Holman R T, Pusch F, Svingen B, Dutton H J
Hormel Institute, University of Minnesota, Austin 55912.
Proc Natl Acad Sci U S A. 1991 Jun 1;88(11):4830-4. doi: 10.1073/pnas.88.11.4830.
Linoleic acid (18:2 omega 6) and linolenic acid (18:3 omega 3) are precursors of two series of essential fatty acids (EFA) formed by alternate desaturations and elongations. In EFA deficiency (EFAD), oleic acid (18:1 omega 9) and palmitoleic acid (16:1 omega 7) undergo the same reactions to form polyunsaturated fatty acids (PUFA) of other structures. Partially hydrogenated soybean oil (PHSO) contains isomeric 18:1 acids that can be converted to unusual isomers of 18:2 by liver microsomes. To test whether 18:2, 20:3, and 20:4 of unusual structure occur in phospholipids as a consequence of EFAD or ingestion of PHSO, rats were fed corn oil, an EFA-deficient diet, or PHSO to provide isomeric 18:1 acids. At 2.5 months the phospholipids were isolated from livers and converted to methyl esters, and the 18:2, 20:2, 20:3, and 20:4 fractions were isolated. The 18:2 and 20:2 fractions were ozonized, and, by using a computer solution of simultaneous equations, the structures and proportions of each isomer were calculated. The 20:3 and 20:4 fractions were analyzed by ozonolysis and capillary gas chromatography. When corn oil was fed, the major isomer in each group was 9,12-18:2, 11,14-20:2, 8,11,14-20:3, and 5,8,11,14-20:4. Patterns in EFAD- and PHSO-fed groups were more diverse, with large proportions of unusual isomers. Feeding EFA-deficient diet and PHSO induced measurable amounts of unusual PUFA at each step of the cascade, and these PUFA may compete in metabolism of normal PUFA and are substrates for oxidative formation of autacoids of unknown structures and function.
亚油酸（18:2 ω6）和亚麻酸（18:3 ω3）是通过交替去饱和作用和延长反应形成的两类必需脂肪酸（EFA）的前体。在必需脂肪酸缺乏症（EFAD）中，油酸（18:1 ω9）和棕榈油酸（16:1 ω7）会经历相同的反应，形成其他结构的多不饱和脂肪酸（PUFA）。部分氢化大豆油（PHSO）含有异构化的18:1酸，这些酸可被肝微粒体转化为18:2的异常异构体。为了测试由于必需脂肪酸缺乏症或摄入部分氢化大豆油而导致的异常结构的18:2、20:3和20:4是否会出现在磷脂中，给大鼠喂食玉米油、必需脂肪酸缺乏的饮食或部分氢化大豆油以提供异构化的18:1酸。在2.5个月时，从肝脏中分离出磷脂并转化为甲酯，然后分离出18:2、20:2、20:3和20:4组分。对18:2和20:2组分进行臭氧化处理，并使用联立方程的计算机解决方案计算每种异构体的结构和比例。通过臭氧化分解和毛细管气相色谱法分析20:3和20:4组分。当喂食玉米油时，每组中的主要异构体为9,12-18:2、11,14-20:2、8,11,14-20:3和5,8,11,14-20:4。喂食必需脂肪酸缺乏饮食和部分氢化大豆油的组中的模式更加多样，含有大量异常异构体。喂食必需脂肪酸缺乏的饮食和部分氢化大豆油会在级联反应的每个步骤中诱导出可测量量的异常多不饱和脂肪酸，并且这些多不饱和脂肪酸可能会在正常多不饱和脂肪酸的代谢中产生竞争，并且是未知结构和功能的自分泌调节物质氧化形成的底物。
