Identification of Adducts Formed in the Reaction of the Bacterial Mutagen 3-Chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone with Cytidine

3-Chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF), a strong bacterial mutagen reacts with cytidine in buffered aqueous solutions. The reaction products were separated by preparative HPLC C18 column chromatography and were structurally characterized by UV absorbance, H-1 NMR and C-13 NMR spectroscopy, and mass spectrometry. The main products were identified as 7-(beta-D-ribofuranosyl)-4-carboxy-6-oxo-6,7-dihydro-4H-pyrimido[1,6-a]pyrimidine-3-carbaldehyde (cM(1)FA-Cyd), and 7-(beta-D-ribofuranosyl)-6-oxo-6,7-dihydro-4H-pyrimido[1,6-a]pyrimidine-3-carbaldehyde (M(1)FA-Cyd). The highest yields of cM(1)FA-Cyd and M(1)FA-Cyd, being 12 and I mol % respectively, were obtained in the reaction performed at pH 4.6 and 37 degrees C for 7 days. M(1)FA-Cyd and cM(1)FA-Cyd are structurally related to pfA-dR, the adduct previously identified in the reaction of 3-chloro-4-(dichloroiiictliyl)-5-hydroxy-2(5H)-furanone (MX) or 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF) with 2'-deoxyadenosine.