Structural Characteristics and Hypolipidemic Activity of Theabrownins from Dark Tea Fermented by Single Species Eurotium cristatum PW-1
Structural Characteristics and Hypolipidemic Activity of Theabrownins from Dark Tea Fermented by Single Species Eurotium cristatum PW-1
复制标题
单种冠散囊菌PW-1发酵黑茶中茶褐素的结构特征及降血脂活性
DOI：
10.3390/biom10020204
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发表时间：
2020-02-01
期刊：
影响因子：
5.5
通讯作者：
Gao, Hong
中科院分区：
文献类型：
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作者：
Xiao, Yue;Li, Maoyun;Gao, Hong
近年来，茶褐素（TB）作为黑茶中主要的生物活性高分子色素，因其保健作用而受到越来越多的关注。到目前为止，有关其结构特征的信息尚不清楚。本研究首次从单种冠突散囊菌PW-1发酵的散茶中分离得到茶褐素，并对其结构和降血脂特性进行了研究。茶褐素通过其分子量分级，然后进行分析。紫外-可见分光光度法（UV-Vis）和傅立叶变换红外光谱法（FT-IR）表明，它们是含有丰富羟基和羧基的聚合酚类物质。所有茶褐素样品均表现出对高脂斑马鱼的降血脂活性，其中TBs-10- 30 k样品在1000 μg/mL时对高脂斑马鱼的血脂水平降低至51.57%，效果最好。扫描电子显微镜（SEM）观察发现，TBs-10- 30 k是一种片状、表面光滑的无定形热稳定聚合物。原子力显微镜（AFM）分析表明，由于茶褐素分子的聚集，其具有岛状结构。热解-气相色谱-质谱（Py-GC-MS）分析进一步表明，TBs-10- 30 k的主要热解产物为十六烷酸（33.72%）、苯酚（14.90%）和二十烷（12.95%），表明TBs-10- 30 k主要由酚类、脂类、脂肪酸和蛋白质组成。这些结果不仅有助于后续茶褐素的鉴定，而且为茶褐素在功能食品中的应用提供了见解。
Recently, studies on theabrownins (TBs), the main bioactive polymeric pigments found in dark tea, have received increasing attention for its health effects. Thus far, information on their structural characteristics is unclear. In the present study, theabrownins were isolated from single species Eurotium cristatum PW-1-fermented loose tea and their structural and hypolipidemic characteristics were studied for the first time. The theabrownins were fractionated by their molecular weights and were then analyzed. Ultraviolet–visible spectrophotometry (UV-Vis) and Flourier transformation infrared spectroscopy (FT-IR) showed that they were polymerized phenolic substances containing abundant hydroxy and carboxyl groups. All theabrownin samples exhibited hypolipidemic activity in high-fat zebrafish; among which TBs-10-30k sample, decreased lipid level in high-fat zebrafish to 51.57% at 1000 μg/mL, was most effective. It was found that TBs-10-30k was a type of amorphous and thermostable polymer with slice shape and smooth surface under scanning electron microscope (SEM). Atomic force microscope (AFM) analysis showed that it had island-like structure because of aggregation of theabrownin molecules. Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) analysis further showed that the main pyrolytic products of TBs-10-30k were hexadecanoic acid (33.72%), phenol (14.90%), and eicosane (12.95%), indicating TBs-10-30k was mainly composed of phenols, lipids, saccharides, and proteins. These results not only facilitate subsequent identification of theabrownins, but also provide insights into the applications of theabrownins in functional foods.