Mutagenicity of structurally related aromatic amines in the Salmonella/mammalian microsome test with various S-9 fractions.

The related monocyclic aromatic amines 2,4-diaminoanisole (DAA), 2,4-diaminopropoxybenzene (DAPB) and 2,4-diaminobutoxybenzene (DABB) were tested for mutagenic activity in Salmonella typhimurium strain TA 1538, using S-9 fractions from livers, kidneys and spleens of male Wistar rats for metabolic activation. In the presence of an uninduced liver S-9 fraction, DAA was weakly mutagenic (a two- or threefold increase), and the other compounds were negative. Uninduced S-9 preparations from kidney, spleen or a mixture of kidney, spleen and liver homogenates did not activate any of the compounds. On the other hand, S-9 fractions from rat liver induced with Aroclor 1254 or with a combination of phenobarbital and 5,6-benzoflavone activated both DAA and DAPB, DAA being by far the more mutagenic of the two. S-9 preparations from mixed liver, kidney and spleen homogenates from animals pretreated with Aroclor or with phenobarbital and 5,6-benzoflavone were less effective than the liver homogenates. Aroclor-induced S-9 fractions from kidneys slightly activated DAA, but S-9 fractions from spleen were ineffective in all cases. The mutagenicity ranking of the aromatic amines was DAA greater than DAPB greater than DABB. The latter compound caused little or no increase over the control numbers of revertant colonies. The order of effectiveness of inducers was Aroclor 1254 greater than phenobarbital + 5,6-benzoflavone greater than no inducer, and that of preparations from different organs was liver greater than mixture of liver, kidney and spleen greater than kidney greater than spleen.