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Photochemical transformation and phototoxicity of 1‐Aminopyrene
Author(s) -
Zeng Kui,
Hwang HueyMin,
Dong Shiming,
Shi Xiaochun,
Wilson Kaneytta,
Green Jacinta,
Jiao Yuguo,
Yu Hongtao
Publication year - 2004
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/03-415
Subject(s) - phototoxicity , chemistry , mutagen , adduct , photochemistry , singlet oxygen , covalent bond , metabolite , dna damage , dna , dithiothreitol , histidine , carcinogen , oxygen , biochemistry , organic chemistry , in vitro , amino acid , enzyme
1‐Aminopyrene (1‐AP) is an environmental mutagen and a metabolite of 1‐nitropyrene (1‐NO 2 P). 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 NaN 3 slows down 1‐AP photochemical reaction. The photoproducts identified include 1‐hydroxyaminopyrene, 1‐nitrosopyrene, 1‐NO 2 P, 1‐amino‐x‐hydroxypyrene, and three covalent dimers. Since it is known that 1‐NO 2 P 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‐NO 2 P are 1.25 μM, 10 μM, and NA (no mutagenic response was seen at this concentration range) in direct medium (no S‐9) and NA, 5 μM, and 0.625 μM 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‐NO 2 P in the direct medium. Thus, 1‐NO 2 P 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.