高效液相層析-固相萃取-核磁共振技術之應用： 一、 金新木薑子葉部生物鹼成分之研究 二、 變葉新木薑子葉部黃酮類成分之研究

Abstract

本論文以高效液相層析-固相萃取-核磁共振技術應用在植物之化學成分分離及結構鑑定，研究金新木薑子及變葉新木薑子葉部之化學成分。 一、 金新木薑子葉部生物鹼成分之研究 新木薑子屬之樟科植物含有異奎寧生物鹼且有些具有心血管之活性，為了徹底地探討蘭嶼植物金新木薑子 (Neolitsea sericea var. aurata) 葉部所含之生物鹼成分，本實驗以高效液相層析-固相萃取-核磁共振 (HPLC-SPE-NMR)之連結技術做研究。 其葉部酒精萃取物之酚性生物鹼部分被分為氯仿可溶及水可溶兩部分，再分別以HPLC-SPE-NMR技術分析及鑑定，自氯仿可溶部分共得到五個已知之異奎寧生物鹼：laurolitsine (1)、boldine (2)、reticuline (3)、laurotetanine (4) 和actinodaphnine (5)。自水可溶部分共得到九個異奎寧生物鹼：9S,17S-pallidine N-oxide (6)、corytuberine (7)、1S,2S-reticuline N-oxide (8)、6R,6aS-boldine N-oxide (9)、1S,2R-reticuline N-oxide (10)、norisocorydine (11)、1R,2R-juziphine N-oxide (12)、6S,6aS-N-methyllaurotetanine N-oxide (13)及6R,6aS-N-methyllaurotetanine N-oxide (14)。其中化合物6、8、9、13為新化合物，而化合物10、12及14乃首見於新木薑子屬植物；化合物6、8、10、14以半合成方式製備以確認其立體化學結構。本研究亦對alpha或 beta-N-oxide對附近氫核化學位移之影響進行探討，並利用分子動力學模擬之技術探討化合物8和10之立體化學，據此可合理解釋。

二、變葉新木薑子葉部黃酮類成分之研究 本論文第二部分是研究樟科新木薑子屬植物變葉新木薑子(Neolitsea variabillima) 的黃酮類成分。植物葉部的乙醇萃取物經過極性分割後，正丁醇可溶部分先利用薄層層析掃瞄儀 (TLC scanner) 做初步分析，續以膠濾層析 (Sephadex LH-20) 分離，最後利用HPLC-SPE-NMR之連結技術，共分離並鑑定三個黃酮類成分，分別為 (2R,3R)-dihydroquercetin 3-O-rhamnoside (a)、quercetin 3-O-rhamnoside (b) 及kaempferol 3-O-rhamnoside (c)；此三個化合物皆為已知，以樣品a, b及c比對無誤。本研究提供一個快速篩選黃酮類的方法，對天然物之研究大有助益。

This thesis was aimed to apply LC-SPE-NMR hyphenated technique in the isolation and structural elucidation of chemical constituents from two plant materials, i.e. the leaves of Neolitsea sericea var. aurata and Neolitsea variabillima. I. Study on the alkaloids from the leaves of Neolitsea sericea var. aurata Lauraceous plants of the Neolitsea genus have been shown to contain isoquinoline alkaloids, some of which possess cardiovascular effects. This study was aimed to investigate thoroughly the alkaloids present in the leaves of N. sericea (Blume) Koidz. var. aurata Hayata, a Lauraceous plant indigenous to Lanyu island, via the application of LC-SPE-NMR hyphenated technique. The phenolic alkaloids obtained by the general method from the EtOH extract were divided into fractions soluble in water and chloroform. The water and chloroform fractions were then analyzed by LC-SPE-NMR method. From the chloroform fraction, five known isoquinoline alkaloids, i.e. laurolitsine (1), boldine (2), reticuline (3), laurotetanine (4) and actinodaphnine (5) were characterized. From the water fraction, nine isoquinoline alkaloids, i.e. 9S,17S-pallidine N-oxide (6), corytuberine (7), 1S,2S-reticuline N-oxide (8), 6R,6aS-boldine N-oxide (9), 1S,2R-reticuline N-oxide (10), norisocorydine (11), 1R,2R-juziphine N-oxide (12), 6S,6aS-N-methyllaurotetanine N-oxide (13) and 6R,6aS-N-methyllaurotetanine N-oxide (14) were characterized. Among them, compounds 6, 8, 9, 13 are new and compounds 10, 12, 14 are first found in the Neolitsea plants. The structural conformations of compounds 6, 8, 10 and 14 were achieved by comparing their spectral data with those synthetic compounds prepared in this study. The effect of alpha and beta- N-oxidation on the chemical shifts of the adjacent protons was investigated and the stereochemistries of compounds 8 and 10 were rationalized by the assistance of Molecular Dynamics Simulation (MD Simulation) technique.

II. Study on the flavonoids from the leaves of Neolitsea variabillima This study was aimed to investigate the flavonoids present in the leaves of Neolitsea variabillima. The EtOH extract was first divided into several fractions by liquid-liquid partitioning. The flavonoids present in the BuOH fraction was further concentrated by Sephadex LH-20 and analyzed by LC-SPE-NMR hyphenated technique. Totally, three flavonoids, i.e. (2R,3R)-dihydroquercetin 3-O-rhamnoside (a), quercetin 3-O-rhamnoside (b) and kaempferol 3-O-rhamnoside (c) were identified. They were confirmed by HPLC analysis spiked with the samples a, b and c. This study provided a method for fast screening of flavonoids.