Biochemistry of radioiodinated free fatty acids

Summary Radioiodinated free fatty acids have been developed to study myocardial metabolism non-invasively in man. In the present study the distribution of radiolabeled lipids in the myocardium and in arterial and coronary sinus blood was evaluated following injection of three commonly used iodinated fatty acids in fasted (n = 5) and lactate loaded (n = 3) dogs. Five minutes after simultaneous i.v. injection of radioiodinated 17-I-heptadecanoic acid (IHDA),15-(p-I-phenyl) pentadecanoic acid (IPPA) and 15-(p-I-phenyl)-3,3-dimethylpentadecanoic acid (DMIPPA) a biopsy specimen and samples of arterial and coronary sinus blood were taken. After extraction and TLC the relative distribution of radioactivity in the aqueous phase (containing the oxidation products), pellet and organic phase was calculated. The organic phase was further divided into phospholipids, diglycerides, free fatty acids, triglycerides and cholesterolesters. Seventy two percent of IHDA was oxidized, 36% of IPPA and 7% of DMIPPA. The organic phase consisted primarily of triglycerides and phospholipids. The ratios of triglycerides to phospholipids were about the same for IHDA, IPPA and DMIPPA (0.58, 0.65 and 0.50, respectively). Free IHDA in tissue samples was low (4%) and elevated for IPPA and DMIPPA, (17% and 37%). During lactate loading triglycerides were higher for all three fatty acids. For IHDA and IPPA this increase was paralleled by a decrease in the aqueous phase, in case of DMIPPA the aqueous phase remained the same. Five minutes after injection most of the organic phase of both arterial and coronary sinus blood consisted of the injected fatty acids, the aqueous phase contained oxidation products. There were only minor differences during lactate loading. During the evaluation of scintigraphic patterns of the radioiodinated fatty acids under normal conditions (eg at rest) and during elevated lactate levels (eg during exercise) the differences in distribution must therefore be considered.     

The presence of odd-chain fatty acids in Drosophila phospholipids

ABSTRACT

Most fatty acids in phospholipids and other lipid species carry an even number of carbon atoms. Also odd-chain fatty acids (OCFAs), such as C15:0 and C17:0, are widespread throughout the living organism. However, the qualitative and quantitative profiles of OCFAs-containing lipids in living organisms remain unclear. Here, we show that OCFAs are present in Drosophila phosphatidylcholine (PC) and phosphatidylethanolamine (PE) and that their level increases in accordance with progression of growth. Furthermore, we found that food-derived propionic acid/propanoic acid (C3:0) is utilized for production of OCFA-containing PC and PE. This study provides the basis for understanding in vivo function of OCFA-containing phospholipids in development and lipid homeostasis.     

Incorporation of free fatty acids into acylthioesters and lipids of developing sunflower seeds

The synthesis of lipids from radioactive fatty acids in developing sunflower seeds has been examined. Lauric, palmitic, stearic and oleic acids were us     

Unbound free fatty acid concentrations are increased in cardiac ischemia

Monitoring increased plasma unbound free fatty acid (FFA_u) concentrations has been proposed as a biomarker for myocardial ischemia. In the current study, 30 acute coronary syndrome (ACS) patients presenting in the emergency department, with chest pain within 12 h of onset, were clinically evaluated along with serial cardiac troponin I (cTnI) and FFA_u measurements. Increased FFA_u were found in 28 of 30 (93%) of ACS patients, ranging from 2.0 to 430 nM. For the nine ACS patients with myocardial infarction (MI), FFA_u levels were increased at presentation for all (100%). In contrast, cTnI was increased in only 9 of 30 (30%) patients, mean 0.7 μg/L, and in only 2 of 9 (22%) MI patients, mean 1.3 μg/L. During the 24 h following admission, cTnI increased in all 9 MI patients. FFA_u concentrations increased in every sample in which cTnI increased. Our findings suggest that FFA_u is increased in ischemia regardless of the presence or absence of myocardial necrosis, as reflected by increased or normal cTnI, respectively.     

Incorporation of n-3 fatty acids into phospholipids of rat liver and white and brown adipose tissues: A time-course study during fish-oil feeding

The aim of this study was to determine the time-course incorporation of dietary n-3 polyunsaturated fatty acids into phospholipids of tissues highly involved in lipid and energy metabolism: the liver and the white (WAT) and brown (BAT) adipose tissues. Rats were fed a diet supplemented with 19% fish oil for up to 4 weeks. Minor changes in the relative proportions of tissue phospholipids were observed in the three tissues. Fish-oil feeding induced rapid and large replacements of n-6 fatty acids by n-3 fatty acids. In liver, the 22:6n-3 level increased progressively and reached a plateau after 3 (phosphatidylethanolamine and phosphatidylserine) or 7 days (phosphatidylcholine and phosphatidylinositol). In contrast, the 20:5n-3 level transiently peaked in all liver phospholipids at days 1–3 before reaching a plateau after day 7. In WAT as in BAT the level of n-3 fatty acids increased progressively and reached in all phospholipids a plateau after day 7. As a general trend, in each phospholipid class the 22:6n-3/20:5n-3 ratio was higher in liver than in the two adipose tissues. This study shows that each dietary n-3 fatty acid is incorporated very rapidly into liver, WAT, and BAT phospholipids but according to time courses and at levels that depend simultaneously on the tissue and phospholipid class considered.     

