nitrobenzanthrone and 1-nitropyrene

Internal combustion engine emissions belong among the major anthropogenic sources of air pollution in urban areas. According to the International Agency for Research on Cancer, there is sufficient evidence of the carcinogenicity of diesel exhaust in human beings. Although alternative fuels, mainly biodiesel, have recently become popular, little is still known about the genotoxicity of emissions from these fuels. We analysed DNA damage expressed as the frequency of micronuclei (MN) in human bronchial epithelial cells (BEAS-2B), induced by extractable organic matter (EOM; tested concentrations: 1, 10 and 25 μg/ml) obtained from particle emissions from various blends of biodiesel with diesel fuels (including neat diesel fuel (B0), a blend of 70% B0 and 30% biodiesel (B30) and neat biodiesel (B100)). We also tested the effect of selected diesel exhaust organic/genotoxic components [benzo[a]pyrene (B[a]P) concentrations: 25, 100 and 200 μM; 1-nitropyrene (1-NP) concentrations: 1, 5 and 10 μM; 3-nitrobenzanthrone (3-NBA) concentrations: 1, 5 and 50 μM]. The cells were treated with the compounds for 28 and 48 hr. Our results showed that most of the tested compounds (except for the 25 μM B[a]P, 28-hr treatment) significantly increased MN frequency. The genotoxicity of EOMs from the engine emissions of diesel and biodiesel engines was comparable. Both nitro-PAH compounds demonstrated higher genotoxic potential in comparison with B[a]P. Considering our results and due to increasing popularity of alternative fuels, it is prudent that the potential genotoxic effects of various fuels are investigated across engine technologies and operating conditions in a relevant model system.

Topics: Air Pollutants; Benz(a)Anthracenes; Benzo(a)pyrene; Biofuels; Cell Line; DNA Damage; Epithelial Cells; Humans; Micronucleus Tests; Particulate Matter; Pyrenes; Vehicle Emissions

We investigated the toxicity of benzo[a]pyrene (B[a]P), 1-nitropyrene (1-NP) and 3-nitrobenzanthrone (3-NBA) in A549 cells. Cells were treated for 4 h and 24 h with: B[a]P (0.1 and 1 μM), 1-NP (1 and 10 μM) and 3-NBA (0.5 and 5 μM). Bulky DNA adducts, lipid peroxidation, DNA and protein oxidation and mRNA expression of CYP1A1, CYP1B1, NQO1, POR, AKR1C2 and COX2 were analyzed. Bulky DNA adducts were induced after both treatment periods; the effect of 1-NP was weak. 3-NBA induced high levels of bulky DNA adducts even after 4-h treatment, suggesting rapid metabolic activation. Oxidative DNA damage was not affected. 1-NP caused protein oxidation and weak induction of lipid peroxidation after 4-h incubation. 3-NBA induced lipid peroxidation after 24-h treatment. Unlike B[a]P, induction of the aryl hydrocarbon receptor, measured as mRNA expression levels of CYP1A1 and CYP1B1, was low after treatment with polycyclic aromatic hydrocarbon (PAH) nitro-derivatives. All test compounds induced mRNA expression of NQO1, POR, and AKR1C2 after 24-h treatment. AKR1C2 expression indicates involvement of processes associated with reactive oxygen species generation. This was supported further by COX2 expression induced by 24-h treatment with 1-NP. In summary, 3-NBA was the most potent genotoxicant, whereas 1-NP exhibited the strongest oxidative properties.

Topics: A549 Cells; Alveolar Epithelial Cells; Benz(a)Anthracenes; Benzo(a)pyrene; Cyclooxygenase 2; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP1B1; Cytochrome P-450 Enzyme System; DNA Adducts; DNA Damage; Humans; Hydroxysteroid Dehydrogenases; NAD(P)H Dehydrogenase (Quinone); Pyrenes; Vehicle Emissions