ANTIOXIDATIVE ACTIVITY OF (E)-2-OCTENAL AMINO-ACIDS REACTION-PRODUCTS

The effects of several compounds, previously identified in nonenzymati c browning reactions between oxidized lipids and amino acids, on prote cting bulk vegetable oils against oxidation were evaluated to investig ate if these naturally formed products may contribute to the overall a ntioxidative activity of foods. Two amino acid residue analogs, N-(car bobenzyloxy)-L-histidine (Z-His) and N-2-(carbobenzyloxy)-L-lysine (Z- Lys), and their products of reaction with (E)-2-octenal, the Michael a dduct 1 and two pyridinium salts, 2 and 3, were added at three levels of concentration (50, 100, and 200 ppm) to soybean oil which was oxidi zed under air in the dark at 60 degrees C. Oil peroxidation was evalua ted by using the thiobarbituric acid-reactive substances (TBARS) assay . Compounds 1-3 significantly decreased TBARS formation on soybean oil (p < 0.05) and showed diverse activity as compared with synthetic ant ioxidants. The order of effectiveness obtained was 1 much less than 2 approximate to butylated hydroxytoluene approximate to 3 < propyl gall ate. These results suggest that some reactions between oxidized lipids and amino acids may contribute to the antioxidant activity of foods i n addition to the development of color and fluorescence.