In vivo incorporation of lauric acid into rat adipose tissue triacylglycerols

Preparative gas chromatography and its applications

Although hundreds of papers related to preparative gas chromatography (pGC) have been published since the late 1950s, the success of the GC technique has largely been associated with analytical instead of preparative purposes. Actually, pGC is an ideal alternative technique for the preparation of pure substances, especially volatile compounds. This paper reviews the papers (written in English) associated with pGC published over the period from the 1950s to the 2010s. For large scale preparation, large sample injection and vaporization, a high loading capacity column, a gas splitter at the end of the column and a special collecting device are fundamentally important for a pGC system. The primary components of pGC system, including injector, column, splitter, detector and collection traps, are briefly introduced. Furthermore, the applications of pGC in the separation and purification of volatile compounds from natural essential oils, in addition to the purification of isotopes, isomers and enantiomers are summarized.

Stereospecific incorporation of palmitoyl, oleoyl and linoleoyl moieties into adipose tissue triacylglycerols of rats results in constant sn-1:sn-2:sn-3 in rats fed rapeseed, olive, conventional or high oleic sunflower oils, but not in those fed coriander oil

We report the stereospecific (sn-1, sn-2, sn-3) distribution of fatty acids in subcutaneous adipose tissue triacylglycerols of male weaned Wistar rats fed either a standard diet or diets containing, in addition to 20 g corn oil/kg feed, 120 g/kg feed, each, of canola-type rapeseed oil, olive oil, conventional or high oleic sunflower oil or high petroselinic coriander oil for 10 wk. The regiospecific distribution of the major acyl moieties in the sn-1 (3) vs. sn-2 positions of the adipose tissue triacylglycerols broadly reflected that of the dietary oils. The saturated palmitoyl and stearoyl moieties were more abundant in the sn-1 and sn-3 positions compared with the sn-2 position of the adipose tissue triacylglycerols, and both occurred at a higher proportion in the sn-1 than in the sn-3 position. Oleoyl moieties were abundant in all the three positions of the adipose tissue triacylglycerols, whereas petroselinoyl moieties were more abundant in the sn-1 and sn-3 positions compared with the sn-2 position. Linoleoyl moieties occurred predominantly in the sn-2 position compared with the sn-1 and sn-3 positions of the adipose tissue triacylglycerols; however, they were more abundant in the sn-3 than in the sn-1 position. Despite widely varying proportions of the palmitoyl, oleoyl and linoleoyl moieties at the three positions of the dietary triacylglycerols, the ratios of each of these acyl moieties at the sn-1, sn-2, and sn-3 positions in adipose tissue triacylglycerols were essentially constant for all groups, with the exception of the group fed coriander oil, indicating a rigid stereospecific incorporation.

The composition of the major molecular species of adipose tissue triacylglycerols of rats reflects those of dietary rapeseed, olive and sunflower oils

We report the composition of constituent fatty acids and molecular species of adipose tissue triacylglycerols of male weaned Wistar rats fed diets containing, in addition to 20 g corn oil/kg feed, 120 g per kg feed canola-type rapeseed oil, olive oil or conventional sunflower oil for 10 wk. The composition of fatty acids and molecular species of the triacylglycerols of subcutaneous, epididymal and perirenal adipose tissues did not differ among groups (P > 0.01), broadly reflecting the corresponding compositions of the dietary oils. The major molecular species of dietary triacylglycerols, especially trioleoylglycerol (OOO) and linoleoyl-dioleoylglycerols (LOO) in the rapeseed oil and olive oil diets, dioleoyl-palmitoylglycerols (OOP) in the olive oil diet, dilinoleoyl-oleoylglycerols (LLO) in the rapeseed oil and sunflower oil diets, and dilinoleoyl-palmitoylglycerols (LLP), linoleoyl-oleoyl-palmitoylglycerols (LOP) as well as trilinoleoylglycerol (LLL) in the sunflower oil diet were also prominent constituents of the corresponding adipose tissue triacylglycerols. On the other hand, predominant molecular species containing alpha-linolenoyl (Ln) moieties, e.g., alpha-linolenoyl-linoleoyl-oleoylglycerols (LnLO) and alpha -linolenoyl-dioleoylglycerols (LnOO) from the rapeseed oil diet were not prominent constituents of rat adipose tissue triacylglycerols, whereas LOP from rapeseed oil and olive oil diets and OOP from rapeseed oil and sunflower oil diets were distinctly enriched in the corresponding adipose tissues. Most of the minor molecular species of the dietary triacylglycerols from all the three diets were distinctly present in the corresponding adipose tissues. Thus, despite numerous biochemical processes involved in the metabolism of dietary triacylglycerols, a substantial proportion of the molecular species of adipose tissue triacylglycerols containing linoleoyl (L), oleoyl (O) and palmitoyl (P) moieties resemble those of dietary triacylglycerols.

