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, 1H 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.