Application of polarography to the study of chemical radiosensitization of DNA components.

The half-wave reduction potentials of a range of nitroheterocyclic compounds were measured polarographically and compared with their radiosensitizing abilities in a simple radiation biochemical assay for damage to 5'-GMP. The chemical enhancement ratio for sensitization of inorganic phosphate release from irradiated 5'-GMP, increased with sensitizer electron affinity, but in a non-linear manner. An onset of sensitization was observed for nitroheterocyclics with half-wave potentials less negative then -0.05V vs. standard calomel electrode and maximum sensitization, approaching the oxygen effect, was obtained at a sensitizer half-wave potential of -0.25 V vs. standard calomel electrode. Nitroheterocyclic sensitizers with half-wave potentials in this range may be potential clinical radiotherapeutic agents.