[Metabolic activation of promutagens in the yeast-microsome test. II. Activation of cyclophosphamide and 2-aminofluorene].

The effect of recombinogenic and mutagenic activation of promutagens, cyclophosphamide and 2-aminofluorene was studied in S9 mouse liver preparations. Cyclophosphamide was activated to induce reversions of an ochre mutation and heteroallelic reversion in yeast tester strains r2089-15V-P4 and P3288, respectively. Metabolic activation of this chemical was greatly enhanced by pretreatment of mice with AROGLOR--1254. 2-aminofluorene was a potent recombinogen after metabolic activation, but proved a poor inducer of reversions of the ochre mutation. For the stationary yeast cells, activated 2-aminofluorene was shown to be not recombinogenic, while for logarithmic cells grown in galactose medium it was moderately recombinogenic, being highly active in this respect for logarithmic cells grown in glucose medium. We recommend to use these compounds as positive controls for exogenous activation in the yeast/microsome test.