Effect of aggregation behaviour on the antioxidant capacity of carotenoids
Dalma Czett, Véronika Nagy, Tibor Kurtán, Sándor Balázs Király, Péter Szabó, Attila Agócs, József Deli, Katalin Böddi
Abstract
• Evaluating the use of aqueous solvents in ABTS-TEAC assays for carotenoids. • Assessing the effect of auxiliary organic solvents in ABTS-TEAC assays. • Exploration of the elevated antioxidant capacity of small carotenoid assemblies. Lipophilic substances such as carotenoids show a tendency to aggregate in aqueous medium, that changes the physical and chemical properties of individual molecules. To estimate the antioxidant properties of carotenoids, trolox-equivalent antioxidant capacity (TEAC) values are routinely determined with ABTS +• solutions. As this reagent is a salt, it is generally applied in aqueous solutions to which carotenoids are added in various organic solvents. Here we present a systematic investigation on the solvent dependence of TEAC measurements of 8 carotenoids, as well as the relationship between the aggregation and TEAC values. The aggregation of carotenoids was found to have two opposite effects on the antioxidant capacity: the higher the aggregate size, the lower the TEAC value, however, smaller size (10–20 nm) assemblies surpass the individual molecules in antioxidant capacity. The type of aggregation manner (H or J) seems to have less influence on the antioxidant behaviour.