A comparative study on the effect of cis (oleic, linoleic) and trans (elaidic, linoelaidic) fatty acids on the in vitro prostaglandin biosynthesis in human blood platelets from (1-14C) arachidonic acid

Raman and infrared spectroscopy of carbohydrates: A review

Carbohydrates are widespread and naturally occurring compounds, and essential constituents for living organisms. They are quite often reported when biological systems are studied and their role is discussed. However surprisingly, up till now there is no database collecting vibrational spectra of carbohydrates and their assignment, as has been done already for other biomolecules. So, this paper serves as a comprehensive review, where for selected 14 carbohydrates in the solid state both FT-Raman and ATR FT-IR spectra were collected and assigned. Carbohydrates can be divided into four chemical groups and in the same way is organized this review. First, the smallest molecules are discussed, i.e. monosaccharides (d-(-)-ribose, 2-deoxy-d-ribose, l-(-)-arabinose, d-(+)-xylose, d-(+)-glucose, d-(+)-galactose and d-(-)-fructose) and disaccharides (d-(+)-sucrose, d-(+)-maltose and d-(+)-lactose), and then more complex ones, i.e. trisaccharides (d-(+)-raffinose) and polysaccharides (amylopectin, amylose, glycogen). Both Raman and IR spectra were collected in the whole spectral range and discussed looking at the specific regions, i.e. region V (3600-3050cm^-1), IV (3050-2800cm^-1) and II (1200-800cm^-1) assigned to the stretching vibrations of the OH, CH/CH₂ and C-O/C-C groups, respectively, and region III (1500-1200cm^-1) and I (800-100cm^-1) dominated by deformational modes of the CH/CH₂ and CCO groups, respectively. In spite of the fact that vibrational spectra of saccharides are significantly less specific than spectra of other biomolecules (e.g. lipids or proteins), marker bands of the studied molecules can be identified and correlated with their structure.

Both (n-3) and (n-6) fatty acids stimulate wound healing in the rat intestinal epithelial cell line, IEC-6

The control of proliferation and epithelial restitution are processes that are poorly understood. The effects of (n-3), (n-6) and trans fatty acids on proliferation of subconfluent IEC-6 cultures and restitution of wounded IEC-6 monolayers were investigated. Incorporation of supplemented fatty acids into cellular phospholipid was also assessed. Sulforhodamine B protein dye binding assay was utilized to assess the proliferative effects of fatty acids on growth of IEC-6 cultures. Incorporation of supplemental fatty acids into cellular phospholipid was examined by thin-layer chromatography combined with gas chromatography. The modulation of epithelial restitution was examined by razor blade wounding confluent IEC-6 monolayers grown in media supplemented with various fatty acids. Inhibition of eicosanoid synthesis by indomethacin during the wounding assay was also assessed. Both (n-3) and (n-6) fatty acids significantly inhibited growth of this intestinal epithelial cell model at concentrations above 125 micromol/L. The trans fatty acid, linoelaidate 18:2(n-6)trans, inhibited growth of IEC-6 cells at concentrations above 250 micromol/L. Another trans fatty acid, elaidate 18:1(n-9)trans, was well-tolerated at concentrations as high as 500 micromol/L. Eicosapentanoic 20:5(n-3), linoleic 18:2(n-6), alpha-linolenic 18:3(n-3), gamma-linolenic 18:3(n-6) and arachidonic 20:4(n-6) acids all significantly enhanced cellular migration in the IEC-6 model of wound healing. Eicosapentanoate, linoleate, alpha-linolenate, gamma-linolenate and arachidonate are all capable of improving reconstitution of epithelial integrity following mucosal injury. Inhibition of eicosanoid synthesis reduced the enhancement of restitution by n-6 fatty acids back to control levels.

