Yang Lin, Huang Yu, James Anthony E, Lam Lik Wang, Chen Zhen-Yu
Department of Chemistry, Henan Normal University, Henan, China.
J Agric Food Chem. 2002 Aug 14;50(17):4941-6. doi: 10.1021/jf020363d.
The incorporation pattern of conjugated linoleic acids (CLA) isomers into the egg yolk of hens in relation to that in the diet was studied. Silver-ion high-performance liquid chromatography (Ag-HPLC) was used to separate individual CLA isomers. It was found that the isomeric distribution pattern in the egg yolk lipids was different from that in the dietary fat. Total cis/trans isomers accounted for 81.2% of total CLA incorporated into the egg yolk, which was in contrast to the value of 92.0% of total CLA in the diet. Total cis/cis isomers accounted for 3.8% total CLA in the diet but they were 6.6% of the total CLA in the egg yolk lipids. In contrast, total trans/trans isomers were 12.2% of the total CLA isomers in the egg yolk lipids, whereas they were only 4.2% of total CLA in the diet. The results showed that total trans/trans-CLA was preferentially incorporated into the egg yolk, whereas the incorporation of total cis/trans-CLA isomers was partially discriminated. Within each group, the incorporation of individual isomers into the egg yolk lipids was also selective. cis-9,trans-11/trans-9,cis-11 and cis-10,trans-12/trans-10,cis-12 were the two major isomers in the diet. Ag-HPLC analysis showed that the former was preferentially transferred into the egg yolk compared with the latter. It was observed that supplementation of CLA in the diet of laying hens decreased the concentration of oleic acid (18:1n-9), arachidonic acid (20:4n-6), and docosahexaenoic acid (22:6n-3) but increased that of linolenic acid (18:3n-3), stearic acid (18:0), and palmitic acid (16:0) in the egg yolk, suggesting that CLA may inhibit Delta6 and Delta9 desaturases.
研究了共轭亚油酸（CLA）异构体在母鸡蛋黄中的掺入模式及其与日粮中掺入模式的关系。采用银离子高效液相色谱法（Ag-HPLC）分离各CLA异构体。结果发现，蛋黄脂质中的异构体分布模式与日粮脂肪中的不同。蛋黄中总顺式/反式异构体占掺入CLA总量的81.2%，这与日粮中CLA总量92.0%的值形成对比。总顺式/顺式异构体占日粮中CLA总量的3.8%，但在蛋黄脂质中占总CLA的6.6%。相反，总反式/反式异构体在蛋黄脂质中占CLA异构体总量的12.2%，而在日粮中仅占CLA总量的4.2%。结果表明，总反式/反式CLA优先掺入蛋黄，而总顺式/反式CLA异构体的掺入则受到部分歧视。在每组中，各异构体掺入蛋黄脂质的过程也是有选择性的。顺式-9，反式-11/反式-9，顺式-11和顺式-10，反式-12/反式-10，顺式-12是日粮中的两种主要异构体。Ag-HPLC分析表明，前者比后者更优先转移到蛋黄中。观察到在蛋鸡日粮中添加CLA会降低蛋黄中油酸（18:1n-9）、花生四烯酸（20:4n-6）和二十二碳六烯酸（22:6n-3）的浓度，但会增加亚麻酸（18:3n-3）、硬脂酸（18:0）和棕榈酸（16:0）的浓度，这表明CLA可能抑制Δ6和Δ9去饱和酶。
