Tea enhances insulin activity
Tea enhances insulin activity
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DOI：
10.1021/jf020514c
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发表时间：
2002-11-20
影响因子：
6.1
通讯作者：
Polansky, MM
中科院分区：
文献类型：
--
作者：
Anderson, RA;Polansky, MM
茶最广为人知的健康益处涉及多酚作为保护免受氧化损伤以及抗菌、抗病毒、抗癌和抗突变活性的主要活性成分，但茶中的多酚也可能增加胰岛素活性。本研究的目的是确定茶及其组分的胰岛素增强特性。在体外附睾脂肪细胞测定中，正常饮用的茶显示出增加胰岛素活性> 15倍。红茶、绿色茶和乌龙茶，但不包括草药茶，草药茶不是传统意义上的茶，因为它们不含山茶叶，都显示出增加胰岛素活性。利用沃茨对称制备C18柱的茶提取物的高效液相色谱分级显示，绿色和乌龙茶的胰岛素增强活性的大部分是由于表没食子儿茶素没食子酸酯。对于红茶，除了表没食子儿茶素没食子酸酯、单宁、茶黄素和其他未定义的化合物之外，该活性存在于色谱图的几个区域中。在茶中发现的几种已知化合物被证明可以增强胰岛素，其中表没食子儿茶素没食子酸酯的活性最大，其次是表儿茶素没食子酸酯，单宁和茶黄素。咖啡因、儿茶素和表儿茶素显示出不显著的胰岛素增强活性。在茶中加入柠檬并不影响胰岛素增强活性。每杯添加5 g 2%牛奶可使胰岛素增强活性降低1/3，每杯添加50 g牛奶可使胰岛素增强活性降低约90%。非乳制品奶精和豆奶也降低了胰岛素增强活性。这些数据表明，茶含有体外胰岛素增强活性，主要活性成分是表没食子儿茶素没食子酸酯。
The most widely known health benefits of tea relate to the polyphenols as the principal active ingredients in protection against oxidative damage and in antibacterial, antiviral, anticarcinogenic, and antimutagenic activities, but polyphenols in tea may also increase insulin activity. The objective of this study was to determine the insulin-enhancing properties of tea and its components. Tea, as normally consumed, was shown to increase insulin activity > 15-fold in vitro in an epididymal fat cell assay. Black, green, and oolong teas but not herbal teas, which are not teas in the traditional sense because they do not contain leaves of Camellia senensis, were all shown to increase insulin activity. High-performance liquid chromatography fractionation of tea extracts utilizing a Waters SymmetryPrep C18 column showed that the majority of the insulin-potentiating activity for green and oolong teas was due to epigallocatechin gallate. For black tea, the activity was present in several regions of the chromatogram corresponding to, in addition to epigallocatechin gallate, tannins, theaflavins, and other undefined compounds. Several known compounds found in tea were shown to enhance insulin with the greatest activity due to epigallocatechin gallate followed by epicatechin gallate, tannins, and theaflavins. Caffeine, catechin, and epicatechin displayed insignificant insulin-enhancing activities. Addition of lemon to the tea did not affect the insulin-potentiating activity. Addition of 5 g of 2% milk per cup decreased the insulin-potentiating activity one-third, and addition of 50 g of milk per cup decreased the insulin-potentiating activity similar to90%. Nondairy creamers and soy milk also decreased the insulin-enhancing activity. These data demonstrate that tea contains in vitro insulin-enhancing activity and the predominant active ingredient is epigallocatechin gallate.