Abstract

Virgin olive oil (VOO) is the main edible oil of Mediterranean diet and provides beneficial effects for human health because its antioxidant capacity (due to its polyphenol content, tocopherols, carotenoids among other constituents), and its excellent organoleptic and nutritional qualities. Two different assays were applied to determine the antioxidant capacity (activity/reactivity) of various antioxidants compounds: the use of free radical 2,2-Diphenyl-1-picrylhydrazyl (DPPH·) and the use of singlet-excited 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO). Sixteen phenols compounds were reacted with DPPH·, and showing to follow four possible reaction kinetic types. The fluorescence quenching of singlet-excited 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO), a fluorescence probe for antioxidants, has been investigated in methanol 24% solvent. Quenching rate constants (Kq) are in the range 108-1010 M-1s-1. The reactivity of singlet-excited DBO exposes steric, polar and stereoelectronic effects on the hydrogen atom abstraction process in the absence of complications because of competitive exciplex formation. These methods were used for determine the antioxidant activity/reactivity of pure phenols. Afterwards, they were applied to the phenol extracts of two varieties of extra virgin olive oil, Picual and Arbequina, obtaining results consistent with their phenol profiles.