Free radical-dependent inhibition of prostaglandin endoperoxide H Synthase-2 by nitro-arachidonic acid.

Prostaglandin endoperoxide H synthase (PGHS) is a heme-enzyme responsible for the conversion of arachidonic acid (AA) to prostaglandin H2 (PGH2). PGHS have both oxygenase (COX) and peroxidase (POX) activities and is present in two isoforms (PGHS-1 and -2) expressed in different tissues and cell conditions. It has been reported that PGHS activity is inhibited by the nitrated form of AA, nitro-arachidonic acid (NO2AA), which in turn could be synthesized by PGHS under nitro-oxidative conditions. Specifically, NO2AA inhibits COX in PGHS-1 as well as POX in both PGHS-1 and -2, in a dose and time-dependent manner. NO2AA inhibition involves lowering the binding stability and displacing the heme group from the active site. However, the complete mechanism remains to be understood. This review describes the interactions of PGHS with NO2AA, focusing on mechanisms of inhibition and nitration. In addition, using a novel approach combining EPR-spin trapping and mass spectrometry, we described possible intermediates formed during PGHS-2 catalysis and inhibition. This literature revision as well as the results presented here strongly suggest a free radical-dependent inhibitory mechanism of PGHS-2 by NO2AA. This is of relevance towards understanding the underlying mechanism of inhibition of PGHS by NO2AA and its anti-inflammatory potential.

Anti-inflammatory signaling actions of electrophilic nitro-arachidonic acid in vascular cells and astrocytes.

Nitrated derivatives of unsaturated fatty acids (nitro-fatty acids) are being formed and detected in human plasma, cell membranes and tissue, triggering signaling cascades via covalent and reversible post-translational modifications of nucleophilic amino acids in transcriptional regulatory proteins. Arachidonic acid (AA) represents a precursor of potent signaling molecules, i.e., prostaglandins and thromboxanes through enzymatic and non-enzymatic oxidative pathways. Arachidonic acid can be nitrated by reactive nitrogen species leading to the formation of nitro-arachidonic acid (NO2-AA). A critical issue is the influence of NO2-AA on prostaglandin endoperoxide H synthases, modulating inflammatory processes through redirection of AA metabolism and signaling. In this prospective article, we describe the key chemical and biochemical actions of NO2-AA in vascular and astrocytes. This includes the ability of NO2-AA to mediate unique redox signaling anti-inflammatory actions along with its therapeutic potential.

Age-related changes in retinoic, docosahexaenoic and arachidonic acid modulation in nuclear lipid metabolism.

The aim of this work was to study how age-related changes could modify several enzymatic activities that regulate lipid mediator levels in nuclei from rat cerebellum and how these changes are modulated by all-trans retinoic acid (RA), docosahexaenoic acid (DHA) and arachidonic acid (AA). The higher phosphatidate phosphohydrolase activity and lower diacylglycerol lipase (DAGL) activity observed in aged animals compared with adults could augment diacylglycerol (DAG) availability in the former. Additionally, monoacylglycerol (MAG) availability could be high due to an increase in lysophosphatidate phosphohydrolase (LPAPase) activity and a decrease in monocylglycerol lipase activity. Interestingly, RA, DHA and AA were observed to modulate these enzymatic activities and this modulation was found to change in aged rats. In adult nuclei, whereas RA led to high DAG and MAG production through inhibition of their hydrolytic enzymes, DHA and AA promoted high MAG production by LPAPase and DAGL stimulation. In contrast, in aged nuclei RA caused high MAG generation whereas DHA and AA diminished it through LPAPase activity modulation. These results demonstrate that aging promotes a different nuclear lipid metabolism as well as a different type of non-genomic regulation by RA, DHA and AA, which could be involved in nuclear signaling events.

Electrophilic nitro-fatty acids prevent astrocyte-mediated toxicity to motor neurons in a cell model of familial amyotrophic lateral sclerosis via nuclear factor erythroid 2-related factor activation.

