Bromodeoxyuridine amplifies free-radical-mediated DNA damage.

Elevated oxygen concentrations and paraquat, a superoxide-generating compound, induce an arrest of cells in the G2 phase of the cell cycle, which can be enhanced by adding bromodeoxyuridine (BrdU) to the culture medium. Experiments with the lipophilic peroxide cumene hydroperoxide and the free-radical scavenger vitamin E demonstrate that the BrdU-dependent G2 arrest is not mediated by lipid peroxidation. The BrdU-dependency of arrest in the G2 phase can be used as a sensitive cell biological assay to detect DNA damage elicited by oxygen free radicals.