食材萃取物對大鼠初代肝細胞中pi屬麩胱甘肽轉移酶蛋白質表現量的影響

The effects of various food extracts on pi form glutathione S-transferase protein expression in rat primary hepatocytes

劉佩佳(Pei-Chia Liu)

指導教授 ： 李宗貴

中山醫學大學/健康管理學院/營養學研究所/碩士(2006年)

https://doi.org/10.6834/CSMU.2006.00072

摘要

Glutathione S-transferase (GST)是重要的phaseⅡ藥物代謝酵素，GST透過催化glutathione (GSH)與多種親電子性外來物 (electrophilic xenobiotics)或內生性反應物結合，增加產物的水溶性，達到解毒目的。GST由多種異構酶 (isozymes)所組成，其中，pi型 (pGST)已知與多種癌症形成有關。本實驗比較熱、寒、涼多種食材萃取物對大鼠初代肝細胞中pGST蛋白質表現及GSH含量的影響。實驗材料共有肉桂、薑、洋蔥三種熱性食材；石蓮、山苦瓜肉、山苦瓜子三種寒性食材和黃菊、白菊二種涼性食材，分別以50%乙醇和乙酸乙酯進行連續萃取。SD大鼠初代肝細胞離體培養24小時後，加入各食材萃出物，再處理48小時。
結果顯示：(1)50%乙醇萃出物中，肉桂總酚類含量最高 (92.1±11.5 mg GAE/g)，薑、黃菊和白菊次之 (38-44 mg GAE/g)；乙酸乙酯萃出物總酚類含量最高為薑 (85±21.7 mg GAE/g)，白菊次之 (44.1±5.6 mg GAE/g)。(2)對pGST蛋白質表現量的影響上：肉桂、薑、黃菊和白菊無論是50%乙醇或乙酸乙酯萃出物均能誘發pGST，且呈現劑量依賴關係；石蓮則只有乙酸乙酯萃出物能誘發pGST。洋蔥、山苦瓜肉與山苦瓜子則無論50%乙醇或乙酸乙酯萃出物，對pGST蛋白質表現均無誘發或僅有些微效應。(3) 比較各食材相同溶劑萃出物對pGST表現之影響：50%乙醇萃出物在0.025 mg/ml劑量下，pGST誘發強度依序為肉桂＞黃菊＞白菊，其餘食材在此劑量則不影響pGST蛋白質表現。乙酸乙酯萃出物在0.025 mg/ml濃度下，pGST誘發強度依序為肉桂＝薑＞黃菊＝白菊＞石蓮。(4)在胞內GSH部份，僅見肉桂乙酸乙酯萃出物 (0.25 mg/ml)、薑乙酸乙酯萃出物 (0.25 mg/ml)與石蓮50%乙醇萃出物 (0.1 mg/ml)增加胞內GSH濃度 (p＜0.05)，且石蓮50%乙醇萃出物濃度增至0.25 mg/ml時，胞內GSH反而低於對照組 (p＜0.05)。
上述結果得知，除了洋蔥，共計熱、涼食材四種誘發pGST表現，寒性食材則較不具誘發效應，似乎顯示溫熱食材傾向誘發pGST表現；但食材熱、寒、涼屬性似乎與肝細胞內GSH含量無直接關係。由於本實驗所選用食材種類有限，仍須加大種類數量方能證實pGST表現可能與食材屬性有關。

關鍵字

pGST ； GSH ； 食材萃出物 ； 初代肝細胞 ； 大鼠

並列摘要

Glutathione S-transferase (GST) is one of the important phase Ⅱ drug-metabolizing enzymes. GST is responsible for catalyzing the conjugation of glutathione (GSH) to electrophilic xenobiotics and facilitates their excretion. GST has been grouped into several isozymes. Among these GST isozymes, pi form of GST (pGST) is known to be closely associated with the carcinogenesis. This study was designed to investigate various food plants on pGST protein expression and also on GSH content in rat primary hepatocytes. A total of three hot-foods (cinnamon, ginger, and onion), three cold-foods (Graptopetalum paraguayense E. (Gp) and the pulp and seed of wild bitter gourd (WBG)) and two cool-foods (yellow (YCM) and white Chrysanthemum morifolium (WCM)) were tested. Food plants were extracted sequentially by 50% ethanol (Et50) and ethyl acetate (EA).Twenty-four h post plating, hepatocytes were treated with ether EtOH or EA extract of each food plants for an additional 48 h.
Results show that: (1) on the phenolic contents: the Et50 extract of cinnamon had the highest total phenolic contents (92.07±11.49 mg GAE/g), following by ginger, YCM, and WCM (38-44 mg GAE/g ); the EA extract of ginger had the highest total phenolic contents (84.99±21.66 mg GAE/g), following by WCM. (2) on the pGST protein level: both Et50 and EA extracts of cinnamon, ginger, YCM, and WCM dose-dependently induced pGST expression. In contrast, the Et50 or EA extract of onion, WBGP, and WBGS had minor or lack of inducing effect on pGST. (3) on the relative potency of pGST induction among food plants: At the dose of 0.025 mg/ml Et50 extract, the inducibility of pGST protein level was cinnamon＞YCM＞WCM, the others had no effect. At the dose of 0.025 mg/ml EA extract, pGST protein level was cinnamon=ginger＞YCM=WCM＞GE, the other had no effect. (4) on the GSH contents: EA extracts of cinnamon and ginger and the Et50 extract of GE (0.1mg/ml) significantly increased intracellular GSH contents compared to control group (p＜0.05).
Results suggest the hot and cool foods tend to induce pGST expression, however, the cold-foods were lack of consistence. Only the EA extract of cinnamon and ginger and the Et50 extract of Gp significantly increased GSH content. The hepatic GSH content seems to have no direct relationship with the character food plants. The better understand the relationship between so called “ hot-cool-cold “ foods and pGST expression, more plant foods are needed to be examined before further conclusion could be made.

並列關鍵字

pGST ； Glutathione ； Food plants ； Primary hepatocytes ； Rats

參考文獻

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靜宜大學應用化學系碩士論文)

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