In vitro antioxidant and pancreatic α-amylase inhibitory activity of isolated fractions from water extract of Qingzhuan tea
In vitro antioxidant and pancreatic α-amylase inhibitory activity of isolated fractions from water extract of Qingzhuan tea
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DOI：
10.1007/s13197-013-1059-y
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发表时间：
2015-02-01
影响因子：
3.1
通讯作者：
Chen, Yuqiong
中科院分区：
文献类型：
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作者：
Cheng, Qian;Cai, Shengbao;Chen, Yuqiong
本研究以后发酵工艺生产的独特黑茶青专茶为研究对象，对其抗氧化和抑制胰-淀粉酶活性进行了研究。采用溶剂分馏法对青转茶水提物进行分离，得到氯仿、乙酸乙酯、正丁醇、沉淀物和残水组分。在不同馏分中，乙酸乙酯馏分的总多酚和儿茶素含量最高，对DPPH自由基的清除能力最强，对猪胰腺α -淀粉酶活性的体外抑制作用最大。用Sephadex LH-20柱进一步分离QEF，得到8个亚段（QEF1-QEF8），其中QEF8为活性最强的亚段。经LC-MS分析，QEF8的主要有效成分为儿茶素、EGCG和ECG，含量分别为22.29%和11.11%。还观察了儿茶素标准品EGCG和ECG对猪胰腺α -淀粉酶活性的抑制作用。综上所述，青转茶或其水提取物有可能作为糖尿病的补充治疗成分，降低餐后血糖，儿茶素EGCG和ECG可能是水提取物中最有效的成分。
In the present work, Qingzhuan tea, a unique dark tea produced by post-fermentation technology, was selected to investigate its antioxidant and pancreatic alpha-amylase inhibiting activities. Water extract of Qingzhuan tea was successively isolated by solvent partitioning procedures to obtain chloroform, ethyl acetate, n-butanol, sediment and residual aqua fractions. Of different fractions, the ethyl acetate fraction (QEF) had the highest total polyphenols and catechins contents, demonstrated the strongest DPPH radical scavenging activity and exhibited the greatest inhibitory effect on porcine pancreatic alpha-amylase activity in vitro. Further separation of QEF by a Sephadex LH-20 column generated eight subfractions (QEF1-QEF8), with QEF8 being the most active subfraction based on the assays above mentioned. The major active components in QEF8 were identified as catechins EGCG and ECG by LC-MS analysis, with contents of 22.29 % and 11.11 % respectively. Inhibitory effects of catechin standards EGCG and ECG on porcine pancreatic alpha-amylase activity were also observed. In conclusion, Qingzhuan tea or its water extract could be potentially used as complementary therapy ingredients for diabetes treatment through lowering postprandial blood glucose, and catechins EGCG and ECG may be the most efficient components in the water extract.