The DNA cleavage induced by a chromium(V) complex and by chromate and glutathione is mediated by activated oxygen...

The number of strand breaks induced by the combination of chromate and glutathione (GSH) in PM2 DNA was effectively reduced upon addition of the hydroxyl radical scavengers dimethyl sulphoxide (DMSO), formate and benzoate. Administration of catalase also led to a depression of DNA degradation whereas superoxide dismutase (SOD) had very little influence. Essentially the same results were obtained in experiments employing a chromium(V) complex Na4(GSH)4Cr.8H20, which is an intermediate chromium species isolated from the reduction of chromate by glutathione. DNA cleavage was dependent on the presence of iron (FeCl3). When compared with the number of breaks produced by FeCl3 and GSH alone, chromate stimulated the generation of single-strand breaks. These findings suggest that hydroxyl radicals are one ultimate DNA cleaving agent in both reactions. A reaction scheme for the production of hydroxyl radicals is proposed.