牡荆素保护DNA氧化损伤的活性评价及机制分析

摘要

In order to study the DNA protection and possible mechanisms of vitexin,it was measured by using three spectrophotometric assays,including DNA protection,Fe2+-complexing,and Cu2+ reducing.In addition,its Fe2+-complexing reaction was also analyzed using UV-Vis spectra.The results showed that the IC50 values of vitexin were (919.6±23.6),(9.3±1.2) and (421.7±29.2) μmol/L,respectively,for DNA protection assay,Fe2+-complexing assay,and Cu2+ reducing assay.When mixed with Fe2+,vitexin gave a UV-Vis peak at 554 nm [molar absorptivity ε =2 680.74 L/(mol · cm)].In conclusion,vitexin can effectively protect DNA from · OH induced damage.The protective mechanism may include electron-transfer (ET) and Fe2+ complexing,and its Fe2+-complexing site is possibly between 4-carbonly and 5-hydroxyl groups.%采用DNA保护能力分析法,测定牡荆素保护DNA的能力;运用Ferrozine法和紫外可见光谱(UV-Vis)分析牡荆素Fe2+络合反应;运用Cu2+还原法,测定牡荆素的电子转移(Electron-transfer,ET)能力.在此基础上,探讨牡荆素保护DNA氧化损伤的可能化学机制.结果表明:牡荆素在DNA保护能力分析法、Ferrozine法和Cu2+还原法中均表现出剂量相关性,其IC50值分别为(919.6±23.6),(9.3±1.2),(421.7±29.2) μmol/L.UV-Vis光谱分析表明,牡荆素与Fe2+混合后,在波长554 nm处出现新的吸收峰[摩尔吸光系数ε=2 680.74 L/(mol·cm)].总之,牡荆素能保护DNA免受羟基自由基(·OH)诱导的氧化损伤.其保护机制可能与电子转移ET和Fe2+络合有关,络合位点可能在4-羰基-5-羟基之间.