Presence Of Polyunsaturated Fatty Acids Research Articles

Exacerbation of alcohol-induced oxidative stress in rats by polyunsaturated fatty acids and iron load

The hypothesis that excessive intake of vegetable oil containing polyunsaturated fatty acids and iron load precipitate alcohol-induced liver damage was investigated in a rat model. In order to elucidate the mechanism underlying this synergism, the serum levels of iron, total protein, serum glutamate pyruvate transaminase, liver thiobarbituric acid reactive substances, and activities of antioxidant enzymes superoxide dismutase, catalase in liver of rats treated with alcohol, polyunsaturated fatty acids and iron per se and in combination were examined. Alcohol was fed to the rats at a level of 10-30% (blood alcohol was maintained between 150-350 mg/dl by using head space gas chromatography), polyunsaturated fatty acids at a level of 15% of diet and carbonyl iron 1.5-2% of diet per se and in combination to different groups for 30 days. Hepatotoxicity was assessed by measuring serum glutamate pyruvate transaminase, which was elevated and serum total protein, which was decreased significantly in rats fed with a combination of alcohol, polyunsaturated fatty acids and iron. It was also associated with increased lipid peroxidation and disruption of antioxidant defense in combination fed rats as compared to rats fed with alcohol or polyunsaturated fatty acids or iron. The present study revealed significant exacerbation of the alcohol-induced oxidative stress in presence of polyunsaturated fatty acids and iron.

Long chain‐polyunsaturated fatty acids modulate membrane phospholipid composition and protein localization in lipid rafts of neural stem cell cultures

Rat neural stem cells/neural progenitors (NSC/NP) are generally grown in serum-free medium. In this study, NSC/NP were supplemented with the main long-chain polyunsaturated fatty acids (PUFAs) present in the brain, arachidonic acid (AA), or docosahexaenoic acid (DHA), and were monitored for their growth. Lipid and fatty acid contents of the cells were also determined. Under standard conditions, the cells were characterized by phospholipids displaying a highly saturated profile, and very low levels of PUFAs. When cultured in the presence of PUFAs, the cells easily incorporated them into the phospholipid fraction. We also compared the presence of three membrane proteins in the lipid raft fractions: GFR and connexin 43 contents in the rafts were increased by DHA supplementation, whereas Gbeta subunit content was not significantly modified. The restoration of DHA levels in the phospholipids could profoundly affect protein localization and, consequently, their functionalities.

Toxicity of unsaturated fatty acids to the biohydrogenating ruminal bacterium, Butyrivibrio fibrisolvens

BackgroundHealth-promoting polyunsaturated fatty acids (PUFA) are abundant in forages grazed by ruminants and in vegetable and fish oils used as dietary supplements, but only a small proportion of PUFA finds its way into meat and milk, because of biohydrogenation in the rumen. Butyrivibrio fibrisolvens plays a major role in this activity. The aim of this study was to investigate the mechanisms by which PUFA affect the growth of B. fibrisolvens, how PUFA are metabolized and the metabolic response to growth in the presence of PUFA.ResultsLinoleic acid (LA; cis-9, cis-12-18:2) and α-linolenic acid (LNA; cis-9, cis-12, cis-15-18:3) increased the lag phase of B. fibrisolvens JW11, LNA having the greater effect. Growth was initiated only when the PUFA had been converted to vaccenic acid (VA; trans-11-18:1). The major fish oil fatty acids, eicosapentaenoic acid (EPA; 20:5(n-3)) and docosahexaenoic acid (DHA; 22:6(n-3)), were not metabolized and prevented growth. Cellular integrity, as determined fluorimetrically by propidium iodide (PI) ingression, was affected as much by 18:1 fatty acids, including VA, as 18:2 fatty acids. The methyl esters of LNA, LA, EPA and DHA had no effect on growth or other measurements. The ATP pool decreased by 2/3 when LA was added to growing bacteria, whereas most acyl CoA pools decreased by >96%.ConclusionsIt was concluded that biohydrogenation occurs to enable B. fibrisolvens to survive the bacteriostatic effects of PUFA, and that the toxicity of PUFA is probably mediated via a metabolic effect rather than disruption of membrane integrity.

