Effects of 7, 8-benzoflavone and SKF 525-A on the enzyme-mediated mutagenicity of phenylenediamines

J Toxicol Sci. 1982 Feb;7(1):61-9. doi: 10.2131/jts.7.61.


The effects of microsomal enzyme inhibitors (7, 8-BF and SKF 525-A) on the S-9-mediated mutagenicity of o-, m- and p-phenylenediamine were investigated using Salmonella typhimurium TA98. SKF 525-A did not affect the enzyme-mediated mutagenicity of m- and p-phenylenediamine, while 7, 8-BF reduced significantly the mutagenicity of all three isomers of phenylenediamine. When the enzyme reactions in the agar overlayer were stopped successively by adding 7, 8-BF directly onto the plate, the number of revertants increased linearly with time at least for 6 hours. These data suggest that cytochrome P-448 takes a main role in the activation of phenylenediamines and that in the agar layer this microsomal enzyme remain active for a period as long as 6 hours at 37 degrees C.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Benzoflavones / pharmacology*
  • Flavonoids / pharmacology*
  • Male
  • Microsomes / enzymology
  • Mixed Function Oxygenases / antagonists & inhibitors
  • Mutagens / metabolism*
  • Phenylenediamines / metabolism
  • Phenylenediamines / toxicity*
  • Proadifen / pharmacology*
  • Rats
  • Rats, Inbred Strains
  • Salmonella typhimurium / genetics


  • Benzoflavones
  • Flavonoids
  • Mutagens
  • Phenylenediamines
  • alpha-naphthoflavone
  • Proadifen
  • Mixed Function Oxygenases
  • cytochrome P448-dependent mono-oxygenase