Chatgilialoglu Chryssostomos, Zambonin Laura, Altieri Alessio, Ferreri Carla, Mulazzani Quinto G, Landi Laura
ISOF, Consiglio Nazionale delle Ricerche, Bologna, Italy.
Free Radic Biol Med. 2002 Dec 15;33(12):1681-92. doi: 10.1016/s0891-5849(02)01143-7.
Thiyl radicals generated either from thiols or disulfides act as the catalyst for the cis-trans isomerization of a variety of monounsaturated fatty acid methyl esters in homogeneous solution. Similar results have also been obtained using alpha-lipoic acid and its reduced form. The effectiveness of the isomerization processes in the presence of the most common antioxidants has been addressed. The ability of thiyl radical scavenging was found to increase along the series alpha-tocopherol < ascorbic acid < all-trans retinol. The cis-trans isomerization of fatty acid residues in multilamellar vesicles of dioleoyl phosphatidyl choline by thiyl radical, in the absence and presence of the various antioxidants, has also been studied in detail. The influence of the isomerization process on the phospholipid bilayer has been tested by permeability measurements of vesicles and it is clearly shown that trans fatty acid-containing membranes have intermediate properties between those formed by all-cis and saturated components. This study contributes to the understanding of radical processes that can alter or protect the naturally occurring cis geometry of unsaturated lipids in cell membranes and demonstrates a new role of essential antioxidants.
由硫醇或二硫化物产生的硫自由基在均相溶液中作为多种单不饱和脂肪酸甲酯顺反异构化的催化剂。使用α-硫辛酸及其还原形式也得到了类似的结果。已探讨了在最常见抗氧化剂存在下异构化过程的有效性。发现硫自由基清除能力沿α-生育酚＜抗坏血酸＜全反式视黄醇的顺序增加。还详细研究了在不存在和存在各种抗氧化剂的情况下，硫自由基对二油酰磷脂酰胆碱多层囊泡中脂肪酸残基的顺反异构化。通过囊泡的渗透性测量测试了异构化过程对磷脂双层的影响，结果清楚表明，含反式脂肪酸的膜具有介于全顺式和饱和成分形成的膜之间的中间性质。这项研究有助于理解可改变或保护细胞膜中天然存在的不饱和脂质顺式几何结构的自由基过程，并证明了必需抗氧化剂的新作用。
