普洱茶的抗氧化酚类化学成分的研究

从云南省双江县勐库产的普洱茶中分离得到11个化合物,分别为:(-)-没食子儿茶素(GC,1),(-)-表儿茶素(EC,2),(+)-儿茶素(C,3),杨梅素(4),没食子酸(5),山奈酚(6),山奈酚-3-O-β-D-葡萄糖甙(7),山奈酚-3-O–芦丁糖甙(8),槲皮素(9),槲皮素-3-O-β-D葡萄糖甙(10)以及2,5-二羟基苯甲酸(11)。其中,化合物6~11为首次从普洱茶中分离得到。DPPH自由基清除活性测试结果表明,化合物2、3、5的活性与阳性对照品抗坏血酸接近。化合物的结构与其活性的关系比较分析表明,简单儿茶素(2,3)和简单酚类化合物(5)的抗氧化活性较高,与阳性对照品抗坏血酸接近;黄酮类化合物(4,6,9)次之,黄酮类配糖体(7,8,10)及化合物11则较差。

Study on Antioxidative Polyphenol Compounds in Pu'er Tea

Eleven phenolic compounds were isolated from the Pu’er tea, which was produced in the post-fermentated process by using the crude green tea prepared from the leaves of Camellia sinensis var. assamica as raw materials. Their structures were identified as gallocatechin(1), (-)-epicatechin(2), (+)-catechin(3), myricetin(4), gallic acid(5), kaempferol(6), kaempferol-3-O-β-D-glucopyranoside(7), kaempferol-3-O-rutinoside(8), quercetin(9), quercetin-3-O-β-D-glucopyranoside(10), 2,5-dihydroxy-benzoic acid(11). This is the first time that compounds 6~11 were found from Pu’er tea. All of isolated compounds were tested for their antioxidative activities by DPPH radical scavenging assay. It was found that compounds 2, 3 and 5 showed antioxidative activity close with that of positive control, L-ascorbic acid, and the flavonoids(5, 6 and 9) are more active than the flavonoid glycosides(7, 8 and 10)and compound 11.