Comparative Study of the Antioxidant Capacity of Four Stilbenes Using ORAC, ABTS+, and FRAP Techniques

Abstract

Researchers use several different analytical techniques, such as ORAC, ABTS·+, or FRAP, for measuring the antioxidant capacity of bioactive compounds. However, many authors do not take into account that these three techniques have different objectives. This contribution reports on the use of two types of tests to evaluate the antioxidant activity of four stilbene tests based first on the hydrogen atom transfer reaction (ORAC method) and the second on the single electron transfer reaction (ABTS·+ and FRAP assays). For the ORAC assay, the greatest antioxidant activity was shown by resveratrol, followed by oxyresveratrol, pterostilbene, and pinosylvin, while in the ABTS.+ assay, the highest antioxidant capacity was presented by oxyresveratrol, followed by resveratrol, pinosylvin, and finally pterostilbene. In the FRAP assay, the reducing activity shown by all the stilbenes was below that obtained for trolox. The role of phenolic hydroxyl groups was studied. The technique used should be selected taking into account the objectives and the conditions of the medium.