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1 August 2012 Electron-Affinic Sensitization
VII. A Correlation between Structures, One-Electron Reduction Potentials, and Efficiencies of Nitroimidazoles as Hypoxic Cell Radiosensitizers
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Abstract

Radiosensitization efficiencies for seven different 2-nitroimidazoles including Ro-07-0582 and its urinary metabolite, Ro-05-9963, and two 5-nitroimidazoles including metronidazole, have been determined in hypoxic Chinese Hamster cells, line V79-379A, X-irradiated in vitro. All the compounds were active hypoxic cell sensitizers with the enhancement ratios increasing with drug concentration. The 2-nitroimidazoles were all more efficient than the 5-nitroimidazoles. Overall, the efficiencies, defined as the concentration required to give a particular enhancement ratio, varied by a factor of about 200. Electron-affinities of the sensitizers were determined by pulse radiolysis as the one-electron reduction potentials and these correlate well with the sensitization efficiencies of the compounds. The correlation extends beyond the nitroimidazole series as is shown by data for p-nitroacetophenone, nifuroxime (a nitrofuran) and oxygen itself. The nitroimidazoles varied by a factor of 70 in their octanol/water partition coefficients, but the effect of this parameter on sensitizing efficiency is small compared with the influence of electron affinity.

G. E. Adams, I. R. Flockhart, C. E. Smithen, I. J. Stratford, P. Wardman, and M. E. Watts "Electron-Affinic Sensitization
VII. A Correlation between Structures, One-Electron Reduction Potentials, and Efficiencies of Nitroimidazoles as Hypoxic Cell Radiosensitizers," Radiation Research 178(2), (1 August 2012). https://doi.org/10.1667/RRAV14.1
Received: 31 October 1975; Published: 1 August 2012
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