Perfil de ácidos graxos na carne de novilhos Charolês e Nelore puros e de gerações avançadas do cruzamento rotativo, terminados em confinamento

Foram avaliados os efeitos da heterozigose e o grupo genético no perfil de ácidos graxos de novilhos puros (Charolês - C e Nelore - N) e mestiços da segunda (G2) (¾C¼N e ¾N¼C), da terceira (G3) (5/8C3/8N e 5/8N3/8C) e da quarta (G4) (11/16C5/16N e 11/16N5/16C) geração de cruzamento rotativo. A carne dos novilhos Nelore e dos 11/16N 5/16C apresentou maior proporção de ácido mirístico (C14:0) em relação à carne dos Charolês e dos 11/16C 5/16N. Por outro lado, a carne dos novilhos 11/16C 5/16N apresentou maior presença de ácido heptadecanóico (C17:0) e de ácido araquidônico (C20:4 n6) em relação aos 11/16N 5/16C. Na G2, os novilhos 3/4C 1/4N apresentaram superioridade nos ácidos esteárico (C18:0) e linoléico (C18:2 n6c), na participação total dos ácidos graxos poliinsaturados estudados e na relação entre os ácidos graxos poliinsaturados e saturados, enquanto que os 3/4N 1/4C apresentaram superioridade no ácido oléico (C18:1 n9c). Na G3, as carnes dos novilhos 5/8C 3/8N apresentaram superioridade na participação dos ácidos esteárico e elaídico (C18:1 n9t) e no total dos ácidos graxos saturados, enquanto que os novilhos 5/8N 3/8C apresentaram maior participação dos ácidos miristoléico (C14:1),cis-10-Heptadecanóico (C17:1) e oléico e no total de ácidos graxos insaturados. A heterose foi significativa na G2 para C17:0, C18:0, C18:1 n9c e C18:2 n6c no total dos ácidos graxos saturados, insaturados e poliinsaturados. Novilhos 3/4C 1/4N apresentaram a carne mais saudável entre os grupos genéticos estudados, apresentando carne com maior presença de ácidos graxos poliinsaturados e maior relação poliinsaturados:saturados.

The Functional Significance of Lipid Diversity: Orientation of Cholesterol in Bilayers Is Determined by Lipid Species

The chemical diversity of lipids and their complex arrangements in supramolecular assemblies are in stark contrast to our previous notions of them as passive structural components. For example, in plasma membranes, sphingolipids are primarily located in the outer monolayer, whereas unsaturated phospholipids are more abundant in the inner leaflet. Our recent results offer a direct contribution to the importance of lipid diversity in biological membranes. We have studied the location of cholesterol within polyunsaturated fatty acid (PUFA) bilayers doped with different amounts of monounsaturated (POPC) or disaturated (DMPC) lipids. Using deuterium labeling and neutron diffraction, we have found that in PUFA bilayers, cholesterol can be flipped from its known position in the bilayer center to its commonly assumed upright orientation simply by varying the amount of POPC. Although it takes approximately 50 mol % POPC to flip cholesterol in PUFA bilayers, the same effect is achieved with only 5 mol % DMPC, elegantly emphasizing cholesterol's affinity for saturated chains. It also suggests that the presence of PUFA in the inner leaflet of a cellular bilayer may enhance the transfer of cholesterol to the outer layer, potentially modifying raft composition and the local function of a membrane.

4-Hydroxynonenal, a lipid peroxidation product of dietary polyunsaturated fatty acids, has anticarcinogenic properties in colon carcinoma cell lines through the inhibition of telomerase activity

The effects of polyunsaturated fatty acids (PUFAs) obtained from the diet on colorectal cancer have been widely explored. However, controversial results have been obtained about the role played by the lipid peroxidation products of PUFAs, such as 4-hydroxy-nonenal (HNE), in the control of colon cancer growth. This aldehyde, indeed, showed both procarcinogenic and protective effects. In an attempt to verify the action of HNE, we studied the effects of a low dose of HNE (1 μM), similar to those “physiologically” found in normal cells and plasma, on telomerase activity, a key parameter of malignant transformation. Caco-2 cells were exposed to HNE and, paralleling cell growth inhibition, we observed the down-regulation of telomerase activity and hTERT expression. Similar effects have also been observed in HT-29 cells, in which HNE inhibited cell proliferation, telomerase activity and hTERT expression, suggesting that the inhibition of telomerase activity could be a general mechanism involved in the antiproliferative effect exerted by this aldehyde. Finally, we elucidated the mechanism of hTERT inhibition by HNE. A reduction of GSH content preceded the decrease of telomerase activity, but this only partially explained the telomerase activity inhibition. The major mechanism of HNE action seems to be the modulation of expression and activity of transcription factors belonging to the Myc/Mad/Max network. Since the presence of PUFAs in the diet exposes epithelial colon cells to HNE, this aldehyde could contribute to cell growth control through the inhibitory action on telomerase activity and hTERT expression, suggesting a protective effect on colon mucosa.

