五爪金英Td-F2萃取物誘導人類肝癌細胞Hep3B細胞週期阻滯及細胞凋亡作用

A Td-F2 Extract from Tithonia diversifolia Induced Cell Cycle Arrest and Apoptosis on Hep3B Human Hepatoma Cells

五爪金英 Tithonia diversifolia (Hemsl.) A. Gary為菊科(Compositae)植物。在民間傳統使用以全草來治療不同肝疾，具有清熱解毒等效用，近年來僅有少許報告指出分離自五爪金英不同成分能抑制肝癌細胞生長，目前於稍早實驗篩選出五爪金英葉部之乙酸乙酯萃取物第二分劃Td-F2具有抑制人類肝癌細胞 HepG2(Wild-type p53)生長，並誘導產生細胞凋亡之活性。此次研究挑選不同基因表現之人類肝癌細胞Hep3B(P53 deletion)進行實驗。經MTT assay測定顯示隨著Td-F2藥物濃度增加，細胞存活率逐漸減少，且處理24小時IC50為15.9 μg/mL；處理48小時IC50為6.3μg/mL，具有時間與濃度依賴性。接著藉由DNA 膠體電泳、ELISA kit、流式細胞儀測定，結果顯示DNA片段化、細胞凋亡率增 加與sub-G1峰之細胞凋亡現象，綜合上述結果證明五爪金英葉部之乙酸乙酯萃 取物第二分劃Td-F2同樣具有誘導人類肝癌細胞Hep3B細胞凋亡之活性，未來更進一步探討相關細胞凋亡調控機制。

Tithonia diversifolia belong to the family of Compositae. The whole plant of Tithonia diversifolia has long been applied to the traditional folk medicine for the treatment of various liver disease, and is believed to be effective in relieving heat and body toxins. In recent years, there are only several reports confirming its effects on hepatoprotective, anti-inflammatory, and anti-cancer activities. However, researches are lacking for the exact anti-cancer mechanisms of Tithonia diversifolia on hepatoma. We had previously shown that the ethyl acetate extract from leaves of Tithonia diversifolia indeed indicated singnificant cytotoxicity effects on the human hepatoma cell HepG2 (Wild-type p53) and induced apoptosis. In this study, we used the human hepatoma cell Hep3B (P53 deletion) to assay the anti-tumor effect of the extracts from Tithonia diversifolia. Our results showed the effective fraction of the Fraction-2(Td-F2) inhibited the tumor cell growth (IC50 =15.9μg/mL at 24 hour and IC50 =6.3μg/mL at 48 hour) in a time and concentration-dependent manner. Moreover, we further analyzed the DNA fragmentation by gel electrophoresis, cell cycle by flow cytometry, and apoptosis by ELISA method. The results clearly showed that Td-F2 indeed induced cell cycle arrest and apoptosis on Hep3B cell.