水丁香Ludwigia octovalvi s (柳葉菜科)為一種水生植物，廣泛分佈於台灣的沼澤地區。在民間傳統上，它用於治療水腫、抗肝炎及降血壓。而對 3T3-L1前驅脂肪細胞，經系統性的活性追蹤，我們證實從水丁香的葉部所分離穫得之化合物〝葉綠素a(CHL-a)〞實驗顯示具有優異的抗增生活性。對3T3-L1細胞之凋亡路徑會造成影響其IC50值為最低。
本研究，我們再深入探究CHL-a對3T3L-1細胞之細胞凋亡分子機制，發現在5-30 nM，CHL-a顯示對sub-G峰呈劑量-依賴性蓄積作用並且細胞週期停滯於G0/G1期。經48小時處理後，30 nM CHL-a會降低細胞存活率，誘導DNA斷裂片的出現及增加caspase-3的活性。以西方墨點分析結果顯示CHL-a會降低Bcl-2之表現，並且提高Bax及CD95 (APO-1/CD95)之表現呈-時間及劑量依賴性效應。然而，CHL-a會提昇AMPK及P-AMPK之表現，調降PPAR-γ的表現。綜合上述研究結果證實CHL-a能誘導脂肪細胞凋亡，主要機制是透過CD95系統，調控Bcl-2家族蛋白質及活化caspase-3所致，並活化AMPK訊息路徑展現抗脂肪合成之作用。 Ludwigia octovalvis (Jacq.) P. H. Raven (Onagraceae) is an aquatic plant widely distributed in the wet area of Taiwan. It is used as a traditional treatment for edema, nephritis, and hypertension. The results showed that ethanol extract of L. octovalvis (EELO) possessed the lowest IC50 value against the 3T3-L1 cells. Fraction 3 was found to induce significant cell death in 3T3-L1 cells. We investigated the effect of chlorophyll a (CHL-a) isolated from the leaves of L. octovalvis on the apoptotic pathway in 3T3-L1 cells. The results showed that CHL-a was the most effective with an IC50 value at 48 h. At concentration of 5~30 nM, CHL-a exhibited a dose-dependent accumulation of the Sub-G1 peak and caused G0/G1-phase arrest. After 48 h treatment, 30 nM CHL-a reduced the cell viability, induced the appearance of DNA fragments, and increased the activity of the caspase-3. Western blot data revealed that CHL-a decreased level of Bcl-2, and increased the expression of Bax and CD95 (APO-1/CD95) in a time- and a dose-dependent manner. Furthermore, CHL-a exposure up-regulated the levels of AMPK and P-AMPK, but the expression of PPAR-γ was down-regulated. These data indicate that CHL-a induced apoptosis of mature adipocytes through mediating the CD95 (APO-1/CD95) system, and modulation of Bcl-2 family proteins and caspase-3 activity, as well as exerting anti-adipogenesis ability by activating the AMPK signaling pathway.
