title: UVA photoirradiation of oxygenated benz[a]anthracene and 3-methylcholanthene--generation of singlet oxygen and induction of lipid peroxidation.
abstract: Polycyclic aromatic hydrocarbons (PAHs) are widespread genotoxic environmental pollutants and potentially pose a health risk to humans. Although the biological and toxicological activities, including metabolism, mutagenicity, and carcinogenicity, of PAHs have been thoroughly studied, their phototoxicity and photo-induced biological activity have not been well examined. We have long been interested in phototoxicity of PAHs and their derivatives induced by irradiation with UV light. In this paper we report the photoirradiation of a series of oxygenated benz[a]anthracene (BA) and 3-methylcholanthene (3-MC) by UVA light in the presence of a lipid, methyl linoleate. The studied PAHs include 2-hydroxy-BA (2-OH-BA), 3-hydroxy-BA (3-OH-BA), 5-hydroxymethyl-BA (5- CH2OH-BA), 7-hydroxymethyl-BA (7-CH2OH-BA), 12-hydroxymethyl-BA (12-CH2OH-BA), 7-hydroxymethyl-12- methyl-BA (7-CH2OH-12-MBA), 5-formyl-BA (5-CHO-BA), BA 5,6-cis-dihydrodiol (BA 5,6-cis-diol), 1-hydroxy-3- methylcholanthene (1-OH-3-MC), 1-keto-3-methylcholanthene (1-keto-3-MC), and 3-MC 1,2-diol. The results indicate that upon photoirradiation by UVA at 7 and 21 J/cm2, respectively all these compounds induced lipid peroxidation and exhibited a relationship between the dose of the light and the level of lipid peroxidation induced. To determine whether or not photoirradiation of these compounds by UVA light produces ROS, an ESR spin-trap technique was employed to provide direct evidence. Photoirradiation of 3-keto-3-MC by UVA (at 389 nm) in the presence of 2,2,6,6-tetramethylpiperidine (TEMP), a specific probe for singlet oxygen, resulted in the formation of TEMPO, indicating that singlet oxygen was generated. These overall results suggest that UVA photoirradiation of oxygenated BA and 3-methylcholanthrene generates singlet oxygen, one of the reactive oxygen species (ROS), which induce lipid peroxidation.
authors.affiliation: Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, College Park, MD 20740, USA.
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Yin
authors.forename: Qingsu
authors.initials: Q
authors.lastname: Xia
authors.forename: Shu-Hui
authors.initials: SH
authors.lastname: Cherng
authors.forename: I-Wah
authors.initials: IW
authors.lastname: Tang
authors.forename: Peter P
authors.initials: PP
authors.lastname: Fu
authors.forename: Ge
authors.initials: G
authors.lastname: Lin
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yu
authors.forename: Diógenes Herreño
authors.initials: DH
authors.lastname: Sáenz
mesh_terms: D001551:Benz(a)Anthracenes / Q000737:chemistry* / Q000528:radiation effects; D004578:Electron Spin Resonance Spectroscopy; D008041:Linoleic Acids / Q000737:chemistry / Q000528:radiation effects; D015227:Lipid Peroxidation / Q000528:radiation effects*; D008748:Methylcholanthrene / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000528:radiation effects; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*; D026082:Singlet Oxygen / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D001551:Benz(a)Anthracenes; D008041:Linoleic Acids; D026082:Singlet Oxygen; C005575:methyl linoleate; D008748:Methylcholanthrene; C030935:benz(a)anthracene; D010100:Oxygen