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Very long chain polyunsaturated fatty acids such as arachidonic acid (ARA, 20:4n-6), eicosapentaenoic acid (EPA, 20:5n-3), docosapentaenoic acid (DPA, 22:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) are essential components of cell membranes, and are precursors for a group of hormone-like bioactive compounds (eicosanoids and docosanoids) involved in regulation of various physiological activities in animals and humans. The biosynthesis of these fatty acids involves an alternating process of fatty acid desaturation and elongation. The desaturation is catalyzed by a unique class of oxygenases called front-end desaturases that introduce double bonds between the pre-existing double bond and the carboxyl end of polyunsaturated fatty acids. The first gene encoding a front-end desaturase was cloned in 1993 from cyanobacteria. Since then, front-end desaturases have been identified and characterized from a wide range of eukaryotic species including algae, protozoa, fungi, plants and animals including humans. Unlike front-end desaturases from bacteria, those from eukaryotes are structurally characterized by the presence of an N-terminal cytochrome b 5 -like domain fused to the main desaturation domain. Understanding the structure, function and evolution of front-end desaturases, as well as their roles in the biosynthesis of very long chain polyunsaturated fatty acids offers the opportunity to engineer production of these fatty acids in transgenic oilseed plants for nutraceutical markets.

:  Some effects of dietary medicinal herbs mixture (HM), Massa medicata fermentata, Crataegi fructus, Artemisia capillaries, and Cnidium officinale, in the proportions 2:2:1:1 were identified in juvenile Japanese flounder Paralichthys olivaceus. In an 8‐week feeding trial, fish were fed with 0.1, 0.3, 0.5, and 1.0% HM in a moist diet composed of horse mackerel and an artificial diet in equal parts. Fish fed the diets with 0.3, 0.5, and 1.0% HM showed higher weight gain and feed efficiency than fish in 0.1 and 0% HM feed groups. No significant differences were found in survival, feed intake, final carcass proximate composition, hemoglobin and hematocrit levels, plasma total cholesterol level, and alanine aminotransferase activity among the dietary treatments. Fish fed with 0.3, 0.5, and 1.0% HM showed higher total carcass unsaturated fatty acid content and docosahexaenoic acid (22:6n‐3) level, and plasma high density lipoprotein‐cholesterol level, but lower carcass saturated fatty acid content and plasma aspartate aminotrasferase activities than the control group. Moreover, a 10‐min air exposure test with five times repeat, and an anesthesia test for 2 min with 200 p.p.m. 2‐phenoxyethanol, also revealed lower mortality and lower recovery time in 0.3, 0.5, and 1.0% HM groups than the control group at the end of the trial. These results indicate that the medicinal herb mixture is useful to improve growth, fatty acid utilization, and stress recovery in the Japanese flounder.

Polymorphisms of the human Δ-5 ( FADS1 ) and Δ-6 ( FADS2 ) desaturase genes have been recently described to be associated with the level of several long-chain n-3 and n-6 polyunsaturated fatty acids (PUFAs) in serum phospholipids. We have genotyped 13 single nucleotide polymorphisms (SNPs) located on the FADS1 – FADS2 – FADS3 gene cluster (chromosome 11q12–13.1) in 658 Italian adults (78% males; mean age 59.7 ± 11.1 years) participating in the Verona Heart Project. Polymorphisms and statistically inferred haplotypes showed a strong association with arachidonic acid (C20:4n-6) levels in serum phospholipids and in erythrocyte cell membranes (rs174545 adjusted P value for multiple tests, P  < 0.0001 and P  < 0.0001, respectively). Other significant associations were observed for linoleic (C18:2n-6), alpha-linolenic (C18:3n-3) and eicosadienoic (C20:2n-6) acids. Minor allele homozygotes and heterozygotes were associated to higher levels of linoleic, alpha-linolenic, eicosadienoic and lower levels of arachidonic acid. No significant association was observed for stearidonic (C18:4n-3), eicosapentaenoic (C20:5n-3) and docosahexaenoic (C22:6n-3) acids levels. The observed strong association of FADS gene polymorphisms with the levels of arachidonic acid, which is a precursor of molecules involved in inflammation and immunity processes, suggests that SNPs of the FADS 1 and FADS 2 gene region are worth studying in diseases related to inflammatory conditions or alterations in the concentration of PUFAs.

