Extract of Lotus Leaf (Nelumbo nucifera) and Its Active Constituent Catechin with Insulin Secretagogue Activity
Extract of Lotus Leaf (Nelumbo nucifera) and Its Active Constituent Catechin with Insulin Secretagogue Activity
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DOI：
10.1021/jf103382h
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发表时间：
2011-02-23
影响因子：
6.1
通讯作者：
Liu, Shing Hwa
中科院分区：
文献类型：
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作者：
Huang, Chun Fa;Chen, Ya Wen;Liu, Shing Hwa
荷叶（Nelumbo nucifera Gaertn.）对糖尿病的影响尚不清楚。我们假设荷叶可以调节胰岛素分泌和血糖水平。研究了荷叶甲醇提取物（NNE）对胰岛素分泌和高血糖的影响。NNE增加β细胞（HIT-T15）和人胰岛的胰岛素分泌。NNE可提高β细胞内钙离子水平。NNE还可增强细胞外信号调节蛋白激酶（ERK）1/2和蛋白激酶C（PKC）的磷酸化，这可被PKC抑制剂逆转。体内实验表明，NNE对正常小鼠和高脂饮食诱导的糖尿病小鼠的血糖水平具有调节作用。此外，在体外和体内的NNE，槲皮素和儿茶素的活性成分，对葡萄糖诱导的胰岛素分泌和血糖调节的影响进行了评价。槲皮素不影响胰岛素的分泌，但儿茶素显着和剂量依赖性地增强胰岛素的分泌。口服儿茶素可显著逆转高脂饮食诱导的糖尿病小鼠的葡萄糖耐受不良。这些发现表明，NNE及其活性成分儿茶素是有用的，在控制高血糖症的非胰岛素依赖型糖尿病，通过他们的行动作为胰岛素促分泌素。
The effect of lotus leaf (Nelumbo nucifera Gaertn.) on diabetes is unclear. We hypothesized that lotus leaf can regulate insulin secretion and blood glucose levels. The in vitro and in vivo effects of lotus leaf methanolic extract (NNE) on insulin secretion and hyperglycemia were investigated. NNE increased insulin secretion from beta cells (HIT-T15) and human islets. NNE enhanced the intracellular calcium levels in beta cells. NNE could also enhance phosphorylation of extracellular signal-regulated protein kinases (ERK)1/2 and protein kinase C (PKC), which could be reversed by a PKC inhibitor. The in vivo studies showed that NNE possesses the ability to regulate blood glucose levels in fasted normal mice and high-fat-diet-induced diabetic mice. Furthermore, the in vitro and in vivo effects of the active constituents of NNE, quercetin, and catechin, on glucose-induced insulin secretion and blood glucose regulation were evaluated. Quercetin did not affect insulin secretion, but catechin significantly and dose-dependently enhanced insulin secretion. Orally administered catechin significantly reversed the glucose intolerance in high-fat-diet-induced diabetic mice. These findings suggest that NNE and its active constituent catechin are useful in the control of hyperglycemia in non-insulin-dependent diabetes mellitus through their action as insulin secretagogues.