N-terminal region of α-synuclein is essential for the fatty acid-induced oligomerization of the molecules

Exposure of α-synuclein (αS), a major component of Lewy bodies in Parkinson’s disease, to polyunsaturated fatty acids (PUFAs) triggers the formation of soluble αS oligomers. Here, we demonstrate that PUFA binds recombinant αS protein through its N-terminal region (residues 2–60). In HEK293 cells, αS mutants lacking the N-terminal region failed to form oligomers in the presence of PUFA. The PUFA-induced αS oligomerization was accelerated by C-terminal truncation or Ser129 phosphorylation of αS; however, this effect was abolished by deletion of the N-terminus. The results indicate that the N-terminus of αS is essential for the PUFA-induced αS oligomerization.

Adaptation to oxidative stress induced by polyunsaturated fatty acids in yeast

To create a conditional system for molecular analysis of effects of polyunsaturated fatty acids (PUFA) on cellular physiology, we have constructed a strain of yeast ( Saccharomyces cerevisiae) that functionally expresses, under defined conditions, the Δ12 desaturase gene from the tropical rubber tree, Hevea brasiliensis. This strain produces up to 15% PUFA, exclusively under inducing conditions resulting in production of 4-hydroxy-2-nonenal, one of the major end products of n − 6 polyunsaturated fatty acid peroxidation. The PUFA-producing yeast was initially more sensitive to oxidative stress than the wild-type strain. However, over extended time of cultivation it became more resistant to hydrogen peroxide indicating adaptation to endogenous oxidative stress caused by the presence of PUFA. Indeed, PUFA-producing strain showed an increased concentration of endogenous ROS, while initially increased hydrogen peroxide sensitivity was followed by an increase in catalase activity and adaptation to oxidative stress. The deletion mutants constructed to be defective in the catalase activity lost the ability to adapt to oxidative stress. These data demonstrate that the cellular synthesis of PUFA induces endogenous oxidative stress which is overcome by cellular adaptation based on the catalase activity.

Microbial biomass and community structure of a stromatolite from an acid mine drainage system as determined by lipid analysis

Lipids were extracted to determine the microbial biomass and community structure of a Fe-rich stromatolite from acid mine drainage (AMD) at the Green Valley coal mine site (GVS) in western Indiana. The distribution of biomarkers correlated well with layers in the laminated stromatolite. Our results show that the biomass of the top layer of the stromatolite was dominated by phototrophic organisms which constituted 83% of the total biomass. Biomass of the lower layers was dominated by prokaryotic microorganisms. The presence of terminal methyl-branched fatty acids and mid methyl-branched fatty acids suggests the presence of Gram-positive and sulfate-reducing bacteria, respectively. Fungi appear to also be an important part of the AMD microbial communities as suggested by sterol profiles and the presence of polyunsaturated fatty acids. Hydroxy fatty acids and C 19 cyclopropane fatty acids were also detected and likely originated from acid-producing, acidophilic bacteria. The presence of Archaea is indicated by abundant phospholipid ether-linked isoprenoid hydrocarbons (phytane and phytadienes). The AMD Fe-rich stromatolites at GVS thus appear to be formed by interactions of microbial communities composed of all three domains of life; Archaea, Bacteria, and Eukarya. The identification of microeukaryote-dominated stromatolites implicates the prominent role of these organisms in the formation and preservation of these structures. In addition, the production of oxygen through photosynthesis by these organisms in AMD systems may be important for retrodicting the interaction of microbial communities in Precambrian environments in the production of microbially-mediated sedimentary structures and oxygenation of Earth's early atmosphere.

