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  • 學位論文

第一部份:芘駢吡咯及雙芘駢吡咯做為氟離子偵測器之機制研究 第二部分:抗神經退化性藥物之研究:腺苷酸類似物之合成

Part 1. A Mechanistic Study of Pyreno[2,1-b]pyrrole and Bis(pyreno[2,1-b]pyrrole) as Selective Chemosensors of Fluoride Ion Part 2. Synthesis of Adenosine Analogues for Therapy of Huntington’s Disease

指導教授 : 方俊民

摘要


第一部份:芘駢吡咯及雙芘駢吡咯做為氟離子偵測器之機制研究 本篇論文當中,我們運用本實驗室過去合成的芘駢吡咯及其衍生物-雙芘駢吡咯做為氟離子的偵測器,且選用多種常見的陰離子進行初步篩選,發現此二化合物對於氟離子具有良好選擇性及靈敏度。而在添加氟離子先後,此二化合物均在可見光波長區域產生明顯的吸收或螢光光譜變化,此一光物理性質將可應用於氟離子的即時偵測上。 我們利用螢光及核磁共振光譜對於氟離子的偵測機制進行詳盡的分析。實驗過程中發現,在初始模式中,芘駢吡咯及雙芘駢吡咯與氟離子形成氫鍵附合物;之後加入的氟離子,因其帶有極強的鹼性,將促使吡咯官能基中氮上氫進行去質子化,而造成吸收及螢光光譜的紅位移現象。另外在1H NMR光譜滴定實驗中,我們紀錄並解釋偵測器分子上其他氫訊號的特殊趨勢,並觀測到 [FHF]–陰離子的訊號,更進一步地證實偵測器分子與氟離子間進行去質子化的作用機制。 第二部分:抗神經退化性藥物之研究:腺苷酸類似物之合成 我們從傳統中藥材-天麻中萃取出兩種具有神經保護性的化合物:T1-C和T1-11,且利用有機合成的方法大量製備此二化合物。在老鼠腎上腺髓質嗜鉻細胞瘤細胞(PC12 cells)測試中發現,此二分子透過刺激A2A腺苷酸受體(A2A-R)使細胞免於凋亡。由於A2A-R屬於G蛋白質受體家族,在其單晶結構難以取得的條件下,我們利用電腦軟體建構的pharmacophore模型輔助整個藥物分子的設計。 因為T1-11具有更好的生物活性,所以本篇論文著重在T1-11的衍生。我們替換T1-11分子結構中N6-位置的取代基,並建立具有代表性的分子庫。進行測試後發現,這些腺苷酸類似物的神經保護性與T1-11相差無幾,也就是說A2A-R 刺激物對於N6-位置官能基變化具有一定程度的容忍性。此外,我們也嘗試修飾T1-11結構中的核糖部分,希望能進一步提高對於A2A-R的親和性。在其他生物活性測試中發現,T1-11分子扮演兩種角色:A2A-R 刺激物及腺苷酸轉運體抑制劑。我們認為這類型可針對多種目標物的藥物分子,對於亨丁頓氏舞蹈症或其他神經退化性疾病的臨床治療,具有一定的潛力。

並列摘要


Part 1. A Mechanistic Study of Pyreno[2,1-b]pyrrole and Bis(pyreno[2,1-b]pyrrole) as Selective Chemosensors of Fluoride Ion Pyreno[2,1-b]pyrrole and its dimeric derivative display excellent selectivity and sensitivity for detection of fluoride ion, in comparison with other anions. The bonding with fluoride ion, both in formation and in subsequent dissociation, provides remarkable colorimetric and fluorescent changes in the visible region that are advantageous for real-time and on-site application. The mechanisms of detection were also investigated by detailed NMR and dynamic fluorescence spectroscopic analyses. The initial interaction modes of pyreno[2,1-b]pyrrole and its dimeric derivative with F− in MeCN can be understood as hydrogen-bonded complexes. Excess F− ions promotes deprotonation of N-protons and results in the bathochromic changes in both absorption and fluorescence spectra. The observation of [FHF]– by 1H NMR in DMSO-d6 also strongly supported the deprotonation mechanism. Part 2. Synthesis of Adenosine Analogues for Therapy of Huntington’s Disease We demonstrated the synthesis and biological function of T1-C and T1-11, which are isolated from a Chinese herb, Gastrodia elata (天麻), These compounds have been characterized to exert neuroprotective effect. Previous works has revealed the potency of T1-11 for the therapy of Huntington’s disease. The neuroprotection was mediated by A2A receptor in the apoptotic model of serum-deprived PC12 cells. Because A2A receptor is a GPCR, pharmacophore modeling was used to provide a putative image of the interactions between the target protein, A2A receptor, and its agonists. There were two approaches to modify T1-11: the alternation of N6-substituted functional groups and the modification of ribose. A representative library of adenosine analogues was developed on the basis of pharmacophore model and screened for the biological activities assays. We also proposed a dual–function mechanism of T1-11, which acted as both A2A receptor agonist and nucleoside transporter inhibitor. Further development of these compounds may promise a novel therapeutic intervention for HD and other neurodegeneration diseases.

參考文獻


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