肝素寡醣的合成及其應用

Synthesis of heparin Oligosaccharides and their applications

盧信安(Xin-An Lu)

指導教授 ： 洪上程 ； 林俊成

國立清華大學/理學院/化學系/博士(2009年)

摘要

肝素(Heparin, HP)/硫酸乙醯肝素(Heparan sulfate, HS)屬於葡胺聚醣(glycosaminoglycan, GAG)的一種，是直線型的多醣分子，其結構由D式葡萄胺醣及羰基醣酸以脉式1→4鏈結所組成的雙醣分子，彼此間以刍式1→4鏈結方式所組成，因位於細胞表面，扮演與血液凝結、細胞成長調控、病毒感染及癌細胞轉移等有關細胞間溝通橋樑的重要角色，但由於肝素及硫酸乙醯肝素寡醣從自然界取得不易，化學合成可提供一種解決方法。本論文的工作在發展肝素寡醣分子的合成方法，並研究其與多種蛋白質的作用關係。
本論文第一章在介紹細胞表面的醣共軛分子，並簡介肝素/硫酸乙醯肝素的結構與生理活性；第二章為文獻回顧部分，簡介了世界上知名醣化學家在合成肝素/硫酸乙醯肝素的工作。第三章則提出本論文的工作目標及目標分子的逆合成分析。
在肝素寡醣的建構單元部分，第四章乃針對D式葡萄胺醣單醣建構單元進行研究討論，我們利用一鍋化的策略進行葡萄胺醣的合成研究，並且以共同中間體的概念，大幅度減少D式葡萄胺醣衍生物的製備步驟；第五章討論了1,6–無水L式艾杜哌喃醣衍生物的合成，以便宜且可購得的雙丙酮保護脉-D葡萄醣衍生物為起始物，僅需要五步即可合成出L式艾杜醣的建構單元，且此製程可放大至三百克。
第六章是探討肝素寡醣的合成研究，我們利用合成出的雙醣中間體，與還原端具脉-甲氧基的D式葡萄胺醣反應則可合成出肝素三醣體，接著利用選擇性移除2–萘甲基並進行重複醣苷化作用，則可順利得到肝素五、七醣體骨架，最後分別經過五步去保護及官能基轉換步驟，即可得到肝素三、五、七醣最終產物。而這些產物則在第七章中描述其生化測試的結果。
第八章則介紹與美國北卡羅萊納大學教堂山分校Jian Liu教授的合作，探討利用化學酵素法合成具各種不同硫酸基的硫酸乙醯肝素寡醣，並利用此方法合成出具抗凝血性質的結果。
第九章結論部分，將第四章至第八章的工作做統整報告；而本論文工作中的詳細實驗步驟及物理性質則列於第十章。

關鍵字

肝素寡醣 ； 合成 ； 化學酵素法 ； 葡胺聚醣 ； 硫酸乙醯肝素 ； 酵素合成

並列摘要

The cell surface heparan sulfate (HS) and its structurally related heparin (HP) are members of the glycosaminoglycan (GAG) family. They are linear polyanionic polysaccharides containing a 1沦4-linked disaccharide repeating unit composed of an uronic acid and 脉-D-glucosamine. HS and HP play important roles in regulating the biological activity of several proteins in the coagulation cascade along with many other processes of biomedical importance including growth factor interactions, viral entry, and angiogenesis. Due to the difficulty in obtaining homogeneous heparin oligosaccharides from natural sources, chemical synthesis may offer a good solution. This dissertation is concerned with the development of methodologies for the synthesis of heparin oligosaccharides and studies their interaction with various proteins.
Chapter 1 begins with a description of glycoconjugates on the cell surface and an introduction to the structural characteristics of HP/HS molecules. The biological properties of HS and HP are briefly summarized to provide more information between HS/HP with proteins. The synthesis of HS/HP oligosaccharides documented in the literature reports are summarized in Chapter 2.
Chapter 3 describes our specific aims and retro-synthetic plan. The studies on the synthesis of monosaccharide building blocks are described in Chapters 4 and 5. Chapter 4 discusses our new strategies to synthesize D-glucosamine-derived glycosyl donors via our new developed regioselective one-pot protection methodology. The reducing end sugar unit can be prepared from a common intermediate. Chapter 5 reveals the shortest route to synthesize the 1,6-anhydro-刍-L-idopyranose, starting from commercially available and cheap diacetone 脉-D-glucose up to 300-gram scale.
Chapter 6 illustrates the synthesis, isolation, purification and structural identification of HP/HS tri-, penta-, and heptasaccharides in detail. The final products were subjected to different bioassays, as specified in Chapter 7.
Chapter 8 describes the chemoenzymatic method to prepare HS oligomers with anticoagulant properties.
The conclusion of this work is summarized in Chapter 9. Finally, Chapter 10 provides the detailed experimental section and physical data of new compounds.

並列關鍵字

heparin oligosaccharides ； synthesis ； chemoenzymatic synthesis ； glycosaminoglycan ； Heparan sulfate ； enzymatic synthesis

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