelation mechanisms [40,41,[54][55][56]. The considered polyphenolic compounds were reported to exhibit a tendency to form complexes with iron ions [51,53].…”

HPLC-DAD phenolic screening and in vitro assessment of antimicrobial, antioxidant and anti-inflammatory activities of Tanteboucht dates

“…26 Indeed, they were found to be good inhibitors, with avonoids, of peroxyl radicals. 27 Rutin and quercetin are considered from the most potent antioxidant agents and several studies 28,29 reported that these avonoids may considerably reduce oxidative stress and lipid peroxidation in brain, kidney and liver by enhancing the expression of key genes involved in antioxidant processes like glutathione S transferase a (GSTa), paraoxonase-1(PON-1) and glutamate-cysteine ligase (GCL). This process will considerably decrease the plasma level of malondialdehyde (MDA) and Glutathione (GSH) considered as the principal markers of oxidative stress.…”