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.

• Authors: Kui Zeng, Huey-Min Hwang, Shiming Dong, Xiaochun Shi, Kaneytta Wilson, Jacinta Green, Yuguo Jiao, Hongtao Yu
• Journal: Environmental toxicology and chemistry (Environ Toxicol Chem) Vol. 23 Issue 6 Pg. 1400-7 (Jun 2004) ISSN: 0730-7268 [Print] United States
• PMID: 15376525 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Mutagens
• Pyrenes
• 1-aminopyrene

Topics

• DNA Damage
• Half-Life
• Mutagenicity Tests
• Mutagens (chemistry, toxicity)
• Photochemistry
• Pyrenes (chemistry, toxicity)
• Ultraviolet Rays
• Vibrio (genetics)