Morin B, Cadet J
CEA/Département de Recherche Fondamentale sur la Matière Condensée, SESAM/LAN, Grenoble, France.
Chem Res Toxicol. 1995 Jul-Aug;8(5):792-9. doi: 10.1021/tx00047a020.
5'-Amino-2',5'-dideoxyguanosine has been synthesized in order to investigate the intramolecular reactivity of an amino group toward the guanine radical produced by type I photosensitization mechanism. Benzophenone-mediated photosensitization of 5'-amino-2',5'-dideoxyguanosine in aerated aqueous solution results in the formation of a predominant cyclic nucleoside together with an unstable nucleoside precursor. The two modified nucleosides have been isolated by reverse phase high performance liquid chromatography and characterized by spectroscopic measurements including 13C and 1H NMR, fast atom bombardment mass spectroscopy, and UV absorption. The stable photoproduct has been identified as 9-oxa-2,4-diazabicyclo[4.2.1]non-2-en-7-ol, 3-amino- (1R-exo), whereas its precursor has been assigned as acetic acid, [(7-hydroxy-9-oxa-2,4-diazabicyclo[4.2.1]non-2-en-3-yl)amino]oxo- (1R-exo). A reaction mechanism, involving nucleophilic addition of the sugar amino group to guanine radical intermediates, is proposed to explain the formation of the two photoproducts.
合成了5'-氨基-2',5'-二脱氧鸟苷，以研究氨基对I型光敏机制产生的鸟嘌呤自由基的分子内反应活性。在曝气水溶液中，二苯甲酮介导的5'-氨基-2',5'-二脱氧鸟苷光敏化反应产生了一种主要的环状核苷以及一种不稳定的核苷前体。通过反相高效液相色谱法分离出这两种修饰核苷，并通过包括13C和1H NMR、快原子轰击质谱和紫外吸收在内的光谱测量对其进行了表征。稳定的光产物被鉴定为9-氧杂-2,4-二氮杂双环[4.2.1]壬-2-烯-7-醇，3-氨基-（1R-外向），而其前体被确定为乙酸，[(7-羟基-9-氧杂-2,4-二氮杂双环[4.2.1]壬-2-烯-3-基)氨基]氧代-（1R-外向）。提出了一种涉及糖氨基对鸟嘌呤自由基中间体亲核加成的反应机制，以解释这两种光产物的形成。
