title: Antioxidative activity and active components of longan (Dimocarpus longan Lour.) flower extracts.
abstract: Three different solvent extracts (methanol, ethyl acetate, and n-hexane) of longan ( Dimocarpus longan Lour.) flowers were assayed with three different antioxidant capacity methods, namely, the DPPH free radical scavenging effect, the oxygen radical absorbance capacity (ORAC) assay, and the inhibition of Cu(2+)-induced oxidation of human low-density lipoprotein (LDL). It was revealed that the methanol extract has the best antioxidative activity, followed by ethyl acetate and n-hexane extracts. The methanol extract was separated by liquid-liquid partition into n-hexane, ethyl acetate, n-butanol, and water fractions. The ethyl acetate fraction was found to have the highest activity of delaying LDL oxidation. After silica gel column chromatography, the fraction having a superior activity was identified as containing two major compounds, (-)-epicatechin and proanthocyanidin A2.
authors.affiliation: Graduate Institute of Food Science and Technology, National Taiwan University, Taipei, Taiwan 106.
authors.forename: Meng-Chieh
authors.initials: MC
authors.lastname: Hsieh
authors.forename: Yi-Jane
authors.initials: YJ
authors.lastname: Shen
authors.forename: Yueh-Hsiung
authors.initials: YH
authors.lastname: Kuo
authors.forename: Lucy Sun
authors.initials: LS
authors.lastname: Hwang
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D002392:Catechin / Q000032:analysis; D005591:Chemical Fractionation; D005419:Flavonoids / Q000032:analysis; D035264:Flowers / Q000737:chemistry*; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000097:blood; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology*; D044945:Proanthocyanidins / Q000032:analysis; D029631:Sapindaceae / Q000737:chemistry*; D012997:Solvents
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D008077:Lipoproteins, LDL; D010936:Plant Extracts; D044945:Proanthocyanidins; D012997:Solvents; C473740:proanthocyanidin A2; D002392:Catechin