Biochemical and mutagenic characterization of plant‐activated aromatic amines

Abstract

Plant activation is the process by which promutagenic agents are activated into rautagens by plant systems. With the widespread use of agricultural chemicals on crop plants and with the global exposure of plants to pollutants, the possibility exists that plant‐activated agents may be introduced into the human food chain. The plant cell/microbe coincubation assay uses cultured plant cell suspensions as the activating system and bacteria or yeast cells as the genetic indicator organism. After a treatment time, the microbes are plated on selective medium. In this way the activation system and the genetic system can be independently studied. In addition, the viability of the plant cells and the microbial cells can be independently determined so that the toxicity of a test agent can be evaluated. Using cytochrome P450 monooxygenase and peroxidase inhibitors, we are studying the biochemical mechanisms of plant activation of environmental contaminants, especially aromatic amines. We propose a working model for the activation of aromatic amines by cultured tobacco cells into stable frameshift mutagens.

Genotoxic effects of the carbamate insecticide Pirimor-50® in Vicia faba root tip meristems and human lymphocyte culture after direct application and treatment with its metabolic extracts

“…Calderón-Segura et al (38) described the phytotoxic effect of the thiocarbamic herbicide butylate in Vicia faba. Cell death by this herbicide is caused by the absence of metabolism, and several other agents have been described to lower plant cell culture viability (56).…”

Genotoxicity of m‐phenylenediamine and 2‐aminofluorene in Salmonella typhimurium and human lymphocytes with and without plant activation

“…Oxidative metabolites of these agents (the N-hydroxylated metabolites) serve as substrates for acetyl-CoA: N-hydroxyarylamine 0-acetyltransferase (OAT). Strain YG1024 is a derivative of S. typhimurium strain TAI 538 (hisD3052), expresses elevated levels of OAT, and is very sensitive to mammalian and plant-activated arylamines [Watanabe et al, 1990;Seo et al, 1993;Wagner et al, 19941. In mammals, 0-acetyltransferase and N-acetyltransferase activities are catalyzed by NATl and NAT2.…”

“…The ultimate mutagenic agents form DNA adducts which induce genetic damage. Arylamines have been used to study the mechanisms of plant activation [Seo et al, 1993;Plewa et al, 1993;Wagner et al, 19941. Arylamines are important environmental mutagens and carcinogens; however, this class of compounds has not been extensively investigated using the alkaline Comet assay [Tice, 19951. The alkaline Comet assay (singlecell gel electrophoresis assay) detects DNA strand breaks, alkali-labile sites, and incomplete excision repair sites in O 1995 Wiley-Liss, Inc. mammalian cells.…”