Characterization of phosphodiester adducts produced by the reaction of cyanoethylene oxide with nucleotides
Cyanoethylene oxide (CEO), a putative toxic and carcinogenic metabolite of acrylonitrile, is a direct-acting mutagen. The focus of this study was to elucidate potential adducts responsible for the mutagenic effect of CEO by characterizing products from the reaction of CEO with nucleotides. The reaction of CEO with the 5'-monophosphates of deoxy-guanosine, deoxyadenosine, deoxycytidine or deoxythymidine resulted in the formation of at least one adduct for each nucleotide. Using two-dimensional NMR spectroscopy and fast atom bombardment mass spectrometry, CEO-nucleotide adducts (25% modification) were characterized as 2-cyano-2-hydrox) ethyl phosphodiesters. The isolate from the reaction of deoxyguanosine-5'-monophosphate (dGMP) with CEO contained a second adduct, identified as N7-(2-cyano-2-hydroxyethyI)-dGMP. Single and double strand breaks, which were observed in supercoiled pBR322 plasmid DNA exposed to CEO (> 50 mM), may arise following formation of cyano-hydroxy ethyl phosphotriester adducts. The characterization of these phosphodiester adducts in vitro may provide insight into the intermediates responsible for the genotoxic effect of CEO in vivo.