龙眼核多酚物质的液质联用分析及其抗氧化活性

HPLC-ESI-MS Analysis of Phenolic Compounds in Different Solvent Fractions of Ethanol Extract of Longan Seeds and Their Antioxidant Activities

为研究龙眼核抗氧化能力与成分的关系,采用不同极性溶剂萃取分离法、HPLC-ESI-MS分析法和DPPH抗氧化能力测定法等对60%乙醇提取的龙眼核多酚粗提物进行分析研究,鉴定出11种物质,其中6种为多酚,确定乙酸乙酯相抗氧化活性最强;进一步对经大孔树脂AB-8柱分离后的乙酸乙酯相各流份进行体外DPPH自由基清除能力和还原能力测定,得知与抗坏血酸相比,流份Fr1～Fr16都具有良好的抗氧化活性,其中流份Fr7、Fr8抗氧化活性最强。结合化学分离结果分析,流份Fr7经反复重结晶,得到较纯的没食子酸,其抗氧化能力较强,与抗氧化分析实验结果相一致。低极性萃取相抗氧化能力最强也表明龙眼核中含有丰富的小分子多酚类物质。

This study was designed to analyze phenolic compounds in different solvent（aqueous,ethyl acetate and 1-butanol） fractions of the ethanol extract of longan seeds by high-performance liquid chromatography coupled with electrospray ionization mass spectrometry（HPLC-ESI-MS） and to evaluate their antioxidant activity.A total of 11 compounds were identified in aqueous,ethyl acetate and 1-butanol fractions,including 6 phenolic compounds.Ethyl acetate fraction had the strongest antioxidant activity among the three fractions.Further separation of ethyl acetate fraction by macroporous resin AB-8 column chromatography resulted in 16 eluates.The measurement of DPPH free radical scavenging activity and reducing potential using ascorbic acid as a reference substance demonstrated that all the eluates had excellent antioxidant activity and eluates No.7 and 8 had the strongest antioxidant activity.Highly pure gallic acid was obtained after repeatedly recrystallizing eluate No.7,thus supporting the excellent antioxidant activity of the eluate.Meanwhile,the strongest antioxidant activity of ethyl acetate fraction as a low-polarity fraction indicated that longan seeds contained abundant amounts of phenolic compounds having small molecular weight.