| Conjugated linoleic acid (CLA) is a term used to describe positional and geometric isomers of linoleic acid with conjugated double bonds, in which c-9, t-11CLA and t-10, c-12CLA isomers have been shown to have a variety of biological activities. Studies indicated that CLA was also physiologically important to our health including anti-arteriosclerosis, anti-oxidation, immune enhancing properties, reduction in body fat accretion, muscle increasing and so on. Hence, it is necessary to establish rapid and accurate technology to analyze isomers of CLA before develop the research on physiologic activity of CLA. Although there are a number of researches on the function of CLA, there is few study about the influence of CLA on fatty acids of heart and brain. However, the composition of fatty acids plays an important role in heart-brain system and has close relationship with the development of high blood fats, high blood cholesterol and atherosclerosis (AS). Therefore it is highly significant to understand the changes in fatty acid composition in tissues caused by CLA supplementation. The aim of this study was to provide guides for preventing the cardiovascular disease using conjugated linoleic acid.Major content of this study: separate fat and fatty acids by TLC; separation of CLA was done by GC and Ag+-HPLC and determined qualitatively and quantitatively with different methyl esterify. The variety of fat and fatty acids of rat was observed after CLA added and malonaldehyde (MDA) value and the superoxide dismutase (SOD) value of rat blood serum was determined in order to realize the influence of CLA on oxidative stability in rat. The detail study was as follows:According to different existing form of CLA, CLA isomers has been changed least after methylized by TMS which is suitable for free fatty acids esterification, however, the acid and alkaline method have influenced on CLA composition. The composition of CLA is easy to isomerize with acid catalyst which increases tt-CLA of free and triglyceride style CLA. It is not good for separating 8tl0t, 9t11t, 10t12t, 8t10c and 9c11c-CLA by GC. However, those CLA isomers could be separated by Ag+-HPLC. So, it is better to combine the GC and HPLC together to determine CLA.It is efficient to separate free fatty acids, triglyceride and phospholipids by TLC. Trans fatty acids is separated well by Ag+-TLC. A three directional TLC system is used to determine the phospholipid acid content.CLA changed the fatty acids composition of fatty acids of atherosclerotic animal tissue, increased n-3 PUFA, reduced n-6 PUFA and the ratio of n-6PUFA and n-3 PUFA, which prevent thromb and improve atherosclerotic of rat. It is sure that correlation between n-3 PUFA and n-6 PUFA is observed and fatty acids in the same series could keep balance by metabolism, which indicated that CLA may reduce the cardiovascular disease. The change of cholesterol and LDL in rat serum after CLA added was observed. CLA increase the saturated fatty acids of phospholipids.The oxidative stability of CLA was investigated by determining the oxidative stability in vitro and inhibited by BHT. When vitamin E is not sufficient, CLA would augment oxidation of rat serum, however, SOD evaluated when low doses of CLA took in. Therefore, we should take the doses of CLA and antioxidant into account when using CLA as functional fatty acids in order to reduce negative effect.
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