Non-enzymatic cyclization of creatine ethyl ester to creatinine

Creatine ethyl ester was incubated at 37 °C in both water and phosphate-buffered saline and the diagnostic methylene resonances in the 1H NMR spectrum were used to identify the resultant products. It was found that mild aqueous conditions result in the cyclization of creatine ethyl ester to provide inactive creatinine as the exclusive product, and this transformation becomes nearly instantaneous as the pH approaches 7.4. This study demonstrates...