Procyanidin dimer B2 [epicatechin-(4beta-8)-epicatechin] in human plasma after the consumption of a flavanol-rich cocoa

BACKGROUND: Epidemiologic studies have linked flavonoid-rich foods with a reduced risk of cardiovascular mortality. Some cocoas are flavonoid-rich and contain the monomeric flavanols (-)-epicatechin and (+)-catechin and oligomeric procyanidins formed from these monomeric units. Both the monomers and the oligomers have shown potential in favorably influencing cardiovascular health in in vitro and preliminary clinical studies. Although previous investigations have shown increasing concentrations of (-)-epicatechin in human plasma after cocoa consumption, no information is available in the published literature regarding the presence of procyanidins in human plasma. OBJECTIVE: This study sought to determine whether procyanidins can be detected and quantified in human plasma after acute consumption of a flavanol-rich cocoa. DESIGN: Peripheral blood was obtained from 5 healthy adult subjects before (baseline, 0 h) and 0.5, 2, and 6 h after consumption of 0.375 g cocoa/kg body wt as a beverage. Plasma samples were analyzed for monomers and procyanidins with the use of reversed-phase HPLC with coulometric electrochemical array detection and liquid chromatography-tandem mass spectrometry. RESULTS: Procyanidin dimer, (-)-epicatechin, and (+)-catechin were detected in the plasma of human subjects as early as 0.5 h (16 +/- 5 nmol/L, 2.61 +/- 0.46 micro mol/L, and 0.13 +/- 0.03 micro mol/L, respectively) after acute cocoa consumption and reached maximal concentrations by 2 h (41 +/- 4 nmol/L, 5.92 +/- 0.60 micro mol/L, and 0.16 +/- 0.03 micro mol/L, respectively). CONCLUSION: Dimeric procyanidins can be detected in human plasma as early as 30 min after the consumption of a flavanol-rich food such as cocoa.     

The role of leukotrienes and eosinophil cationic protein in acute respiratory syncytial virus bronchiolitis

The Respiratory Syncytial Virus (RSV) is the leading cause of lower respiratory tract infection in infants and by 2.5 to 3 years of age most children have been infected with approximately 1-2% of all infected infants requiring hospital admission. Both immunologic and nonimmunologic factors have been implicated in the susceptibility to symptomatic RSV-induced disease although most attention has been directed towards host responses and their role in the pathogenesis of the associated airway obstruction. Although the mechanisms and host responses associated with symptomatic RSV disease are not yet clear, products more usually associated with allergic inflammation such as cysteinyl leukotrienes and eosinophil cationic protein have been detected in airway secretions of affected infants. Leukotrienes are synthesized through the 5-lipoxygenase pathway from the arachidonic acid which is released from the phospholipids forming the membrane of activated cells. They are potent inflammatory mediators and can cause increased secretion of mucus, airway oedema, bronchoconstriction, airway obstruction. Eosinophil cationic protein is a unique protein from the noncore matrix of the eosinophil cells. Eosinophils and eosinophil mediators are involved in the process of airway obstruction found in many common paediatric pulmonary disorders. The potential role of leukotrienes and eosinophil cationic protein in RSV disease, especially bronchiolitis, are reviewed.     

Anti-inflammatory activity of the ethanol extract of Chungkukjang, Korean fermented bean: 5-lipoxygenase inhibition

The anti-inflammatory activity of Chungkukjang, a Korean traditional fermented soybean food (Korean-style Natto), was examined for the first time. From the results, it was found that the ethanol extract of Chungkukjang inhibited 5-lipoxygenase from A23187-treated RBL-1 cells, reducing leukoriene production (50% inhibitory concentration = 54.1 microg/mL). However, it did not greatly affect cyclooxygenase-2-catalyzed prostaglandin E(2) and inducible nitric oxide synthase-catalyzed nitric oxide production from lipopolysaccharide-treated RAW 264.7 cells at the same concentration ranges. Since leukotrienes are intimately involved in some allergic disorders, the anti-allergic activity of Chungkukjang was further examined in animal models of passive cutaneous anaphylaxis (type I hypersensitivity) and arachidonic acid-induced ear edema, two well-known in vivo models sensitive to 5-lipoxygenase inhibitors. After oral administration for 5 consecutive days, Chungkukjang significantly reduced (27.3%) passive cutaneous anaphylaxis in rats at 400 mg/kg/day. It also showed in vivo anti-inflammatory activity against arachidonic acid-induced mouse ear edema. Therefore, it is suggested that Chungkukjang may be beneficial for several allergic conditions such as asthma and atopic dermatitis.     

