UVA Photoirradiation of Nitro-Polycyclic Aromatic Hydrocarbons—Induction of Reactive Oxygen Species and Formation of Lipid Peroxides †

Qingsu Xia,Jun-Jie Yin,Yuewei Zhao,Liang Ma,Yuh-Sen Wu,Hongtao Yu,Yu-Qui Wang,Peter Fu,Xin Sun,Shoujun Chen

doi:10.3390/ijerph10031062

Abstract

Nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) are a class of genotoxic environmental contaminants. We have long been interested in determining the mechanisms by which nitro-PAHs induce genotoxicity. Although the metabolic activation of nitro-PAHs leading to toxicological activities has been well studied, the photo-induced activation of nitro-PAHs has seldom been reported. In this paper, we report photo-induced lipid peroxidation by 19 nitro-PAHs. The results indicated that all but two of the nitro-PAHs can induce lipid peroxidation. Mechanistic studies suggest that lipid peroxidation by nitro-PAHs is mediated by free radicals generated in the reaction. There was no structural correlation between the nitro-PAHs and their ability to induce lipid peroxidation upon UVA irradiation, or between the HOMO-LUMO gap and the ability to cause lipid peroxidation. Most of the nitro-PAHs are less potent in terms of causing lipid peroxidation than their parent PAHs. The lack of correlation is attributed to the complex photophysics and photochemistry of the nitro-PAHs and the yield of reactive oxygen species (ROS) and other factors.

Highlights

Since 1978, nitro-polycyclic aromatic hydrocarbons have been identified as widespread genotoxic environmental contaminants from different environmental sources, including diesel emissions, combustion emissions from kerosene heaters, gas fuel, and liquefied petroleum, airborne particulates, coal fly ash, and food [1,2,3,4,5,6]
Seventeen of the nitro-PAHs exposed to UVA light induce lipid peroxidation in a light dose response manner (Table 1)
The mechanisms of inducing lipid peroxidation were determined by using free radical scavengers or enhancers and by electron spin resonance (ESR) spin trapping methodology

Summary

Introduction

Since 1978, nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) have been identified as widespread genotoxic environmental contaminants from different environmental sources, including diesel emissions, combustion emissions from kerosene heaters, gas fuel, and liquefied petroleum, airborne particulates, coal fly ash, and food [1,2,3,4,5,6]. Nitro-PAHs require metabolic activation in order to exert their mutagenic and carcinogenic activities [7,8,9,10,11,12]. Because of their widespread presence in the environment and genotoxic activities, many of these compounds may pose a health risk to humans. There has no systematic report on the study of induction of lipid peroxidation by photoirradiation of nitro-PAHs on a basis of structure-activity relationships. This is because, in most cases, the structurally related nitro-PAHs are not available for study.

Methods

Results

Conclusion