Identification of adducts formed in reactions of 2 '-deoxyadenosine and calf thymus DNA with the bacterial mutagen 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone

3-Chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF) is a strong direc t acting bacterial mutagen found in chlorine-disinfected drinking water. We studied the reaction of CMCF with 2'-deoxyadenosine;in buffered aqueous so lutions and found that three main adducts were formed. The adducts were iso lated and purified by C18 column chromatography and HPLC, and characterized on the basis of their UV absorbance, fluorescence emission, H-1 and C-13 N MR spectroscopic, and mass spectrometric features. The adducts were identif ied as 3-(2'-deoxy-beta-D-ribofuranosyl) -7H-8-formyl[2, 1-i]pyrimidopurine (pfA-dR), 3-(2'-deoxy-beta-D-ribofuranosyl)-7H-8-carboxy[2,1-i]pyrimidopur ine (pcA-dR), and 4-(N-6-2'-deoxyadenosinyl)-3-formyl-2-hydroxy-3-butenoic acid (OH-fbaA-dR). In the reactions performed at pH 7.4 and 37 degrees C, t he yields of pfA-dR, pcA-dR, and OH-fbaA-dR were 1.1, 6.7, and 5.5 mol %, r espectively. The adduct pfA-dR was detected also in calf thymus DNA reacted with CMCF. The yield was about six adducts per 10(5) bases. To elucidate t he mechanisms of formation of the adducts, C-13-3-labeled CMCF was reacted with 2'-deoxyadenosine. The adducts are structurally related to the adducts previously identified in the reactions of structurally analogous chlorohyd roxyfuranones with 2'-deoxyadenosine.