Differential incorporation of fatty acids into and peroxidative loss of fatty acids from phospholipids of human spermatozoa

Intact human sperm incorporated radiolabelled fatty acids into membrane phospholipids when incubated in medium containing bovine serum albumin as a fatty acid carrier. The polyunsturated fatty acids were preferentially incorporated into the plasmalogen fraction of phospholipid. Uptake was linear with time over 2 hr; at this time sufficient label was available to determine the loss of fatty acids under conditions of spontaneous lipid peroxidation. Loss of the various phospholipid types, the loss of the various fatty acids from these phospholipids, and the overall loss of fatty acids were all first order. The loss of saturated fatty acids was slow with first order rate constant k₁ = 0.003 hr^?1; for the polyunsaturated fatty acids, arachidonic and docosahexaenoic acids, k₁ = 0.145 and 0.162 hr^?1, respectively. The rate of loss of fatty acids from the various phospholipid types was dependent on the type, with loss from phosphatidylethanolamine being the most rapid. Among the phospholipid types, phosphatidylethanolamine was lost at the greatest rate. Analysis of fatty acid loss through oxidation products was determined for radiolabelled arachidonic acid. Under conditions of spontaneous lipid peroxidation at 37°C under air in the absence of albumin, free arachidonic acid was found in the medium, along with minor amounts of hydroxylated derivative. All the hydroperoxy fatty acid remained in the cells. In the presence of albumin, all the hydroperoxy fatty acid was found in the supernatant bound to albumin; none could be detected in the cells. Albumin is known as a very potent inhibitor of lipid peroxidation in sperm; its action may be explained, based on these results, as binding the damaging hydroperoxy fatty acids. These results also indicate that a phospholipase A₂ may act in peroxidative defense by excising a hydroperoxy acyl group from phospholipid and providing the hydroperoxy fatty acid product as substrate to glutathione peroxidase. This formulation targets hydroperoxy fatty acid as a key intermediate in peroxidative degradation. © 1995 wiley-Liss, Inc.     

Conversion of volatile fatty acids into polyhydroxyalkanoate by Ralstonia eutropha

Aims:  The aims of this study were to optimize condensed corn solubles (CCS) as a medium for growth of Ralstonia eutropha and to determine the effects of individual volatile fatty acids (VFAs) on polyhydroxyalkanoate (PHA) production .
Methods and Results:  A CCS medium of concentration 240 g l⁻¹ with a carbon : nitrogen ratio of 50 : 1 was developed as the optimal medium. Cultures were grown in 1-l aerated flasks at 250 rev min⁻¹ at 30°C for 120 h. Comparable growth rates were observed in CCS vs a defined medium. At 48 h, VFAs were fed individually at different levels. Optimal levels of all the acids were determined to maximize PHA production. An overall comparison of the VFAs indicated that butyric and propionic acids provided the best results.
Conclusion:  An optimized CCS medium supported growth of R. eutropha . Butyric and propionic acids were the most efficient carbon sources to maximize PHA production when added at the 5 g l⁻¹ level.
Significance and Impact of the Study:  The study shows that a byproduct of ethanol industry can be effectively used as a low cost medium for PHA production, thus partly reducing the cost of commercialization of biopolymers.     

不饱和脂肪酸在逆境胁迫中的作用

生物膜是将细胞与环境分开的第一道屏障,是环境胁迫造成损伤的主要位点.脂肪酸是生物膜的主要组成成分,不饱和脂肪酸在决定生物膜的生理特性中具有重要作用,增加脂肪酸的不饱和程度能增加膜脂的流动性.近年来,很多研究发现,生物通过脂肪酸脱饱和维持膜的流动性来适应外界环境变化.本文主要从不饱和脂肪酸在环境温度胁迫、盐胁迫、氧化胁迫、酸碱胁迫、干旱胁迫、乙醇胁迫及铝胁迫中的作用研究进展进行了综述.     

