Radiation-Induced Degradation of Purine and Pyrimidine 2′-Deoxyribonucleosides in Aqueous KBr Solutions

Abstract

Steady-state γ-radiolysis of 5 × 10-4 M pyrimidine and purine 2′-deoxyribonucleosides in aqueous solutions saturated with N2, N2O and O2, respectively, have been carried out in the presence of 0.1 M KBr. The main final degradation products have been isolated and characterised by various spectroscopic measurements including 1H and 13C NMR, UV, C.D. and mass spectrometry. The radiation-induced decomposition of thymidine is mostly accounted for by an ionic mechanism involving Br2, the decay product of Br2-·, as the reactive oxidising specie. On the other hand the degradation of the purine ring of 2′-deoxy-adenosine and 2′-deoxyguanosine may be accounted for by the action of Br2-·or Br3 ·2-