Plant Activation of Bicyclic Aromatic Amines, Benzidine and 4-Aminobiphenyl
Ju, Young Hwa
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https://hdl.handle.net/2142/87670
Description
Title
Plant Activation of Bicyclic Aromatic Amines, Benzidine and 4-Aminobiphenyl
Author(s)
Ju, Young Hwa
Issue Date
1998
Doctoral Committee Chair(s)
Plewa, Michael J.
Department of Study
Agronomy
Discipline
Agronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Plant Physiology
Language
eng
Abstract
Bicyclic aromatic amines, benzidine and 4-aminobiphenyl (4-ABP) have been known as human bladder carcinogens and used in industrial manufacturing. Using the plant cell/microbe coincubation assay, this study showed that benzidine and 4-ABP were activated by plant peroxidase into frameshift- and base pair substitution-mutagens by plant-activation. Bacterial acetyl O-acetyltransferase as well as human N-acetyltransferase play a key role in the activation of benzidine and 4-ABP, and bacterial nitroreductase is partially involved in the mutagenic activation in Salmonella typhimurium. The mutagenic plant-activated benzidine and 4-ABP metabolites were fractionated using ultrafiltration membrane separation. The mutagenic metabolites were recovered in a retentate fraction with a molecular weight of $\ge$100 kDa and stable for more than 7 months when stored at 4$\sp\circ$C. To define the mutagenic specificity of the plant-activated aromatic amine metabolite, mutant spectra of spontaneous revertants and revertants induced by the plant- and mammalian-activated of aromatic amines were analyzed at the hisG46 allele in S. typhimurium strain YG1029. The plant-activated aromatic amines induced different types of base pair substitutions from the mammalian S9-activated aromatic amines. To isolate and characterize the plant-activated benzidine product(s), we generated polyclonal anti-benzidine antibodies. The anti-benzidine antibody did not recognize the plant-activated benzidine metabolites. This suggests that the plant-activated benzidine product is structurally different from benzidine parent compound. To define the molecular effects of plant- and mammalain-activated benzidine DNA adducts were induced from plant-activated benzidine in S. typhimurium and analyzed using $\sp{32}$P-postlabelmg and HPLC. Mammalian- and plant-activate benzidine metabolites induced DNA adducts in bacteria. To determine the genotoxicity of plant-activated benzidine in Chinese hamster lung cells a rapid single cell gel electrophoresis assay was employed. The plant-activated benzidine did not directly induce any DNA damage in mammalian cells. However, the plant-activated benzidine after treatment with pectinase was a potent genotoxin in mammalian cells. These data suggest that plant-activated xenobiotics may be converted into stable forms, perhaps in the pectin component in the plant cell wall. This plant activation may be a process to transport xenobiotics laterally through the environment and vertically through the food chain.
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