Comparative mutagenicity of nitrofluoranthenes in Salmonella typhimurium TA98, TA98NR, and TA98/1,8DNP6.
The nitration of fluoranthene, one of the most abundant polycyclic aromatic hydrocarbons (PAH) in diesel fuels, occurs in the laboratory under either electrophilic or free-radical conditions to give nitro-PAH. 3-Nitrofluoranthene (3-NF) is the major product under electrophilic ionic conditions while 2-nitrofluoranthene (2-NF) is the major product under free-radical nitration conditions. The free-radical nitration of fluoranthene also yields 1,2- and 1,3-dinitrofluoranthene (1,2-DNF and 1,3-DNF). Nitration on the 3-position of fluoranthene enhances the mutagenic potency more strongly than on the 2-position. Thus, 3-NF is a more potent mutagen than 2-NF and 1,3-DNF is more potent than 1,2-DNF, an isomer with one near coplanar nitro group and one nitro group substantially out of plane with the fluoranthene skeleton, when tested against Salmonella typhimurium TA98, TA98NR, and TA98/1,8-DNP6. In addition, the activation of these dinitro-PAH to mutagens does not depend on the "classical nitroreductase" and/or O-acetylase, suggesting that they are activated via different pathways. Despite the fact that 3-NF and 1-phenyl-4-nitronaphthalene (1-P-4NN), a non-planar analog of 3-NF, have virtually identical reduction potentials, their mutagenic potencies differ by three orders of magnitude. This finding suggests that when nitro-PAH of varying steric requirements are compared, the reduction potential may not predict mutagenic potency as well as had been previously suggested.
Shane
B S
BS
Institute for Environmental Studies, Louisiana State University, Baton Rouge 70803.
Squadrito
G L
GL
Church
D F
DF
Pryor
W A
WA
D004563:Electrochemistry; D005449:Fluorenes / Q000633:toxicity*; D005609:Free Radicals; D009152:Mutagenicity Tests; D009153:Mutagens; D010084:Oxidation-Reduction; D012486:Salmonella typhimurium / Q000235:genetics*; D013045:Species Specificity
D005449:Fluorenes; D005609:Free Radicals; D009153:Mutagens; C033643:3-nitrofluoranthene; C049030:2-nitrofluoranthene