The Electron Affinity of Some Radiotherapeutic Agents Used in Cancer Therapy

Abstract

To evaluate whether chemotherapeutic compounds applied in cancer treatment might interact with radiation as anoxic cell sensitizers, the electron-affinic properties of DTIC [5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide], AIC [4(5)-aminoimidazole-5(4)-carboxamide], hydroxyurea, busulfan and cyclophosphamide were studied by pulse radiolysis. Reaction rates with hydrated electrons were determined for all compounds. With the exception of DTIC, they reacted much more slowly with electrons than do most electron-affinic sensitizers. One-electron reduction potentials were determined for DTIC, AIC and hydroxyurea. The values were all in the region for the onset of sensitization, with hydroxyurea as the most promising (E71 = -0.552 V). For busulfan and cyclophosphamide no value was determined, but the compounds are probably less electron-affinic than hydroxyurea. A possible application of chemotherapeutic agents as radiosensitizers is discussed.