山欖葉部之成份研究

Abstract

中文摘要 糖尿病是一種在全世界罹患率逐漸升高的慢性疾病，其目前的治療目標多為降低病患過高的血糖值。在口服降血糖藥物中，其中一類治療藥物是甲型葡萄糖酶抑制劑。甲型葡萄糖酶抑制劑的作用機轉為抑制分佈在小腸的甲型葡萄糖酶將澱粉、寡糖以及雙糖消化成單糖，以此減緩餐後血糖值的升高，達到治療糖尿病的效果。 山欖科植物山欖是一原生於蘭嶼的長青樹種，初步研究發現其葉部甲醇萃取物具抑制甲型葡萄糖酶的活性，經極性分割後，正丁醇和乙酸乙酯可溶部分相對於氯仿層具較高的活性(在100μg/mL的濃度下，分別為97.3 %、87.2 %、41.6 %)。因此本研究著重於丁醇及乙酸乙酯可溶部分之研究。 利用Sephadex LH-20、離心式分配層析及高效液相層析法分離自正丁醇及乙酸乙酯部分得到九個化合物，包含四個Iriflophenone { 2-O-β-D-glucopyranoside-(1)、2-O-(6-O-galloyl)-β-D-glucopyranoside-(2)、2-O-[6-O-(4-hydroxybenzoyl)]-β-D-glucopyranoside-(3)、2-O-(2,6-di-O-galloyl)-β-D-glucopyranoside-(7)}及五個黃酮苷：Kaempferol [ 3-O-β-galactopyranoside-(4)與3-O-robinobioside-(5)]、Isorhamnetin-3-O-robinobioside-(6)、Quercetin [ 3-O-β-D-glucopyranoside-(8)、3-O-α-L-arabinopyranoside-(9)]。 經由光譜分析鑑定這些化合物的結構。其中化合物2、3、7是含二苯酮類架構之新化合物，然而其抑制甲型葡萄糖水解酶的活性並不顯著。

Abstract Diabetes mellitus is a chronic disease growing in prevalence worldwide. One of therapies to lower blood sugar level is the inhibition of α-glucosidase activity which serves the digestion of starch, oligosaccharides and disaccharides into monosaccharide. The methanol extract of leaves of Planchonella obovata (R.Br) Pierre (Sapotaceae), an evergreen shrub, indigenous to Lanyu Island, was found to be active against α-glucosidase. Further study indicated that the n-butanol-soluble and ethylacetate fraction possessed better activity than chloroform layer (97.3 %, 87.2 %, 41.6 % inhibition at 100 μg/mL, respectively). Thus, this study focused on the chemical investigation of these two fractions. Repeated separation of these two fractions over Sephadex LH-20, centrifugal partition chromatography and high performance liquid chromatography led to the isolation of nine compounds. They are four Iriflophenone { 2-O-β-D-glucopyranoside-(1), 2-O-(6-O-galloyl)-β-D-glucopyranoside-(2), 2-O-[6-O-(4-hydroxybenzoyl)]-β-D-glucopyranoside-(3), 2-O-(2,6-di-O-galloyl)-β-D-glucopyranoside-(7)}, and five flavonols: Kaempferol [ 3-O-β-galactopyranoside-(4) and 3-O-robinobioside-(5)], Isorhamnetin-3-O-robinobioside-(6), Quercetin [ 3-O-β-D-glucopyranoside-(8) and 3-O-α-L-arabinopyranoside-(9)]. Their structures were elucidated on the basis of elaborated spectroscopic analysis. Of these compounds, 2, 3 and 7 represent the first occurrence of such dibenzophenone natural products. Their anti-α-glucosidase activity, however, was not significant.