肥胖是現代常見的一種健康問題,研究顯示肥胖會增加糖尿病、高血壓及血脂異常等慢性疾病的發生率,因此預防肥胖及改善代謝症候群為一個重要的課題。荔枝(Litchi chinensis Sonn.)為無患子科(Sapindaceae)荔枝屬(Sapindaceae)植物。荔枝花開花時期為每年的3~4月,其一般以廢棄物處理。先前研究發現荔枝花萃取物含有豐富的酚類化合物,並具有優異的抗氧化、抗發炎以及抗癌功用。有文獻指出:花富含酚類化合物,且具有多種生理活性,然而,荔枝花在抗肥胖之作用與機轉尚無較完整的研究。因此,本研究將以3T3-L1脂肪細胞模式評估荔枝花乙醇萃取物之抗肥胖功用。研究中藉由三酸甘油酯 (Triglyceride, TG) 生成、Oil red O染色、Glycerol-3-phosphate dehydrogenase(GPDH)酵素活性等指標,以及對脂肪細胞分化 (differentiation)、脂質生合成(adipogenesis)與脂質分解代謝之影響,探討可能之分子機轉。本研究結果顯示:荔枝花乙醇萃取物可以抑制3T3-L1脂肪細胞之胞內三酸甘油酯及降低GPDH酵素活性,其中在500 μg/mL濃度之下顯著降低TG的抑制率為13.97%,而GPDH酵素活性的抑制率達30.81%。荔枝花萃取物在3T3-L1脂肪細胞之抗肥胖調控機制可透過多種路徑:(1) 抑制脂肪細胞分化相關訊息分子 (PPARγ、C/EBPα) 表現 (2) 抑制脂肪合成與代謝相關訊息分子 (FAS、FABP4、ACC、LPL) 表現 (3) 促進脂肪酸分解氧化相關訊息分子 (CPT-1) 表現 (4) 抑制脂肪細胞激素相關訊息分子 (resistin) 表現,達到抗肥胖作用。
Obesity is a common health problem in modern time. Researches showed that obesity increases an incidence of chronic diseases such as diabetes, hypertension, and dyslipidemia. Therefore, a prevention of obesity and reduction of metabolic syndrome is an important issue. Litchi (Litchi chinensis Sonn.) belonging to Sapindaceae family, which blooms from March to April. The flower is usually considered as disposable byproducts. Our pervious studies found that litchi flower extracts have a plenty amount of polyphenol and also exhibit a good antioxidant capacity, anti-inflammatory and anti-cancer effect. Studies indicated that flowers contain rich phenolic compounds, and has a variety of bioactivity. However, an anti-obesity effect and its mechanism of litchi flower is not yet completely studied. Therefore, in this thesis, ethanol extract from litchi flower were to evaluated with 3T3-L1 adipocytes for in vitro anti-obesity effect. In the study, the effect of ethanol extract from litchi flower on triglyceride (TG) generation, Oil red O staining, Glycerol-3-phosphate dehydrogenase (GPDH) activity, adipogenesis, and lipid catabolism in 3T3-L1 adipocytes were used to explore the possible molecular mechanism. The results showed that the ethanol extract from litchi flower (500 μg/mL) could inhibited intracellular triglyceride (13.97%) and decreased the GPDH activity (30.81%) in 3T3-L1 adipocytes.The in vitro anti-obesity action of litchi flower in 3T3-L1 adipocytes throught some pathways were as followings:(1) Inhibition of adipocyte differentiation related gene expressions (including PPARγ and C/EBPα) (2) Inhibition of fatty acid synthesis and metabolism related gene expressions (FAS, FABP4, ACC, and LPL) (3) Promoting lipolysis related gene expression (CPT-1) (4) Inhibition of adipocytokine related gene expression (resistin).