Conjugated linoleic acid: an anticarcinogenic fatty acid present in milk fat
Conjugated linoleic acid: an anticarcinogenic fatty acid present in milk fat
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共轭亚油酸：乳脂中存在的一种抗癌脂肪酸
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
P. Parodi
中科院分区：
文献类型：
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作者：
P. Parodi
共轭亚油酸(CLA)是含有共轭不饱和度的亚油酸的位置和几何异构体的混合物。顺-9，反-11-十八碳二烯酸异构体是由瘤胃细菌Butyrivibrio fisolvens产生的亚油酸异构酶在反刍动物体内作为饲料亚油酸生物氢化的第一中间体。共轭亚油酸对7，12-二甲基苯并[a]蒽(DMBA)诱发的小鼠皮肤癌变、苯并[a]芘诱发的小鼠前胃肿瘤和DMBA诱发的大鼠乳腺肿瘤均有抑制作用。此外，CLA在体外对人恶性黑色素瘤、结直肠癌细胞和乳腺癌细胞具有细胞毒作用。顺-9，反-11-十八碳二烯酸是小鼠前胃和大鼠乳腺肿瘤磷脂中唯一的CLA异构体，被认为是生物活性因子。共轭亚油酸发挥抗癌活性的机制尚不清楚。然而，已发现它可以调节细胞色素P450的活性，减少鸟氨酸脱羧酶和蛋白激酶C的诱导，这是已知的肿瘤产生指标，并可能抑制蛋白质和核苷酸的生物合成。共轭亚油酸的一些抗癌特性可能是由于其有效的抗氧化特性。乳制品是共轭亚油酸最丰富的膳食来源，根据牧场条件的不同，乳脂可能含有高达30毫克/克的脂肪，并且主要是生物活性顺式-9，反式-11-异构体。一般来说，反刍动物的肉类脂肪比非反刍动物的脂肪含有更多的共轭亚油酸，后者可以通过饮食和亚油酸的一些细菌异构体来获得共轭乳酸。植物油和人造黄油只含有少量的共轭亚油酸。共轭亚油酸存在于人体组织和体液中，富含共轭亚油酸的饮食可提高血清水平
Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid containing conjugated unsaturation. The cis-9, trans-11-octadecadienoic acid isomer is produced in ruminant animals as a first intermediate in the biohydrogenation of dietary linoleic acid by a linoleic acid isomerase from the rumen bacteria Butyrivibrio fibrisolvens. CLA has been shown to inhibit initiation of mouse skin carcinogenesis by 7,12-dimethylbenz[a]anthracene (DMBA), mouse forestomach neoplasia induced by benzo[a]pyrene and rat mammary tumorgenesis induced by DMBA. Furthermore, CLA was shown to be cytotoxic to human malignant melanoma, colorectal and breast cancer cell lines in vitro. Cis-9, trans-11-octadecadienoic acid was the only CLA isomer incorporated into phospholipids of mouse forestomach and rat mammary tumors and is considered to be the biologically active factor. The mechanism whereby CLA exerts its anticarcinogenic activity is still uncertain. However, it has been found to modulate the activity of cytochrome P450 and reduce the induction of ornithine decarboxylase and protein kinase C, known tumor production indicators, and possibly inhibit protein and nucleotide biosynthesis. Some of the anti-carcinogenic properties of CLA may be due to its effective antioxidant properties. Dairy products are the richest dietary sources of CLA, depending upon pasture conditions, milk fat may contain up to 30 mg/g fat and is predominantly the biologically active cis-9, trans-11-isomer. In general, fat from meat of ruminant animals contains more CLA than fat from non-ruminants who may obtain their CLA by dietary means and some bacterial isomerism of linoleic acid. Vegetable oils and margarines only contain small amounts of CLA. CLA is present in the tissue and body fluid of humans and blood serum levels can be increased by diets rich in CLA