Reactions of cobalt(III) complexes with free radicals derived from thymine

The nature of interaction of Co(III) complexes such as Co(III)EDTA and Co(III)NTA with transient adducts of thymine such as TOH^˙, T^˙?, and TH^˙ formed in the gamma radiolysis of thymine were studied. The study shows that TOH radicals do not undergo electron transfer reaction with Co(III) complexes whence no radiosensitization of thymine by Co(III) complexes was observed. Electron transfer however, takes place from T^˙? and TH^˙ to Co(III) complexes. A plausible mechanism of radiolysis of thymine in presence of Co(III) complexes is discussed. © 1994 John Wiley & Sons, Inc.