Photochemical transformation and phototoxicity of 1‐Aminopyrene

Abstract

1-Aminopyrene (1-AP) is an environmental mutagen and a metabolite of 1-nitropyrene (1-NO2P). On light irradiation, 1-AP transforms into oxidation products with a half-life of 7.1 min in 10% methanolic buffer. The presence of DNA or free-radical/ singlet oxygen scavengers 1,4-dithiothreitol, histidine, or NaN3 slows down 1-AP photochemical reaction. The photoproducts identified include 1-hydroxyaminopyrene, 1-nitrosopyrene, 1-NO2P, 1-amino-x-hydroxypyrene, and three covalent dimers. Since it is known that 1-NO2P and 1-nitrosopyrene are genotoxic and 1-hydroxyaminopyrnene can react with DNA to form covalent adducts, we used the Mutatox test to assess the toxicity of 1-AP and its photoproducts. It was found that the lowest-observed-effect concentrations for 1-AP, 1-AP photoproducts, and 1-NO2P are 1.25 microM, 10 microM, and NA (no mutagenic response was seen at this concentration range) in direct medium (no S-9) and NA, 5 microM, and 0.625 microM in S-9 medium, respectively. Therefore, 1-AP photoproducts are more genotoxic than 1-AP itself in the S-9 medium and more mutagenic than 1-NO2P in the direct medium. Thus, 1-NO2P alone cannot account for all the mutagenicity of the photoproducts. Irradiation of 1-AP together with DNA leads to covalent DNA adduct formation possibly via the 1-hydroxyaminopyrene intermediate. In this study, ultraviolet-A (UVA) was used at approximately the same magnitude as the outdoor UVA irradiance. Considering the half-life of 1-AP in the test solutions in this study, the aquatic biota (including humans) near the surface layer of a static water body are most likely subjected to the photoinduced toxicity of the study compound. The biota at the lower depths will also be affected if turbulence becomes a significant factor in enhancing the exposure risk for aquatic organisms.

Electronic Spectroscopy of Protonated 1‐Aminopyrene in a Cold Ion Trap

“…Herein, we investigated the photofragmentationo fp rotonated aminopyrene (APH + + ). The neutralm olecule (AP) is aknown mutagen [22] and abiodegradation product of nitropyrene, [23] itselfam utagen that is produced by the combustion of diesel or the reaction of atmosphericn itrogen oxidesw ith PAHs. [24] This molecule is of particularp hotophysical interest, owing to its previously observed behavior in the liquid phase.…”

Structure-dependent lipid peroxidation by photoirradiation of pyrene and its mono-substituted derivatives

“…1-AP, 1-HP, and to a lesser extent, 1-NP’s ability to absorb UVA light enables them to change the electronic distribution about the nucleus, employing bond breaking and creation [54] . This was demonstrated previously that 1-AP can be oxidized into 1-hydroxyaminopyrene, 1-nitrosopyrene, 1-nitropyrene, and 1-amino-x-hydroxypyrene [52] . The photoproducts of 1-HP are 1,6- and 1,8-pyrene quinones and a pyrene dimer [53] , and the photo-induced reactions of 1-NP include pyrene, 1-HP, hydroxynitropyrenes, and pyrenediones [49, 50, 55] .…”

“…The leveling off at 40 min for the 1-HP induced lipid peroxidation is because the quinines, though formed as photoproducts, were not produced in significant amounts as it is indicated in the HPLC chromatograms in Figure 1S (supplementary materials). Similarly, 1-AP does not generate significant amount of ML hydroperoxides due to its relatively fast photochemical reaction, producing sequentially 1-hydroxyamino, 1-nitroso, and 1-NP [52] . It means that these photoproducts of 1-AP are not causing significant amount of lipid peroxidation.…”

“…This explains why the lipid peroxidation levels off after 40 min of irradiation. For 1-AP, upon UVA irradiation, it leads to the formation of 1-hydroxyamino, 1-nitroso, and 1-nitropyrene and some smaller fragmented molecules quickly [52] , causing no lipid peroxidation. Conversely, 1-NP itself is a weak inducer of lipid peroxidation, but its photoproducts are stronger lipid peroxidation inducers, resulting in the ramping up of lipid peroxidation observed from 40–60 min of irradiation.…”

Integrating Field Analyses with Laboratory Exposures to Assess Ecosystems Health

“…Evidence of damage to cell membranes following irradiation (near UV, 290-400 nm) of benzo [a]pyrene, anthracene or 1-nitropyrene mixed with cells has also been reported (Kagan et al, 1989;Tuveson et al, 1990;Zeng et al, 2002Zeng et al, , 2004. Possible DNA damage induced by the combination of light and a photoreactive chemical includes: (i) single-strand breaks, (ii) double-strand breaks, (iii) release of DNAbases (depurination/depyrimidination), (iv) oxidation of guanine to 8-hydroxy-or 8-oxoguanine, (v) induction of covalent DNA adducts, (vi) induction of DNA-DNA cross-links and (vii) induction of DNA-protein cross-links (Yu, 2002).…”