Synthesis and electron spin resonance study of spin-labelled compounds related to tumour-growth inhibitory nitroarylaziridines.

Three stable free radicals have been prepared which are akin to 5-aziridino-2,4-dinitrobenzamide (CB 1954); these compounds all contain a nitroxide function. The metabolism and excretion of two such compounds in mice has been monitored by electron spin resonance (ESR) spectroscopy and compared with that of the simpler nitroxide, 4-keto-2,2,6,6-tetramethylpiperidino-1-oxyl (tempone).