Leukotrienes as inflammation mediators

Leukotrienes are biologically active metabolites derived from arachidonic acid playing an important role in inflammatory responses. There are two main groups of leukotrienes: dihydroxyleukotrienes (LTB4) and cysteinyl-leukotrienes (LTC4, LTD4, LTE4). By activating specific G-protein coupled receptors, leukotrienes take part in immune responses, like activation and chemotaxis of leukocytes. Several studies have shown that leukotrienes may play a significant role in pathomechanisms of inflammatory diseases of human airways, skin, digestive tract and heart.     

The effects of low-fat diets rich in arachidonic acid on the composition of plasma fatty acids and bleeding time in Australian aborigines

In the present study we measured the bleeding times in fourteen Aborigines (10 diabetic, 4 non-diabetic) before and after 2 weeks on a diet of tropical seafood (rich in both arachidonic acid and the omega 3 PUFA), followed by 3 weeks on a diet in which kangaroo and freshwater fish (linoleic and arachidonic acid-rich) were the major fat sources. Both diets were very low in fat. Bleeding times increased in all subjects after the 2 weeks of tropical seafood and continued to rise on the mixed diet. The increase over 5 weeks from 4.1 +/- 0.4 to 5.9 +/- 0.4 min was highly significant (p less than 0.01). Due to the extreme isolation of the study location it was only possible to measure the plasma fatty acid composition at the beginning and end of the study. The concentration of arachidonic acid in the plasma lipids doubled whereas that of linoleic acid was almost halved, despite the fact that the diet in the second part of the study contained considerably more linoleic than arachidonic acid. That there appeared to be preferential incorporation of arachidonic acid into the plasma lipids is further supported by the observation that the rise in arachidonic acid in the cholesterol ester and phospholipid fractions was almost exactly counter-balanced by the fall in linoleic acid. In conclusion, the present study demonstrated a rise in bleeding time associated with an increased concentration of arachidonic acid and decreased concentration of linoleic acid in plasma lipids, and suggests that the mechanism by which diet modulates haemostatic function may be more complex than currently assumed.     

The absorption, metabolism and excretion of flavan-3-ols and procyanidins following the ingestion of a grape seed extract by rats

Rats were fed a grape seed extract (GSE) containing (+)-catechin, (-)-epicatechin and dimers, trimers, tetramers and polymeric procyanidins. Liver, kidney, brain and gastrointestinal (GI) tract together with plasma, urine and faeces were collected over a 24 h period and their flavan-3-ol content was analysed by HPLC with tandem mass spectrometry and diode array detection. Small amounts of the GSE flavan-3-ols moved out of the stomach and into the duodenum/jejunum, and to a greater extent the ileum 1 h after ingestion, and into the caecum after 2 h with relatively small amounts being detected in the colon after 3 h. The GI tract contained the parent GSE flavan-3-ols and procyanidins with only trace amounts of metabolites and there were no indications that proanthocyanidins were depolymerised in the GI tract releasing monomeric flavan-3-ols. Plasma contained exclusively catechin glucuronides and methylated glucuronide metabolites which were also detected in the liver and kidneys. These metabolites were also present in urine together with sulphated metabolites and low amounts of the procyanidin dimers B1, B2, B3 and B4 as well as the trimer C2 and an unknown GSE trimer. The amounts of (+)-catechin and (-)-epicatechin metabolites excreted in urine relative to the quantity of the monomers ingested were 27 and 36 %, respectively, after 24 h. This is similar to the levels of urinary excretion reported to occur by other investigators after feeding (-)-epicatechin to rats and provides further, albeit indirect, evidence that the procyanidin oligomers in the GSE were not depolymerised to monomers to any extent after ingestion. No convincing analytical data were obtained for the presence of flavan-3-ol metabolites in the brain.     

