Potential Use of Nitrofurans in Radiotherapy

Abstract

IT has been suggested that the hypoxic centres within a tumour mass are likely to be relatively resistant to sterilization by ionizing radiation¹. Compounds which could be introduced into such hypoxic centres and which can mimic the radiation sensitizing effect of oxygen may therefore be of great value in the radiation therapy of cancer. A number of chemicals are known to sensitize mammalian cells to the effects of ionizing radiation². One such compound is para-nitroacetophenone (PNAP), which was selected as a potential radiosensitizer because of its strong electron affinity³. Subsequent studies demonstrated that PNAP was a good selective hypoxic radiosensitizer in mammalian cells^4,5. Recent studies with analogues of PNAP indicate that the nitro group is essential for radio-sensitizing activity in Chinese hamster cells, and furthermore that sensitizing ability improves with increasing electro-negativity (manuscript in preparation). Because 5-nitrofurans are known to be more electronegative than the corresponding nitrobenzene derivatives⁶, we tested two well documented nitrofuran derivatives for radiosensitizing activity.