以脂肪細胞探討台灣藜中具調節血糖之活性成分

Abstract

糖尿病是由於缺乏胰島素、胰島素作用不良或是兩者皆有缺陷，而導致高血糖的一種代謝性疾病。約90%的病患屬於第二型糖尿病，其主要的病因為胰島素阻抗，胰島素阻抗是由於周邊組織對於胰島素的反應不良，而使血液中的葡萄糖無法被攝取進入細胞中。台灣藜為藜科草本植物，是台灣的特有種，若不將其外殼去除，則味道苦澀，因此較少被人食用，近年來研究發現台灣藜的營養及機能性成分含量相當豐富，其可能的生理活性也日漸受到重視。本研究使用3T3-L1脂肪細胞進行葡萄糖攝取試驗，探討台灣藜中具調節血糖之活性成分。初步以六種溶劑進行台灣藜脫穀粒及外殼之萃取，結果顯示，外殼之水萃物可以顯著增加細胞的葡萄糖攝取量，因此進一步利用不同極性之溶劑進行區分，發現水層在低濃度就可以展現良好的降血糖活性。接著以XAD-7管柱層析後，分離出兩個主要的活性成分P1及P2。這兩個樣品在5~10 ppm下，就可以展現其降血糖活性。當在10 nM胰島素刺激下，P1具有協同胰島素的作用，而P2則會降低脂肪細胞之葡萄糖攝取量，推測P2可能具有類似胰島素的活性。

Diabetes mellitus is a group of metabolic diseases characterized by high blood sugar resulting from defects in insulin secretion, insulin action or both. Most patients with type 2 diabetes are deficient in glucose uptake by muscle and fat cells due to peripheral insulin resistance. Chenopodium formosanum Koidz. (djulis) is a native pseudocereal plant grown in Taiwan, it possesses numerous nutrients and bioactive components. However, it tastes bitter if the husk is not removed. Mature 3T3-L1 adipocyte was used in this investigation as cell model to study the active hypoglycemic components of djulis. Initially, six solvents with different polarities were used to extract the whole seed or the husk of djulis. Djulis husk water crude extract (DHW) was found to significantly increase glucose uptake of 3T3-L1 cell. After solvent partition of the crude extract, the water layer showed the best glucose uptake activity at low concentrations. There were two components (P1and P2) isolated from the water layer by column chromatography. They showed hypoglycemic activity at 5~10 ppm. Co-treatment with 10 nM insulin, P1 showed synergistic effect with insulin, however, P2 reduced insulin-stimulated glucose uptake. P2 might act as an insulin-mimetic substance.