Synthesis and one-electron reduction characteristics of radiation-activated prodrugs possessing two 5-fluorodeoxyuridine units

Two molecules of an antitumor agent, 5-fluorodeoxyuridine (5-FdUrd), were connected by a 2-oxoalkyl linker (Oxo-linker) at the N(3) position to obtain radiation-activated prodrugs, FdUrd2 A and FdUrd2 B. The prodrugs in this study released 5-FdUrd via one-electron reduction initiated by hypoxic X-irradiation. The release of 5-FdUrd from FdUrd2 A and FdUrd2 B proceeded more efficiently than that of previous prodrug, Oxo-FdUrd, which possessed one molecule of 5-FdUrd. FdUrd2 A exhibited increased cytotoxicity against A549 cells when the FdUrd2 A solution had been irradiated with a large dose of X-rays before administration to the cells. However, we observed no effect on cytotoxicity when the cells were X-irradiated under hypoxic conditions in the presence of FdUrd2 A because the amount of 5-FdUrd released in the cells seemed to be too low to induce cytotoxic activity.

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