SYNTHESIS AND ANTIOXIDANT PROPERTIES OF 1,3-DIMETHYL-6-ETHYLURACILE DERIVATIVES

Pyrimidine derivatives are known for their ability to stimulate regeneration processes and modulate the immune response. The authors of the present work studied synthesis and antioxidant activity of 1,3-dimethyl-5-nitro-6-ethyluracil, 1,3-dimethyl-5-amino-6-ethylura-cil, and 1,3-dimethyl-5-hydroxy-6-ethyluracil. It is shown that these compounds can be ob-tained with good yield from simple reagents. Styrene substrates are useful in testing of chain-breaking antioxidants and determination of the inhibition rate constant. The antioxidant activity of synthesized derivatives in the model reaction of autoxidation of styrene in-itiated by azobis(isobutyronitrile) (AIBN) in chlorobenzene was studied. This reaction (in-itiated by the thermal decomposition of AIBN at 37°C under air atmosphere) was followed by monitoring the oxygen consumption with a recording gas-absorption apparatus, which uses as detector a differential pressure transducer. The rate of initiation was measured in a preliminary set of experiments from the length of the induction period, using alpha-tocopherol as a reference antioxidant. Antioxidant properties was determined for 5-amino and 5-hydroxy derivatives. The studied uracil derivatives should be classified as inhibitors of medium reactivity 7.4 × 10 4 1/(M×s). The ethyl group in the 6-position of the pyrimidine ring increases the rate constant of the reaction with peroxyl radicals by 1.2 times for 5-hydroxy derivative and decreases the rate constant and the stoichiometric coefficient for 5-amino derivatives by 1.8 times toward corresponding 6-methyl derivatives. 1,3-Dimethyl-5-hydroxy-6-ethyluracil is became more strong inhibitor by the addition of a ethyl group at the 6-position in comparison with 1,3-dimethyl-5-hydroxyuracil and 1,3-dimethyl-5-hyd-roxy-6-methyluracil.