探討紅甘藷葉對餵食炸油老鼠結直腸癌化生成之效應

Effect of purple sweet potato leaf on the colorectal carcinogenesis of oxidized frying oil-fed F344 rats

鄭雅分(Ya-Fen Chang)

指導教授 ： 劉珍芳

臺北醫學大學/公共衛生暨營養學院/保健營養學研究所/碩士(2005年)

摘要

本研究之目的乃在探討多酚類含量豐富之紅甘藷葉，對餵食炸油和腹腔注射DMH (1,2-dimethylhydrazine)之F344大鼠，所引發結直腸細胞之保護作用。DMH為專一誘發結腸癌之致癌物，已有許多研究將DMH作為誘發結腸癌形成之initiator。本實驗所使用之炸油為黃豆油經24小時，200±5℃油炸馬鈴薯而成。自國家動物中心購入，54隻5?6週雄性F344大白鼠，其中27隻經腹腔注射30 mg DMH/kg BW，每週一次，連續注射六週，再隨機分成3組 (n=9)，分別餵食含20%新鮮油之FD0組、20%炸油之OD0組及含有20%炸油及添加2.5%紅甘藷葉粉末之OD2.5組；對照組則分別為注射生理食鹽水之FS0、OS0、OS2.5。 大鼠餵食32週後予以犧牲，取出其肝臟、結腸組織、血漿進行分析。結果顯示，經24小時油炸之炸油其酸價及紫外光吸收值皆高於新鮮油，顯示油脂已有裂解和酸敗的現象。當給予高量炸油飲食 (OS0組) 之後大鼠體內之脂質過氧化物 (TBARS) 顯著高於等量新鮮油飲食組 (FS0)，然而其總抗氧化力 (TAS) 及抗氧化物—Vitamin E則低於新鮮油飲食組；當餵予含紅甘藷葉之炸油飼料 (OS2.5組) 後，TBARS顯著降低，同時TAS也有顯著的增加，並有節省Vitamin E消耗之作用。飼料中所添加紅甘藷葉之多酚類含量為37.95 mgGAE/g，血漿中所測得之多酚類含量OS2.5、OD2.5顯著地高於OS0、OD0組，但在肝臟中所測得之多酚類並無顯著差異。在結直腸部位腫瘤之發生情形顯示，對照組皆無腫瘤之生成，於注射DMH的各組中，則發現腫瘤發生率於FD0、OD0、OD2.5組分別為 66.7%、50% 、44.5%。在結直腸癌之前病灶Aberrant crypt foci (ACF) 及結直腸細胞增殖之生化指標Ornithine decarboxylase (ODC) 方面，發現ACF於三組間並無顯著差異，但攝食紅甘藷葉後 (OD2.5組)，可減少老鼠結直腸中ODC及COX-2蛋白質的表現量。由結果可知，飼料中添加紅甘藷葉可以改善餵食炸油所帶來老鼠體內之氧化壓力，並具有降低結直腸細胞病變之潛在效應。

關鍵字

炸油、DMH、紅甘藷葉、結直腸癌、ACF

並列摘要

The aim of this study was to investigate the effect of purple sweet potato leaf and oxidized frying oil (OFO) on colorectal carcinoma of F344 rats treated with DMH (1,2-dimethylhydrazine). Twenty-seven male F344 rats received 30mg/kg body weight DMH by intraperitoneal injection, once weekly for 6 weeks. Vehicle-treated groups received an equal volume of normal saline. Rats were assigned to 6 groups which diets containing 20% fresh soybean oil (FO): FS0 and FD0, 20% OFO: OS0 and OD0, 20% OFO with 2.5% purple sweet potato leaf: OS2.5 and OD2.5. Rats were sacrificed after feeding with experimental diets for 32 weeks; liver were examined for quinone reductase (QR)、cytochrome P450 (CYP450), colon for the measurements of Aberrant crypt foci (ACF)、Ornithine decarboxylase (ODC)、cycloxygenase-2 (COX-2), and plasma for total antioxidant status (TAS) thiobarbituric-acid-reactive-substances (TBARS). The results showed that CYP450 activity were elevated by OFO feeding. TAS was elevated and TBARS was decreased after feeding purple sweet potato leaf. Aberrant crypt foci had no significant difference in both OD0 and OD2.5. The results of ODC and COX-2 protein expression were lower in OD2.5 group. In conclusion, fed rats with purple sweet potato leaf could lower phase I enzyme activity, increase antioxidant activity, and decreased ODC and COX-2 protein expression. Keywords: purple sweet potato, colon cancer, Aberrant crypt foci , oxidized frying oil, 1,2-dimethylhydrazine

並列關鍵字

purple sweet potato, colon cancer, Aberrant crypt foci , oxidized frying oil, 1,2-dimethylhydrazine

參考文獻

林雅玲 (2004) 探討台灣鄉土蔬菜-紅甘藷葉中多酚類之生體可利用率及對人體抗氧化狀態之影響。台北醫學大學保健營養學研究所碩士論文。

吳依蟬 (2004) 探討飲食中油脂含量及品質對大鼠結直腸病變及促進癌化之作用。台北醫學大學保健營養學研究所碩士論文。

陳雅妍 (2002) 蕺菜對餵食炸油之大鼠肝解毒酵素系統之影響及其抗氧化與抗致突變力之效應。台北醫學大學保健營養學研究所碩士論文。

施純光 (2004) 薏仁對大腸癌形成之影響。國立台灣大學食品科技研究所博士論文。 陳美華、謝明哲、張瑞郎、蔡玉吉 (1983) 飼料中不同蛋白質含量對老鼠攝食炸油殘油之營養及毒性研究。中華民國營養學會雜誌8: 21-28。

Bird RP (1987) Observation and quantification of aberrant crypt foci in the murine colon treated with a colon carcinogen: preliminary findings. Cancer Lett 37: 147-151.