Antioxidant Effect of Phenolic Compounds, α-Tocopherol, and Other Minor Components in Virgin Olive Oil

Abstract

The effect of acidity, squalene, hydroxytyrosol, aldehydic form of oleuropein aglycon, hydroxytyrosyl acetate, tyrosol, homovanillic acid, luteolin, apigenin, alpha-tocopherol, and the mixtures hydroxytyrosol/hydroxytyrosyl acetate, hydroxytyrosol/tyrosol, and hydroxytyrosol/alpha-tocopherol on the oxidative stability of an olive oil matrix was evaluated. A purified olive oil was spiked with several concentrations of these compounds and, then, subjected to an accelerated oxidation in a Rancimat apparatus at 100 degrees C. Acidity, squalene, homovanillic acid, and apigenin showed negligible effect. At the same millimolar concentrations, the different o-diphenolic compounds yielded similar and significant increases of the induction time, alpha-tocopherol a lesser increase, and tyrosol a scarce one. At low concentrations of o-diphenols and alpha-tocopherol, a linear relationship between induction time and concentration was found, but at high concentrations the induction time tended toward constant values. To explain this behavior, a kinetic model was applied. The effect of the mixtures hydroxytyrosol/hydroxytyrosyl acetate was similar to that of a single o-diphenol at millimolar concentration equal to the sum of millimolar concentrations of both compounds. Concentrations of tyrosol >0.3 mmol/kg increase the induction time by 3 h. The mixtures hydroxytyrosol/alpha-tocopherol showed opposite effects depending on the relative concentrations of both antioxidants; so, at hydroxytyrosol concentrations <0.2 mmol/kg, the addition of alpha-tocopherol increased the induction time, whereas at higher hydroxytyrosol concentrations, the alpha-tocopherol diminished the stability.

Total Phenolic Compounds and Tocopherols Profiles of Seven Olive Oil Varieties Grown in the South-West of Spain

“…3.3 Contribution of phenolic compound and tocopherol to oxidative stability in VOOs It is interesting to evaluate the relationship between the two examined fractions of phenolic compounds with the oxidative stability of these VOO varieties since previous literature supports that α-tocopherol content together with the phenolic compounds contributes to the stability of the oil 38,44 .…”

“…Hence, some researchers 55 Deiana et al 49 and Mateos el at. 44 indicated that tocopherols seem to have a synergic effect in association with some phenolic compounds with significant antioxidant activity and α-tocopherol content becomes effective when the activity of the fraction of polar compounds is reduced and the primary products of autooxidation reach the critical concentration. According to this suggestion, the evaluation of the correlation between oxidative stability and α-tocopherol plus total phenolic compounds content seemed of interest.…”

Olive oil hydroxytyrosol reduces toxicity evoked by acrylamide in human Caco-2 cells by preventing oxidative stress

“…In line with this, olive oil, the major fat source of Mediterranean diet, is recognized for its antioxidant properties and its positive effects on oxidative stress associated processes (Fitó et al 2007). The phenolic fraction of virgin olive oil has proved to have antioxidant activity in vitro, scavenging peroxyl radicals (Saija et al 1998), other free radicals (Gordon et al 2001) and reactive nitrogen species (De la Puerta et al 2001), or breaking peroxidative chain reactions and preventing metal ion catalyzed production of reactive oxygen species (Manna et al 1997;Mateos et al 2003). The main phenolic compounds in virgin olive oil are secoiridoid derivatives of 2-(3,4-dihydroxyphenyl)ethanol (hydroxytyrosol) (HTy) and of 2-(4-hydroxyphenyl)ethanol or tyrosol, and 2-(3,4-dihydroxyphenyl)ethyl acetate (Mateos et al 2001).…”

Oxidative stability and radical scavenging activity of extra virgin olive oils: An electron paramagnetic resonance spectroscopy study

“…Similar results have been 272 reported by Baldioli et al [2] concerning the antioxidant effect 273 of hydrophilic phenols and tocopherols on the oxidative stabil-274 ity of VOO as determined by the Rancimat method. Recently, 275 Mateos et al [18] reported that ␣-tocopherols (the most abundant 276 tocopherol in VOO) seem to have small contribution to VOO sta-277 bility whereas o-diphenols are the most effective antioxidants.…”