Li W, Zheng R, Jia Z, Zou Z, Lin N
Department of Biology, Lanzhou University, Lanzhou 730000, China.
Biophys Chem. 1997 Sep 1;67(1-3):281-6. doi: 10.1016/s0301-4622(97)00055-0.
Repair effects on thymine radical anion by six phenylpropanoid glycosides (PPGs), isolated from Pedicularis species, were studied using pulse radiolysis method. The thymine radical anion was produced by the reaction of hydrated electron with thymine. PPGs were added into the thymine solution saturated with N(2). Kinetic analysis showed that transient absorption spectrum of thymine radical anion formed at first, and then after several microseconds of pulse radiolysis changed to that of PPG radical anion. The evidence indicated that thymine radical anion was repaired through one-electron transfer between the radical anion and PPG. Electrophilic phenyl-substituted unsaturated carboxylic group containing in PPGs' structure was able to capture electron from thymine radical anion before it undergo reversible protonation. The reaction rate constants of electron transfer from thymine radical anion to PPGs were within 1.16-2.29 x 10(9) dm(3) mol(-1) s(-1).
采用脉冲辐解方法研究了从马先蒿属植物中分离得到的6种苯丙素苷（PPGs）对胸腺嘧啶自由基阴离子的修复作用。胸腺嘧啶自由基阴离子由水合电子与胸腺嘧啶反应产生。将PPGs加入到用N₂饱和的胸腺嘧啶溶液中。动力学分析表明，首先形成胸腺嘧啶自由基阴离子的瞬态吸收光谱，然后在脉冲辐解几微秒后变为PPG自由基阴离子的瞬态吸收光谱。证据表明，胸腺嘧啶自由基阴离子通过自由基阴离子与PPG之间的单电子转移得到修复。PPGs结构中含有的亲电苯基取代不饱和羧基能够在胸腺嘧啶自由基阴离子发生可逆质子化之前从其捕获电子。从胸腺嘧啶自由基阴离子到PPGs的电子转移反应速率常数在1.16 - 2.29×10⁹ dm³ mol⁻¹ s⁻¹范围内。
