CHARACTERIZATION OF THYMIDINE ADDUCTS FORMED BY ACROLEIN AND 2-BROMOACROLEIN

Thymidine was permitted to react with the known mutagens acrolein and 2-bromoacrolein under physiological conditions. The products of these reactions were separated by HPLC and characterized by UV, FAB/MS, electrospray MS, H-1 NMR and chemical transformation. The reaction with acrolein gave one major product, N3-(3"-oxopropyl)thymidine, which is unstable in aqueous solution and was reduced with sodium borohydride to the corresponding alcohol. Reaction with 2-bromoacrolein yielded the unstable intermediate, N3-(2"-bromo-3"-oxopropyl)thymidine, and two stable products, the diastereomers of N3-(2"-hydroxy-3"-oxopropyl)thymidine, which are slowly transformed to N3-(2"-oxo-3"-hydroxypropyl)thymidine. Reactions with both mutagens proceed most rapidly at pH 9.2, less rapidly at pH 7.4, and no products are found at pH 4.2. Stable adducts found in the reaction of 2-bromoacrolein were also identified in reactions with single-strand oligodeoxynucleotides using a sensitive, selected ion monitoring GC/MS procedure.