針對過氧化氫來發展分子工具之研究

Abstract

由於在特定病理狀況下常伴隨細胞內積累異常高濃度的過氧化氫(H2O2)的現象，因此本研究室在2003年首創以苯硼酸酯(arylboronate ester)為基本架構，發展出能選擇性與過氧化氫作用的探針分子。本論文延續此一架構，來設計並合成出一系列可藉由過氧化氫來啟動的分子工具；其中包括（一）以抗癌藥物阿黴素(Doxorubicin)為酬載的前驅藥物，利用前驅藥物與介孔二氧化矽納米粒子(Mesoporous silica nanoparticle)結合來探討此選擇性運輸系統(Drug Delivery Systems, DDS)，以及前驅藥物的活化與釋放效能。此外，亦在硼酸酯的苯環上修飾硝基，嘗試利用其拉電子基的特性來提高其對過氧化氫的反應性，以改善原本硼酸酯低反應性的問題。（二）嘗試合成帶有苯硼酸酯啟動端的多官能基重要中間體，此中間體具有可搭配雙酬載的特性，其中Benzylic alcohol的部份可用以連接可經由過氧化氫作用而被釋放的酬載，而結構末端含有以聚乙二醇(Polyethylene glycol)來橋接的疊氮基(azide)則可應用點擊化學(Click chemistry)來引入另一酬載。為了測點及化學的效能，我們合成出具有標靶功能的基團如葉酸等的bicyclo[6.1.0]nonyne (BCN)衍生物。（三）β-拉帕醌及其衍生物的合成。β-拉帕醌為天然產物，可與細胞中NADPH氧化還原酶反應產生活性含氧物，提高細胞中過氧化氫的濃度。由於NADPH氧化還原酶在特定癌細胞中有過量表達的現象，因此我們希望探討β-拉帕醌及其衍生物能否促進硼酸酯與過氧化氫的反應，以提高癌細胞中藥物釋放的效率。綜合上述實驗結果，我們成功獲得了一部分分子工具並且測試其與過氧化氫反應的選擇性，但另一部分在藥物酬載上的純化並不容易，因此我們考慮在將來以結構較簡單的螢光團例如香豆素作為酬載的分子，希望能夠解決純化上的困難。

There are increasing evidences to point out that many pathological conditions are related to abnormal high level of reactive oxygen species (ROS) such as H2O2. Therefore, our laboratory first developed the molecular probes of aryl boronate ester that interacts selectively with hydrogen peroxide in 2003. This thesis continues this framework to design and synthesize a series of molecular tools that can be activated by hydrogen peroxide which include : (1) a prodrug based on the anticancer drug (Doxorubicin), which uses a combination of a prodrug and mesoporous silica nanoparticles to explore this selective drug delivery system (DDS), activation, and release efficacy of prodrugs. In addition, the nitro group is also modified on the benzene ring of the boric acid ester, and attempts are made to improve the reactivity to hydrogen peroxide by utilizing the characteristics of the electron-withdrawing group to improve the problem of low reactivity of the original boronic acid ester. (2) Attempting to synthesize a polyfunctional intermediate with a phenylborate, which has the property of being compatible with double-paying, wherein a part of benzylic alcohol can be used to connect and be released via hydrogen peroxide. The azide, which is bridged with polyethylene glycol at the end of the structure, can be click chemistry to introduce another payload. To test the potency of click chemistry, we also synthesized bicyclo[6.1.0]nonyne (BCN) derivatives with a target functional group such as folic acid. (3) Synthesis of β-lapachone and its derivatives. β-lapachone is a catechol that reacts with NADPH oxidoreductase in cells to produce ROS, increasing the concentration of hydrogen peroxide in the cells. Because of the overexpression of NADPH oxidoreductase in specific cancer cells, we hope to investigate whether β-lapachone and its derivatives can promote the reaction of borate with hydrogen peroxide to increase drug release in cancer cells effectively. We ave successfully obtained some molecular tools and tested their selectivity for reaction with hydrogen peroxide, but the purification of the other part on the drug ayload is not easy, so we consider to use a simpler fluorophore like coumarin in the future as a molecule for the payload. Therefore, the synthesis step should be carried out and purified more esaily.