Nitro-fatty acids (NO2-FA) are electrophilic signaling mediators formed in tissues during inflammation, which are able to induce pleiotropic cytoprotective and antioxidant pathways including up regulation of Nuclear factor erythroid 2-related factor 2 (Nrf2) responsive genes. Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease characterized by the loss of motor neurons associated to an inflammatory process that usually aggravates the disease progression. In ALS animal models, the activation of the transcription factor Nrf2 in astrocytes confers protection to neighboring neurons. It is currently unknown whether NO2-FA can exert protective activity in ALS through Nrf2 activation. Herein we demonstrate that nitro-arachidonic acid (NO2-AA) or nitro-oleic acid (NO2-OA) administrated to astrocytes expressing the ALS-linked hSOD1(G93A) induce antioxidant phase II enzyme expression through Nrf2 activation concomitant with increasing intracellular glutathione levels. Furthermore, treatment of hSOD1(G93A)-expressing astrocytes with NO2-FA prevented their toxicity to motor neurons. Transfection of siRNA targeted to Nrf2 mRNA supported the involvement of Nrf2 activation in NO2-FA-mediated protective effects. Our results show for the first time that NO2-FA induce a potent Nrf2-dependent antioxidant response in astrocytes capable of preventing motor neurons death in a culture model of ALS.

Dopaminergic Neurons Respond to Iron-Induced Oxidative Stress by Modulating Lipid Acylation and Deacylation Cycles.

Metal-imbalance has been reported as a contributor factor for the degeneration of dopaminergic neurons in Parkinson Disease (PD). Specifically, iron (Fe)-overload and copper (Cu) mis-compartmentalization have been reported to be involved in the injury of dopaminergic neurons in this pathology. The aim of this work was to characterize the mechanisms of membrane repair by studying lipid acylation and deacylation reactions and their role in oxidative injury in N27 dopaminergic neurons exposed to Fe-overload and Cu-supplementation. N27 dopaminergic neurons incubated with Fe (1 mM) for 24 hs displayed increased levels of reactive oxygen species (ROS), lipid peroxidation and elevated plasma membrane permeability. Cu-supplemented neurons (10, 50 µM) showed no evidence of oxidative stress markers. A different lipid acylation profile was observed in N27 neurons pre-labeled with [3H] arachidonic acid (AA) or [3H] oleic acid (OA). In Fe-exposed neurons, AA uptake was increased in triacylglycerols (TAG) whereas its incorporation into the phospholipid (PL) fraction was diminished. TAG content was 40% higher in Fe-exposed neurons than in controls. This increase was accompanied by the appearance of Nile red positive lipid bodies. Contrariwise, OA incorporation increased in the PL fractions and showed no changes in TAG. Lipid acylation profile in Cu-supplemented neurons showed AA accumulation into phosphatidylserine and no changes in TAG. The inhibition of deacylation/acylation reactions prompted an increase in oxidative stress markers and mitochondrial dysfunction in Fe-overloaded neurons. These findings provide evidence about the participation of lipid acylation mechanisms against Fe-induced oxidative injury and postulate that dopaminergic neurons cleverly preserve AA in TAG in response to oxidative stress.

6 Iodo-δ-lactone: a derivative of arachidonic acid with antitumor effects in HT-29 colon cancer cells.

BACKGROUND: IL-δ (5-hydroxy-6 iodo-8,11,14-eicosatrienoic delta lactone) an iodinated arachidonic acid (AA) derivative, is one of the iodolipids biosynthesized by the thyroid. Although IL-δ regulates several thyroid parameters such as cell proliferation and goiter growth it was found that this iodolipid inhibits the growth of other non thyroid cell lines. OBJECTIVES: To study the effect of IL-δ on cell proliferation and apoptosis in the colon cancer cell line HT-29. RESULTS: Treatment with IL-δ reduced cell viability in a concentration-dependent manner: 1µM 20%, 5µM 25%, 10µM 31%, 50µM 47% and caused a significant decrease of PCNA expression (25%). IL-δ had pro-apoptotic effects, evidenced by morphological features of programmed cell death such as pyknosis, karyorrhexis, cell shrinkage and cell blebbing observed by fluorescence microscopy, and an increase in caspase-3 activity and in Bax/Bcl-2 ratio (2.5 after 3h of treatment). Furthermore, IL-δ increased ROS production (30%) and lipid peroxidation levels (19%), suggesting that apoptosis could be a result of increased oxidative stress. A maximum increase in c-fos and c-jun protein expression in response to IL-δ was observed 1h after initiation of the treatment. IL-δ also induced a tumour growth delay of 70% compared to the control group in NIH nude mice implanted with HT-29 cells. CONCLUSION: Our study shows that IL-δ inhibits cell growth and induces apoptosis in the colon cancer cell line, HT-29 and opens the possibility that IL-δ could be a potential useful chemotherapy agent.

