- 學位論文
龍眼花萃取物降血糖功效成分探討
Investigation on the Active Hypoglycemic Compounds of Longan Flower
摘要
糖尿病是體內血糖代謝異常的疾病，病患因為高血糖而導致酮酸中毒、驚攣、昏迷甚至是死亡。而且在這些急性病癥以外，跟正常人比較起來糖尿病患也更容易罹患心血管疾病及腎臟病變等併發症，所以如何改善糖尿病，降低體內的高血糖病癥一直是已開發國家的重要課題。 本研究室之前的研究中發現，在STZ藥物誘導的糖尿病老鼠中，龍眼花萃取物具有改善高血糖、高三酸甘油酯的能力，也改善了胰島素阻抗的現象。且其萃取物次區分層中又以乙酸乙酯區分層(LFEA)效果尤佳，但其作用機制仍未明瞭，因此本研究期望可以藉由細胞實驗，加上天然物分離技術，來分析龍眼花萃取物乙酸乙酯區分層降血糖的功效成分與機制。 在本研究中，我們利用Sephadex管柱將LFEA進行管柱層析，從中得到七個次區分產物，並利用分化後的3T3-L1脂肪細胞進行葡萄糖攝取實驗，以尋找可能之有效成分。實驗發現龍眼花乙酸乙酯萃取物，以及次區分產物中的F4、F5兩產物，具有顯著增加脂肪細胞吸收葡萄糖的能力。推測龍眼花中具有某些化合物，可以刺激脂肪細胞攝取葡萄糖，藉此達到降低血糖的現象，而這些化合物，應該位於F4、F5次區分層中。 確認有效區分層後，我們使用西方墨點法來試圖了解龍眼花乙酸乙酯區分層降血糖機制。結果顯示龍眼花乙酸乙酯區分層及其次區分層在3T3-L1脂肪細胞中，並不會影響Akt蛋白及AMPK蛋白的磷酸化情形。因此本實驗推測，龍眼花的有效成分，並非藉由這兩條路經來刺激脂肪細胞攝取葡萄糖。
並列摘要
Diabetes is a popular metabolic diseases, the patients with hyperglycemia lead to ketoacidosis, spasm, coma or even death, and more likely to get some complications, such as cardiovascular disease and renal disease. Consequently, how to improve diabetes is an important issue for developed countries. In our previous study, we have shown that ethyl acetate fraction of Longan flower water extract (LFEA) improved hyperglycemia, hypertriglyceridemia and insulin resistance in streptozotocin induced type 2 diabetic rats. Nevertheless, the molecular mechanism and effective compounds remain unknow. In this study, Sephadex gel column chromatography was employed to fractionate LFEA, and seven sub-fractions were obtained. The effects of LFEA and sub-fractions on glucose uptake by 3T3-L1 adipocytes were tested to find the active compounds with hypoglycemic effect. The data showed that LFEA could increase the glucose uptake of 3T3-L1 adipocyte. And among the seven sub-fractions, sub-fraction F4 and F5 showed the strong activity in enhancing glucose uptake of adipocytes. Thus, we suggested the active compounds in LFEA might exist in these two sub-fraction. We also used western blotting to investigate the hypoglycemic mechanism of LFEA and the effective sub-fractions. Our data showed that LFEA treatment would not affect the phosphorylation level of Akt and AMPK protein in 3T3-L1 adipocyte. Our finding suggested that LFEA increased glucose uptake of 3T3-L1 adipocytes not through PI3K-Akt or AMPK pathway.