Reactivity of nucleosides with a hydroxyl radical in non-aqueous medium

摘要

An experiment was conducted to demonstrate the reactivity of nucleosides with a hydroxyl radical (H?) in non-aqueous medium. Five nucleosides and three purine-derived lesions were taken as targets for H? attack. The reactivity with H? radical was determined by laser flash photolysis (LFP) of N-hydroxypyridine-2-thione (NPT) at 355 nm. Following an established kinetic model, the rate constants for the reaction between H? and the modified nucleobases were determined by using naphthalene as a standard. The values obtained for the silylated 2 -deoxyribonucleosides in acetonitrile are of the same order of magnitude and remarkably lower than diffusion control in this solvent, pointing to a similar reactivity pattern. The result confirmed that the reaction of a hydroxyl radical with 2'-deoxyribonucleosides is in general somewhat slower in acetonitrile than in water.