BIO-MODULATING FUNCTIONS OF TRANS ISOMERS OF POLYUNSATURATED FATTY ACIDS ORIGINATING FROM MARINE LIVES

研究了EPA反式异构体的产生及其功能。(1)EPA乙酯反式异构体在亲水和疏水溶剂中的氧化稳定性均高于其顺式异构体。反式异构体对15-LOX的抗性也高于顺式异构体。异构体之间的结构和极性差异似乎是其稳定性的原因。(2)反式异构体对大鼠腹膜渗出细胞产生炎症介质LTB4的影响不大。从细胞膜中磷脂的脂肪酸分析来看，反式异构体似乎很难进入细胞膜。5-LOX更容易对反式异构体进行修饰，生成LTB4。这些结果表明，摄入反式异构体会导致所有顺式异构体的不同生理功能的诱导。(3)常规烹饪温度并不能将所有顺式异构体转化为反式异构体。虽然自由基发射体AMVN也不产生反式异构体，但NO2在室温下很容易诱导出反式异构体，这表明反式异构体的可能形成是在体内进行的，因为食品添加剂亚硝酸盐可能会在食品加工过程中诱导反式酸的形成。(4)EPA的所有顺式异构体和反式异构体都显著抑制了小鼠BL6黑色素瘤细胞黑素的形成。

Production and functions of EPA trans isomers were investigated.(1) EPA ethyl ester trans isomers showed higher oxidative stability compared with its all cis isomer both in hydrophilic and hydrophobic solvents. The trans isomers also showed higher resistant against 15-LOX than the all cis isomer. The structural and polar difference between isomers seemed to be responsible for their stability properties.(2) Production of LTB4, a mediator of inflammation, in rat peritoneal exudate cells was not affected by the trans isomers very much. Judging from fatty acid analysis of phospholipids in the cell membrane, the trans isomers seem to be difficult to be incorporated into the membrane. 5-LOX more easily modified the trans isomers to produce LTB4. These results suggested that intake of the trans isomers lead to induction of different physiological functions from the all cis isomer.(3) Conventional cooking temperature did not convert the all cis isomer into the trans isomers. While AMVN, a radical emitter, also produced no trans isomer, NO2 very easily induced the isomer at room temperature suggesting that the possible formation of the trans isomers proceeds in vivo anal nitrite as food additives may induce formation of the trans acids during food processing.(4) Melanin formation in mouse Bl6 melanoma cells were significantly suppressed by both all cis isomer and trans isomers of EPA.