Abstract
Flavonoids are a class of natural phenolic compounds that show antioxidant properties. Besides the known mechanisms of action of flavonoids (binding/inactivation of free radicals and other reactive oxygen species) that determine this effect, an important factor is their ability to bind transition metal ions. In this paper, we used a HPLC method with a prechromatographic reaction of a sample with Fe2+ ions (FeCA-HPLC) to characterize the Fe2+-chelating properties of individual compounds, their mixtures, and plant extracts. Using two classes of flavonoids (flavones, flavonols) the ability of compounds to bind Fe2+ ions due to a number of structural features of the compounds was shown. If the compounds possessed Fe2+-chelating properties, the decrease in the area of the chromatographic peaks on the chromatogram was marked. By comparing the resulting chromatogram with that of the untreated sample, it was possible to estimate the value of the effect. Application of this method for the analysis of plant extracts representing a mixture of substances allows determination of the compounds that have the greatest influence on the Fe2+-chelating activity.
Highlights
Transition metals play a major role in the generation of reactive oxygen species (ROS) in organisms
In order to reveal the effectiveness of the proposed technique investigating Fe2+-chelating activity (Fe-CA), the experimental part of the work was carried out on samples of standard compounds during the first stage of the study
Based on the data regarding the different abilities of the compounds to be solubilised in solvents that are used for working with phenolic compounds, we proposed DMSO as a universal solvent
Summary
Transition metals play a major role in the generation of reactive oxygen species (ROS) in organisms. The most common ROS include the superoxide anion (O2−), the hydroxyl radical (OH), singlet oxygen (O2), and hydrogen peroxide (H2O2). Superoxide anion is readily produced through the one-electron reduction of oxygen by the Fe2+ ion, and is largely dismuted into hydrogen peroxide by enzymatic and nonenzymatic mechanisms [1]. Hydrogen peroxide is further converted to a hydroxyl radical by the Fenton reaction, which requires the ions of Cu2+ or Fe2+ [2]. Forms after binding Fe2+, which is reduced with molecular oxygen [3,4]. ROS are potent oxidizing and reducing agents that directly damage cellular membranes by lipid peroxidation [5]
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