Phototoxicity and Environmental Transformation of Polycyclic Aromatic Hydrocarbons (PAHs)—Light-Induced Reactive Oxygen Species, Lipid Peroxidation, and DNA Damage

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are a class of mutagenic and tumorigenic environmental contaminants. Although the mechanisms by which PAHs induce cancer in experimental animals have been extensively studied and the metabolic activation pathways have been determined, the environmental fate of PAHs and the phototoxicity exerted by PAHs, as well as their photoreaction products formed in the environment, have received much less attention. In this review, the formation of oxygenated PAHs, PAH quinones, nitro-PAHs, and halogenated PAHs from photoreaction of environmental PAHs are addressed. Upon light irradiation, PAHs and all PAH photoreaction products can absorb light energy to reach photo-excited states, which react with molecular oxygen, medium, and coexisting chemicals to produce reactive oxygen species (ROS) and other reactive intermediates, such as oxygenated PAHs and free radicals. These intermediates, including ROS, induce lipid peroxidation, and DNA damage including DNA strand breakage, oxidation to 8-oxo-2'-deoxyguanosine, and DNA-adducts. Since these toxicological endpoints are associated with age-related diseases, including cancer, environmental PAHs concomitantly exposed to sunlight may potentially promote human skin damage, leading to ageing and skin cancers. Thus, we suggest that (i) in addition to the widely recognized metabolic pathways, more attention must be paid to photoreaction as an important activation pathway for PAHs, (ii) risk assessment of environmental PAHs should take into consideration the complex photochemical reactions leading to mixtures of products that are also phototoxic; and (iii) the study of structure-toxicity relationships should be expanded to cover the complex photoreactions and extrinsic factors that affect phototoxicity endpoints.

Effect of Cadmium and Lead Exposure on Tissue Specific Antioxidant Response in Spodoptera litura

“…Many studies have been revealed that the capacity of insect detoxification enzymes to be induced by xenobiotic and the relationship between elevated detoxifying enzyme levels and tolerance to chemical insecticides. 53 Our work demonstrates that Cadmium chloride and Lead nitrate exposure against larval tolerance and antioxidant enzymes. Our results confirm that both Cd and Pb heavy metals induced toxicity and significantly increased antioxidant enzymes.…”

Evaluating the mutagenic potential of aerosol organic compounds using informatics-based screening

“…The formation of ROS in atmospheric SOA and the genotoxic effect of oxidative stress caused by PM exposure have been documented by a number of studies (e.g. Risom et al, 2005;Valavanidis et al, 2008;Rattanavaraha et al, 2011;Oh et al, 2011;Fu et al, 2012).…”

“…However, SOA modelling studies indicate that they can account for a significant fraction of SOA mass formed by substituted benzene oxidation (Ruggeri et al, 2016), which translates into ambient concentrations of several ng m −3 in very polluted environments (such as in Yuan et al, 2013; Table S10). The formation of endoperoxides and epoxides and of other reactive oxygenated organic compounds, such as those in Clusters 7 and 8, was hypothesized by Fu et al (2012) to explain the DNA damage caused by photodegraded aromatic compounds. Moreover, the finding of biogenic SOA components with potential mutagenic properties (Cluster 0 and some compounds in Clusters 7 and 8) is in agreement with the results of Alves et al (2016), showing that the mutagenicity of the aerosol is enhanced when pollution is mixed with emissions in rural areas.…”

“…They could contribute to explaining the yet unknown composition of the most polar fraction of mutagenic compounds in atmospheric aerosol (Barale et al, 1994;Gutiérrez-Castillo et al, 2006;Palacio et al, 2016). First, five-membered lactones formed by the oxidation of monoterpenes are alkylating agents and possibly mutagenic (Cluster 0).…”

Current application of phytocompound-based nanocosmeceuticals for beauty and skin therapy

“…60,61 This is not limited to the aged population; younger individuals exposed to various harsh environmental conditions such as infrared and ultraviolet rays, chemical pollution, and other physical stresses can also be affected. 62,63 Currently, various synthetic and natural antiaging creams using nanosize technology are available on the market with enhanced skin protection to moisturize, lift, and whiten skin. [64][65][66][67][68] Recently, Lohani et al 4 reviewed some nanoproducts produced by few companies for enhanced beauty, such as Hydra Zen Cream, Revitalift, and Skin Caviar Ampoules that contain phytocompounds, using various nanotechnologies.…”