Composition and structure of triacylglycerols in brown adipose tissue of rats fed fish oil

This study examines the incorporation of highly unsaturated n-3 fatty acids (HUFA) into triacylglycerols (TAG) of brown adipose tissue (BAT), and their effect on the positional distribution of saturated (SFA) and of unsaturated (UFA) 16- or 18-carbon fatty acids. To this end, rats were fed a fish oil diet for up to four weeks. The stereospecific analysis of TAG was based on generation of sn-1,2- and sn-2,3-acylglycerols by Grignard degradation, followed by synthesis of phosphatidic acid and specific hydrolysis with phospholipase A2. From the end of the first week of fish oil feeding, a steady-state in the fatty acid composition of TAG in BAT was reached. HUFA concentration increased 30-fold, mainly at the expense of n-9 UFA and of SFA. The amount of SFA decreased selectively at position 3, where these fatty acids were progressively replaced by n-3 HUFA. By contrast, the amount of UFA decreased at all positions, and their positional distribution was not affected. About 60% of HUFA was incorporated at position 3. Nearly twice as much 22:6n-3 was incorporated into TAG than had been previously observed in white adipose tissue (WAT) [Leray, C., Raclot, T., and Groscolas, R. (1993) Lipids 28, 279-284]. At the steady-state, the distribution of HUFA was characterized by high proportions of 22:6n-3 and 20:5n-3 in position 3. Moreover, in each position of TAG, a steady level was reached rapidly (within 1 wk).(ABSTRACT TRUNCATED AT 250 WORDS)

Positional distribution of n-3 fatty acids in triacylglycerols from rat adipose tissue during fish oil feeding

The present study was designed to investigate the metabolism of the n-3 polyunsaturated fatty acids (PUFA) in adipose tissue and its dependence upon dietary factors. Changes in the positional distribution of the fatty acids in triacylglycerols from retroperitoneal adipose tissue were studied as a function of time on rats fed for 4 wk a diet enriched with fish oil. The stereospecific analysis of triacylglycerols by Grignard degradation. This was followed by synthesis of rac-phosphatidic acids and treatment with phospholipase A2. In the triacylglycerols of the fish oil diet, 57% of the total n-3 fatty acids were in position 3, i.e., two-thirds of 20:5n-3 and 22:5n-3 were esterified in sn-3 position, whereas 22:6n-3 was equally distributed in positions 2 and 3. After 4 wk of feeding fish oil, the fatty acid composition of adipose tissue triacylglycerols reached a steady state. Half of the n-3 fatty acids were found in position 3, namely 75% of 22:5n-3, 50% of 20:5n-3 and 18:4n-3 and 45% of 22:6n-3, the latter being equally distributed in positions 2 and 3. This pattern of distribution resembled that found in triacylglycerols of the fish oil diet, except for a higher proportion of 20:5n-3 in adipose tissue in position 1 at the expense of position 3. Throughout the 4-wk period of fish oil feeding, the distribution pattern of minor n-3 fatty acids (18:4n-3 and 22:5n-3) in adipose tissue triacylglycerols remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonessential fatty acids in formula fat blends influence essential fatty acid metabolism and composition in plasma and organ lipid classes in piglets

