Gantchev T G
Department of Nuclear Medicine and Radiobiology, Faculty of Medicine, University of Sherbrooke, Quebec, Canada.
Int J Radiat Biol. 1995 Jul;68(1):29-36. doi: 10.1080/09553009514550891.
In order to obtain information concerning the mechanism(s) of metallo-phthalocyanine (MePcS4) photosensitized damage of DNA constituents, the EPR-spin trapping method in conjunction with liquid chromatography was used to study thymidine (dThd) free radicals formed during photosensitization or exposure to gamma-radiation in solution. Under specified conditions two dThd free radical species, 5-hydroxy-5,6-dihydrothymidine-6-yl and 6-hydroxy-5,6-dihydrothymidine-5-yl, were formed both during exposure to ionizing radiation and photosensitization. These results imply that identical reactive intermediates (*OH radicals) are involved in the radiolytic and photosensitized oxidation of dThd. A light-dependent, Fenton-type mechanism is proposed to explain the generation of hydroxyl radicals during MePcS4 photosensitization.
为了获取有关金属酞菁（MePcS4）对DNA成分进行光致敏损伤的机制的信息，采用电子顺磁共振自旋捕获法结合液相色谱，研究了在溶液中光致敏过程或γ辐射暴露期间形成的胸苷（dThd）自由基。在特定条件下，在电离辐射暴露和光致敏过程中均形成了两种dThd自由基，即5-羟基-5,6-二氢胸苷-6-基和6-羟基-5,6-二氢胸苷-5-基。这些结果表明，相同的反应中间体（*OH自由基）参与了dThd的辐射分解和光致敏氧化。提出了一种光依赖的芬顿型机制来解释MePcS4光致敏过程中羟基自由基的产生。
