Photochemistry of <i>N</i>-Isopropoxy-Substituted 2(1<i>H</i>)-Pyridone and 4-<i>p</i>-Tolylthiazole-2(3<i>H</i>)-thione: Alkoxyl-Radical Release (Spin-Trapping, EPR, and Transient Spectroscopy) and Its Significance in the Photooxidative Induction of DNA Strand Breaks
作者:Waldemar Adam、Jens Hartung、Hideki Okamoto、Stefan Marquardt、Werner M. Nau、Uwe Pischel、Chantu R. Saha-Möller、Kristina Špehar
DOI:10.1021/jo025856w
日期:2002.8.1
N-O bond scission [Phi(N)(-)(O) = (75 +/- 8)% for 2b and (65 +/- 7)% 3b] as the dominating primary photochemical process to afford the DNA-damaging radicals. Product studies and laser-flash experiments reveal that the thiazolethione 3b leads primarily to the disulfide 5, from which through C-S bond breakage, the bithiazyl 6, the thiazole 7, and the isothiocyanate 8 are derived. Upon irradiation of pyridone
UV-Fenton试剂N-异丙氧基吡啶酮2b和N-异丙氧基噻唑-2(3H)-硫酮3b的UVA辐照会释放自由基,从而引起链断裂。瞬态光谱法确定NO键断裂[2(b)的(Phi(N)(-)(O)=(75 +/- 8)%和3b(65 +/- 7)%)为主要的主要光化学过程,以提供DNA-有害的自由基。产品研究和激光闪光实验表明,噻唑硫酮3b主要导致二硫键5,通过CS键断裂,生成二噻唑基6,噻唑7和异硫氰酸酯8。在水介质中辐照吡啶酮2b(300 nm)后,形成了异丙氧基和2-羟基丙-2-基的混合物,这是通过用5,5-二甲基-1-吡咯啉N-氧化物(DMPO)和四氯化碳进行捕集而确认的。 EPR光谱。相反,噻唑硫酮3b(350 nm)的光解仅产生异丙氧基的DMPO加合物。对照实验表明,噻唑硫酮衍生的光产物二硫化物5或中间的噻吩基基团B清除了以碳为中心的2-羟基丙-2-基基团,该基团是通过氢转移由异丙氧基基团产生的。使用H(2)O-MeCN