[Express evaluation of antioxidant activity of uracil derivatives]

Using photometric methods the antioxidant activity of 19 uracil derivatives has been analyzed. The test using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals can be applied for the rapid assessment of antioxidant activity of uracils. Among uracil derivatives studied the compounds possesing a proton-donor group in C-5 position--free or alkylated amino group, as well as hydroxyl group were the most active: 5-aminouracil (IC50 3 mg/ml), 5-amino-6-methyluracil (IC50 of 5 mg/ml), 5-hydroxy-6-methyluracil (IC50 of 15 mg/ml), 5-hydroxy-1,3,6-trimethyluracil (IC50 of 15 mg/ml), 5-ethylamino-6-methyluracil (IC50 of 20 mg/ml), 5-methylamino-6-methyluracil (IC50 of 20 mg/ml), 5-allylaminouracil (IC50 of 20 mg/ml), 5-amino-1,3,6- trimethyluracil (IC50 of 25 mg/ml). These uracil derivatives were more active than the reference compounds ionol (IC50 of 30 mg/ml) and a-naphthylamine (IC50 of 45 mg/ml), but less active than ascorbic acid (IC50 0.8 mg/ml). There was a correlation between the results of DPPH test (IC50) and coupling constants of uracil derivatives with peroxide radicals of 1,4-dioxane (fk7). Uracil with proton-donor group at C-5 also showed high ferrum-reducing activity as determined by FRAP.