- 學位論文
由Nrf2/表觀遺傳調控機制探討荷葉水萃物之護肝潛力
Evaluation of hepatoprotective potential of lotus leaf water extract by promoting Nrf2 and epigenetics-mediated cellular antioxidant capacity
摘要
肝臟是人體內負責解毒代謝的主要器官，而根據台灣近幾年來十大死因統計中可發現，每年皆有超過10,000人是死於肝臟相關疾病，由此可知肝病對於國人健康有一定影響。乙醯胺基苯酚 (acetaminophen, APAP) 是市售止痛成藥中的主要成分，已有研究指出於短時間內攝取過量 APAP會造成肝臟細胞氧化損傷。本研究欲探討荷葉水萃物 (LL-WE) 是否能提升肝細胞內之抗氧化能力，進而減緩由 APAP 誘發肝細胞內氧化壓力所造成的損傷作用。首先，由活性成分分析結果得知 LL-WE 中富含多種酚類化合物，且於穩定轉染 ARE-luciferase 質體的人類 HepG2-C8細胞內，LL-WE (500 μg/mL) 能顯著活化 Nrf2/ARE 路徑 (p < 0.05)。LL-WE (500 μg/mL) 也能顯著活化小鼠 AML-12 正常肝細胞中 Nrf2入核情形，進而使下游抗氧化/解毒酵素 HO-1、NQO1及 UGT1A 之 mRNA 和蛋白質表現量皆顯著提升 (p < 0.05)。此外，LL-WE (100-500 μg/mL) 能夠顯著降低表觀遺傳調控相關酵素 (DNMTs 和 HDACs) 蛋白質表達量，顯著抑制體外 DNA 甲基轉移酶 (M.SssI) 之活性，以及顯著降低由 APAP 所造成的AML-12 細胞死亡比例 (p < 0.05)。綜合上述結果，LL-WE能夠促進Nrf2入核情形並活化下游抗氧化路徑，且亦能透過表觀遺傳調控機制影響抗氧化酵素之表達，進而減緩由APAP誘發氧化壓力上升所導致AML-12 肝細胞受損之作用。
並列摘要
The liver is the main organ responsible for detoxification and metabolism in the human body. According to ten leading causes of death in Taiwan, more than 10,000 people die from liver-related diseases. This shows that liver disease has a certain impact on the health of Taiwanese. Acetaminophen (APAP) is the main ingredient in commercially available painkillers. Studies have pointed out that excessive intake of APAP at a short notice can cause oxidative damage to liver cells. This study intends to investigate whether lotus leaf water extract (LL-WE) can improve the antioxidant capacity in liver cells and protect liver from APAP-induced oxidative injury. LL-WE (500 μg/mL) can significantly increase the activity of the Nrf2/ARE pathway in HepG2-C8 cells. LL-WE (100-500 μg/mL) stimulate Nrf2 translocates to the nucleus, and can enhance the Nrf2/ARE-mediated mRNA and protein levels of detoxifying or antioxidant enzymes (HO-1, NQO1 and UGT1A). Furthermore, LL-WE reduces the protein expression of epigenetic regulation-related enzymes (DNMTs and HDACs). In addition, LL-WE can effectively reduce the activity of in vitro DNA methyltransferase (M.SssI). LL-WE (500 μg/mL) can significantly reduce AML-12 cell death ratios caused by APAP. The results suggesred that LL-WE increase Nrf2 translocates to the nucleus and activate the transcription of its downstream targets, which be likely to regulated through epigenetics. Because of this, LL-WE can protect APAP-induced oxidative injury in AML-12 cells.
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