Wen Rourou, Chai Xianghua, Wang Pingping, Wu Kegang, Duan Xuejuan, Chen Jiasi, Zhang Tong, Zeng Liya
School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China.
Guangdong Province Laborary of Chemistry and Fine Chemical Engineering Jieyang Center, Jieyang 515200, China.
Foods. 2024 Dec 23;13(24):4183. doi: 10.3390/foods13244183.
Tea polyphenols have been reported to decrease the rate of starch hydrolysis by inhibiting α-glucosidase. However, the effect of the tea harvesting season and the structure of catechin monomers on the inhibitory activity of α-glucosidase is not understood. In this study, the inhibitory effect and underlying mechanism of four seasons of Dancong tea against α-glucosidase were investigated by in vivo and in vitro experiments, multi-spectroscope and molecular dynamic. The Dancong tea harvested in spring and winter showed a stronger inhibitory effect on α-glucosidase due to a higher content of catechin, especially EGCG ((-)-epigallocatechin-3-gallate). The results of in vivo and in vitro experiments showed that EGCG and ECG ((-)-epicatechin-3-gallate) with a higher content of gallate and hydroxyl groups exhibited a stronger inhibitory effect on starch hydrolysis, rise of postprandial blood glucose and activities of α-glucosidase compared to EGC ((-)-epigallocatechin) and EC ((-)-epicatechin). These gallate and hydroxy groups were more effective in interacting with the amino acid residues in the active site of α-glucosidase, leading to structural changes in the enzyme. Certainly, the inhibitory effect of Dancong tea on α-glucosidase explains one of the mechanisms by which it helps alleviate diabetes; the other hypoglycaemic mechanisms of Dancong tea will be further explored.
据报道，茶多酚可通过抑制α-葡萄糖苷酶来降低淀粉水解速率。然而，茶叶采摘季节和儿茶素单体结构对α-葡萄糖苷酶抑制活性的影响尚不清楚。在本研究中，通过体内和体外实验、多光谱分析及分子动力学研究了四季单枞茶对α-葡萄糖苷酶的抑制作用及潜在机制。由于儿茶素含量较高，尤其是表没食子儿茶素没食子酸酯（(-)-epigallocatechin-3-gallate，EGCG），春季和冬季采摘的单枞茶对α-葡萄糖苷酶表现出更强的抑制作用。体内和体外实验结果表明，相比于表没食子儿茶素（(-)-epigallocatechin，EGC）和表儿茶素（(-)-epicatechin，EC），没食子酸酯和羟基含量较高的EGCG和表儿茶素没食子酸酯（(-)-epicatechin-3-gallate，ECG）对淀粉水解、餐后血糖升高及α-葡萄糖苷酶活性表现出更强的抑制作用。这些没食子酸酯和羟基在与α-葡萄糖苷酶活性位点的氨基酸残基相互作用方面更有效，导致酶的结构发生变化。当然，单枞茶对α-葡萄糖苷酶的抑制作用解释了其有助于缓解糖尿病的机制之一；单枞茶的其他降血糖机制将进一步探索。
