In vitro activation of chemicals by plants: a comparison of techniques.

We have studied the ability of two in vitro plant activation techniques to enhance the mutagenicity of 4-nitro-o-phenylenediamine (NOP) and to activate 2-aminofluorene (2AF). Mutagenic activities of NOP and 2AF were both increased by plant S9 in the Salmonella plate-incorporation and preincubation assays. They were also increased during preincubation with intact plant cells. NOP mutagenic activity was enhanced to a similar extent by plant S9 and by intact plant cells in Salmonella assay, whereas 2AF was activated more extensively by the plant cells than by plant S9. NOP was not enhanced by mammalian hepatic S9 in any assay, whereas 2AF was activated by hepatic S9 under all conditions tested.