【作者】 李脉泉； 董云霞； 全威； 李雯斓； 陶甜甜； 刘仲华；

【Author】 Li Maiquan;Dong Yunxia;Quan Wei;Li Wenlan;Tao Tiantian;Liu Zhonghua;College of Food Science and Technology,Hunan Agricultural University;Key Laboratory of Tea Science of Ministry of Education,National Research Center of Engineering and Technology for Utilization of Botanical Functional Ingredients,Co-innovation Center of Education Ministry for Utilization of Botanical Functional Ingredients,Key Laboratory for Evaluation and Utilization of Gene Resources of Horticultural Crops,Ministry of Agriculture and Rural Affairs of China,Hunan Agricultural University;

【机构】 湖南农业大学食品科学技术学院； 湖南农业大学茶学教育部重点实验室国家植物功能成分利用工程技术研究中心植物功能成分利用省部共建协同创新中心；

【摘要】 红茶是世界上最受欢迎的茶种之一,长期以来一直被用作治疗高血糖症的民间疗法。然而,其降低高血糖的机制尚不清楚。本研究通过体内实验发现,红茶茶黄素提取物能显著降低糖尿病小鼠的血糖水平,提高血清胰岛素水平,恢复肝糖原含量。进一步研究发现,红茶茶黄素提取物及四种茶黄素单体对α-淀粉酶均有剂量依赖性抑制作用;抑制动力学分析表明,茶黄素2A和茶黄素2B是α-淀粉酶的竞争性抑制剂,茶黄素1和茶黄素3是α-淀粉酶的混合型抑制剂。分子对接结果表明,四种茶黄素单体通过氢键、范德华键、碳氢键、π-π堆叠等方式结合到α-淀粉酶活性位点周围的疏水区域。紫外-可见吸收光谱和荧光吸收光谱联合证实了茶黄素单体和α-淀粉酶通过静态猝灭机制依赖疏水相互作用形成二者复合物。综上,本研究阐明红茶中的茶黄素通过抑制α-淀粉酶活性显示出降低高血糖的作用,为茶黄素开发为天然α-淀粉酶抑制剂及其深入开发成降低高血糖的功能性食品奠定了理论基础。更多还原

【Abstract】 Black tea is the most popular worldwide and has long been used as a folk remedy for the treatment of hyperglycemia.However,the mechanism underlying is unclear.This study was aimed to investigate the anti-hyperglycemia effect of black tea extract via inhibiting α-amylase.In vivo experiments showed that black tea extract significantly reduced blood glucose level,increased serum insulin level,restored liver glycogen content and successfully elevated body weight of diabetic mice.In vitro experiments showed that black tea extract as well as the four theaflavins monomers has a dose-dependent inhibitory effect against α-amylase.Inhibition kinetic analysis suggested that TF2 A and TF2 B were competitive inhibitors of α-amylase,while TF1 and TF3 were mixed type inhibitors of α-amylase.Molecular docking analysis showed that theaflavins monomers inserted into the hydrophobic region around the active site of α-amylase through hydrogen bonds,Van der waals,Carbon bydrogen bonds,π-π Stacking.Ultraviolet-Visible Absorption Spectroscopy combined with Fluorescence Absorption Spectroscopy verified that theaflavins monomers/α-amylase complex was formed depending on the hydrophobic interactions through a static quenching mechanism.Taken together,theaflavins from black tea showed potential anti-hyperglycemia effect via inhibiting α-amylase activity.This study suggests that black tea theaflavins may be used as a natural α-amylase inhibitor and can be depth developed into functional food for prevention of hyperglycemia.更多还原