In the present study we evaluated the uptake of ALA and its conversion to EPA + DHA in rats given linseed oil (LSO) in native form or as a microemulsion in whey protein or in lipoid. In a single oral dose study in which rats maintained on rodent pellets deficient in ω-3 fatty acids were intubated with 0.35 g LSO in lipoid, the amount of ALA present in lymph was increased reaching a maximum concentration of 16.23 mg/ml at 2.5 h. The amount of ALA present in lymph was increased to a maximum level of 10.95 mg/ml at 4 h in rats given LSO as a microemulsion in whey protein. When LSO was given without emulsification, the amount of ALA present in lymph was found to reach a maximum level of 7.08 mg/ml at 6 h. A similar result was observed when weaning rats were intubated with 0.15 g of LSO per day for a period of 60 days. Higher levels of ALA by 41 and 103 % were observed in lymph lipids of rats given microemulsions of LSO in whey protein and in lipoid respectively as compared to rats given LSO without pre-emulsification. Very little conversion of ALA to EPA and DHA was observed in lymph lipids but higher amounts of EPA + DHA was observed in liver and serum of rats given LSO in microemulsion form. This study indicated that ALA concentration in lymph lipids was increased when LSO was given in microemulsion form in lipoid and further conversion to EPA and DHA was facilitated in liver and serum.

Maresin-1 (MaR1) and Resolvin E1 (RvE1) are specialized pro-resolving lipid mediators (SPMs) that regulate inflammatory processes. We have previously demonstrated the hard and soft tissue regenerative capacity of RvE1 in an model of the periodontal disease characterized by inflammatory tissue destruction. Regeneration of periodontal tissues requires a well-orchestrated process mediated by periodontal ligament stem cells. However, limited data are available on how SPMs can regulate the regenerative properties of human periodontal ligament stem cells (hPDLSCs) under inflammatory conditions. Thus, we measured the impact of MaR1 and RvE1 in an model of hPDLSC under stimulation with IL-1β and TNF-α by evaluating pluripotency, migration, viability/cell death, periodontal ligament markers (α-smooth muscle actin, tenomodulin, and periostin), cementogenic-osteogenic differentiation, and phosphoproteomic perturbations. The data showed that the pro-inflammatory milieu suppresses pluripotency, viability, and migration of hPDLSCs; MaR1 and RvE1 both restored regenerative capacity by increasing hPDLSC viability, accelerating wound healing/migration, and up-regulating periodontal ligament markers and cementogenic-osteogenic differentiation. Protein phosphorylation perturbations were associated with the SPM-induced regenerative capacity of hPDLSCs. Together, these results demonstrate that MaR1 and RvE1 restore or improve the regenerative properties of highly specialized stem cells when inflammation is present and offer opportunities for direct pharmacologic treatment of lost tissue integrity.

Omega-3 polyunsaturated fatty acids (n-3 PUFA) are noted for their ability to diminish inflammatory and immune responses in vitro and in a variety of animal-based models of autoimmunity and inflammation. Yet, recent systematic reviews suggest that the evidence for these fatty acids having beneficial effects on inflammation or autoimmunity in humans is equivocal. A possible explanation for these disappointing and somewhat paradoxical findings emerged from the analyses described in this review. The available data on the changes in immune cell fatty acid profiles in mice, rats and humans, fed various forms and amounts of n-3 PUFA are summarized and displayed graphically. The dose-response curves generated provide new insights into the relationship between dietary n-3 PUFA and immune cell fatty acid profiles. The author suggests that the poor predictive value of most in vitro as well as many animal trials may, in part, be a consequence of the frequent adoption of experimental conditions that create differences in immune cell fatty acid profiles that far exceed what is possible in free-living humans through dietary intervention. Recommendations for improving the preclinical value of future in vitro and animal-based studies with n-3 PUFA are provided.

Lipid metabolism, inflammation, oxidative stress and endothelial function play important roles in the pathogenesis of cardiovascular disease (CVD), which may be affected by an imbalance in the n-6/n-3 polyunsaturated fatty acid (PUFA) ratio. This study aimed to investigate the effects of the n-6/n-3 PUFA ratio on these cardiovascular risk factors in rats fed a high-fat diet using plant oils as the main n-3 PUFA source. The 1:1 and 5:1 ratio groups had significantly decreased serum levels of total cholesterol, low-density lipoprotein cholesterol, and proinflammatory cytokines compared with the 20:1 group (p < 0.05). Additionally, the 20:1 group had significantly increased serum levels of E-Selectin, von Willebrand factor (vWF), and numerous markers of oxidative stress compared with the other groups (p < 0.05). The 1:1 group had a significantly decreased lipid peroxide level compared with the other groups (p < 0.05). Serum levels of malondialdehyde, reactive oxygen species and vWF tended to increase with n-6/n-3 PUFA ratios increasing from 5:1 to 20:1. We demonstrated that low n-6/n-3 PUFA ratio (1:1 and 5:1) had a beneficial effect on cardiovascular risk factors by enhancing favorable lipid profiles, having anti-inflammatory and anti-oxidative stress effects, and improving endothelial function. A high n-6/n-3 PUFA ratio (20:1) had adverse effects. Our results indicated that low n-6/n-3 PUFA ratios exerted beneficial cardiovascular effects, suggesting that plant oils could be used as a source of n-3 fatty acids to prevent CVD. They also suggested that we should be aware of possible adverse effects from excessive n-3 PUFA.

