Hu Chun, Kitts David D
Food, Nutrition and Health, Faculty of Agricultural Sciences, University of British Columbia, 6650 N.W. Marine Drive, Vancouver, Canada.
J Agric Food Chem. 2003 Jan 1;51(1):301-10. doi: 10.1021/jf0258858.
This study was conducted to investigate the chemical antioxidant and bioactive properties of the water (WF) and ethyl acetate fractions (EAF) derived from dandelion (Taraxacum officinale) flower extract (DFE). HPLC analysis showed the presence of both luteolin and luteolin 7-glucoside in the DFE, which contributed to noted in vitro antioxidant and Caco-2 cell cytotoxic activities. Both WF and EAF of DFE exhibited free radical scavenging activities in a stable 2,2-diphenyl-1-picrylhydrazyl radical model and reduced the breakage of supercoiled DNA strand induced by both non-site-specific and site-specific hydroxyl radical. Oxidation of structured phosphatidylcholine liposome induced by peroxyl radical was reduced in the presence of both EAF and WF. EAF had greater (p < 0.05) affinity to scavenge peroxyl radical than WF, as measured by the formation of conjugated diene. At low concentration, prooxidant activity of both fractions was observed in Cu(2+)-induced structured liposome and hLDL oxidation models, thus indicating that the reducing power of the DFE had resulted in generation of reactive cuprous ion. However, at high concentrations the EAF did not promote oxidation in the presence of Cu(2+), suggesting that the free radical scavenging activity of this fraction was sufficient to minimize the potential oxidative mechanism attributed to the metal ion reducing activity associated with prooxidant activity.
本研究旨在探究蒲公英（Taraxacum officinale）花提取物（DFE）的水相部分（WF）和乙酸乙酯相部分（EAF）的化学抗氧化及生物活性特性。高效液相色谱分析表明，DFE中存在木犀草素和木犀草素7-葡萄糖苷，这两种成分促成了显著的体外抗氧化及对Caco-2细胞的细胞毒性活性。DFE的WF和EAF在稳定的2,2-二苯基-1-苦基肼自由基模型中均表现出自由基清除活性，并减少了非位点特异性和位点特异性羟基自由基诱导的超螺旋DNA链断裂。在EAF和WF存在的情况下，过氧自由基诱导的结构化磷脂酰胆碱脂质体氧化减少。通过共轭二烯的形成测定，EAF清除过氧自由基的亲和力比WF更强（p < 0.05）。在低浓度下，在铜离子诱导的结构化脂质体和人低密度脂蛋白氧化模型中观察到这两个部分的促氧化活性，这表明DFE的还原能力导致了活性亚铜离子的产生。然而，在高浓度下，EAF在铜离子存在时并未促进氧化，这表明该部分的自由基清除活性足以将与促氧化活性相关的金属离子还原活性所导致的潜在氧化机制降至最低。
