title: Photosensitization with anticancer agents. 20--EPR studies on the photodynamic action of phleichrome: formation of semiquinone radical and activated oxygen species on illumination with visible light.
abstract: When phleichrome was illuminated with visible light, the semiquinone radical, singlet oxygen, and superoxide anion radical were detected. The formation of the semiquinone radical and activated oxygen species and the transformations and competitions between them depend on quinone and oxygen concentration, duration and intensity of illumination, and the nature of the substrate. In anaerobic solution, the semiquinone radical was predominantly photoproduced via the self-electron transfer between the excited and ground species. In contrast, in aerobic solution, singlet oxygen is the principal product in the photosensitization of phleichrome. In addition to singlet oxygen, superoxide anion radical is also generated by the quinones upon illumination in aerobic solution, but to a lesser extent. The generation of the superoxide anion is significantly enhanced by the presence of electron donors.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Canada.
authors.forename: Z
authors.initials: Z
authors.lastname: Diwu
authors.forename: J W
authors.initials: JW
authors.lastname: Lown
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D008027:Light; D009281:Naphthalenes; D010100:Oxygen / Q000737:chemistry; D011083:Polycyclic Compounds / Q000737:chemistry* / Q000528:radiation effects; D011809:Quinones / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry*; D026082:Singlet Oxygen; D013481:Superoxides / Q000737:chemistry
chemical_list: D005609:Free Radicals; D009281:Naphthalenes; D011083:Polycyclic Compounds; D011809:Quinones; D017382:Reactive Oxygen Species; D013481:Superoxides; D026082:Singlet Oxygen; C061463:calphostin D; D010100:Oxygen