The n-6 and n-3 fatty acid status of developing organs is the cumulative result of the diet lipid composition and many complex events of lipid metabolism. Little information is available, however, on the potential effects of the saturated fatty acid chain length (8:0-16:0) or oleic acid (18:1) content of the diet on the subsequent metabolism of the essential fatty acids 18:2n-6 and 18:3n-3 and their elongated/desaturated products. The effects of feeding piglets formulas with fat blends containing either coconut oil (12:0 + 14:0) or medium chain triglycerides (MCT, 8:0 + 10:0) but similar levels of 18:1, 18:2n-6 and 18:3n-3, or MCT with high or low 18:1 but constant 18:2n-6 and 18:3n-3 on the fatty acid composition of plasma, liver and kidney triglycerides, phospholipids and cholesteryl esters, and of brain total lipid, were studied. Diet-induced changes in the fatty acid composition of lipid classes were generally similar for plasma, liver and kidney. Dietary 18:1 content was reflected in tissue lipids and was inversely associated with levels of 18:2n-6. Lower percentage of 18:2n-6, however, was not associated with lower levels of its elongated/desaturated product 20:4n-6 but was associated with higher levels of 22:6n-3. Feeding coconut oil vs. MCT resulted in lower 18:1 levels in all lipids, and higher percentages of 20:4n-6 in tissue phospholipid. Increasing the dietary n-6/n-3 ratio from 5 to 8 significantly increased tissue percentage of 18:2n-6 and decreased phospholipid 22:6n-3.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary linoleic acid content on the distribution of triacylglycerol molecular species in rat adipose tissue

The present study examined the effect of varying dietary linoleate intake (0.01, 0.24, 2.4, 24, 80 or 160 g/kg diet) for 24 weeks on the distribution of triacylglycerol (TG) molecular species in rat epididymal adipose tissue. Adipose TG fractions were purified by thin-layer chromatography and separated into different molecular species by reverse-phase high-performance liquid chromatography. The identification of TG species was based on fatty acid composition, retention time and the theoretical carbon number. When the dietary 18:2n-6 content was equal to or less than 24 g/kg, no significant amounts of n-6 fatty acids (mainly 18:2n-6) were observed in adipose tissue TG despite the fact that the levels of 20:4n-6 in liver phospholipids increased significantly. There were 12 major molecular species in adipose tissue when the dietary 18:2n-6 content was less than 2.4 g/kg. When the dietary 18:2n-6 content reached 24 g/kg, an additional six TG species containing one, two or three molecules of 18:2n-6 were observed. The levels of TG molecules containing two or three 18:2n-6 residues were further increased when the diet contained very large amounts of linoleic acid (160 g/kg). Conversely, those TG species containing only one 18:2n-6 residue became less abundant. It is suggested that the accumulation of these linoleate-rich TG molecular species in adipose tissue, particularly di- and trilinoleoyl containing TG, is the result of an adequate or an excessive intake of linoleic acid.

Medium chain length fatty acids stimulate triacylglycerol synthesis in tissue culture cells

In the presence of undecanoic acid (C11) or lauric acid (C12) the synthesis of triacylglycerols was stimulated up to 10-fold both in tumor cell lines and in normal cell lines. Monocarboxylic acids of shorter or longer chain length either had no effect at all or were less effective. The increased triacylglycerol production was demonstrated, on the one hand, by the incorporation of radiolabeled glycerol into triacylglycerols and, on the other, by the incorporation of radiolabeled monocarboxylic acids, the incorporation of all (1-14C)-labeled monocarboxylic acids (C6, C12, C16, C18) regardless of their chain length, being preferentially enhanced by C11 and C12. C12 stimulated the de novo synthesis of triacylglycerols to such a degree that a 7-fold increase in the total amount of triacylglycerols per cell was observed during the first 10 hr of incubation. After removal of C12 from the tissue culture medium levels of triacylglycerols reach initial values again within 6 hr, indicating that the stimulatory effect of C12 is dependent on its continued presence. This led to the speculation that medium chain length monocarboxylic acids might be involved in the control of triacylglycerol synthesis.

Determination of bovine butterfat triacylglycerols by reversed-phase liquid chromatography and gas chromatography

Triacylglycerols (TGs) from a sample of summer butterfat (bovine milk) were analysed and fractionated by reversed-phase liquid chromatography (RPLC). Fatty acid and TG composition of eac of the 47 RPLC fractions ranging from 0.1 to 6.9% were determined by capillary gas chromatography. The data were used together to determine the quantitative composition of the molecular species of TGs. A large number of TG species, accounting for 80% of the total, could be unequivocally identified and individually determined. The combination of the chromatographic methods used proved to be a powerful and accurate approach for the determination of molecular species of TGs in a complex fat, but also a difficult and time-consuming task.