Relative yields of monomeric and dimeric adducts induced by sulphur mustard in isolated and cellular DNA as determined by HPLC/tandem mass spectrometry

Sulphur mustard (SM) is known as an efficient vesicating agent as well as a carcinogenic chemical. This warfare agent remains a threat for both civilians and militaries. DNA alkylation is one of the critical molecular pathways at the origin of the symptoms associated with SM exposure. SM forms monoadducts with guanine and adenine as well as a biadduct between two guanine bases. The aim of the present work is to determine the relative yields of these three lesions in DNA samples after SM exposure without using radiolabeled SM as in earlier works. For this purpose, we have developed a high performance liquid chromatography/tandem mass spectrometric method to simultaneously quantify the SM monoadducts and biadduct in the same DNA sample. We observed in isolated and cellular DNA that the guanine monoadduct was the predominant lesion, while the biadduct was present in twofold lower yield. The adenine monoadduct was generated in lowest amounts. The analytical approach was extended to 2?chloroethyl ethyl sulphide, a widely used SM analog. Again, the adenine adduct was much less frequent than the guanine derivative. The developed assay will allow performing studies involving large numbers of samples.