Comparative genotoxicity of nitrogen mustard and nor-nitrogen mustard

Nitrogen mustard and nor-nitrogen mustard were investigatedin Salmonella typhimurium and human lymphocytes for genotoxicity.Point mutations were assessed using the plate test, the conventionalspot test and a method in which the substances were not in directcontact with the microorganisms. Both compounds were active,but nornitrogen mustard was far more potent than nitrogen mustardin all bacterial systems. Cytogenetic experiments with humanlymphocytes revealed that both compounds induced a dose dependentincrease in chromosomal aberrations and sister chromatid exchanges,but that nitrogen mustard was 10 times more potent than nor-nitrogenmustard. Thus, the spectrum of activity for nor-nitrogen mustardand nitrogen mustard differ. Nor-nitrogen mustard was more effectivein inducing point mutation damage than nitrogen mustard anda reversal of potency was found for cytogenetic damage. Theseresults indicate that although these two substances induce thesame type of DNA lesions the amounts of the different DNA adductsvary.