电子顺磁共振法(EPR)对银杏叶提取物及其卷烟捕获自由基能力研究

自由基存在于人体和卷烟烟气中,会引起人体病理反应和氧化损伤,种类和形态多样,如: O-·2,HO·,R·,RO·,ROO·. 电子顺磁共振法(EPR)是检测和定量分析自由基的重要方法之一. 银杏叶提取物(EGB)是由黄酮、内酯、原花青素类成分组成的植物药,具有较好清除自由基和抗氧化能力. 本文以槲皮素、芦丁、原花青素等化合物为对照,运用EPR法结合自旋捕集技术研究EGB和EGB卷烟对DPPH,HO·,O2-·、烟气气相自由基、烟气粒相自由基的抑制水平. 结果表明,EGB能够有效抑制化学/生物系统和卷烟烟气产生的自由基. 尽管抑制自由基整体水平比黄酮单体和原花青素弱,但EGB提取方法简单容易得到,可作为天然抗氧化剂和自由基清除剂用于食品和烟草等行业. EPR法灵敏度高,稳定性好,是用于自由基研究的可靠方法. 捕集剂D EPMPO捕集O2-·更加高效,PBN捕集烟气气相自由基比DMPO更有优势. 该研究讨论了EGB清除自由基的机理,丰富的酚羟基结构是其抗氧化作用的主要原因.

Electron Paramagnetic Resonance (EPR) Studies on Free Radical Scavenging Capacity of EGB and EGB Cigarette

Free radicals exist both in human body and cigarette smoke,in the forms of many species,i.e.superoxide radical (O-·2),hydroxyl radical (HO·),al kyl radical (R·),alkoxyl radical (RO·) or alkyl peroxyl radical (ROO·),there is no doubt of their pathophysioligical reaction and oxidative damage.E lectron paramagnetic resonance (EPR) in conjunction with spin trapping technique is a selected method for free radical detection and quantification.Ginkgo bi loba leaves extract (EGB),a phytomedicine mainly composed of flavonoids,terp enoids and proanthocyanidins,is potential in free radical scavenging and antiox idant.In current paper,the scavenging effect against chemical/biological syste m radical (DPPH,HO·,O-·2) and cigarette smoke radical (gas-phase and particulate-phase radical) for EGB and EGB cigarette have been studied usin g EPR method,respectively.Several selected flavonoids (Quercetin,Rutin) and P roanthocyanidin also have been assayed and compared.The results show that EGB i s managed to scavenging free radical originated by chemical/biological system an d cigarette smoke.Although inhibitory capacity is weaker than flavonoids and pr oanthocyanidin,EGB is obtained easily through extraction and can be developed t o natural antioxidant and free radical scavenger in food and tobacco.EPR is a r eliable tool in free radical scavenging duing to its good sensitivity and high s tability.The spin trap DEPMPO exhibits superiority in trapping superoxide radic al and PBN is more efficient in trapping smoke gas-phase radical than DMPO.The mechanism of EGB scavenging free radical has been discussed,multiple phenolic hydroxyl groups are the main reason.