穿心蓮內酯衍生物的合成探討及其應用

Abstract

穿心蓮內酯 (Andrographolide, Andro) 是由穿心蓮 (Andrographis paniculata) 中分離出的雙萜內酯類天然物，其本身以及衍生物已被證實具有多種抗癌、抗病毒、抗發炎等藥理活性。穿心蓮內酯衍生物所產生之藥理活性主要來自於自身多個活性位點，許多文獻已證實透過結構的修飾，可提升其生物活性。因此透過化學修飾進行生物應用已成為重要研究方向。本研究將分為兩部分，對於穿心蓮內酯進行衍生化後之結構合成進行探討。 第一部分為延續本實驗室先前所開發螢光標記穿心蓮內酯衍生物，基於穿心蓮內酯本身具消炎、抗腫瘤等特性，我們在 C-14 的羥基以酯化反應修飾消炎藥物與醋酸根結構，並在 C-3、C-19 雙羥基上鍵結螢光團 (NBD)，該螢光團有助於後續生物應用上的顯影並增加細胞滲透性。預期該螢光探針在進入目標蛋白的活化位後，不僅能以螢光標記蛋白，還能藉由麥可加成 (Michael addition) 反應，釋放出藥物，達到更佳抑制效果，作為雙功能螢光探針。 第二部分針對穿心蓮內酯結構進行醣基化反應 (glycosylation)，醣基化反應是天然物常見的修飾方法之一，可調節天然物的生物活性和性質，增加其結構與功能的多樣性。其中，老化細胞相關半乳醣苷酶 (senescence-associated β-galactosidase) 常做為檢測細胞老化的生物標記物，許多相關研究皆指出老化細胞與多種發炎性疾病、癌前病變和癌症密切相關。因此本論文將著重在穿心蓮內酯上進行 β-半乳醣基化反應，並成功在穿心蓮內酯的多個羥基位置修飾 β-乙醯化半乳醣，同時，在溫和條件下選擇性去除穿心蓮內酯衍生物上的醣基保護基。我們預期該系列探針能針對老化細胞 (senescence cells) 發揮抑制效果。本論文期許透過對不同羥基活性位點的修飾，能在後續的生物應用中展現出更多潛力。

Andrographolide (Andro) is a diterpenoid lactone compound isolated from Andrographis paniculata. It has demonstrated promising pharmacological activities, including anticancer, antiviral, and anti-inflammatory effects. Derivatives of andrographolide show enhanced pharmacological activities through modifications at multiple active sites, and numerous studies have confirmed that structural modifications can further improve its bioactivity. Consequently, chemical modification of andrographolide has become a significant area of research. This study will be divided into two parts to discuss the synthesis of andro derivatives after structure modification. The first part builds on our laboratory's previous work with fluorescent modification on andrographolide derivatives. Given andrographolide's inherent anti-inflammatory and antitumor properties, we modified the hydroxyl group at the C-14 position by esterifying it with anti-inflammatory drugs and acetate structures. Additionally, we attached a fluorescent group (NBD) to the hydroxy groups at the C-3 and C-19 positions. This fluorescent group enhances imaging in biological applications and increases cellular permeability. Upon entering the active site of the target protein, the fluorescent probe is expected to not only label the protein with fluorescence but also release the drug via a Michael addition reaction, thereby achieving enhanced inhibitory effects. This design establishes the probe as a bifunctional tool, combining fluorescence labeling with therapeutic activity. The second part focuses on the glycosylation of the andrographolide structure. Glycosylation is a common modification method that can regulate the bioactivity and properties of natural compounds, thus increasing their structural and functional diversity. Among various glycosylation targets, senescence-associated β-galactosidase is widely used as a biomarker to detect cellular senescence. Many studies indicate that senescent cells are highly associated with various inflammatory diseases, precancerous lesions, and cancers. Therefore, this part of the study emphasizes the β-galactosylation of andrographolide. We have successfully modified multiple hydroxyl positions on andrographolide by adding β-acetylated galactose. Furthermore, we intend to selectively remove the protecting groups from galactose under mild conditions. We expect that this series of probes can inhibit senescent cells, showing potential for future biological applications through structural modification.