Mossoba M M, Rosenthal I, Riesz P
Int J Radiat Biol Relat Stud Phys Chem Med. 1981 Nov;40(5):541-52. doi: 10.1080/09553008114551501.
gamma-Radiolysis in the polycrystalline state and U.V. photolysis in aqueous solution at 220 nm of several dihydropyrimidines and their derivatives have been investigated by spin-trapping and electron spin resonance. 2-Methyl-2-nitrosopropane was used as the spin-trap. The spin-adducts of the 6-yl radicals obtained fall into two categories. Those from dihydro-1-methyluracil, dihydro-6-methyluracil, dihydro-1-ethyluracil and dihydro-1-methylcytosine exhibit a beta-nitrogen hyperfine coupling constant (alpha beta N) equal to or less than 2.0 G while the ones fom dihydro-orotic acid, dihydrouracil and dihydrothymine showed much larger alpha beta N values (greater than 3.3 G). Dihydrouridine gives radicals characteristic of both the dihydropyrimidine ring and the sugar moiety. The same radicals were obtained by gamma-radiolysis or U.V. photolysis. For all the 5-yl radicals obtained by U.V. photolysis, a direct photoexcitation mechanism is proposed.
通过自旋捕集和电子自旋共振研究了几种二氢嘧啶及其衍生物在多晶态下的γ辐射分解和在220nm水溶液中的紫外光解。使用2-甲基-2-亚硝基丙烷作为自旋捕集剂。所得到的6-位自由基的自旋加合物分为两类。来自二氢-1-甲基尿嘧啶、二氢-6-甲基尿嘧啶、二氢-1-乙基尿嘧啶和二氢-1-甲基胞嘧啶的自旋加合物表现出β-氮超精细偶合常数（αβN）等于或小于2.0G，而来自二氢乳清酸、二氢尿嘧啶和二氢胸腺嘧啶的自旋加合物显示出大得多的αβN值（大于3.3G）。二氢尿苷产生的自由基具有二氢嘧啶环和糖部分的特征。通过γ辐射分解或紫外光解获得相同的自由基。对于通过紫外光解获得的所有5-位自由基，提出了直接光激发机制。
