Zambonin Laura, Ferreri Carla, Cabrini Luciana, Prata Cecilia, Chatgilialoglu Chryssostomos, Landi Laura
Dipartimento di Biochimica, Università di Bologna, Via Irnerio 48, 40126 Bologna, Italy.
Free Radic Biol Med. 2006 May 1;40(9):1549-56. doi: 10.1016/j.freeradbiomed.2005.12.021. Epub 2006 Jan 13.
Trans isomers of unsaturated fatty acids are absorbed from the diet, due to their presence in diary fat and hydrogenated vegetable oils, and health concern has risen due to their effects on lipid risk factors in cardiovascular diseases. On the basis of the efficiency of the thiyl-radical-catalyzed cis/trans isomerization in vitro and the presence of many sulfur-containing compounds in the cell, the aim of this study was to demonstrate that trans geometry of lipid double bonds can be endogenously generated within membrane phospholipids. The study reports trans fatty acids occurrence in tissue and erythrocyte phospholipids of young adult rats fed a diet completely free of trans isomers. Results show that tissues are differently prone to the endogenous isomerization and that, following a free radical attack, trans fatty acids can reach very high amounts. The effectiveness of this process is considerably inhibited in the presence of all-trans retinol, confirming previous data in model membranes. Our results suggest that geometrical isomerization of unsaturated fatty acids, which causes a structural modification of membrane lipids and may influence basic membrane properties and vital biochemical functions, can occur under radical stress conditions and could be efficiently prevented by vitamin A.
由于不饱和脂肪酸的反式异构体存在于乳脂肪和氢化植物油中，所以会从饮食中被吸收，并且由于它们对心血管疾病中脂质风险因素的影响，人们对其健康问题的关注度不断提高。基于体外硫自由基催化的顺/反异构化效率以及细胞中存在许多含硫化合物，本研究的目的是证明脂质双键的反式构型可在膜磷脂内源性生成。该研究报告了在喂食完全不含反式异构体饮食的年轻成年大鼠的组织和红细胞磷脂中反式脂肪酸的存在情况。结果表明，不同组织对内源性异构化的倾向不同，并且在自由基攻击后，反式脂肪酸的含量会非常高。在全反式视黄醇存在下，这一过程的效率会受到显著抑制，这证实了之前在模型膜中的数据。我们的结果表明，不饱和脂肪酸的几何异构化会导致膜脂质的结构改变，并可能影响基本的膜特性和重要的生化功能，这种异构化可在自由基应激条件下发生，并且维生素A可以有效地预防。