Polyunsaturated fatty acids activate human uncoupling proteins 1 and 2 in planar lipid bilayers

Uncoupling proteins 1 (UCP1) and 2 (UCP2) belong to the family of mitochondrial anion transporters and share 59% sequence identity with each other. Whereas UCP1 was shown to be responsible for the rapid production of heat in brown adipose tissue, the primary function and transport properties of ubiquitously expressed UCP2 are controversially discussed. Here, for the first time, the activation pattern of the recombinant human UCP2 in comparison to the recombinant human UCP1 are studied using a well-defined system of planar lipid bilayers. It is shown that despite apparently different physiological functions, hUCP2 exhibited its protonophoric function similar to hUCP1--exclusively in the presence of long-chain fatty acids (FA). The calculated hUCP2 transport rate of 4.5 s(-1) is the same order of magnitude, as shown previously for UCP1. It leads to the conclusion that the differences in the activity of both proteins in living mitochondria are based exclusively on their different expression level. Both proteins are activated much more effectively by polyunsaturated than by saturated FA. The proton and total membrane conductances increased in the range palmitic < oleic < eicosatrienoic < linoleic < retinoic < arachidonic acids. The higher uncoupling protein (UCP)-dependent conductance in the presence of polyunsaturated FA is explained on the basis of the FA cycling hypothesis.

α-Synuclein Adopts an α-Helical Conformation in the Presence of Polyunsaturated Fatty Acids To Hinder Micelle Formation

Alpha-synuclein is a small cytosolic protein involved in the pathogenesis of Parkinson's disease and other neurodegenerative disorders. Recent studies suggested a lipid-related function for this brain-enriched protein. Since the brain carries a high level of docosahexaenoic acid (DHA) and since the extent of alpha-synuclein gene expression increases in response to DHA intake, we have investigated the interaction of alpha-synuclein with this essential omega-3 fatty acid. We show that alpha-synuclein allows DHA to be present in a soluble rather than micellar form. Upon interaction with DHA, the normally unstructured alpha-synuclein rapidly adopts an alpha-helical conformation. Prolonged exposure to DHA, however, gradually converts alpha-synuclein into amyloid-like fibrils. These results identify a potential biological function for alpha-synuclein and define an omega-3-linked pathway leading to alpha-synuclein aggregation.

Increased expression of a molecular chaperone GroEL in response to unsaturated fatty acids by the biohydrogenating ruminal bacterium,Butyrivibrio fibrisolvens

Butyrivibrio fibrisolvens is the most active bacterial species in the biohydrogenation of polyunsaturated fatty acids (PUFA) in the rumen. It needs to remove the unsaturated bonds in order to detoxify the PUFA to enable the growth of the bacterium. Here, we investigated the response of cell membrane-associated proteins in B. fibrisolvens to growth in the presence of PUFA. Numerous changes were observed in the cell membrane-associated proteome. One of the main modifications occurring when the 18:2 fatty acids, linoleic acid and conjugated linoleic acid, were added, was an increased expression of the molecular chaperone GroEL.

Diacylglycerolipids isolated from a thermophile cyanobacterium from the Euganean hot springs

The Phormidium sp. ETS-05 thermophile blue-green alga is one of the most typical and widespread species of cyanobacteria of the thermal muds of the Euganean hot springs, the therapeutic properties of which have been known since ancient times. The polar diacylglycerolipids of this cyanobacterium consists of monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol and phosphatidylglycerol. We have isolated and purified these four diacylglycerolipids from ETS-05, and then analysed them for their quantitative and structural features and fatty acid contents. The monogalactosyldiacylglycerol and digalactosyldiacylglycerol show a marked presence of polyunsaturated fatty acids, of which C18 : 4 is the most common. We propose that these glycoglycerolipids can be used as markers for monitoring the thermal mud colonisation process.

Functional Fatty Fish Supplemented with Grape Procyanidins. Antioxidant and Proapoptotic Properties on Colon Cell Lines

This work shows the properties of grape procyanidins with additional anticarcinogenic properties for increasing the shelf life of functional seafood preparations. Galloylated procyanidins (100 ppm, 2.7 mean degree of polymerization, 25% galloylation) extended the shelf life of minced horse mackerel muscle stored at 4 degrees C more than 8 days compared to controls without addition of polyphenols. The levels of endogenous alpha-tocopherol, EPA, and DHA of fish muscle were also preserved after 10 days at 4 degrees C. Therefore, the presence of procyanidins increased the stability of a product based on minced fish muscle during cold storage and maintained its functionality associated with the presence of polyunsaturated fatty acids and alpha-tocopherol. In addition, grape procyanidins showed a significant capacity to induce apoptosis in colon cancer cells (HT29 cell line) while being inactive in noncancer control cells (IEC-6). Thus, the product based on fatty fish muscle supplemented with grape procyanidins appears to be a stable functional food offering the combined action of omega-3 fatty acids and natural polyphenols.