Competitive incorporation of arachidonic acid analogs by cultured rat keratinocytes

Arachidonic acid (20:4 n-6) and its metabolic products, such as prostaglandins and leukotrienes, have been known to be associated with skin inflammatory reactions. However, the mechanism of the competitive incorporation of 20:4 n-6 into keratinocytes among polyunsaturated fatty acids (PUFAs) remains uncertain. To investigate the relationship between the molecular structure of PUFAs and the rate of incorporation of PUFAs into cells, a fetal rat skin keratinocyte (FRSK) cell line was used. The cells were incubated for 24 h with any two of the following arachidonic acid analogs: mead acid (20:3 n-9), dihomo-gamma-linolenic acid (20:3 n-6), 11,14,17-cis-eicosatrienoic acid (20:3 n-3), arachidonic acid (20:4 n-6), eicosapentaenoic acid (20:5 n-3) and 5,8,11,14-cis-nonadecatetraenoic acid (19:4 n-5), at the ratio of 1:0, 0.5:0.5, or 0:1; and their incorporation into lipid was measured by capillary gas-liquid chromatography. The experiments indicated that 20:3 n-6 was preferentially incorporated into phospholipids of FRSK rather than 20:3 n-9 or 20:3 n-3, and 19:4 n-5 as well as 20:4 n-6 was preferentially incorporated into total cellular lipid and phospholipids rather than 20:3 n-9 or 20:5 n-3. When two PUFAs were added simultaneously to the medium, 19:4 n-5 most effectively reduced the competitive incorporation of 20:4 n-6 into phospholipids. These results suggest that keratinocytes discriminate 20:4 n-6 from other arachidonic acid analogs by its double bond positions from the carboxyl group.     

Metabolic aspects of trans fatty acids

The consumption of trans isomers of unsaturated fatty acids has been associated withuntoward metabolic effects. Several clinical investigations demonstrated that trans fatty acids increase plasma LDL-cholesterol and lipoprotein (a) and reduce HDL-cholesterol concentrations. These alterations of plasma lipid profiles indicate an atherogenic effect of trans fatty acids. Both in preterm infants and in healthy children aged 1-15 years, we found blood plasma arachidonic acid (C20:4omega-6) levels and the product/substrate ratios of arachidonic acid synthesis (C20:4omega-6/C18:2omega-6) inversely correlated to the level of the principal trans fatty acid, trans octadecaenoic acid (C18:1omega-9/7, trans), which is compatible with a dose-dependent inhibition of arachidonic acid synthesis by trans fatty acids. Moreover, in premature infants trans fatty acids in blood plasma correlated inversely with birth weight in an observational study, indicating that trans fatty acids may impair early human growth. It appears desirable to limit the dietary intake of trans fatty acids. The major dietary sources of trans fatty acids are partially hydrogenated vegetable and fish oils. Refinement of the industrial technology of partial hydrogenation and appropriate food labelling may lead to a considerably decrease of human exposure to trans fatty acids.     

p-Coumaric acid, a common dietary phenol, inhibits platelet activity in vitro and in vivo

p-Coumaric acid (3-(4-hydroxyphenyl)-2-propenoic acid; 4CA), is a ubiquitous plant metabolite with antioxidant and anti-inflammatory properties. The antiplatelet activity of this compound was analysed both ex vivo and in vitro. 4-CA, administered to rabbits for 2 weeks at the dose of 5 mg/kg, mixed with food, inhibited ADP-induced platelet aggregation without affecting blood coagulation. This effect was associated with a marked increase in plasma antioxidant activity, measured as ferric reducing ability of plasma, and with the reduction of thromboxane B2 production. The antiplatelet effect was confirmed by in vitro experiments on human blood: 4CA (500 microM and 1 mM) reduced ADP-induced platelet aggregation (55 x 2 (se 4 x 01) % and 35 x 6 (se 2 x 35) % relative to basal level, respectively). 4CA was able to modify platelet function, measured with PFA-100, a shear-inducing device that simulates primary haemostasis. 4CA interfered also with arachidonic acid cascade, reducing thromboxane B2 production and lipopolysaccharide-induced prostaglandin E2 generation (ic50 371 and 126 microM, respectively). The data show that 4CA is an antioxidant compound with good antiplatelet activity at doses that can be obtained with dietary intervention, suggesting possible applications for primary prevention of vascular disease.     

