Polarographic screening test for the radiosensitizing effect of imidazole and triazole drugs on tumor cells

The radiosensitizing effect of 25 nitroimidazoles (including misonidazole) and 19 nitrotriazoles on hypoxic tumor cells (Chinese Hamster V 79 and Mouse EMT 6) in vitro was examined in relation to their polarographic half-wave potentials. All those tested gave a well-defined reduction wave on the DC polarogram obtained in a pH 6.8 phosphate buffer solution. From the controlled potential electrolysis, the wave was found to be ascribed to the reduction of their nitro groups to form corresponding hydroxylamines, by reference to UV absorption spectra and Rf values of this layer chromatography. The half-wave potential of the drugs was correlated with the-logarithm-of the drug concentration (C1.6) producing the radiosensitivity enhancement ratio of 1.6. The method will serve as a simple screening test for evaluating the radiosensitizing effect of drugs on tumor cells. (author)