title: Nile blue can photosensitize DNA damage through electron transfer.
abstract: The mechanism of DNA damage photosensitized by Nile blue (NB) was studied using (32)P-5'-end-labeled DNA fragments. NB bound to the DNA strand was possibly intercalated through an electrostatic interaction. Photoirradiated NB caused DNA cleavage at guanine residues when the DNA fragments were treated with piperidine. Consecutive guanines, the underlined G in 5'-GG and 5'-GGG, were selectively damaged through photoinduced electron transfer. The fluorescence lifetime of NB was decreased by guanine-containing DNA sequence, supporting this mechanism. Single guanines were also slightly damaged by photoexcited NB, and DNA photodamage by NB was slightly enhanced in D2O. These results suggest that the singlet oxygen mechanism also partly contributes to DNA photodamage by NB. DNA damage photosensitized by NB via electron transfer may be an important mechanism in medicinal applications of photosensitizers, such as photodynamic therapy in low oxygen.
authors.affiliation: Department of Applied Chemistry and Biochemical Engineering, Graduate School of Engineering, Shizuoka University , Johoku 3-5-1, Naka-ku, Hamamatsu, Shizuoka 432-8561, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Hirakawa
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ota
authors.forename: Junya
authors.initials: J
authors.lastname: Hirayama
authors.forename: Shinji
authors.initials: S
authors.lastname: Oikawa
authors.forename: Shosuke
authors.initials: S
authors.lastname: Kawanishi
mesh_terms: D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004579:Electron Transport; D010078:Oxazines / Q000737:chemistry*; D017319:Photosensitizing Agents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D010078:Oxazines; D017319:Photosensitizing Agents; C008619:Nile Blue; D004247:DNA