Repair activities of thymine radical anion by echinocoside, isolated from Pedicularis plicata. were studied using pulse radiolysis technique. The thymine radical anion was produced by the reaction of hydrated electron...Repair activities of thymine radical anion by echinocoside, isolated from Pedicularis plicata. were studied using pulse radiolysis technique. The thymine radical anion was produced by the reaction of hydrated electron with thymine. Echinocoside. one of the polyphenols of phenylpropanoid glycoside, was added to the thymine aqueous solution saturated with N2. Kinetic analysis by transient absorption spectrum showed that thymine radical anion was formed at first, and then after several decades of microseconds of pulse radiolysis. the spectrum of thymine radical anion was changed to that of echinocoside radical anion. The evidence indicated that thymine radical anion was repaired through one-electron-transfer between the DNA base radical anion and echinocoside. The rate constant of electron transfer by echinocoside was 1.45× 109 dm3 · mol1 · s 1.展开更多
本文运用脉冲辐解探究了不同自由基与药物氟西汀(FLX)之间的反应。羟基自由基(?OH)与FLX反应生成苯环上的羟基加成物,而硫酸根阴离子自由基(SO_4?^-)则通过单电子氧化FLX生成苯阳离子自由基,该中间产物再进一步与水反应生成苯环上的羟...本文运用脉冲辐解探究了不同自由基与药物氟西汀(FLX)之间的反应。羟基自由基(?OH)与FLX反应生成苯环上的羟基加成物,而硫酸根阴离子自由基(SO_4?^-)则通过单电子氧化FLX生成苯阳离子自由基,该中间产物再进一步与水反应生成苯环上的羟基加成物。本研究测定了三种自由基?OH,水合电子(e_(aq)^-)以及SO_4?^-与FLX反应的反应速率常数分别为:7.8×10~9,2.3×10~9和1.1×10~9mol?L^(-1)?s^(-1)。本文还运用电子束辐照技术探究了不同辐照条件下的FLX降解效果,结合HPLC和紫外可见光谱仪进行分析。在N_2O和空气饱和的两种条件下,FLX溶液经1.5 k Gy辐照后降解效率均达到90%以上,而N_2饱和条件下,加入0.1 mol?L^(-1)的叔丁醇的FLX溶液经1.5 k Gy辐照后仅有43%分解。此外,酸性和中性条件下FLX的降解效率均大于碱性条件下的。结果阐明了饱和空气的FLX溶液在中性条件下的降解效果最佳,且?OH诱导的反应比SO_4?^-更有利于FLX的分解。本研究期望对于进一步探究FLX的降解反应提供有益的帮助。展开更多
The reactions between gatifloxacin(GFX) and various one-electron oxidants,such as ˙OH,N3˙,Br2˙ˉ,and SO4˙ˉ,have been studied by pulse radiolysis techniques.The GFX radical anion formed in the reaction of GFX with...The reactions between gatifloxacin(GFX) and various one-electron oxidants,such as ˙OH,N3˙,Br2˙ˉ,and SO4˙ˉ,have been studied by pulse radiolysis techniques.The GFX radical anion formed in the reaction of GFX with eaqˉ could either be protonated or deprotonated,and the absorption of GFX radical anion was located at 390 nm.The transient species produced by the reaction of GFX with ˙OH radical shows a broad band in the 380?600 nm region with a shoulder,while the oxidation by N3˙,SO4˙ˉ,and Br2˙ˉ results in an absorption band with λmax = 370 nm.At neutral condition(pH 7),the rate constants of GFX reacting with ˙OH,N3˙,Br2˙ˉ,SO4˙ˉ and eaqˉ are estimated to be 1.0 × 1010,3.1 × 109,2.8 × 109,3.0 × 109,and 1.8 × 1010 dm3 mol?1 s?1,respectively.From the pH dependence on the formation of electron adducts and on the rate constant of GFX with eaqˉ,the pKa of GFX radical anion is estimated to be 5.5 and 9.3.展开更多
基金Project supported by the National Natural Science Foundation of China, Doctoral Programme of State Education Commission and Open Laboratory of Radiation Chemistry,the Chinese Academy of Sciences.
文摘Repair activities of thymine radical anion by echinocoside, isolated from Pedicularis plicata. were studied using pulse radiolysis technique. The thymine radical anion was produced by the reaction of hydrated electron with thymine. Echinocoside. one of the polyphenols of phenylpropanoid glycoside, was added to the thymine aqueous solution saturated with N2. Kinetic analysis by transient absorption spectrum showed that thymine radical anion was formed at first, and then after several decades of microseconds of pulse radiolysis. the spectrum of thymine radical anion was changed to that of echinocoside radical anion. The evidence indicated that thymine radical anion was repaired through one-electron-transfer between the DNA base radical anion and echinocoside. The rate constant of electron transfer by echinocoside was 1.45× 109 dm3 · mol1 · s 1.
基金supported by the National Natural Science Foundation of China(21173252,41430644,11675098)~~
文摘本文运用脉冲辐解探究了不同自由基与药物氟西汀(FLX)之间的反应。羟基自由基(?OH)与FLX反应生成苯环上的羟基加成物,而硫酸根阴离子自由基(SO_4?^-)则通过单电子氧化FLX生成苯阳离子自由基,该中间产物再进一步与水反应生成苯环上的羟基加成物。本研究测定了三种自由基?OH,水合电子(e_(aq)^-)以及SO_4?^-与FLX反应的反应速率常数分别为:7.8×10~9,2.3×10~9和1.1×10~9mol?L^(-1)?s^(-1)。本文还运用电子束辐照技术探究了不同辐照条件下的FLX降解效果,结合HPLC和紫外可见光谱仪进行分析。在N_2O和空气饱和的两种条件下,FLX溶液经1.5 k Gy辐照后降解效率均达到90%以上,而N_2饱和条件下,加入0.1 mol?L^(-1)的叔丁醇的FLX溶液经1.5 k Gy辐照后仅有43%分解。此外,酸性和中性条件下FLX的降解效率均大于碱性条件下的。结果阐明了饱和空气的FLX溶液在中性条件下的降解效果最佳,且?OH诱导的反应比SO_4?^-更有利于FLX的分解。本研究期望对于进一步探究FLX的降解反应提供有益的帮助。
基金supported by the National Natural Science Foundation of China (21173252)
文摘The reactions between gatifloxacin(GFX) and various one-electron oxidants,such as ˙OH,N3˙,Br2˙ˉ,and SO4˙ˉ,have been studied by pulse radiolysis techniques.The GFX radical anion formed in the reaction of GFX with eaqˉ could either be protonated or deprotonated,and the absorption of GFX radical anion was located at 390 nm.The transient species produced by the reaction of GFX with ˙OH radical shows a broad band in the 380?600 nm region with a shoulder,while the oxidation by N3˙,SO4˙ˉ,and Br2˙ˉ results in an absorption band with λmax = 370 nm.At neutral condition(pH 7),the rate constants of GFX reacting with ˙OH,N3˙,Br2˙ˉ,SO4˙ˉ and eaqˉ are estimated to be 1.0 × 1010,3.1 × 109,2.8 × 109,3.0 × 109,and 1.8 × 1010 dm3 mol?1 s?1,respectively.From the pH dependence on the formation of electron adducts and on the rate constant of GFX with eaqˉ,the pKa of GFX radical anion is estimated to be 5.5 and 9.3.
