Antioxidative Activity and Active Components of Longan (Dimocarpus longan Lour.) Flower Extracts

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• 作者：Meng-Chieh Hsieh ; Yi-Jane Shen ; Yueh-Hsiung Kuo ; Lucy Sun Hwang
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2008
• 出版时间：August 27, 2008
• 年：2008
• 卷：56
• 期：16
• 页码：7010-7016
• 全文大小：176K
• 年卷期：v.56,no.16(August 27, 2008)
• ISSN：1520-5118

文摘

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 Cu²⁺-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.