Linoleic acid requirement of rats fed trans fatty acids

The amount of linoleic acid required to prevent undesirable effects of C18 trans fatty acids was investigated. In a first experiment, six groups of rats were fed diets with a high content of trans fatty acids (20% of energy [en%]), and increasing amounts of linoleic acid (0.4 to 7.1 en%). In a second experiment, four groups of rats were fed diets designed to compare trans fatty acids with saturated and cis-monounsaturated fatty acids of the same chain length at the 2 en% linoleic acid level. After 9-14 weeks, the oxygen uptake, lipid composition and ATP synthesis of heart and liver mitochondria were determined. The phospholipid composition of the mitochondria did not change, but the fatty acid compositions of the two main mitochondrial phospholipids were influenced by the dietary fats. Trans fatty acids were incorporated in all phospholipids investigated. The linoleic acid level in the phospholipids, irrespective of the dietary content of linoleic acid, increased on incorporation of trans fatty acids. The arachidonic acid level had decreased in most phospholipids in animals fed diets containing 2 en% linoleic acid. At higher linoleic acid intakes, the effect of trans fatty acids on the phospholipid arachidonic acid level diminished. However, in heart mitochondrial phosphatidylethanolamine, trans fatty acids significantly increased the arachidonic acid level. Despite these changes in composition, neither the amount of dietary linoleic acid nor the addition of trans fatty acids influenced the mitochondrial function. For rats, a level of 2 en% of linoleic acid is sufficient to prevent undesirable effects of high amounts of dietary C18 trans fatty acids on the mitochondrial function.

Cardiovascular actions of dietary polyunsaturates and related mechanisms. A state-of-the-art-review

A survey of the effects of dietary polyunsaturates on the function of the cardiovascular system is given. In isolated hearts of rats dietary linoleate supply increases both coronary flow and heart muscle function. Hearts of rats fed high amounts of linoleic acid are protected against catecholamine (over)-stimulation. Polyunsaturate rich vegetable oils are effective in lowering blood pressure in several murine hypertension models. This effect seems to be closely related to antihypertensive changes in kidney function and in the function of the arterial vessel wall. Dietary polyunsaturates augment the hypotensive effect of antihypertensive drugs. Cardiovascular effects of dietary polyunsaturates are at least partly mediated via changes in the prostanoid metabolism as well as a reduction of the sympathetic activity. Evidence has been accumulated that cardiovascular effects of dietary polyunsaturates in animal and man are comparable. The observed effects are discussed against the background of a reduced risk of cardiovascular disease after a polyunsaturate rich diet in man.

Influence of dietary partially hydrogenated vegetable and marine oils on membrane composition and function of liver microsomes and platelets in the rat

The aim of the present study was to investigate the influence of partially hydrogenated vegetable and marine oils on membrane composition and function of liver microsomes and platelets with particular reference to the metabolism of linoleic acid and the production of arachidonic acid metabolites. Four groups of male weanling rats were fed linoleic acid supplemented diets containing 20% (w/w) of partially hydrogenated low erucic acid rapeseed oil (HLRSO), partially hydrogenated herring oil (HHO), olive oil (OO) and trierucin + triolein (TE) for 10 weeks. An additional two groups were fed partially hydrogenated low erucic acid rapeseed oil and partially hydrogenated herring oil without linoleic acid supplementation (HLRSO- and HHO-, respectively). Substantial amounts of trans fatty acids were incorporated into liver microsomes (12.6% in group HLRSO) and platelets (7.0% in group HLRSO-). This incorporation was not dependent on the dietary linoleic acid level. Hepatic microsomal delta5 -desaturase activity was significantly increased after HLRSO feeding compared to 00 feeding. Delta6 -Desaturase activity did not vary in the linoleic acid supplemented groups. Both delta5 -and delta6 -desaturase activities were significantly increased in groups without linoleic acid supplementation. Docosenoic acid was incorporated into platelet phospholipids in contrast to liver microsomes. In the platelet, docosenoic acid seemed to have a special preference for phosphatidylserine. Very small amounts were incorporated into platelet phosphatidylinositol. Feeding diets HLRSO, HHO and 00 did not influence rat platelet cyclooxygenase or 12-lipoxygenase activity. Platelets from rats fed TE, however, produced significantly less 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) than platelets from rats fed OO. Feeding of HLRSO- and HHO- resulted in a significantly diminished production of the arachidonic acid metabolites 12-HETE, 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 6-keto-prostaglandin F1alpha in stimulated platelets and aorta. Thus, high dietary levels of trans isomers of monoenoic acids do not interfere with platelet cyclooxygenase or lipoxygenase activity provided sufficient amounts of linoleic acid are available.

