| 摘要: | Ugonstilbenes A、B、C是由錫蘭七指蕨分離出來的天然物，錫蘭七指蕨為傳統中藥作為消炎解熱劑，ugonstilbenes A–C結構屬於stilbenoid，都帶有cyclogeranyl group，乃為白藜蘆醇(resveratrol)的類似物，ugonstilbenes A–C在抗氧化作用上具有不錯的清除自由基的活性。由於天然物分離的量很少，且這個天然物到目前為止並未有合成之報導，為了探討其全合成與天然物的絕對立體結構，在本論文中，建立了一個有效的合成方法來合成ugonstilbenes A–C，並探討這些化合物的抗癌活性。
在本論文中，以4-bromo-3,5-dihydroxybenzoic acid與cyclogeranic acid為起始物，經由14個合成步驟，合成出ugonstilbenes A和B，以4-hydroxybenzaldehyde及cyclogeranic acid為起始物，經由14個合成步驟，合成出ugonstilbene C，合成的ugonstilbenes A–C與文獻報導的天然物ugonstilbenes A–C的1HNMR、13C NMR 和 MS的圖譜比對相同，經由旋光度比對，天然物ugonstilbenes A和C皆為R組態，天然物ugonstilbene B為4aR,9aS組態。
抗癌研究中ugonstilbene A具有抑制大腸癌細胞(HT29)與肺癌細胞(H460)的活性，IC50為1.3–8.3 uM，ugonstilbene B具有抑制肺癌細胞(H460)與急性淋巴白血病細胞(CEM)的活性，IC50為2.1–5.5 uM。
Ugonstilbenes A, B, and C were isolated and characterized as three new stilbenoids from the rhizomes ofHelminthostachyszeylanica. The rhizomes of H. zeylanica is a Chinese herbal medicine used as an antipyretic and antiphlogistic agent. Ugonstilbenes A, B, and C have a resveratrol structure with a cyclogeranyl group substituent. Ugonstilbenes A, B, and C were found to show antioxidative activity. Until now, the total synthesis of ugonstilbenes A, B, and C were not reported yet, and their absolute stereochemistry were not determined. In order to obtain more material for further study the biological activities, the total synthesis of ugonstilbenes A, B, and C were carried out.
In this thesis, an efficient method to synthesize ugonstilbene A and ugonstilbene B was performed in fourteen steps starting from 4-bromo-3,5-dihydroxybenzoic acid and cyclogenanic acid.Ugonstilbene C was successfully synthesized from 4-hydroxybenzaldehyde and cyclogenanic acid in fourteen steps. The spectroscopic properties (1H NMR,13C NMR and MS) of synthesized ugonstilbenes A, B, and C were identical with those of natural occurring ugonstilbenes A, B, and C, respectively. By optical rotation comparison, the absolute stereochemistry of both naturally occurring ugonstilbene A and ugonstilbene C was assigned as R-configuration, and the absolute stereochemistry of ugonstilbene B was assigned as 4aR,9aS-configuration.
The cytotoxic activity of synthesized ugonstilbenes A, B, and C were evaluated against several human cancer cell lines including human breast cancer cells (MCF-7), human colon cancer cells (HT29), human lung cancer cells (H460), and acute lymphoblastic leukemia cells (CEM). The results showed that ugonstilbene A was potent against HT29 and H460 with an IC50 valuesof 1.3–8.3 uM and ugonstilbene B was potent against CEM and H460 with an IC50 values of 2.1–5.5 uM. |