In silico studies of Echinococcus granulosus FABPs.

Fatty acid (FA) binding proteins are small intracellular proteins whose members exhibit great diversity and low similarity at the primary structure level, but a highly conserved three-dimensional structure. Characterised by a high-affinity non-covalent binding of hydrophobic ligands, these proteins have a molecular mass of 14-15 kDa with a characteristic ß-barrel structure. Members of this family have been identified along the zoological scale, with Platyhelminthes being the more primitive organisms where they have been reported. Two FA binding proteins (FABPs), EgFABP1 and EgFABP2, with 88% similarity have been identified in Echinococcus granulosus. In an effort to understand why two such similar proteins are expressed by this organism, we performed an in silico analysis of the binding capabilities of both proteins. The crystallographic structure of EgFABP1 was utilised as a template to model EgFABP2, and both were docked against palmitate, oleate, linoleate and arachidonate. The docked structures were submitted to 4 ns molecular dynamics simulations, and their protein-ligand interaction energies were measured. The collected data demonstrated that linoleate and arachidonate had the higher interaction energies when bound to EgFABP1 and that palmitate and linoleate had the higher interaction energies when bound to EgFABP2. External and internal binding surfaces were analysed, showing differences at both levels. Internal surface compositions suggested that both proteins could have preferences for certain FAs. Comparisons of the holo and apo forms of each protein indicated that the ligand imposed subtle, but specific modifications that could trigger surface signals. The differences found between the proteins under study suggest that they could have functional uniqueness in the parasite's metabolism.

Dynamics of different arachidonic acid orientations bound to prostaglandin endoperoxide synthases.

Prostaglandin endoperoxide synthases (PGHSs) catalyze the conversion of arachidonic acid (AA) into prostaglandin endoperoxide H(2). This reaction requires a specific orientation of AA within the active site, but an alternative crystallographic binding orientation for AA also exists. Since the origin of this alternative complex, and its potential relevance, have been neglected so far, we have characterized the dynamics of both orientations of AA, bound to PGHS-1 and -2, in order to obtain new insights for designing PGHSs inhibitors. Our results indicate that AA in the alternative orientation seems to be less stable, moving toward Arg120. Such potentially minor orientation of AA can be related to crystallographic complexes of anti-inflammatory agents, pointing to an alternate SAR on PGHSs inhibitors.

Potential interaction of natural dietary bioactive compounds with COX-2.

Bioactive natural products present in the diet play an important role in several biological processes, and many have been involved in the alleviation and control of inflammation-related diseases. These actions have been linked to both gene expression modulation of pro-inflammatory enzymes, such as cyclooxygenase 2 (COX-2), and to an action involving a direct inhibitory binding on this protein. In this study, several food-related compounds with known gene regulatory action on inflammation have been examined in silico as COX-2 ligands, utilizing AutoDock Vina, GOLD and Surflex-Dock (SYBYL) as docking protocols. Curcumin and all-trans retinoic acid presented the maximum absolute AutoDock Vina-derived binding affinities (9.3 kcal/mol), but genistein, apigenin, cyanidin, kaempferol, and docosahexaenoic acid, were close to this value. AutoDock Vina affinities and GOLD scores for several known COX-2 inhibitors significatively correlated with reported median inhibitory concentrations (R² = 0.462, P < 0.001 and R² = 0.238, P = 0.029, respectively), supporting the computational reliability of the predictions made by our docking simulations. Moreover, docking analysis insinuate the synergistic action of curcumin on celecoxib-induced inhibition of COX-2 may occur allosterically, as this natural compound docks to a place different from the inhibitor binding site. These results suggest that the anti-inflammatory properties of some food-derived molecules could be the result of their direct binding capabilities to COX-2, and this process can be modeled using protein-ligand docking methodologies.

A complex between 6-iodolactone and the peroxisome proliferator-activated receptor type gamma may mediate the antineoplastic effect of iodine in mammary cancer.