Docosahexaenoic acid (C22:6 omega 3) and linoleic acid are anti-aggregatory, and alter arachidonic acid metabolism in human platelets

Effects of various concentrations (12.5-500 uM) of linoleic acid and docosahexaenoic acid (C22:6 omega 3)(sod. salt) were examined on the platelet metabolism of labelled arachidonate (AA) under two different incubation conditions. In the first platelets were pretreated with either fatty acid prior to incubation with labelled AA; and in the second incubation platelets were incubated with a mixture containing a fatty acid (linoleic acid or DHA) and labelled AA. At all concentrations the two fatty acids reduced the formation of TxB2. At lower concentrations (up to 200 uM) the fatty acids inhibited platelet cyclooxygenase as shown by a reduced formation of prostaglandins (PGs) and TxB2. At higher concentrations (400 and 500 uM), however, the fatty acids behaved differently. Although TxB2 formation was reduced, there was observed an increased formation of PGs. In DHA pretreated platelets only PGE2 increased (to double control values). Platelets pretreated with linoleic acid produced increased amounts of all PGs (PGF2 alpha, PGE2, PGD2), and this effect was greatest for PGE2 which increased by 5-6 fold of control values. DHA showed a dose-dependent inhibition of platelet aggregation induced by arachidonate, epinephrine and collagen.

In vitro effect of unsaturated fatty acids on the balance between thromboxane A2 and prostacyclin in the blood vascular system

Unsaturated fatty acids (FAs) (oleic, linoleic, alpha -linolenic, and gamma -linolenic acids) were found to inhibit platelet thromboxane synthetase. This conclusion was based on the following experimental evidence. 1. Reduced formation of TxB2 and increased formation of prostaglandins F2 alpha, E2 and D2 as seen in autoradiography of TLC plate. 2. Inhibition of ADP- and collagen-induced aggregation of PRP samples in the presence of the unsaturated FAs. 3. Reduced formation of TxB2 determined by RIA in PRP samples pretreated with the unsaturated FAs followed by collagen-induced aggregation. 4. Reduced formation of MDA in the presence of the unsaturated FAs. 5. Increased formation of PGI2 (determined as 6-keto-PGF1 alpha), PGE2, PGF2 alpha and PGD2 (redirection effect) in the presence of the unsaturated FAs in a system consisting of washed human platelet preparation and a piece of rat aorta from labelled arachidonate. TxB2 was reduced. 6. Aggregation experiment confirming above.

Unsaturated fatty acids and platelet aggregation: in vitro study

The effects of several cis and two trans fatty acids (elaidic and linoelaidic acids) - sodium salt and also in free acid form - on ADP-induced platelet aggregation were studied. The effects of the cis and trans fatty acids (sod. salt) on collagen-induced aggregation were also examined. Besides, the effects of several cis fatty acids, including dihomo-gamma-linolenic acid, on arachidonic acid induced aggregation were examined. The results indicate that unsaturated fatty acids inhibit platelet aggregation induced by ADP and collagen. The unsaturated fatty acids, however, with most blood samples did not show any antiaggregation effect on arachidonic acid-induced aggregation. While showing an antiaggregation effect on collagen-induced aggregation and failing to do so on arachidonic acid-induced aggregation, this difference in the behaviour of the unsaturated fatty acids in the two aggregations can be explained on the basis of binding of exogenous test fatty acids to plasma proteins. The mechanism(s) by which unsaturated fatty acids, in general, may exert their antiaggregation effect is discussed.