薏仁麩皮乙醇萃取之乙酸乙酯層區分物對DMH誘發F344鼠大腸癌前期病變之預防效果

Preventive effects of ethyl acetate fraction of adlay bran ethanolic extract on DMH-induced preneoplastic lesions of colon in F344 rats

許倖華(Hsing-Hua Hsu)

指導教授 ： 江文章

共同指導教授 ： 施純光

國立臺灣大學/生物資源暨農學院/食品科技研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02092

摘要

惡性腫瘤位居2007年台灣十大死因之首位，其中結腸直腸癌(大腸癌)高居惡性腫瘤死因的第三位；流行病學研究顯示大腸癌與飲食因子關係密切，因此藉由飲食預防大腸癌深具發展潛力。薏苡(adlay, Coix lachryma-jobi L. var. ma-yuen Stapf)為禾本科植物，是中國傳統藥食同源之食材，具有消炎和抗腫瘤等功效。近年來大腸癌的相關研究證實，在動物飼料中部分以糙薏仁、薏仁麩皮及薏仁麩皮乙醇萃取物取代皆能有效降低大腸癌癌前病變異常腺窩病灶(aberrant crypt foci, ACF)數目；且薏仁麩皮甲醇萃取之乙酸乙酯層區分物對人類大腸癌細胞株(human colon cancer cells,HT-29)具抑制生長的作用。本研究利用動物模式探討不同劑量的薏仁麩皮乙醇萃取之乙酸乙酯層區分物(ethyl acetate fraction of adlay bran ethanolic extract, ABE-Ea)對大腸癌的預防效果，並探討此區分物是否藉由調控發炎相關因子來影響大腸癌的致癌過程。實驗組別分成管餵蒸餾水之空白組(0.5 ml water/day； blank, B)、0.5%羧甲基纖維素(carboxymethyl cellulose, CMC)之負控制組(0.5 ml 0.5% CMC/day；negative control, NC)、抗發炎藥物 piroxicam之正控制組(1.50 mg piroxicam/day；positive control, PC)、薏仁麩皮乙醇萃取之乙酸乙酯層區分物低劑量組(8.64 mg ABE-Ea /day；low level of ABE-Ea, L)、薏仁麩皮乙醇萃取之乙酸乙酯層區分物中劑量組(17.28 mg ABE-Ea /day；medium level of ABE-Ea, M)及薏仁麩皮乙醇萃取之乙酸乙酯層區分物高劑量組(34.56 mg ABE-Ea /day；high level of ABE-Ea, H)，並腹腔注射1,2-dimethylhydrazin (DMH)誘發F344鼠大腸病變，DMH劑量為40 mg/kg body weight，每週注射一劑，共注射4週(空白組注射等劑量生理食鹽水)，誘發9週及18週後將動物犧牲，從形態學上觀察大腸癌癌前病變ACF、大腸黏液素(mucin)及大腸腫瘤生成的前驅指標MDF (mucin-depleted foci, 缺乏黏液素病灶)，並分析大腸黏膜上與發炎相關之誘導型一氧化氮合成酶(inducible nitric oxide synthase, iNOS)與第二型環氧合酶(cyclooxygenase-2, COX-2)的蛋白質表現量。實驗結果顯示，ABE-Ea顯著降低含1個異常腺窩之ACF數及抑制含7和8個異常腺窩之ACF的形成，顯示ABE-Ea能抑制ACF內腺窩的分裂；ABE-Ea些微降低遠端大腸之ACF數，並顯著抑制ACF上黏液素的轉變及抑制大腸黏膜COX-2蛋白的表現，顯示ABE-Ea可降低發炎反應而延緩大腸的癌化。實驗組中以17.28 mg/day組效果最好，結果顯示可顯著降低含1個異常腺窩之ACF數、降低單位長度之ACF數及抑制MDF的生成。本研究結果顯示ABE-Ea藉由影響不同類型的癌前病變及降低大腸的發炎反應，進而延緩大腸的癌化。

