The nitrosation products of creatine and creatinine in model systems

The formation of N-nitrososarcosine from creatine, creatinine-5-oxime and l-methylhydantoin-5-oxime from creatinine was investigated in model solutions under various conditions (temperature, pH, concentration of sodium nitrite). N-nitrososarcosine was formed from creatine only in strongly acidic medium and its concentration increased with temperature and concentration of sodium nitrite. No N-nitrososarcosine was detected at 0 degrees C and in the presence of an equimolar amount of sodium nitrite. Creatinine-5-oxime and l-methylhydantoin-5-oxime was formed from creatinine in a broad region of pH, the highest concentration of these compounds was found in pH 3.6. The main reaction product was l-methylhydantoin-5-oxime. At a given pH, the concentrations of these two oximes increased generally with increased temperature and/or concentration of sodium nitrite. No oxime were detected at O degrees C and in the presence of equimolar amounts of sodium nitrite. Likewise was studied the influence of temperature on the decomposition of the above mentioned compounds. The activation energies of the studied reactions in acidic medium were 4.12 (n-nitrososarcosine), 19.3 (creatinine-5-oxime), and 20.2 kcal/mol (l-methylhydantoin-5-oxime), respectively.