Design,synthesis and biological evaluation of new endocannabinoid transporter inhibitors

In the present work we describe the synthesis and the in vitro evaluation of a series of arachidonic acid derivatives of general structure I as endocannabinoid transporter inhibitors. In addition, we report the first in vivo studies of the most potent derivative (4, UCM707) within this series. The majority of compounds studied are highly potent (IC(50)=24-0.8 micro M) and selective endocannabinoid uptake inhibitors with very low affinities for either the enzyme fatty acid amide hydrolase (IC(50)=30-113 micro M) or for cannabinoid receptor subtype 1 (CB(1)), cannabinoid receptor subtype 2 (CB(2)) and vanilloid receptor subtype 1 (VR(1)) (K(i)=1000-10000 nM). Among them, (5Z,8Z,11Z,14Z)-N-(fur-3-ylmethyl)icosa-5,8,11,14-tetraenamide (UCM707) behaves as the most potent endocannabinoid transporter inhibitor described to date (IC(50)=0.8 micro M) and exhibits improved potency for the anandamide transporter, high selectivity for CB(1) and VR(1) receptors, and modest selectivity for CB(2). In vivo it enhances the analgesia and hypokinetic effects induced by a subeffective dose of anandamide.     

A medicinal extract of Scutellaria baicalensis and Acacia catechu acts as a dual inhibitor of cyclooxygenase and 5-lipoxygenase to reduce inflammation

A mixed extract containing two naturally occurring flavonoids, baicalin from Scutellaria baicalensis and catechin from Acacia catechu, was tested for cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) inhibition via enzyme, cellular, and in vivo models. The 50% inhibitory concentration for inhibition of both ovine COX-1 and COX-2 peroxidase enzyme activities was 15 microg/mL, while the mixed extract showed a value for potato 5-LOX enzyme activity of 25 microg/mL. Prostaglandin E2 generation was inhibited by the mixed extract in human osteosarcoma cells expressing COX-2, while leukotriene production was inhibited in both human cell lines, immortalized THP-1 monocyte and HT-29 colorectal adenocarcinoma. In an arachidonic acid-induced mouse ear swelling model, the extract decreased edema in a dose-dependent manner. When arachidonic acid was injected directly into the intra-articular space of mouse ankle joints, the mixed extract abated the swelling and restored function in a rotary drum walking model. These results suggest that this natural, flavonoid mixture acts via "dual inhibition" of COX and LOX enzymes to reduce production of pro-inflammatory eicosanoids and attenuate edema in an in vivo model of inflammation.     

Chocolate procyanidins decrease the leukotriene-prostacyclin ratio in humans and human aortic endothelial cells

BACKGROUND: Polyphenolic phytochemicals inhibit vascular and inflammatory processes that contribute to disease. These effects are hypothesized to result from polyphenol-mediated alterations in cellular eicosanoid synthesis. OBJECTIVE: The objective was to determine and compare the ability of cocoa procyanidins to alter eicosanoid synthesis in human subjects and cultured human aortic endothelial cells. DESIGN: After an overnight fast, 10 healthy subjects (4 men and 6 women) consumed 37 g low-procyanidin (0.09 mg/g) and high-procyanidin (4.0 mg/g) chocolate; the treatments were separated by 1 wk. The investigation had a randomized, blinded, crossover design. Plasma samples were collected before treatment and 2 and 6 h after treatment. Eicosanoids were quantitated by enzyme immunoassay. Endothelial cells were treated in vitro with procyanidins to determine whether the effects of procyanidin in vivo were associated with procyanidin-induced alterations in endothelial cell eicosanoid synthesis. RESULTS: Relative to the effects of the low-procyanidin chocolate, high-procyanidin chocolate induced increases in plasma prostacyclin (32%; P<0.05) and decreases in plasma leukotrienes (29%; P<0.04). After the in vitro procyanidin treatments, aortic endothelial cells synthesized twice as much 6-keto-prostaglandin F(1alpha) (P<0.01) and 16% less leukotriene (P<0.05) as did control cells. The in vitro and in vivo effects of procyanidins on plasma leukotriene-prostacyclin ratios in culture medium were also comparable: decreases of 58% and 52%, respectively. CONCLUSION: Data from this short-term investigation support the concept that certain food-derived flavonoids can favorably alter eicosanoid synthesis in humans, providing a plausible hypothesis for a mechanism by which they can decrease platelet activation in humans.     

