In vitro enhancement of the mutagenicity of 4‐nitro‐o‐phenylenediamine by plant S‐9

Abstract

The direct-acting mutagen 4-nitro-o-phenylenediamine (NOP) was activated in vitro by pea or tobacco S-9 into a more potent mutagen in Salmonella typhimurium strain TA98. NOP mutagenicity was not altered by Aroclor 1254-induced rat liver S-9. The plant S-9 activation of NOP was heat-sensitive but was not NADPH-dependent, did not involve superoxide radicals, and was not inhibited by CO. A direct relationship between plant peroxidase and NOP activation was established. Several purified peroxidases including horseradish peroxidase, chloroperoxidase, and lactoperoxidase also activated NOP. The perodoxidative process was not H2O2-dependent but was partially inhibited by a peroxidase inhibitor.

Modulating effect of dimethylbenzanthracene on gamma-ray mutagenesis in the soybean test system.

“…Recent investigations indicated that plant metabolism efficiently convert promutagens to mutagenic products (Higashi et al 1981;Plewa 1978;Scott et al 1978;Takehisa and Kanaya 1983). Metabolic activation in vitro with S9 preparations of several plant species including Helianthus, Nicotiana, Zea, Tradescantia resulted in the activated compounds inducing mutations in microbial test systems (Gentile et al 1985). Krahan and Heidelberger (1977) suggested that variation in activating potential depended on inducerspecific qualitative and quantitative differences in metabolism.…”