Differential regulation of ATP‐binding cassette transporter A1 (ABCA1) expression by fatty acids in HepG2 and RAW 264.7 macrophages

We investigated whether individual fatty acids affect the expression of ATP binding cassette transporter A1 (ABCA1), a membrane transporter critical for high-density lipoprotein formation by effluxing cellular cholesterol and phospholipids to acceptors. HepG2 cells (human hepatoma cell line) and murine RAW 264.7 macrophages were incubated with a selection of individual fatty acids, including 16:0, 16:1, 18:0, 18:1, 18:2, 18:3 and EPA (100 μM, 2.5:1 of fatty acid to BSA molar ratio), along with a control for 6-12 hrs. After fatty acid incubation, a vehicle or TO901317 (10 μM), a liver X receptor (LXR) agonist, were added to media for additional 18-hr incubation. Realtime PCR analysis was performed to determine mRNA abundance of ABCA1. In the absence of TO901317, all unsaturated fatty acids decreased ABCA1 mRNA levels by 60–90% in RAW 264.7 macrophages, whereas only 18:2 reduced (50%) and EPA increased (75%) ABCA1 mRNA levels in HepG2 cells compared with control treatment. When HepG2 cells were treated with TO901317, repression of ABCA1 mRNA expression by 18:2 disappeared, and all of the polyunsaturated fatty acids (18:2, 18:3, and EPA) induced a 2-3.5-fold increase in ABCA1 expression. In contrast, saturated and monounsaturated fatty acids did not alter the ABCA1 expression compared with control. The data suggest the presence of differential regulation of ABCA1 expression by fatty acids, and activation of LXR pathway antagonizes the inhibitory effect of 18:2 on ABCA1 expression and further increases ABCA1 expression in the presence of polyunsaturated fatty acids in HepG2 cells. (Supported by NSF-EPSCoR grant EPS-0346476)

Saccharomyces cerevisiae strain expressing a plant fatty acid desaturase produces polyunsaturated fatty acids and is susceptible to oxidative stress induced by lipid peroxidation

Although oxygen is essential for aerobic organisms, it also forms potentially harmful reactive oxygen species. For its simplicity, easy manipulation, and cultivation conditions, yeast is used as an attractive model in oxidative stress research. However, lack of polyunsaturated fatty acids in yeast membranes makes yeast unsuitable for research in the field of lipid peroxidation. Therefore, we have constructed a yeast strain expressing a Δ12 desaturase gene from the tropical rubber tree, Hevea brasiliensis. This yeast strain expresses the heterologous desaturase in an active form and, consequently, produces Δ9/Δ12 polyunsaturated fatty acids under inducing conditions. The functional expression of the heterologous desaturase did not affect cellular morphology or growth, indicating no general adverse effect on cellular physiology. However, the presence of polyunsaturated fatty acids changed the yeast's sensitivity to oxidative stress induced by addition of paraquat, tert-butylhydroperoxide, and hydrogen peroxide. This difference in sensitivity to the latter was followed by the formation of 4-hydroxy-2-nonenal, one of the end products of linoleic fatty acid peroxidation, which is known to play a role in cell growth control and signaling. Here we show that this yeast strain conditionally expressing the Δ12 desaturase gene provides a novel and well-defined eukaryotic model in lipid peroxidation research. Its potential to investigate the molecular basis of responses to oxidative stress, in particular the involvement of reactive aldehydes derived from fatty acid peroxidation, especially 4-hydroxy-2-nonenal, will be addressed.

