An Effective Method for Evaluating Antioxidant Capacity: Integrating Chemical Kinetics and Stoichiometry Based on the Study of the Antioxidant Behavior in the Mixture

The existing studies regarding the evaluation of antioxidant capacity frequently concentrate solely on a single aspect, either stoichiometry or kinetics. And limited research has focused on elucidating antioxidant behavior of antioxidants within mixtures. In this study, we selected 12 phenolic compounds and formulated mixtures with both uniform and varying concentrations for antiradical assay. The change curves of compounds eliminated in response to variations in DPPH and ABTS concentrations were determined by UHPLC-UV-HRMS. An intriguing observation was that the change curves of compounds eliminated in response to variations in DPPH or ABTS concentrations exhibited high similarity across mixtures of varying compositions and concentrations. To better characterize antiradical efficiency, a new parameter (antiradical efficiency (ARE)) was proposed. This parameter integrates both the scavenging capacity and kinetic factors and can be simply evaluated based on the priority and quantity of its elimination within the mixture. Furthermore, when we conducted an experiment to test the DPPH resistance of actual samples (mixed vitamin E capsules), we found that the antioxidants with higher ARE values were more capable of protecting VE from being eliminated by DPPH.