title: Capillary electrophoretic studies on the photogenotoxic potential of pharmaceutical substances.
abstract: Drug-induced phototoxic skin responses, including photoirritation, photoallergy and photogenotoxicity, are identified as adverse reactions. In this study, we attempted to develop effective analytical tools to predict the photogenotoxic potential of pharmaceutical substances with the use of pBR322 DNA, a plasmid DNA. pBR322 DNA was irradiated with simulated solar light in the presence of photosensitizers, and its structural conversion was assessed by agarose gel electrophoresis (AGE), transmission electron microscopy (TEM) and capillary gel electrophoresis (CGE). The generation of reactive oxygen species (ROS) from photoirradiated photosensitizers was also assessed by spectrophotometrical determination. Concomitant ultraviolet (UV) exposure of pBR322 DNA and photosensitizers resulted in significant oxidative damage to the DNA, as evidenced by AGE, TEM and CGE data, indicating a structural transition from supercoiled form to open circular form. Photosensitizer-induced DNA damage was attenuated by the addition of radical scavengers, especially sodium azide, a typical scavenger of singlet oxygen (1 O2), and enhanced by the addition of deuterium water, an enhancer of the life time of 1 O2. These data, taken together with the results of the ROS assay, suggest that singlet oxygen might act as a major toxic species in quinine-induced photogenotoxicity. The structural analysis of plasmid DNA by CGE after exposure to UVA/B in the presence of photosensitizers could be automated, allowing easy, fast and highly reliable prediction for the photogenotoxic potential of a large number of drug candidates.
authors.affiliation: Analytical Research and Development, Pfizer Global Research and Development, Nagoya Laboratories, Pfizer Japan Inc., 5-2 Taketoyo, Aichi 470-2393, Japan. onoue@u-shizuoka-ken.ac.jp
authors.forename: Satomi
authors.initials: S
authors.lastname: Onoue
authors.forename: Naoko
authors.initials: N
authors.lastname: Igarashi
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Kitagawa
authors.forename: Koji
authors.initials: K
authors.lastname: Otsuka
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Tsuda
mesh_terms: D004249:DNA Damage / Q000528:radiation effects; D003627:Data Interpretation, Statistical; D017484:Dermatitis, Phototoxic; D004587:Electrophoresis, Agar Gel; D019075:Electrophoresis, Capillary; D008027:Light; D046529:Microscopy, Electron, Transmission; D009153:Mutagens / Q000528:radiation effects / Q000633:toxicity*; D016877:Oxidants / Q000737:chemistry; D018384:Oxidative Stress; D004364:Pharmaceutical Preparations; D010957:Plasmids / Q000187:drug effects / Q000528:radiation effects; D011803:Quinine / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000737:chemistry; D013481:Superoxides / Q000737:chemistry
chemical_list: D009153:Mutagens; D016877:Oxidants; D004364:Pharmaceutical Preparations; D017382:Reactive Oxygen Species; D013481:Superoxides; D011803:Quinine