Recently we and other groups have shown that molecular iodine (I(2)) exhibits potent antiproliferative and apoptotic effects in mammary cancer models. In the human breast cancer cell line MCF-7, I(2) treatment generates iodine-containing lipids similar to 6-iodo-5-hydroxy-eicosatrienoic acid and the 6-iodolactone (6-IL) derivative of arachidonic acid (AA), and it significantly decreases cellular proliferation and induces caspase-dependent apoptosis. Several studies have shown that AA is a natural ligand of the peroxisome proliferator-activated receptors (PPARs), which are nuclear transcription factors thought to participate in regulating cancer cell proliferation. Our results show that in MCF-7 cells: (1) 6-IL binds specifically and with high affinity to PPAR proteins (EMSA assays), (2) 6-IL activates both transfected (by transactivation assays) and endogenous (by lipid accumulation) peroxisome proliferator response elements, and (3) 6-IL supplementation increases PPAR gamma and decreases PPAR alpha expression. These results implicate PPARs in a molecular mechanism by which I(2), through formation of 6-IL, inhibits the growth of human breast cancer cells.

Isolation of syringaldehyde from Mikania laevigata medicinal extract and its influence on the fatty acid profile of mice / Extrato medicinal de Mikania laevigata: influência no perfil de ácidos graxos em camundongos e isolamento de siringaldeído por CLAE semipreparativa

The Mikania genus is widely known as "guaco" and is used to treat fever, rheumatism, flu and respiratory diseases. Our previous work evidenced the synergism among M. laevigata extract components to produce desirable effects, and included the coumarin precursor, o-coumaric acid as marker. Many Mikania species are producers of ent-kaurene diterpenes which presented antiespasmodic and relaxant activities on smooth muscle. Seeking to standardize the guaco extract, which is registered in the Brazilian Pharmacopoea, this paper deals with the determination of kaurenoic acid through LC-PDA and the isolation through LC of syringaldehyde. Kaurenoic acid was not found in the extract, and syringaldehyde is one of the major compounds of pharmacopoeal extract, together with coumarin and o-coumaric acid. Samples from the lung and liver of Balb-C isogenic allergic pneumonitis bearing mice, treated with the same extract, were analyzed through GC-FID, and the fatty acid content was determined and analyzed. The results obtained by measuring the arachidonic acid (ARA) and docosahexaenoic acid (DHA) in the liver and lung of treated animals demonstrated that the fatty acid composition is distinct in both tissues, and that in the liver, only the DHA was altered as a result of the treatments. DHA is absent in the lung and in both organs, no significant difference in ARA production was observed. The aqueous extract, coumarin and o-coumaric acid stimulated DHA synthesis in the liver (p < 0.05).

O gênero Mikania é popularmente conhecido como "guaco" e é utilizado para tratar febre, reumatismo, resfriados e afecções respiratórias. Em trabalho prévio demonstramos sinergismo entre os componentes do extrato de M. laevigata para produzir os efeitos farmacológicos esperados, incluindo a cumarina e seu precursor ácido o-cumárico como marcadores. Muitas espécies de Mikania são produtoras de diterpenos ent-caurenos que apresentam atividade antispasmódica e relaxante da musculatura lisa. Buscando a padronização do extrato medicinal de guaco (preparado segundo a farmacopéia brasileira 1ª edição), este trabalho visou determinar a presença de ácido caurenóico através de CLAE-DAD e isolou siringaldeído através de CLAE semipreparativa, sendo que o primeiro não foi encontrado no extrato e o siringaldeído é um dos seus componentes majoritários. Camundongos isogênicos Balb-C portadores de pneumonite alérgica foram tratados com este extrato, e amostras de pulmão e fígado foram analisadas por CG-DIC quanto ao seu conteúdo de ácidos graxos. A quantidade de ácido araquidônico (ARA) e de ácido docosahexaenóico (DHA) encontrada demonstrou que a composição é distinta em ambos tecidos, e apenas a concentração de DHA hepático foi alterado em função do tratamento, o qual não foi encontrado no pulmão. Não foi detectada diferença significativa na produção de ARA. Tanto o extrato aquoso, quanto a cumarina e o ácido o-cumárico, estimularam a síntese de DHA no fígado (p < 0.05).

Synthesis, isomer characterization, and anti-inflammatory properties of nitroarachidonate.