Polyunsaturated Fatty Acids Block Dendritic Cell Activation and Function Independently of NF-κB Activation

Polyunsaturated fatty acids (PUFAs) modulate immune responses leading to clinically significant beneficial effects in a variety of inflammatory disorders. PUFA effects on T cells have been extensively studied, but their influence on human dendritic cells (DCs), which are the most potent antigen-presenting cells and play a key role in initiating immune responses, has not been elucidated so far. Here we show that PUFAs of the n-3 and n-6 series (arachidonic and eicosapentaenoic acid) affect human monocyte-derived DC differentiation and inhibit their activation by LPS, resulting in altered DC surface molecule expression and diminished cytokine secretion. Furthermore, the potency to stimulate T cells was markedly inhibited in PUFA-treated DCs. The PUFA-mediated block in LPS-induced DC activation is reflected by diminished TNF-alpha, IL-12p40, CD40, and COX-2 mRNA levels. Strikingly, typical LPS-induced signaling events such as degradation of IkappaB and activation of NF-kappaB were not affected by PUFAs, even though DC membrane lipid composition was markedly altered. Arachidonic and eicosapentaenoic acid both altered DC prostaglandin production, but inhibitors of cyclooxygenases and lipoxygenases did not abolish PUFA effects, indicating that the observed PUFA actions on DCs were independent of autoregulation via eicosanoids. These data demonstrate a unique interference with DC activation and function that could significantly contribute to the well known anti-inflammatory effects of PUFAs.

Effects of polyunsaturated fatty acids on the proliferation of mitogen stimulated bovine peripheral blood mononuclear cells

The present study aimed at analysis of the effects of polyunsaturated fatty acid (PUFA), linoleic acid (LA, C18:2n - 6) and linolenic acid (LNA, C18:3n - 3) on bovine peripheral blood mononuclear cells (PBMC) in vitro. Both mitogen (ConA)-induced proliferative lymphocyte responsiveness during 4 days of culture and eicosanoid (prostaglandin E(2) (PGE(2)) and leukotriene B(4) (LTB(4))) production during 36 h were determined in relation to the absence or presence of various concentrations of LA and LNA (0, 1, 5, 25, 125 and 250 microM). Mitogen-driven proliferative responses of lymphocytes tended to be uninfluenced in the presence of lower concentrations of LA, whereas significant inhibition was observed at the higher concentrations of LA (125 and 250 microM). However, increasing amounts of LNA did not affect the proliferation. ConA stimulation induced a clear PGE(2) response, which significantly decreased in the presence of 250 microM of LA. In addition, increasing amounts of LNA, but not LA, led to a significant decrease in LTB(4) levels. However, The production of LTB(4) did not alter due to mitogenic stimulation. In conclusion, the present study shows that bovine mononuclear cells may functionally be influenced by the presence of PUFA in their environment. Further studies need to be conducted to clarify in vivo consequences of these findings in a situation of PUFA enriched rations in ruminants.

(13)C nuclear magnetic resonance spectra of natural undiluted lipids: docosahexaenoic-rich phospholipid and triacylglycerol from fish.

In the (13)C NMR spectra of natural, unenriched docosahexaenoic acid-rich sardine oil and cod muscle glycerophosphocholine significant signal intensity differences across the 1D spectrum between undiluted and diluted samples were observed. In undiluted samples (13)C-(13)C 2D nuclear Overhauser enhancement spectroscopy (NOESY) interchain cross-peaks for CH, CH(2), CH(3), and C=C structures were observed. Results indicate that in undiluted natural lipids, NMR signal intensity is influenced by polarization transfer from the extended lipid structure. The NOE enhancement of specific molecular sites especially in unsaturated lipids is evidence that some natural lipids remain oriented relative to each other and in an orderly arrangement at the molecular level long enough for the effect to be detected by the NMR experiment. The presence of polyunsaturated fatty acids in mixtures of natural lipids could stabilize specific local molecular conformations within the remaining less saturated lipids.

Trapping of 2,7-dichlorodibenzo-p-dioxin in aqueous solution by enzymatic reaction of fungal manganese peroxidase in the presence of polyunsaturated fatty acids.

In the presence of polyunsaturated fatty acids, including cis-4,7,10,13,16,19-docosahexaenoic acid (DHA), 2,7-dichlorodibenzo-p-dioxin (DCDD) was treated with manganese peroxidase (MnP) from white rot basidiomycete Phanerochaete sordida YK-624. After incubation with MnP, DCDD could not be extracted from the reaction mixture with n-hexane and was trapped in the water layer. DCDD was released by alkalification of the water layer. DCDD was also trapped after treatment with lipoxidase, which produces hydroperoxides from unsaturated lipids. The amounts of thiobarbituric acid-reactive substances produced in the MnP reactions with three highly unsaturated fatty acids were higher than the amounts produced with three fatty acids with a lower degree of unsaturation. These results suggest that a DCDD-trapping compound may be produced by peroxidation of the polyunsaturated fatty acids.