摘要
采用光谱、电化学和质谱分析方法研究抗坏血酸对DPPH自由基清除机理,发现DPPH在溶液中是以自由基形态和含氮-氮双键的高度共轭结构的正离子态(DPPH+)存在且抗坏血酸对上述两种形态都有清除作用。由于DPPH自由基与DPPH+在溶液中处于平衡态,故同种抗氧化剂用517nm波长处DPPH+的吸收强度变化可间接评价对DPPH自由基的清除作用,但对不同抗氧化剂而言,因抗氧化剂对DPPH的不同形态相对清除作用的不同会带来较大的误差或误判。本研究对准确评价抗氧化剂的自由基清除作用具有一定指导意义。
DPPH radical scavenging properties of antioxidants are generally evaluated by determining absorbance（A517 nm） at 517 nm wavelength.Herein,the radical scavenging mechanisms of ascorbic acid on DPPH radicals were investigated by UV-Vis spectrometric,electrochemical and mass spectrometric determinations.It was found that DPPH existed in two different forms,radical form（DPPH·） and highly conjugated form（DPPH＋）,and ascorbic acid could scavenge both of them in the solution.Generally,the two forms of DPPH were at equilibrium in the solution.This makes it possible to indirectly evaluate DPPH radical scavenging properties of the same kinds of antioxidants based on A517 nm changes of DPPH＋,but for different kinds of antioxidants,it is impossible to correctly evaluate radical scavenging properties because of their different relative scavenging effects on the two forms of DPPH.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2011年第1期86-90,共5页
Food Science
关键词
抗坏血酸
DPPH自由基
清除机理
分光光度法
循环伏安法
质谱法
ascorbic acid
DPPH free radical
scavenging mechanism
spectrometry
cyclic voltammetry
mass spectrometry