Flavanol monomer-induced changes to the human faecal microflora

We have investigated the bacterial-dependent metabolism of ( - )-epicatechin and (+)-catechin using a pH-controlled, stirred, batch-culture fermentation system reflective of the distal region of the human large intestine. Incubation of ( - )-epicatechin or (+)-catechin (150 mg/l or 1000 mg/l) with faecal bacteria, led to the generation of 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone, 5-phenyl-gamma-valerolactone and phenylpropionic acid. However, the formation of these metabolites from (+)-catechin required its initial conversion to (+)-epicatechin. The metabolism of both flavanols occurred in the presence of favourable carbon sources, notably sucrose and the prebiotic fructo-oligosaccharides, indicating that bacterial utilisation of flavanols also occurs when preferential energy sources are available. (+)-Catechin incubation affected the growth of select microflora, resulting in a statistically significant increase in the growth of the Clostridium coccoides-Eubacterium rectale group, Bifidobacterium spp. and Escherichia coli, as well as a significant inhibitory effect on the growth of the C. histolyticum group. In contrast, the effect of ( - )-epicatechin was less profound, only significantly increasing the growth of the C. coccoides-Eubacterium rectale group. These potential prebiotic effects for both (+)-catechin and ( - )-epicatechin were most notable at the lower concentration of 150 mg/l. As both ( - )-epicatechin and (+)-catechin were converted to the same metabolites, the more dramatic change in the growth of distinct microfloral populations produced by (+)-catechin incubation may be linked to the bacterial conversion of (+)-catechin to (+)-epicatechin. Together these data suggest that the consumption of flavanol-rich foods may support gut health through their ability to exert prebiotic actions.     

Interaction between fish and vegetable oils in relation to rat leucocyte leukotriene production.

We examined the influence of mixtures of dietary fish oil and three vegetable oils (linseed, olive and sunflower) on the incorporation of dietary eicosapentaenoic acid (EPA) into rat leucocyte phospholipids and the subsequent metabolism of EPA and arachidonic acid by 5-lipoxygenase. Eicosapentaenoic acid in leucocyte phospholipids of fish oil-fed rats was decreased by the addition of each vegetable oil to the dietary fish oil, with sunflower oil, the oil highest in linoleate (LA), having the largest EPA-lowering effect (66% decrease). The rate of synthesis of leukotriene B4 (LTB4) was increased by the addition of each vegetable oil to the basic fish oil diet, with sunflower oil having a significant effect on LTB4 synthesis (145% increase). The effects of olive oil (enriched in oleate) were similar to those of linseed oil (enriched in alpha-linolenic acid) with regard to EPA incorporation (mean decrease = 30%) and LTB4 synthesis (mean increase = 72%). The level of arachidonic acid in leucocyte membranes and the rate of synthesis of LTB4 were proportional to the level of dietary LA added to the basic fish oil diet. The results indicate that olive or linseed oil ingested in combination with fish oil have less effect than does sunflower oil on leucocyte EPA content and LTB4 production. They further suggest that, when ingested with fish oil, dietary linoleic acid is more important than oleate or alpha-linolenic acid as a determinant of these variables.     

