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MUTAGENICITY OF NITRODIBENZOPYANONES IN THE SALMONELLA PLATE-INCORPORATION AND MICROSUSPENSION ASSAYS
Citation:
Watanbe, T., M. Kohan, D. Walsh, L. Ball, D.M. DeMarini, AND J. Lewtas. MUTAGENICITY OF NITRODIBENZOPYANONES IN THE SALMONELLA PLATE-INCORPORATION AND MICROSUSPENSION ASSAYS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-96/057.
Description:
The mutagenicity of three isomers of nitro-6-H-dibenzo[b,d]pyran-6-one (NDBP), 3-NDBP and 4-NDBP, was characterized in the plate-incorporation (P1) and microsuspension (MS) assays using Salmonella typhimurium tester stains in the presence or absence of S9 mix. n both assays, all of th NDBPs showed mutagenicity in every strain. n the absence of S9 mix, TA98 was the strain most sensitive to the mutagenicity NDPBs. he activity of NDBPs was reduced in TA98NR and TA98/1.8-DNP6 strains relative to TA98, suggesting that NDBPs cause frameshift mutation and the nitroreduction by classical nitroreductase and acetylation are significant steps for their metabolic activation. n the P1 assay, frameshift and base-substitution activities of both isomers were enhanced by the addition of the pKM101 plasmid, suggesting the induction by these isomers of complex frameshifts (frameshifts with associated base substitutions) in strain TA98. n the P1 assay, 2-NDBP generally exhibited more base-substitution than frameshift activity; however, the reverse was true for 3-NDBP. n the MS assay, both isomers exhibited more frameshift than base-substitution activity.