普洱茶抗氧化活性成分的LC-MS分析

Liquid Chromatographic-mass Spectrometric Analysis of Antioxidant Compounds from Pu-erh tea

采用不同的有机溶剂分步萃取普洱茶的水提物,得到氯仿、乙酸乙酯、正丁醇等物质。采用有机自由基二苯基苦基偕腙肼(DPPH)的分光光度法比较各提取物的清除自由基能力,结果表明:普洱茶水提物中的乙酸乙酯萃取层组分对DPPH自由基有最强的清除能力。通过液质联用分析,从普洱茶乙酸乙酯层中鉴定出4类化合物:1.酚酸类(3个):4-羟基苯甲酸、二羟基苯甲酸、没食子酸;2.儿茶素类(7个):儿茶素、表儿茶素、没食子儿茶素、表没食子儿茶素、表儿茶素没食子酸酯、表没食子儿茶素没食子酸酯、表阿福豆素-3-O-没食子酸酯;3.儿茶素衍生物(9个):原花青色素二聚物及特征性的金鸡纳素型氧化黄烷醇类内酯化合物,包括普洱茶素A与B、表儿茶素-[8,7-e]-4α-(4-羟基苯)-3,4-二氢-2(3H)-吡喃酮、表儿茶素-[8,7-e]-4α-(3,4-二羟基苯)-3,4-二氢-2(3H)-吡喃酮、表没食子儿茶素-[8,7-e]-4α-(3,4-二羟基苯)-3,4-二氢-2(3H)-吡喃酮、表儿茶素-[8,7-e]-4β-(4-羟基苯)-3,4-二氢-2(3H)-吡喃酮、表儿茶素-[8,7-e]-4β-(3,4-二羟基苯)-3,4-二氢-2(3H)-吡喃酮、表没食子儿茶素-[8,7-e]-4β-(3,4-二羟基苯)-3,4-二氢-2(3H)-吡喃酮;4.黄酮醇及其糖苷类(6个):槲皮素、槲皮素-3-O-b-D葡萄糖甙、槲皮素-鼠李糖、槲皮素-芸香苷、槲皮素-已糖-鼠李糖-鼠李糖、山奈酚-芦丁糖苷。

The pu-erh tea was extracted with water and separated by the order of chloroform, ethyl acetate and nbutanol. The antioxidant activity of pu-erh tea extracts was investigated by the 2, 2-diphenyl-l-picrylhydrazyl （DPPH） free radical-scavenging assay. The result pointed pu-erh tea ethyl acetate extract （PEAF） had the strongest DPPH scavenging activity. High performance liquid chromatography combined with diode array and electrospray-ion trap-mass spectra detection was used to separate and identify the compounds present in PEAF. There are three phenolic acids, i.e., 4-hydroxy-benzoic acid, dihydroxy-benzoic acid and gallic acid, seven catechins, i.e., catechin, epicatechin （EC）, gallocatechin, epigallocatechin （EGC）, epicatechin gallate, epigallocatechin gallate and epiafzelechin-3-O-gallate, nine catechins derivatives, i.e., procyanidins dimmer, puerin A, puerin B, EC- [8, 7-el -4α- （4-hydroxyphenyl） -3, 4-dihydro-2 （3H） -pyranone, EC-[8, 7-e] -415- （4-hydroxyphenyl） -3, 4-dihydro-2 （3H） -pyranone, Cinchonain lb （or and 15）, EGC- [8, 7-e] -4α- （3, 4-dihydroxyphenyl） -3, 4-dihydro-2 （3H） -pyranone and EGC- [8, 7-e] -415- （3, 4-dihydroxyphenyl）-3, 4-dihydro-2 （3H） -pyranone, and six flavonol glycosides, i.e., quercetin, quercetin-glucoside, quercetin- rhamnoside, quercetin-rutinoside, quercetin-glucoside-rhamnoside-rhamnoside and kaempferol-rutinoside.