Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University , Xiangtan 411105, Hunan, People's Republic of China.
J Agric Food Chem. 2012 Oct 10;60(40):10126-32. doi: 10.1021/jf302426w. Epub 2012 Oct 1.
The water extraction and composition of pu-erh tea, as well as the hypoglycemic effect of the water extract of pu-erh tea (WEPT) in vivo and in vitro, are reported to investigate its hypoglycemic effect on diabetes. High-performance liquid chromatography and colorimetric methods are used to analyze the tea catechins, caffeine, polyphenols, amino acids, and polysaccharides of the WEPT. The effect of the WEPT on glucose uptake by cultured HepG2 cells and the inhibition effect of rat intestinal sucrase, maltase, and porcine pancreatic amylase are determined in vitro. Then, the blood glucose and insulin levels of intragastrically administered WEPT on fasting and oral glucose tolerance test (OGTT) using type 2 diabetic db/db (BKS.Cg-m +/+ Lepr(db)/J) mice are determined in vivo. The results showed that the WEPT dose-dependently and significantly increased glucose uptake by HepG2 cells and inhibited rat intestinal sucrase, maltase, and porcine pancreatic amylase activity. The WEPT intragastrically given for 4 weeks suppressed the increase in blood insulin and glucose levels of db/db mice fasted overnight. In OGTT, the WEPT improved impaired glucose tolerance and ameliorated retarded insulin response at 60 and 120 min in db/db mice. These results suggest that the WEPT has beneficial effects on glucose homeostasis in type 2 diabetes and in amendment of insulin resistance.
报道了普洱茶叶的水提物成分及其水提物（WEPT）在体内和体外的降血糖作用，以研究其对糖尿病的降血糖作用。采用高效液相色谱法和比色法分析 WEPT 中的茶儿茶素、咖啡因、多酚、氨基酸和多糖。体外测定 WEPT 对培养的 HepG2 细胞葡萄糖摄取的影响以及对大鼠肠蔗糖酶、麦芽糖酶和猪胰淀粉酶的抑制作用。然后，体内测定口服给予 WEPT 对空腹和口服葡萄糖耐量试验（OGTT）的 2 型糖尿病 db/db（BKS.Cg-m +/+ Lepr(db)/J）小鼠的血糖和胰岛素水平。结果表明，WEPT 呈剂量依赖性显著增加 HepG2 细胞的葡萄糖摄取，并抑制大鼠肠蔗糖酶、麦芽糖酶和猪胰淀粉酶活性。4 周口服给予 WEPT 可抑制禁食过夜的 db/db 小鼠的胰岛素和血糖水平升高。在 OGTT 中，WEPT 改善了 db/db 小鼠的葡萄糖耐量受损，并改善了 60 和 120 分钟时胰岛素反应迟缓。这些结果表明，WEPT 对 2 型糖尿病的血糖稳态和胰岛素抵抗的改善具有有益作用。
