ANTIOXIDATIVE ACTIVITY OF PYRROLE, IMIDAZOLE, DIHYDROPYRIDINE, AND PYRIDINIUM SALT DERIVATIVES PRODUCED IN OXIDIZED LIPID AMINO-ACID BROWNING REACTIONS

The antioxidative activity of several models of nonenzymatic browning reaction products was evaluated to determine if the Lipid peroxidation process in the presence of amino acids is always accompanied by forma tion of products with antioxidative properties. 1-Methylpyrrole (1), 1 ,2,5-trimethylpyrrole (2), 2-(1-hydroxyethyl)-1-methylpyrrole (3), 2-a cetyl-1-methylpyrrole (4), yl-4-pentyl-1,4-dihydropyridine-3,5-dicarba ldehyde (5), 1-(2-hydroxyethyl)-2-hexyl-3,5-dipentylpyridinium chlorid e (6), 1-(1-ethyl-2-formylethyl)-4-methylimidazole (7), and 1-(1-ethyl -3-hydroxypropyl)-4-methylimidazole (8) were added at two levels of co ncentration (100 and 200 ppm) to soybean oil which was oxidized under air in the dark at 60 degrees C. Oil peroxidation was evaluated by usi ng the thiobarbituric acid-reactive substances assay. Compounds 2-8 si gnificantly decreased TEARS formation on soybean oil (p < 0.05) and sh owed diverse activity as compared among them and with synthetic antiox idants. The order of effectiveness obtained at 200 ppm was 1 < 2 < 3 < 4 approximate to 6 < 7 approximate to 5 < 8 < butylated hydroxytoluen e < propyl gallate. These results suggest that reactions between oxidi zed Lipids and amino acids produce many compounds with antioxidative p roperties that may contribute to the stability of foods.