Evaluation of synergistic interactions of antioxidants from plant foods by a new method using soybean lipoxygenase
- Publication date
- Publisher
Abstract
A proper evaluation of synergism among antioxidants remains so far rather difficult to obtain. We recently reported
that a new method for antioxidant activity measurement, based on the secondary reaction of soybean lipoxygenase
(LOX)-1 isoenzyme with 4-nitroso-N,N-dimethylaniline (RNO), so-called LOX/RNO method, may assess very well
the synergism among antioxidants from durum wheat whole semolina. To evaluate whether this behaviour is generalizable
to different food matrices, herein, antioxidants from other very different sources were analysed. For this purpose,
antioxidant activity of food-grade preparations enriched in catechins, quercetin, resveratrol, tyrosol/hydroxytyrosol
and lycopene was evaluated by the LOX/RNO method in comparison with the Trolox equivalent antioxidant ca pacity
(TEAC) assay. The antioxidant activity values obtained by LOX/RNO method were 2–90-times higher than those
obtained by the TEAC protocol, depending on the tested antioxidant. Synergism was evaluated by comparing antioxidant
activity of the mixture of compounds (AAmix) with the sum of antioxidant activity values of individual compounds
(AAsum). The LOX/RNO method revealed a strong synergism, being AAmix 5.69 ± 0.31 times higher than AAsum (statistically
significant, p < 0.001), while the TEAC method showed a synergistic increase of only 0.31 ± 0.04 (statistically
significant, p < 0.01). These findings suggest that the LOX/RNO method is able to assess very well the synergism in
various food samples