仙草萃取物對高脂飲食誘導肥胖大鼠之抗肥胖作用與分子機制探討

Antiobesity effects and molecular mechanisms of Hsian-tsao extracts in high-fat diet-induced obese rats

李欣怡(Hsin-Yi Lee)

指導教授 ： 徐慶琳

中山醫學大學/健康管理學院/營養學研究所/碩士(2016年)

摘要

全球人口之肥胖盛行率逐年攀升，肥胖與許多慢性疾病具有相關性，例如：心血管疾病、第二型糖尿病和癌症。過去文獻指出，仙草具有抗氧化、抗發炎和保肝護腎等作用。本實驗利用仙草0-100%乙醇萃取物 (0-100% ethanol extracts of Hsian-tsao, 0-100EEHT) 作為素材，探討其抗肥胖潛力。本實驗分為二部份：(一) 仙草及其萃取物之成分分析與體外抗肥胖潛力評估。(二) 以動物模式評估第一部份篩選出之仙草乙醇萃取物之抗肥胖作用。結果顯示：(一) 仙草粉末主要由粗纖維與無氮萃取物組成。以40EEHT具有最高之總多酚含量、抗氧化能力和酚酸 (原兒茶酸、綠原酸、p-水楊酸、咖啡酸、香草酸和p-香豆酸) 含量。以0-100EEHT處理3T3-L1脂肪細胞後，篩選出40EEHT可顯著降低3T3-L1脂肪細胞數目與胞內三酸甘油酯堆積。(二) 給予高脂飲食誘導肥胖大鼠40EEHT，能顯著抑制其體重、肝臟和脂肪組織重量之增加，並降低肝臟總脂質、三酸甘油酯和膽固醇含量，以及增加糞便總脂質、三酸甘油酯和膽固醇排出。此外，給予40EEHT可顯著降低血清中三酸甘油酯與酮體之含量，以及顯著降低血清與肝臟中丙二醛濃度，提升肝臟總抗氧化能力與抗氧化酵素 (GST與GPx) 活性。觀察肝臟與脂肪組織切片，40EEHT能改善高脂飲食誘導肥胖大鼠之肝臟油滴堆積與腎周脂肪細胞增大情形。在脂肪組織基因表現上，40EEHT可提升脂質生合成抑制基因 (SIRT1)、脂肪酸氧化相關基因 (AMPK、PGC-1alpha、PGC-1beta、CPT-1、ACO和UCP-1)、脂質分解相關基因 (ATGL與HSL) 和脂肪細胞激素 (adiponectin) 之基因表現，以及抑制脂質生合成相關基因 (PPAR-gamma、SREBP-1c、ACC和FAS)、脂質運輸與代謝相關基因 (aP2、FATP1和CD36) 和脂肪細胞激素 (TNF-alpha) 之基因表現。在肝臟基因表現上，40EEHT亦可提升脂質生合成抑制基因 (SIRT1)、脂肪酸氧化相關基因 (AMPK、PGC-1alpha、PGC-1beta、PPAR-alpha、CPT-1和ACO) 和脂質分解相關基因 (ATGL與HSL) 之基因表現，並抑制脂質生合成相關基因 (ACC、FAS和SCD-1) 及脂質運輸與代謝相關基因 (FATP1與LPL) 之基因表現。仙草乙醇萃取物中生理活性物質 (綠原酸、p-水楊酸和咖啡酸) 可顯著降低3T3-L1脂肪細胞之胞內三酸甘油酯堆積。綜合以上結果得知，40EEHT具有改善肥胖之作用，且與所含之咖啡酸有關，未來可進一步開發成不易形成體脂肪功能之健康食品。

關鍵字

仙草 ； 酚酸 ； HPLC ； 3T3-L1脂肪細胞 ； 高脂飲食 ； Wistar大鼠

並列摘要

Among the world’s population, the prevalence of obesity has been steadily increasing. Obesity is linked to numerous chronic diseases, such as cardiovascular diseases, type 2 diabetes mellitus, and cancers. Hsian-tsao has been reported to exhibit various beneficial biological activities such as antioxidant, anti-inflammatory, hepatoprotective, and renal protective activities. This study aimed to investigate the anti-obesity effects of 0-100% ethanol extracts of Hsian-tsao (0-100EEHT) in vitro and in vivo models. There are two topics included in this study: (1) Composition analyses and in vitro antiobesity effects of Hsian-tsao and 0-100EEHT. (2) Anti-obesity effect of 40EEHT on high-fat diet (HFD)-induced obese rats was also investigated. (1) The result indicated that the crude fiber and nitrogen free extract were the major proximate composition of Hsian-tsao. Total polyphenolics content, antioxidant activity, and the content of phenolic acids (including protocatechuic acid, chlorogenic acid, p-hydroxybenzoic acid, caffeic acid, vanillic acid, p-coumaric acid) in 40EEHT were higher than that of the other EEHTs. The result indicated that 40EEHT significantly decreases the cell number and intracellular triglyceride content in 3T3-L1 adipocytes. (2) In animal model, the result showed that the weights of body, liver, adipose tissues, as well as hepatic total lipid, triglyceride, and cholesterol in 40EEHT group are significantly decreased as compared to the HFD group. Fecal total lipid, triglyceride, and cholesterol in 40EEHT group were significantly increased as compared to those in the HFD group. Furthermore, the serum levels of triglyceride, ketone body, and MDA, and hepatic MDA in 40EEHT group were significantly decreased as compared to those in the HFD group. Moreover, 40EEHT also significantly increased the levels of hepatic trolox equivalent antioxidant capacity (TEAC) and antioxidant enzymes (including GST and GPx) as compared to the HFD group. In histological analyses of liver and adipose tissue, 40EEHT could reduce the lipid accumulation and adipocyte size as compared to the HFD group. In gene expressions, supplementation with 40EEHT upregulated the gene expressions of SIRT1, AMPK, PGC-1α, PGC-1βCPT-1, ACO, UCP-1, ATGL, HSL, and Adiponectin in the perirenal adipose tissues of HFD rats, whereas it downregulated PPAR-r SREBP-1c, ACC, FAS, aP2, FATP1, CD36, and TNF-α. In gene expressions of livers, 40EEHT significantly increased the gene expressions of SIRT1, AMPK, PGC-1α, PGC-1β,PPAR-α,CPT-1, ACO, ATGL, and HSL in the liver of HFD rats, but downregulated ACC, FAS, SCD-1, FATP1, and LPL. The data indicated that the active compounds of chlorogenic acid, p-hydroxybenzoic acid, and caffeic acid from EEHT significantly decrease the intracellular triglyceride content in 3T3-L1 adipocytes. The results demonstrated that the amelioration of 40EEHT on high-fat diet-induced obesity rats might be related to the active compound (caffeic acid). Therefore, 40% ethanol extracts of Hsian-tsao can be developed as a potential nutraceutical ingredient for preventing obesity.

並列關鍵字

Hsian-tsao ； phenolic acids ； HPLC ； 3T3-L1 adipocytes ； high-fat diet ； Wistar rat

參考文獻

王嘉煒 (2015) 仙草萃取物改善高尿酸血症及腎損傷之功效評估 國立中興大學食品暨應用生物科技所碩士論文

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World Health Organization (2016) http://www.who.int/topics/obesity/en/

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