Impact of omega-3 fatty acid enriched TPN on leukotriene synthesis by leukocytes after major surgery

Major surgery leads to post-traumatic immune dysregulation which is driven by the activation of potent proinflammatory mediators including the leukotrienes (LTs). The LTs of the four-series derive from arachidonic acid (an omega-6 fatty acid). In contrast, LTs of the five-series are metabolic products of eicosapentaenoic acid (an omega-3 fatty acid) and exert less biological activities. Therapeutical strategies to attenuate proinflammatory signals include the provision of omega-3 fatty acids. Thirty patients with major elective abdominal surgery and an indication for total parenteral nutrition (TPN) were compared in a prospective, double blind, randomized study of two parallel groups. Group 1 (n=14) received an omega-3 fatty acid enriched 20% lipid emulsion (MCT:LCT:fish oil = 5:4:1, MLF541; Lipoplus) for 5 days postoperatively. Group 2 (n=16) received a standard 20% fat emulsion (LCT; Intralipid). The LT release from whole blood leukocytes stimulated with Ca-ionophore was analyzed preoperatively and on postoperative days 1, 6 and 8 by HPLC. There was a significant increase in the generation of LTB(5) (P=0.0035) and in the ratio of LTB(5)/LTB(4) (P=0.0017) the omega-3 group, but not in the reference group after 5 days infusion of the lipid emulsions. The omega-6/omega-3 fatty acid ratio 3:1 of the newly developed MLF541 lipid emulsion is appropriate to increase the synthesis of the biologically less active leukotrienes of the five-series. Nutritive enrichment with omega-3 fatty acids in a balanced ratio with omega-6 fatty acids is an important step to avoid hyperinflammatory situations in patients after major surgery.     

Changes in the fatty acid profiles of plasma lipid fractions induced by dietary nucleotides in infants born at term

This study was designed to determine the polyunsaturated fatty acid (PUFA) composition of plasma lipid fractions in newborn infants fed human milk (HM), milk formula (MF) or nucleotide-supplemented milk formula (NMF) during the first month of life. Linoleic acid was increased in infants fed formulas in all plasma lipid fractions with respect to those fed HM. Plasma phospholipids in MF-fed infants had lower percentages of PUFA of both omega 6 and omega 3 series, namely arachidonic and docosahexaenoic acids, than those fed HM or NMF; the unsaturation index was decreased in infants fed MF as compared to those fed HM or NMF. Arachidonic acid showed a similar behaviour in plasma cholesteryl esters as in phospholipids. No changes for long chain PUFA among the groups studied were observed for plasma triglycerides and free fatty acids. These results support previous findings that dietary nucleotides are involved in the regulation of desaturation and elongation of linoleic and linolenic acid to their longer superior homologous fatty acids. We suggest that dietary nucleotides may reverse the partial inhibition of delta 5-desaturase caused by an excess of linoleic acid in the diet during early postnatal life.     

Effects of ingestion of tomatoes, tomato juice and tomato purée on contents of lycopene isomers, tocopherols and ascorbic acid in human plasma as well as on lycopene isomer pattern

Tomatoes are an important part of the diet. Lycopene, the predominant carotenoid in tomatoes, is hypothesised to mainly mediate the health benefits of tomato products. Anticancer activity of tomato products and lycopene has been suggested by numerous studies. The aim of the present study was to investigate the effect of ingestion of three different tomato-based foodstuffs on plasma contents of lycopene, tocopherols and ascorbic acid. Because isomers of lycopene may have different biological activities, a special interest was to look how the lycopene isomer pattern is changed depending on the matrix of tomato products. Following a 2-week depletion phase volunteers ingested 12.5 mg lycopene/d for 4 weeks comprising tomatoes, tomato juice or tomato purée. The basal levels of lycopene in plasma were comparable for all groups and decreased significantly during the 2 weeks of depletion to approximately half of the basal values. Following intervention, plasma lycopene concentration increased significantly. Conversely, supplementation did not significantly affect levels of tocopherols and ascorbic acid in plasma. Regarding isomers of lycopene, the (Z)-lycopene:(all-E)-lycopene plasma isomer ratio was significantly changed during the study for all groups. A remarkable enrichment of the relative contents of (5Z)-lycopene was observed during the depletion period, which supports the hypothesis that lycopene (Z)-isomers are formed within the human body after ingestion of (all-E)-lycopene. After dietary intervention with lycopene-rich products the isomer ratios returned to those observed at the start of the study. Further investigations will clarify the process of isomerisation in more detail.     

