Investigation of the adducts formed by reaction of butenedioic acids with adenosine

Several genotoxic butenedioic acids present in chlorine-disinfected drinking water were allowed to react with adenosine, guanosine, and cytidine in aqueous solution. HPLC analyses, with detection at 254 and 310 nm, showed that clearly detectable products were formed only in the reactions with adenosine. The major products from the reactions between either 2-chloro-3- methyl-2-butenedioic acid (ox-MCF) or 2-chloro-3-(chloromethyl)-2- butenedioic acid (ox-CMCF) and adenosine were the same. This substance was isolated by C18 column chromatography and characterized by UV absorbance, ¹H and ¹³C NMR spectroscopy, and mass spectrometry. It was identified as 3-(β-D-ribofuranosyl)-7-carboxy-7-formyl-8-[9'-(β-D-ribofuranosyl)-N⁶- adenosinyl]-1,N⁶-ethanoadenosine (cfεA,A). The yields of cfεA,A in reactions performed at pH 7.4 and 37 °C were 0.7% and 0.3% with ox-MCF and ox-CMCF, respectively.