薑精油抗酒精性脂肪肝之代謝體學研究

Abstract

脂肪肝與肝硬化及肝癌有高度相關性，臨床上一般可分為非酒精性脂肪肝 (non-alcoholic fatty liver disease, NAFLD)及酒精性脂肪肝 (alcoholic fatty liver disease, AFLD)。非酒精性脂肪肝發生原因主要與代謝症候群如肥胖、胰島素阻抗等有關，造成肝臟中三酸甘油酯過度累積。此外，過量攝取酒精則會導致酒精性脂肪肝。已有研究證實，食用薑能夠增強肝臟中抗氧化系統及解毒系統功能，進而達到護肝功效。因此，本研究利用給予酒精液態飼料 (Lieber-DeCarli diet)誘導C57BL/6 (B6)小鼠脂肪肝之動物模式，實驗過程中以管灌餵食方式給予小鼠薑精油 (ginger essential oil, GEO)或檸檬醛 (citral)，進行為期四週之動物試驗，探討薑精油保護肝臟之功效及機制，進一步以超高效能液相層析結合四極柱-飛行式質譜儀 (ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry, UHPLC-QTOF-MS)分析小鼠血清及尿液代謝物，進行代謝體學之探討。由實驗結果得知，小鼠食用酒精液態飼料四週即會生成脂肪肝；此外，由血液生化分析、肝臟抗氧化酵素分析及肝臟組織病理切片之結果可推測，管灌餵食GEO之小鼠，其酒精性脂肪肝生成情況具有顯著改善之效果。由酒精所誘導之脂肪肝小鼠，其血清及尿液中有數種代謝物可能是關鍵的生化代謝途徑物質，包括葡萄糖醛酸內酯 (D-glucurono-6,3-lactone)、甘油-3-磷酸鹽 (glycerol-3-phosphate)、丙酮酸 (pyruvic acid)、石膽酸 (lithocholic acid)、焦兒茶酸 (2-pyrocatechuic acid)、前列腺素E1 (prostaglandin E1)、甲硫胺酸 (methionine)、古羅糖酸內酯 (L-gulono-1,4-lactone)、乳酸 (lactate)等九種血清代謝物，及絲胺酸 (serine)、尿囊素 (allantoin)、甲基硫化腺苷 (5'-methylthioadenosine)、牛磺酸 (taurine)等四種尿液代謝物。代謝體學分析結果顯示，這些代謝物可能與酒精性脂肪肝之生成及改善有相關性，可提供作為健康管理及臨床應用上之生物標記物 (biomarker)。

Fatty liver is highly associated with hepatic cirrhosis, and liver cancer. The pathogenesis of fatty liver is mainly divided into two categories: non-alcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (AFLD). Alcoholic and non-alcoholic fatty livers could be induced by alcohol consumption, obesity and hyperlipidemia. Ginger has been reported to exhibit antioxidant potential and hepatoprotective activity. In present study, a mouse model for AFLD was developed and validated by employing male C57BL/6 (B6) mice with alcohol containing liquid diet (Lieber-DeCarli diet) ad libitum. In the treatment groups, ginger essential oil (GEO) and citral, one of the major active compounds in GEO, were administered orally every day for 4 weeks. Metabolites in serum and urine samples were profiled by ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). Serum biochemical analysis, liver antioxidant enzyme activity and histopathological evaluation, of GEO treated mice exhibited hepatoprotective activity on alcohol-induced fatty liver. Several metabolites involved in key biochemical pathways were identified to be implicated by AFLD after four weeks of alcohol administration, such as D-glucurono-6,3-lactone, glycerol-3-phosphate, pyruvic acid, lithocholic acid, 2-pyrocatechuic acid, prostaglandin E1, methionine, L-gulono-1,4-lactone, lactate in serum samples, and serine, allantoin, 5'-methylthioadenosine, taurine in urine samples. The metabolomics result indicated these metabolites were related to AFLD. These metabolites can be use as biomarker candidates for the healthy management and clinical application on AFLD.