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

研究了EPA反式异构体的生成和功能。(1) EPA乙酯反式异构体在亲水和疏水溶剂中均表现出更高的氧化稳定性。反式异构体对15-LOX的抗性也高于所有顺式异构体。异构体之间的结构和极性差异似乎是其稳定性的原因。(2)大鼠腹膜渗出细胞中炎症介质LTB4的产生不受反式异构体的影响。从细胞膜磷脂的脂肪酸分析来看，反式异构体似乎很难被纳入细胞膜。5-LOX更容易修饰反式异构体生成LTB4。这些结果表明，反式异构体的摄入导致了不同的生理功能诱导的所有顺式异构体。(3)常规蒸煮温度不能将所有顺式异构体转化为反式异构体。而自由基发射器AMVN也不产生反式异构体，NO2在室温下很容易诱导反式异构体的形成，这表明反式异构体的形成可能是在体内进行的，而食品添加剂亚硝酸盐可能在食品加工过程中诱导反式酸的形成。(4) EPA所有顺式异构体和反式异构体均显著抑制小鼠Bl6黑色素瘤细胞黑色素形成。

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.