The identification and role of a novel eicosanoid in the reproductive behaviour of barnacles (Balanus balanus)

Marine unsaturated fatty acids: structures, bioactivities, biosynthesis and benefits

Unsaturated fatty acids (UFAs) are an important category of monounsaturated and polyunsaturated fatty acids with nutritional properties. These secondary metabolites have been obtained from multitudinous natural resources, including marine organisms. Because of the increasing numerous biological importance of these marine derived molecules, this review covers 147 marine originated UFAs reported from 1978 to 2018. The review will focus on the structural characterizations, biological properties, proposed biosynthetic processes, and healthy benefits mediated by gut microbiota of these marine naturally originated UFAs.

Lipids, fatty acids and hydroxy-fatty acids of Euphausia pacifica

Euphausia pacifica is a good candidate for a resource of marine n-3 PUFA. However, few reports exist of the lipid and fatty acid composition of E. pacifica. To examine the potential of E. pacifica as a resource of marine n-3 PUFA, we analyzed E. pacifica oil. We extracted lipids from E. pacifica harvested from the Pacific Ocean near Sanriku, Japan. Lipid classes of E. pacifica oil were analyzed by TLC-FID and the fatty acid composition of the oil was analyzed by GC/MS. Free fatty acids and hydroxy-fatty acids were analyzed by LC/QTOFMS. The lipid content of E. pacifica ranged from 1.30% to 3.57%. The ratios of triacylglycerols, phosphatidylcholine, phosphatidylethanolamine and free fatty acids in E. pacifica lipids were 5.3-23.0%, 32.6-53.4%, 8.5-25.4% and 2.5-7.0%, respectively. The content of n-3 PUFA in E. pacifica lipids was 38.6-46.5%. We also showed that E. pacifica contains unusual fatty acids and derivatives: C16-PUFAs (9,12-hexadecadienoic acid, 6,9,12-hexadecatrienoic acid and 6,9,12,15-hexadecatetraenoic acid) and hydroxy-PUFAs (8-HETE and 10-HDoHE). E. pacifica is a good resource of marine n-3 PUFA. Moreover, E. pacifica can provide C16-PUFA and hydroxy-PUFAs.

Differential regulation of the lipoxygenase pathway in shrimp hepatopancreases and ovaries during ovarian development in the black tiger shrimp Penaeus monodon

Dietary polyunsaturated fatty acids (PUFAs) are critical to the success of ovarian development in marine crustaceans, especially for domesticated species such as the black tiger shrimp Penaeus monodon. These fatty acids are stored in a midgut gland called the hepatopancreas and subsequently serve as an energy source or are incorporated in yolk during ovarian development. PUFAs are known precursors of hydroxy fatty acids, including hydroxyeicosatetraenoic acid and hydroxyeicosapentaenoic acid (HEPE), which are catalyzed by lipoxygenases (LOX). In previous studies, 8-HEPE has been shown to regulate female reproduction and adipogenesis in marine crustaceans. However, whether the biosynthesis of 8-HEPE in these species is the result of LOX activity has yet to be investigated. In this study, 8-HEPE was identified exclusively in P. monodon hepatopancreases using liquid chromatography-mass spectrometry. Treatment with nordihydroguaiaretic acid resulted in the reduction of 8-HEPE, suggesting the enzyme-dependent catalysis of 8-HEPE in hepatopancreases. Additionally, a full-length P. monodon LOX (PmLOX) was amplified from shrimp ovary cDNA. Sequence analysis revealed that the putative PmLOX contains domains and catalytic residues required for LOX catalytic function. Furthermore, PmLOX expression increased steadily as shrimp ovary maturation progressed, while PmLOX expression and the amount of 8-HEPE decreased in shrimp hepatopancreases. These findings not only suggest differential requirements for hydroxy fatty acid biosynthesis in shrimp ovaries and hepatopancreases during the P. monodon ovarian development, but also provide insights into the LOX pathway in marine crustaceans.

Emerging importance of omega-3 fatty acids in the innate immune response: molecular mechanisms and lipidomic strategies for their analysis

The beneficial health properties of dietary omega-3 polyunsaturated fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have long been known and their metabolic dysfunction has been linked to a range of diseases including various inflammatory disorders, cardiovascular diseases, and cancer. However, the molecular mechanisms underlying their health benefits have remained unclear. Recent technological advances in lipidomic analytical strategies have resulted in the discovery of a range of bioactive mediators derived from EPA and DHA that possess potent anti-inflammatory and pro-resolving properties and that may be responsible, at least in part, for the beneficial effects observed. These mediators include resolvins, protectins and maresins, as well as EPA derivatives of classical arachidonic acid derived eicosanoids, such as prostaglandin E3 . The aim of this review is to provide an overview of the biosynthetic pathways and biological properties of these omega-3 mediators, with a particular focus on the emerging importance of the counter-regulatory role of omega-3 and -6 fatty acids in the spatial and temporal regulation of the inflammatory response. It will also provide an insight into a range of lipidomic approaches, which are currently available to analyse these fatty acids and their metabolites in biological matrices.

Marine natural products

This review covers the literature published in 2006 for marine natural products, with 758 citations (534 for the period January to December 2006) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, cnidaria, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (779 for 2006), together with their relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

Biosynthesis and functions of eicosanoids generated by the coelomocytes of the starfish, Asterias rubens

Eicosanoids are a group of oxygenated fatty acid derivatives formed from C20 polyunsaturated fatty acids, including arachidonic and eicosapentaenoic acids. The potential of the coelomocytes of the starfish, Asterias rubens, to generate eicosanoids through the cyclooxygenase (COX) and lipoxygenase (LOX) pathways was investigated using reverse-phase high performance liquid chromatography, enzyme immunoassay and gas chromatography-mass spectrometry. The principal LOX product was identified as 8-hydroxyeicosatetraenoic acid (8-HETE) with 8-hydroxyeicosapentaenoic acid (8-HEPE) synthesised at significantly lower levels. No classical prostaglandins (PG), such as PGE2 or PGD2, were found to be generated by ionophore-challenged coelomocytes. Incubation of coelomocytes with lipopolysaccharides from either Escherichia coli or Salmonella abortus failed to induce an increase in generation of LOX products and the presence of 8-HETE (0-25 microM) had no significant effect on the in vitro phagocytic activity of Asterias coelomocytes. Neither indomethacin (a COX inhibitor) or esculetin (a LOX inhibitor) had any effect on the clearance of the bacterium, Vibrio splendidus, from the coelomic cavity of starfish suggesting that products of these enzymes are not involved in such coelomocyte responses to foreign particles.