體外活化過氧化體增殖劑活化受器──α之食材萃取物   全文下載

In Vitro Activation of Peroxisome Proliferator Activated Receptor α by Some Extracts from Food Materials

過氧化體增殖劑活化受器α（PPARα）是屬於依賴配體活化之轉錄因子，能調節與脂質代謝有關基因之表現。已知PPARα 之活化劑可能具有降血脂之潛力，如同fibrate 類之降血脂藥的作用。因此本研究之目的欲從日常之食材中篩選出具降血脂功能潛力之PPARα 活化劑。實驗採用穩定轉染之方式成功地將受器基因及報導基因質體轉染至CHO-K1 細胞。篩選出來之細胞株對於PPARα 已知之活化劑Wy-14643 有最佳之活化反應，可藉此作為測試食材中是否具有PPARα 活化潛力成分之篩選工具。食材用乙酸乙酯萃取並進行冷皂化反應，然後以篩選出來之細胞株進行活化能力測試並以Wy-14643（10 μM）當作正對照。在所有測試之食材當中以苦瓜之乙酸乙酯萃取物具有最佳之活化能力甚至超過正對照Wy-14643。而洋蔥乙酸乙酯萃取物的非皂化區分物與正對照相比其活化能力是Wy-14643 的91%。此外，花生、荔枝、蓖麻籽及龍眼之萃取物與正對照相比具有中等（30%~50%）之活化效果。而蓖麻籽、芝麻及花生的皂化區分物與正對照相比也具有中等（30%~50%）之活化能力。本研究找到具活化PPARα 潛力之食材萃取物，其對人體健康的益處則有待進一步之研究與探討。

Peroxisome proliferator activated receptor α (PPARα) is a ligand-dependent transcription factor that regulates the expression of genes involved in lipid metabolism and transport. Activators of PPARα may be potential hypolipidemic agents, like the fibrate-type drugs. This study was therefore aimed at identifying potential hypolipidemic functional foods by screening activators of PPARα from food materials. CHO-K1 cells were stably transfected with vectors (pBKCMV) carrying cDNAs of a (UAS)4-tk-alkaline phosphatase reporter and a chimeric receptor Gal4-PPARα LBD successively. Clones of cells responsive to Wy-14643, a known PPARα activator were selected, characterized and used for testing the PPARα activating potency of fractions extracted from food materials. Food materials were extracted with ethyl acetate and the extract (EAE) was cold-saponified and tested for the PPARα activating ability using the selected stable transfected clone of cells. 10 μM Wy-14643 (WY) was used as the positive control. Among food materials tested, EAE of bitter gourd showed the highest activity that exceeded Wy-14643, although the activity significantly decreased after saponification. The non-saponifiable fraction of onion EAE had a high maximal fold of activation equivalent to Wy-14643, while that of peanut, lychee, ricinus seed and longan showed moderate activity. The saponifiable fraction of ricinus seed, sesame and peanut also showed moderate activity. Further investigation is needed to explore the health benefit of the PPARα activating food extracts found in this study.