Nitrated fatty acids (nitroalkenes) have been recently detected and quantified in cell membranes and human plasma. However, nitration of arachidonate (AA), that could redirect AA-dependent cell signaling pathways, has not been studied in detail. Herein, we synthesized and determined for the first time the isomer distribution of nitroarachidonate (AANO2) and demonstrate its ability to modulate inflammation. Synthesis of AANO2 was achieved by AA treatment with sodium nitrite in acidic conditions following HPLC separation. Mass spectrometry (MS) analysis showed the characteristic MS/MS transition of AANO2 (m/z 348/301). Moreover, the IR signal at 1378.3 cm(-1) and NMR studies confirmed the presence of mononitrated nitroalkenes. Positional isomer distribution was determined by NMR and MS fragmentation with lithium; four major isomers (9-, 12-, 14-, and 15-AANO2) were identified, which exhibited key anti-inflammatory properties. These include their ability to release biologically relevant amounts of nitric oxide, induce cGMP-dependent vasorelaxation, and down-regulate inducible nitric oxide synthase (NOS2) expression during macrophage activation, providing unique structural evidence and novel regulatory signaling properties of AANO2.

Hepatic arachidonic acid metabolism is disrupted after hexachlorobenzene treatment.

Hexaclorobenzene (HCB), one of the most persistent environmental pollutants, can cause a wide range of toxic effects including cancer in animals, and hepatotoxicity and porphyria both in humans and animals. In the present study, liver microsomal cytochrome P450 (CYP)-dependent arachidonic acid (AA) metabolism, hepatic PGE production, and cytosolic phospholipase A2 (cPLA2) activity were investigated in an experimental model of porphyria cutanea tarda induced by HCB. Female Wistar rats were treated with a single daily dose of HCB (100 mg kg(-1) body weight) for 5 days and were sacrificed 3, 10, 17, and 52 days after the last dose. HCB treatment induced the accumulation of hepatic porphyrins from day 17 and increased the activities of liver ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), and aminopyrine N-demethylase (APND) from day 3 after the last dose. Liver microsomes from control and HCB-treated rats generated, in the presence of NADPH, hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatrienoic acids (EETs), 11,12-Di HETE, and omega-OH/omega-1-OH AA. HCB treatment caused an increase in total NADPH CYP-dependent AA metabolism, with a higher response at 3 days after the last HCB dose than at the other time points studied. In addition, HCB treatment markedly enhanced PGE production and release in liver slices. This HCB effect was time dependent and reached its highest level after 10 days. At this time cPLA2 activity was shown to be increased. Unexpectedly, HCB produced a significant decrease in cPLA2 activity on the 17th and 52nd day. Our results demonstrated for the first time that HCB induces both the cyclooxygenase and CYP-dependent AA metabolism. The effects of HCB on AA metabolism were previous to the onset of a marked porphyria and might contribute to different aspects of HCB-induced liver toxicity such as alterations of membrane fluidity and membrane-bound protein function. Observations also suggested that a possible role of cPLA2 in the early increase of AA metabolism cannot be excluded. However, the existence of other pathway(s) for metabolizable AA generation different from cPLA2 activation is also proposed.

The protection of long chain polyunsaturated fatty acids by melatonin during nonenzymatic lipid peroxidation of rat liver microsomes.

The in vivo and in vitro effects of melatonin (N-acetyl-5-methoxytryptamine) on lipid peroxidation of long chain polyunsaturated fatty acids (PUFA) located in rat liver microsomes were determined. The effect of intraperitoneal administration of melatonin (10 mg/kg weight/24 hr) on ascorbate-Fe++ induced lipid peroxidation of isolated rat liver microsomes was first examined. The ascorbate induced light emission in hepatic microsomes was inhibited by melatonin treatment [control group: 10.714 +/- 0.894; melatonin group: 3.162 +/- 0.515, counts per minute (cpm) x 10(-5)]. Significant differences in the content of arachidonic C20:4 n-6 and docosahexaenoic acid C22:6 n-3 were observed when control microsomes were lipid peroxidized in the presence of ascorbic acid. These changes were less pronounced in liver microsomes isolated from melatonin treated rats. In vitro assays showed that after incubation of rat liver microsomes in an ascorbate-Fe++ system, at 37 degrees C for 210 min, the total cpm originated from light emission (chemiluminescence) was found to be lower in those membranes incubated in the presence of melatonin. The fatty acid composition of total lipids isolated from rat liver microsomes was substantially modified when subjected to nonenzymatic lipid peroxidation with a considerable decrease of docosahexaenoic acid 22:6 n-3 and arachidonic acid 20:4 n-6. The inhibition of the lipid peroxidation process evaluated as chemiluminescence (total cpm at selected times) was melatonin concentration dependent. Melatonin, at a concentration 1.2 mm, inhibited almost completely the lipid peroxidation process. Arachidonic and docosahexaenoic acids were more affected than docosapentaenoic acid during the lipid peroxidation process. Not all fatty acids were equally protected after the addition of melatonin to the incubation medium. Our results indicate that melatonin may act in vivo and in vitro as an antioxidant protecting long chain PUFA present in rat liver microsomes from the deleterious effect by a selective mechanism that reduces the loss of docosahexaenoic and arachidonic acids.

