Lyberg Ann-Marie, Adlercreutz Patrick
Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, SE-221 00 Lund, Sweden.
Lipids. 2006 Jan;41(1):67-76. doi: 10.1007/s11745-006-5072-z.
The oxidation of free DHA has been investigated with respect to monohydroperoxides and polyhydroperoxides, which were analyzed with a novel HPLC method. The temperature and physical system, i.e., bulk and liposome, were varied. We have also studied the effects of antioxidants such as alpha-tocopherol, ascorbic acid, and juice from sea buckthorn on DHA. The HPLC method, which was performed isocratically, eluted eight peaks, each containing one or two isomers of monohydroperoxy-DHA. This method showed that the double bond farthest from the carboxyl group was easily oxidized, as shown by the rapid increase in the amount of C20-monohydroperoxy-DHA, which always provided the largest contribution to the total amount of monohydroperoxides. The monohydroperoxy-DHA containing the hydroperoxy group located on the double bond nearest the carboxyl group also was shown to increase considerably during an increase in the total amount of monohydroperoxides. This demonstrates that the double bonds located nearest and farthest from the carboxyl group were the most prone to hydroperoxide formation. DHA was more stable when stored in liposomes than as bulk. Addition of alpha-tocopherol to the DHA-containing liposomes reduced the oxidation of these double bonds. The antioxidant effect of alpha-tocopherol was prolonged when combined with ascorbic acid, since alpha-tocopherol was regenerated.
已针对单氢过氧化物和多氢过氧化物对游离DHA的氧化进行了研究，这些过氧化物采用一种新型HPLC方法进行分析。温度和物理体系（即本体和脂质体）有所变化。我们还研究了抗氧化剂（如α-生育酚、抗坏血酸和沙棘汁）对DHA的影响。等度洗脱的HPLC方法洗脱了8个峰，每个峰包含一种或两种单氢过氧化DHA的异构体。该方法表明，离羧基最远的双键很容易被氧化，C20-单氢过氧化DHA的量迅速增加就表明了这一点，它对单氢过氧化物的总量贡献始终最大。在单氢过氧化物总量增加期间，含有位于离羧基最近的双键上的氢过氧基的单氢过氧化DHA也显示出大幅增加。这表明离羧基最近和最远的双键最容易形成氢过氧化物。DHA储存在脂质体中时比作为本体时更稳定。向含DHA的脂质体中添加α-生育酚可减少这些双键的氧化。当与抗坏血酸结合时，α-生育酚的抗氧化作用会延长，因为α-生育酚会再生。
