Determination of c9,t11-CLA in major human plasma lipid classes using a combination of methylating methodologies

Chromatographic Methods in the Separation of Long-Chain Mono- and Polyunsaturated Fatty Acids

This review presents various chromatographic systems, TLC, HPLC, GC, and also SFC, developed for identification and accurate quantification of long-chain mono- and polyunsaturated fatty acids from different samples with emphasis on selected literature which was published during last decade. Almost all the aspects such as preseparation step of fatty acids (cisandtrans), stationary phase, solvent system, and detection mode are discussed.

Effects of margarine and butter consumption on distribution of trans-18:1 fatty acid isomers and conjugated linoleic acid in major serum lipid classes in lactating women

Trans FA (TFA) have at least one trans double bond and comprise several isomers and types, including many of the CLA (e.g., c9,t11-18:2 CLA). Some TFA may have adverse effects (e.g., cardiovascular disease), whereas some are thought to have beneficial effects (e.g., anticarcinogenicity). The presence of TFA in human tissues and fluids is related to dietary intake, although this relationship is not completely understood--especially in regard to serum lipid fractions. This study was conducted as part of an investigation designed to test the influence of butter (B), "low TFA" margarine (LT), and regular margarine (RM) on milk fat content. Here we tested the secondary hypothesis that consumption of B, LT, and RM by lactating women would result in differential distribution of TFA and CLA in major serum lipid classes. Breast-feeding women (n = 11) participated in this randomized Latin-square study consisting of five periods: intervention I (5 d), washout I (7 d), intervention II (5 d), washout II (7 d), and intervention III (5 d). Extracted serum lipid was separated into cholesterol ester (CE), TAG, and phospholipid (PL) fractions and analyzed for total and isomeric TFA and CLA concentrations. Data indicate that TAG consistently contained the highest concentration of total t-18:1. No interaction between treatment and fraction was found for any of the t-18:1 isomers identified. Absolute concentration of each t-18:1 isomer was greatest during the RM period, regardless of fraction. On a relative basis, concentrations of t10-18:1 and t12-18:1 were most responsive to treatment in the CE fraction. The concentration of c9,t11-18:2 CLA was highest in the TAG fraction and lowest in the PL fraction, regardless of treatment. In summary, these results indicate (i) that there is a differential distribution of some isomeric TFA and CLA among human serum lipid fractions and (ii) that dietary TFA intake influences absolute and relative concentrations of some of the isomers in selected fractions.

Determination of conjugated linoleic acid in human plasma by fast gas chromatography

A new method for the determination of the main isomers of conjugated linoleic acid (CLA) in human and animal plasma was developed by gas chromatography coupled to flame ionization detection (GC-FID). The new method introduces three main advantages in comparison to the current available methodologies: firstly it does not require previous lipid extraction, secondly the chromatographic separation of CLA isomers was performed on an Rtx-2330 column significantly shorter and thinner than the typical long highly polar capillary columns in use that allows a faster analysis than in current methodologies, and thirdly the amount of sample needed to perform the analyses was substantially lower than the amount used in current routine methodologies. Its application to human plasma and rat plasma showed to be robust and reliable for quick and correct identification of the main CLA isomers in particular, and the total fatty acid profile in general, in routine analysis.

A direct method for fatty acid methyl ester synthesis: application to wet meat tissues, oils, and feedstuffs

A simplified protocol to obtain fatty acid methyl esters (FAME) directly from fresh tissue, oils, or feedstuffs, without prior organic solvent extraction, is presented. With this protocol, FAME synthesis is conducted in the presence of up to 33% water. Wet tissues, or other samples, are permeabilized and hydrolyzed for 1.5 h at 55 degrees C in 1 N KOH in MeOH containing C13:0 as the internal standard. The KOH is neutralized, and the FFA are methylated by H(2)SO(4) catalysis for 1.5 h at 55 degrees C. Hexane is then added to the reaction tube, which is vortex-mixed and centrifuged. The hexane is pipetted into a gas chromatography vial for subsequent gas chromatography. All reactions are conducted in a single screw-cap Pyrex tube for convenience. The method meets many criteria for fatty acid analysis, including not isomerizing CLA or introducing fatty acid artifacts. It is applicable to fresh, frozen, or lyophilized tissue samples, in addition to oils, waxes, and feedstuffs. The method saves time and effort and is economical when compared with other methods. Its unique performance, including easy sample preparation, is achieved because water is included rather than eliminated in the FAME reaction mixtures.

Lipid class distribution of fatty acids including conjugated linoleic acids in healthy and cancerous parts of human kidneys

In this study the FA compositions of healthy and cancerous human renal tissues from the same patients are compared with special reference to the CLA and PUFA content. CLA was preferentially incorporated into neutral lipid compared with phospholipid classes. Its distribution profile was similar to that of monounsaturated FA, but unlike that found with 18:2n-6. Different incorporation patterns were found for individual CLA isomers. Comparing renal cell carcinoma (RCC) and healthy kidney, the total CLA content was significantly lower in the cholesterylester fraction and significantly higher in the PE and PS fractions from RCC. The most significant differences between healthy and cancerous renal tissue were in the content of t10,c12-CLA. Furthermore, the lipid class distributions of n-6 PUFA were determined, and several significant differences between RCC and healthy renal tissue were found. This is of interest, as it has been proposed that the anticarcinogenic properties of dietary CLA are associated with their interference in the metabolism of 20:4n-6. The involvement of CLA in preventing renal cancer cannot be definitively demonstrated from the design of this study, nor was it intended, but the complete determination of the FA composition of adjacent healthy and cancerous tissues may provide an insight if lipids are involved in this disease.