Ingestion of fish oil or a derived n-3 fatty acid concentrate containing eicosapentaenoic acid (EPA) affects fatty acid compositions of individual phospholipids of rat brain, sciatic nerve and retina

The effect of feeding redfish (Sebastes marinus or mantella) oil or a derived n-3 fatty acid concentrate containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the fatty acid compositions of individual phospholipids in selected neural tissues was studied in growing male rats. Control animals were given sunflower oil in the diet for the 5-wk feeding trial. Lipid analyses revealed that EPA (20:5n-3) became significantly enriched in all phospholipid fractions (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol) in the tissues studied (brain, retina and sciatic nerve) in the two n-3 fatty acid dietary groups relative to controls. Corresponding changes were also found in the 22:5n-3 contents of these tissues, whereas little or no significant elevation in DHA (22:6n-3) was found. In contrast, the percentages by weight of the n-6 fatty acids including 18:2n-6, 20:4n-6 (arachidonic acid, AA), 22:4n-6 and 22:5n-6 were generally lower in the various phospholipids/tissues of the animals given fish oil or the n-3 fatty acid concentrate; the levels of 22:5n-6 and 22:4n-6 were markedly affected in this regard. These results indicate that dietary n-3 fatty acids (as EPA plus DHA) can greatly affect the fatty acid compositions of the various membrane phospholipids in nervous tissues within a relatively short time. These biochemical alterations may be important for functional changes including altered membrane fluidity, cellular responses, ion transport and the biosyntheses of AA- and EPA-derived prostaglandins and leukotrienes.     

Vitamin E supplementation effect on human platelet function, arachidonic acid metabolism, and plasma prostacyclin levels

A randomized, placebo-controlled double-blind trial was conducted on 20 adults to assess the effect of vitamin E (800 IU/d 727 mg/d for 5 wk) on platelet function, arachidonic acid metabolism, and prostacyclin generation. Platelet aggregation was measured in response to collagen, arachidonic acid, and adenosine diphosphate. Thromboxane B2 was assayed in serum and in the supernatant plasma after platelet aggregation. Platelets were labeled with [3H]arachidonic acid to assess production and release of cyclooxygenase products (MDA, TXB2, and HHT), a lipoxygenase product (12-HETE), and arachidonic acid in response to stimulation by thrombin or collagen. Prostacyclin was measured in plasma and in blood collected from bleeding-time incisions by a sensitive HPLC-RIA procedure. Despite marked increases in plasma and erythrocyte vitamin E levels in the vitamin E group, there were no significant differences between the vitamin E and placebo groups in any of the variables measured.     

Reversal of experimental essential fatty acid deficiency by cutaneous administration of safflower oil.

The intriguing observation that cutaneous application of essential fatty acid (EFA)-rich oil corrects the biochemical abnormalities of EFA deficiency was evaluated in EFA-deficient rats. Approximately 185 mg of safflower oil (140 mg of linoleic acid) were applied daily for 15 days to the kin of EFA-deficient rats. Before and after treatment with the safflower oil, the fatty acid patterns of plasma and erythrocyte phospholipid as well as of plasma triglyceride and cholesterol ester fractions were determined. The linoleic and arachidonic acid content of both plasma and erythrocyte phospholipid increased, while the eicosatrienoic acid content of both fractions decreased. The linoleic acid content of plasma triglyceride increased with safflower oil treatment, but little change occurred in the almost undetectable pretreatment levels of arachidonic and eicosatrienoic acid. In the plasma cholesterol ester fraction, arachidonic acid increased with treatment and eicosatrienoic acid decreased, but the small increase in the linoleic acid content was not statistically significant. Thus, the study confirms the observation that cutaneous application of EFA-rich oils reverses the plasma biochemical manifestation of EFA deficiency. In addition cutaneously applied EFA-rich oils reversed the biochemical manifestations of EFA deficiency in erythrocytes. Whether or not cutaneous application of such oils will prevent EFA deficiency, however, remains to be proven.