| Abstract
| - Phosphatidylethanolamine (PE), phosphatidylcholine (PC), lysine (Lys), and mixtures of them weretested for antioxidative activity in a tocopherol-stripped olive oil (TSO) and the same oil after additionof 250 μg of α-tocopherol g of oil/(tocopherol-added olive oil, TAO) to evaluate the role of tocopherolin the antioxidant activity of oxidized lipid−amine products. Neither PE nor PC nor Lys protectedTSO when tested alone, but both PE and Lys increased the induction period (IP) of TAO. On thecontrary, PE/Lys and PC/Lys mixtures, but not PC/PE mixtures, protected both TSO and TAO. Theseresults were a consequence of both the formation of oxidized lipid−amine products, which weredetermined by gas chromatography−mass spectrometry after their conversion into volatile derivatives,and a synergism between α-tocopherol and the produced compounds. These results were confirmedby analyzing the antioxidative activity of two of the produced carbonyl−amine products: 6-amino-2-(1H-pyrrol-1-yl)hexanoic acid (1) and 2,3-dipalmitoylpropyl 2-(1H-pyrrol-1-yl)ethyl phosphate (2).The hydrophilic compound 1 was more antioxidant than the analogous lipophilic compound 2, andthis antioxidative activity was observed in TAO and not in TSO. All these results suggested thatantioxidative activity of carbonyl−amine products may be greatly increased with the addition oftocopherols, and those products derived from Lys are more antioxidant in bulk oils than those derivedfrom PE. Keywords: Carbonyl−amine reactions; antioxidants; lipid oxidation; nonenzymatic browning; phospholipids; pyrrolized phospholipids; Rancimat
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