Fatty acid composition and dynamics of phospholipids from fresh water fish Prochilodus lineatus brain and spinal cord.

The phospholipid and fatty acid composition of the brain and spinal cord lipids of fresh water fish Prochilodus lineatus ("sábalo") were studied. The fluorescence anisotropy of phospholipids labelled with 1.6-diphenyl 1.3.5-hexatriene, was also investigated. Phosphatidyl-choline was the most abundant phospholipid followed by phosphatidyl-ethanolamine, phosphatidyl-serine, phosphatidyl-inositol and sphingomyelin. The fatty acid composition of all phospholipids except sphingomyelin showed the presence of n-9, n-6 and n-3 series of unsaturated acids. The presence of n-6 polyunsaturated fatty acid was represented by arachidonic acid that was found preferentially in phosphatidyl-inositol. N-3 fatty acids were represented by 20:5n-3, 22:5n-3 and 22:6n-3. Docosa 4,7,10,13,16,19 hexaenoic acid was the most abundant of n-3 fatty acids and was preferentially found in phosphatidyl ethanolamine and phosphatidyl-serine. The percentage of 22:6n-3 acid decreased with age. The simultaneous presence of n-6 fatty acids (arachidonic acid) and n-3 fatty acids in fresh water fishes contrast with the absence of n-6 fatty acids in nervous tissue of marine fishes. Phosphatidyl choline was the most fluid of all phospholipids from brain and spinal cord.

Fatty acid composition and dynamics of phospholipids from fresh water fish Prochilodus Lineatus brain and spinal cord

Se estudió la composición de fosfolípidos y ácidos grasos de lípidos de cerebro y médula del pez de de agua dulce Prochilodus lineatus (sábalo). También hemos investigado la anisotropía de fluorescencia de fosfolípidos marcados con 1.6-difenil-1.3.5 hexatrieno. Se halló que la fosfatidilcolina era el fosfolípido más abundante, seguido por la fosfatidil etanolamina, fosfatidil-serina, fosfatidil-inositol y la esfingomielina. La composición de ácidos grasos de todos los fosfolípidos, exceptuando la esfingomielina, mostró la presencia de ácidos no saturados de la series n-3, n-6 y n-9. El ácido araquidónico evidenció la presencia de ácidos grasos polinosaturados de la serie n-6, y se lo encontró preferentemente en el fosfatidil-inositol. Los ácidos grasos n-3 fueron representados por los ícidos 20:5n-3, (araquidónico) y 3 en peces de agua dulce contrasta con la ausencia de los n-6 en el tejido nervioso de peces marinos. La fosfatidilcolina mostró la mayor fluidez de todos los fosfolípidos de cerebro y médula (AU)

Fatty acid composition and dynamics of phospholipids from fresh water fish Prochilodus Lineatus brain and spinal cord

Se estudió la composición de fosfolípidos y ácidos grasos de lípidos de cerebro y médula del pez de de agua dulce Prochilodus lineatus (sábalo). También hemos investigado la anisotropía de fluorescencia de fosfolípidos marcados con 1.6-difenil-1.3.5 hexatrieno. Se halló que la fosfatidilcolina era el fosfolípido más abundante, seguido por la fosfatidil etanolamina, fosfatidil-serina, fosfatidil-inositol y la esfingomielina. La composición de ácidos grasos de todos los fosfolípidos, exceptuando la esfingomielina, mostró la presencia de ácidos no saturados de la series n-3, n-6 y n-9. El ácido araquidónico evidenció la presencia de ácidos grasos polinosaturados de la serie n-6, y se lo encontró preferentemente en el fosfatidil-inositol. Los ácidos grasos n-3 fueron representados por los ícidos 20:5n-3, (araquidónico) y 3 en peces de agua dulce contrasta con la ausencia de los n-6 en el tejido nervioso de peces marinos. La fosfatidilcolina mostró la mayor fluidez de todos los fosfolípidos de cerebro y médula