Identification of fluorescent 2 '-deoxyadenosine adducts formed in reactions of conjugates of malonaldehyde and acetaldehyde, and of malonaldehyde and formaldehyde

2'-Deoxyadenosine was reacted with malonaldehyde in the presence of formald ehyde or acetaldehyde. The reactions were carried out at 37 degreesC in aqu eous solution at acidic conditions. The reaction mixtures were analyzed by HPLC. In both reactions, two major products were formed. The reaction produ cts were isolated and purified by C18 chromatography, and their structures were characterized by UV absorbance, fluorescence emission, H-1 and C-13 NM R spectroscopy, and mass spectrometry. The reaction products isolated from the mixture containing formaldehyde, malonaldehyde, and deoxyadenosine were identified as beta-(2'-deoxy-beta -D-ribofuranosyl)-7H-8-formyl [2,1-i] py rimidopurine (M(1)FA-dA) and 9-( 2'-deoxy-beta -D-ribofuranosyl)-6-(3,5-dif ormyl-1,4-dihydro-1-pyrid (M(2)FA-dA). In the reaction mixture consisting o f acetaldehyde, malonaldehyde, and deoxyadenosine, the identities of the pr oducts were determined to be 3-(2'-deoxy-beta -D-ribofuranosyl)-7-methyl-8f ormyl[2,1i]pyrimidopurine (M-1-AA-dA) and 9-(2'-deoxy-beta -D-ribofuranosyl )-6-(3,5-di (M(2)AA-dA). The yields of the compounds were 1.8 and 0.7% for M(1)FA-dA and M(2)FA-dA, respectiviely, and 6.8 and 10% for M(1)AA-dA and M (2)AA-dA, respectively. AU compounds exhibited marked fluorescent propertie s. These findings show that in addition to direct reaction of a specific al dehyde with 2'-deoxyadenosine, aldehyde conjugates also may react with the base. Although three of the adducts (M(1)FA-dA, M(2)FA-dA, and M(1)AA-dA) c ould not be detected in reactions carried out under neutral conditions, the possibility that trace anlounts of the adducts may be formed under physiol ogical conditions cannot be ruled out. Therefore, conjugate adducts must be considered in work that aims at clarifying the mechanism of aldehyde genot oxicity.