Hypoxic radiosensitizers: substituted styryl derivatives.

A number of novel styryl epoxides, N-substituted-styryl-ethanolamines, N-mono and N,N'-bis-(2-hydroxyethyl)-cinnamamides - analogues to the known radiosensitizers RSU- 1069, pimonidazole and etanidazole - dis play selective hypoxic radiosensitizing activity. The styryl group, especially when substituted by electron withdrawing groups, was found to be bio-isosteric to the nitroimidazolyl functionality. The most active derivative 2-(2'-nitrophenyl)ethen-1-yl-oxirane 8a displayed a sensitizer enhancement ratio (SER) of 5 relative to misonidazole.