| Abstract
| - This study was conducted to investigate the chemical antioxidant and bioactive properties of thewater (WF) and ethyl acetate fractions (EAF) derived from dandelion (Taraxacum officinale) flowerextract (DFE). HPLC analysis showed the presence of both luteolin and luteolin 7-glucoside in theDFE, which contributed to noted in vitro antioxidant and Caco-2 cell cytotoxic activities. Both WFand EAF of DFE exhibited free radical scavenging activities in a stable 2,2-diphenyl-1-picrylhydrazylradical model and reduced the breakage of supercoiled DNA strand induced by both non-site-specificand site-specific hydroxyl radical. Oxidation of structured phosphatidylcholine liposome induced byperoxyl radical was reduced in the presence of both EAF and WF. EAF had greater (p< 0.05) affinityto scavenge peroxyl radical than WF, as measured by the formation of conjugated diene. At lowconcentration, prooxidant activity of both fractions was observed in Cu2+-induced structured liposomeand hLDL oxidation models, thus indicating that the reducing power of the DFE had resulted ingeneration of reactive cuprous ion. However, at high concentrations the EAF did not promote oxidationin the presence of Cu2+, suggesting that the free radical scavenging activity of this fraction wassufficient to minimize the potential oxidative mechanism attributed to the metal ion reducing activityassociated with prooxidant activity. Keywords: Dandelion; antioxidant; reactive oxygen species; cytotoxicity
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