Antioxidant and antiradical properties of some examples of flavonoids and coumarins—potentiometric studies

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. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.The work was carried out with financial support from the Ministry of Science and Higher Education of the Russian Federation, State Contract no. FEUZ-2020-0058 (H687.42B.223/20)