關鍵字

薏仁麩皮 ； 大腸癌 ； 異常腺窩病灶 ； 黏液素 ； 黏液素缺乏病灶 ； 誘導型一氧化氮合成酶第二型環氧合酶

並列摘要

Malignant neoplasm is the first cause of ten leading causes of death in 2007 in Taiwan and colorectal cancer is the third cause of cancer death in Taiwan. Epidemiological studies have indicated that colorectal cancer is strongly associated with diet, and thus the occurrence of colorectal cancer may be prevented by dietary modification. Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) is a grass crop used in traditional Chinese medicine and as a nutritious food. It has been reported that adlay pocesses anti-inflammatory and anti-tumor activity. In animal model, recent studies have shown that diet substituted with 20% dehulled adlay, 1.6% adlay bran and 0.29% ethanolic extract of adlay bran can significantly suppress the formation of preneoplastic lesions (aberrant crypt foci, ACF) in colon carcinogenesis. In addition, ethyl acetate fraction of adlay bran methanolic extract exhibited the growth-inhibiting effect on HT-29 human colon cancer cells. The purpose of this study was to investigate the effect of different levels of ethyl acetate fraction of adlay bran ethanolic extract (ABE-Ea) on colon carcinogenesis in animal model and to investigate whether ABE-Ea could affect colon carcinogenesis through modulation of inflammation-related proteins. Male F344 rats consumed different samples (blank: 0.5 ml water/day, negative control: 0.5% carboxymethyl cellulose /day, positive control: 1.50 mg piroxicam/day, low level of ABE-Ea: 8.64 mg ABE-Ea/day, medium level of ABE-Ea: 17.28 mg ABE-Ea/day, high level of ABE-Ea: 34.56 mg ABE-Ea/day) by tube feeding and received colon-specific carcinogen 1,2-dimethylhydrazin (DMH) by intraperitoneal injection (40 mg/kg body weight, once a week for 4 weeks, blank were received the same dosage of normal saline). After 9 and 18 weeks of induction, rats were sacrificed and colons were removed to examine for ACF, mucin and mucin-depleted foci (MDF, preneoplastic lesions of colon cancer). Colonic mucosa was examined for inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression. The results indicated that ABE-Ea significantly reduced the numbers of ACF with 1 crypt and inhibited the formation of ACF with 7 and 8 crypts, showing that ABE-Ea could suppress the fission of ACF. ABE-Ea slightly reduced the numbers of ACF in distal colons, significantly suppressed the mucin alteration of ACF and significantly suppressed the COX-2 expression in overall colons, showing that ABE-Ea could delay the colon carcinogenesis by suppressing colonic inflammation. ABE-Ea at the level of 17.28 mg/day exhibited the best preventive effects on colon carcinogenesis as it significantly reduced the number of ACF with 1 crypt, reduced the number of ACF/cm and inhibited the formation of MDF. Results from this study suggest that ABE-Ea reduces different preneoplastic lesions, reduces colonic imflammation and thus delays colon carcinogenesis.

並列關鍵字

adlay bran ； colon cancer ； aberrant crypt foci (ACF) ； mucin ； mucin-depleted foci (MDF) ； inducible nitric oxide synthase (iNOS) ； cyclooxygenase-2 (COX-2)

參考文獻

王德宏教授消化醫學基金會。2000。腸治久安-淺談大腸直腸疾病。健康文化事業股份有限公司。p.158-168。

施純光。2004。薏仁對大腸癌形成之影響。國立臺灣大學食品科技研究所博士論文。臺北。

謝銘鈞。2004。臺大內科學講義。橘井文化事業股份有限公司。p.617-624。

李明怡。2008。薏仁麩皮中防癌即抗發炎活性成分之分離與鑑定。國立臺灣大學食品科技研究所博士論文初稿。臺北。

林紓慧。2007。薏苡麩皮乙醇萃取物及乙醇萃取殘餘物對F344鼠大腸癌前期病變預防效果之探討。臺北醫學大學保健營養學系碩士論文。臺北。