Factors influencing the antioxidant properties of binary mixtures of quercetin and chlorogenic acid as well as quercetin and kaempferol

Abstract Antioxidant properties are considered a measure of the ability of a given antioxidant or mixture to counteract or neutralize reactive oxygen species. Polyphenols commonly found in plants are compounds with antioxidant properties. The aim of the presented paper is to assess the antioxidant properties of selected polyphenolic compounds (i.e., chlorogenic acid, kaempferol and quercetin) and selected binary mixtures thereof. These properties were determined in the systems that differ not only in the contents of antioxidants but also of metal ions, hydrogen ions, water and the reaction solvents. The obtained results indicate both antagonistic and additive antioxidant effects in the tested systems, the magnitude or change of which depends on the differentiating factor used in the tests. The greatest impact on the antioxidant effect of the mixture is observed in the presence of metal and hydrogen ions in the system containing chlorogenic acid and quercetin. The relationships discussed in this paper reveal the complexity of the problem regarding the assessment of antioxidant properties, and the obtained results will develop social awareness of naturally occurring antioxidant mixtures. Graphic abstract