Docosahexaenoic acid

About: Docosahexaenoic acid is a research topic. Over the lifetime, 14412 publications have been published within this topic receiving 620852 citations. The topic is also known as: all-cis-DHA & all-cis-docosa-4,7,10,13,16,19-hexaenoic acid.

Formation of Amylose-Lipid Complexes and Effects of Temperature Treatment. Part 2. Fatty Acids

Abstract: This article is the second part of research on amylose-lipid complexes, where the first article dealt with monoglycerides. Here, a variety of fatty acids with chain lengths between 3 and 22 carbons and with varying degree of unsaturation were studied regarding their ability to form amylose-lipid complexes. In the present paper it is intended to investigate the formation of different fatty acid- amylose complexes under conditions that are not optimised for complex formation. Such conditions are common in the processing of starch. Differential scanning calorimetry (DSC) was used to analyse transition temperatures and enthalpies (H). The transition enthalpy H was taken as a measure of the quantity of the complexes in the samples. Except for the two shortest fatty acids (propionic and butyric acid), all the fatty acids showed DSC-peaks corresponding to transition of amylose-lipid complexes. Form II complexes, i.e. the crystalline form of the complex, were also formed for all fatty acids with a chain length of 12, even with polyunsaturated fatty acids. In this investigation, the amount and type of complexes formed do not reflect equilibrium conditions, but are instead a result of the rate of all the different sub-processes involved in complex formation, and these are influenced by the availability of the fatty acids and the heat treatment. The highest amounts of complexes were created by arachidonic and docosahexaenoic acid when the sample had not been subjected to any previous heat treatment. Heat treatment of the sample changed this and for heat treated samples the saturated palmitic and stearic acid yielded highest total amount of complexes. However, the ratio between complexes of form II and form I differed between the fatty acids complexes and during extended temperature treatment, most form II complexes were created by arachidonic and linoleic acid. Comparing the results from each fatty acid to the corresponding monoglyceride (with chain lengths of 10-18), it can be concluded that fatty acids seem to form complexes more easily than monoglycerides do, but monoglycerides create complex form II more easily than fatty acids, especially in case of shorter-chain lipids. (Less)

Partial substitution of fish oil with rapeseed, linseed and olive oils in diets for European sea bass (Dicentrarchus labrax L.): effects on flesh fatty acid composition, plasma prostaglandins E2 and F2α, immune function and effectiveness of a fish oil finishing diet

Abstract: Triplicate groups of European sea bass (Dicentrarchus labrax L.), of initial weight 90 g, were fed four practical-type diets in which the added oil was 1000 g kg−1 fish oil (FO) (control diet), 600 g kg−1 rapeseed oil (RO) and 400 g kg−1 FO, 600 g kg−1 linseed oil (LO) and 400 g kg−1 FO, and 600 g kg−1 olive oil (OO) and 400 g kg−1 FO for 34 weeks. After sampling, the remaining fish were switched to the 1000 g kg−1 FO diet for a further 14 weeks. Fatty acid composition of flesh total lipid was influenced by dietary fatty acid input but specific fatty acids were selectively retained or utilized. There was selective deposition and retention of docosahexaenoic acid (DHA; 22:6n-3). Eicosapentaenoic acid (EPA; 20:5n-3) and DHA were significantly reduced and linolenic (LNA; 18:3n-3), linoleic (LA; 18:2n-6) and oleic (OA; 18:1n-9) acids significantly increased in flesh lipids following the inclusion of 600 g kg−1 RO, LO and OO in the diets. No significant differences were found among different treatments on plasma concentrations of prostaglandin E2 and prostaglandin F2α. Evaluation of non-specific immune function, showed that the number of circulating leucocytes was significantly affected (P < 0.001), as was macrophage respiratory burst activity (P < 0.006) in fish fed vegetable oil diets. Accumulation of large amounts of lipid droplets were observed within the hepatocytes in relation to decreased levels of dietary n-3 HUFA, although no signs of cellular necrosis was evident. After feeding a FO finishing diet for 14 weeks, DHA and total n-3 HUFA levels were restored to values in control fish although EPA remained 18% higher in control than in the other treatments. This study suggests that vegetable oils such as RO, LO and OO can potentially be used as partial substitutes for dietary FO in European sea bass culture, during the grow out phase, without compromising growth rates but may alter some immune parameters.

Highly Unsaturated Fatty Acid Synthesis in Atlantic Salmon: Characterization of ELOVL5- and ELOVL2-like Elongases

Abstract: Fish species vary in their capacity to biosynthesize the n-3 long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids that are crucial to the health of higher vertebrates. The synthesis of LC-PUFA involves enzyme-mediated fatty acyl desaturation and elongation. Previously, a complementary DNA (cDNA) for an elongase, now termed elovl5a, had been cloned from Atlantic salmon. Here, we report on the cloning of two new elongase cDNAs: a second elovl5b elongase, corresponding to a 294-amino-acid (aa) protein, and an elovl2-like elongase, coding for a 287-aa protein, characterized for the first time in a nonmammalian vertebrate. Heterologous expression in yeast showed that the salmon Elovl5b elongated C18 and C20 PUFA, with low activity towards C22, while Elovl2 elongated C20 and C22 PUFA with lower activity towards C18 PUFA. All three transcripts showed predominant expression in the intestine and liver, followed by the brain. Elongase expression showed differential nutritional regulation. Levels of elovl5b and particularly of elovl2, but not of elovl5a, transcripts were significantly increased in liver of salmon fed vegetable oils (VO) compared to fish fed fish oil (FO). Intestinal expression showed a similar pattern. Phylogenetic comparisons indicate that, in contrast to salmon and zebra fish, Acanthopterygian fish species lack elovl2 which is consistent with their negligible ability to biosynthesize LC-PUFA and to adapt to VO dietary inclusion, compared to predominantly freshwater salmonids. Thus, the presence of elovl2 in salmon explains the ability of this species to biosynthesize LC-PUFA and may provide a biotechnological tool to produce enhanced levels of LC-PUFA, particularly DHA, in transgenic organisms.