The purpose of the present study is to investigate the effects of krill oil and fish oil on serum lipids and markers of oxidative stress and inflammation and to evaluate if different molecular forms, triacylglycerol and phospholipids, of omega-3 polyunsaturated fatty acids (PUFAs) influence the plasma level of EPA and DHA differently. One hundred thirteen subjects with normal or slightly elevated total blood cholesterol and/or triglyceride levels were randomized into three groups and given either six capsules of krill oil (N = 36; 3.0 g/day, EPA + DHA = 543 mg) or three capsules of fish oil (N = 40; 1.8 g/day, EPA + DHA = 864 mg) daily for 7 weeks. A third group did not receive any supplementation and served as controls (N = 37). A significant increase in plasma EPA, DHA, and DPA was observed in the subjects supplemented with n-3 PUFAs as compared with the controls, but there were no significant differences in the changes in any of the n-3 PUFAs between the fish oil and the krill oil groups. No statistically significant differences in changes in any of the serum lipids or the markers of oxidative stress and inflammation between the study groups were observed. Krill oil and fish oil thus represent comparable dietary sources of n-3 PUFAs, even if the EPA + DHA dose in the krill oil was 62.8% of that in the fish oil.

The American Heart Association recommends consuming fish (particularly oily fish) at least two times per week, which would provide ≈ 0.5 g/day of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) for cardiovascular disease risk reduction. Previous analyses indicate that this recommendation is not being met; however, few studies have assessed different ethnicities, subpopulations requiring additional n-3 fatty acid intake (i.e., children and pregnant and/or lactating women), or deciles of intake. Data from the National Health and Nutrition Examination Survey 2003–2008 was used to assess n-3 fatty acid intake from foods and supplements in the US population, according to age, sex, and ethnicity. A unique “EPA equivalents” factor, which accounts for potential conversion of shorter-chain n-3 fatty acids, was used to calculate total long-chain n-3 fatty acid intake. Data are reported for 24,621 individuals. More than 90% consumed less than the recommended 0.5 g/day from food sources (median = 0.11 g/day; mean = 0.17 g/day). Among the top 15% of n-3 fatty acid consumers, fish was the largest dietary contributor (71.2%). Intake was highest in men aged 20 years or more, and lowest in children and women who are or may become pregnant and/or are lactating. Among ethnicities, intake was lowest in Mexican-Americans. Only 6.2% of the total population reported n-3 fatty acid supplement use, and this did not alter median daily intake. Additional strategies are needed to increase awareness of health benefits (particularly among Mexican-Americans and women of childbearing age) and promote consumption of oily fish or alternative dietary sources to meet current recommendations.

This study examined the effects of sesamin inclusion in vegetable oil-based diets fed to Atlantic salmon ( Salmo salar L.). The diets used differed in n-6/n-3 fatty acid (FA) ratio (0.5 and 1) and sesamin content (high 5.8 g/kg, low 1.16 g/kg and no sesamin). The oils used in the feeds were a mixture of rapeseed, linseed and palm oil. Fish were fed for 4 months. Fatty acids and expression of hepatic genes involved in transcription, lipid uptake, desaturation, elongation and β-oxidation were measured. No major effects on the percentage of DHA in white muscle, liver triacylglycerol and phospholipid fraction were detected. Genes involved in β-oxidation, elongation and desaturation were affected by sesamin addition. Limited effects were seen on any of the transcription factors tested and no effect was seen on the expression of peroxisome proliferator-activated receptors (PPAR). Expression of both SREBP-1 and SREBP-2 increased with sesamin addition. It was concluded that supplementation of fish feed with a high level of sesamin had a negative effect on the growth rate and live weight and did not alter the proportions of DHA in tissues even though gene expression was affected. Thus, more studies are needed to formulate a diet that would increase the percentage of DHA in fish without negative effects on fish growth.