Ozonolysis of 2'-deoxycytidine: isolation and identification of the main oxidation products

The ozone-mediated oxidation of 2'-deoxycytidine (dCyd) was investigated on the basis of final product identification. The oxidation reaction gave rise to five major modified nucleosides which were isolated and characterized on the basis of extensive 1H NMR and mass spectrometry measurements. The comparison with the current knowledge of the hydroxyl radical mediated oxidation reactions of 2'-deoxycytidine in aerated aqueous solution, indicates that the formation of ozone oxidation products may be mostly explained by the opening of the pyrimidine C5-C6 double bond. Thus, the formation of the identified products obtained by ozonolysis of 2'-deoxycytidine is accounted for by the initial generation of an ozonide.