Incorporation of deuterium-labeled fatty acids into human milk, plasma, and lipoprotein phospholipids and cholesteryl esters

Fatty acid metabolism and the contribution of dietary fatty acids to milk cholesteryl ester (CE) and phospholipid (PL) were investigated in normal lactating mothers. The approach used was to feed mixtures of triglycerides containing deuterium-labeled palmitic acid (16:0-2H2), oleic acid (18:1-2H6), and linoleic acid (18:2-2H4). Milk and plasma samples were collected for 72 hr. Triglyceride (TG), CE, and PL fractions from milk, plasma, and lipoprotein were isolated and analyzed by gas-liquid chromatography and mass spectrometry. Data for the milk CE and PL fractions showed a definite selectivity for incorporation of 16:0-2H2 and 18:1-2H6 relative to 18:2-2H4. Based on the ratios of the deuterated fatty acids incorporated into the milk CE and PL samples, their incorporation times and isotopic enrichment data, it appears that these fatty acids are supplied mainly by the TG derived from chylomicrons and very low density lipoproteins. Plasma and lipoprotein CE data showed a progressive increase in 18:2-2H4 content, with 16:0-2H2 and 18:1-2H4 remaining relatively constant over the collection period. Plasma and lipoprotein PL data showed a higher rate for incorporation of 18:2-2H4 than 16:0-2H2 and 18:1-2H6 over the course of the sampling period. Comparison to previous data from adult males indicates lactation does not have a major effect on the general metabolism of these fatty acids. An increase with time in the isotopic enrichment of 18:2-2H4 in the plasma and lipoprotein CE and PL samples was observed which is consistent with in vitro selectivities reported for lecithin:cholesterol acyltransferase and phosphatidylcholine acyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Maternal dietary n-3 fatty acids alter cardiac ventricle fatty acid composition, prostaglandin and thromboxane production in growing chicks

The effects of feeding n-6 and n-3 fatty acids to broiler hens on cardiac ventricle fatty acid composition, and prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) production of hatched chicks were investigated. Fertile eggs obtained from hens fed diets supplemented with 3.5% sunflower oil (Low n-3), 1.75% sunflower+1.75% fish oil (Medium n-3), or 3.5% fish oil (High n-3) were incubated. The hatched chicks were fed a diet containing 18:3 n-3, but devoid of longer chain n-6 and n-3 fatty acids for 42 days. Arachidonic acid content was lower in the cardiac ventricle of High n-3 and Medium n-3 compared to Low n-3 birds for up to 2 weeks (P<0.002). Long chain n-3 fatty acids were higher in the cardiac ventricle of chicks from hens fed High and Medium n-3 diets when compared to chicks from hens fed the Low n-3 diet. Differences in long chain n-3 fatty acids persisted up to four weeks of age (P<0.001). Peripheral blood mononuclear cells (PBMNC) of 7-day-old High n-3 broilers produced significantly lower PGE2 and TXA2 than PBMNC from Low n-3 and Medium n-3 birds. These results indicate that maternal dietary n-3 fatty acids increases cardiac ventricle n-3 fatty acids while reducing arachidonic acid and ex vivo PGE2 and TXA2 production during growth in broiler chickens.     

Glycosides of polyenoic branched fatty acids from myxomycetes

The determination of chemical structures of five novel compounds, i.e. one multibranched polyunsaturated fatty acid ((2E,4E,7S,8E,10E,12E,14S)-7,9,13,17-tetramethyl-7,14-dihydroxy-2,4,8,10,12,16-octadecahexaenoic acid) and its four glycosides from seven different myxomycetes is described. The absolute configuration of both hydroxyl groups was determined. The glycosides containing glucose, mannose and rhamnose. These compounds were identified by means of 1H and 13C NMR, MS, UV and IR spectra. Three of them were identified in Arcyria cinerea (Bull.) Pers., two in A. denudata (L.) Wetts., and A. nutans (Bull.) Grev., Fuligo septica (L.) Wigg., Lycogala epidendrum (L.) Fries, Physarum polycephalum Schwein., and Trichia varia Pers. contained one of the identified glycosides each.     

Nature of DNA-bound fatty acids in Pseudomonas aurantiaca

The existence of Pseudomonas aurantiaca DNA-bound fatty acids and lipids is presented in this work. The isolation of DNA was carried out by two different procedures, namely, phenol and detergent-based phenol isolation in order to prove the presence of DNA-bound lipids. The lipid content of DNA is expressed in terms of fatty acid profile. A high level of 16:0, 18:0 and 18:1 is characteristic for tightly bound DNA lipids. On the other hand, the fatty acids such as 14:1, iso14:0 and iso16:0 are found in trace amounts only in DNA lipid fraction, but these fatty acids are not found in the whole-cell lipids. Absolutely no 3-hydroxy fatty acids were found in DNA lipids. However, both C16 and C18 species represent the main fatty acids of whole-cell and DNA-bound lipids. The presence of DNA-bound lipids even under tough treatment of DNA allows to conclude that these lipids represent a special pool among cellular lipids.     

The distribution of fatty acids in gill phospholipids of the Chinese crab Eriocheir sinensis

The fatty acid composition of the different classes of phospholipids isolated from 10,000 g fractions of posterior and anterior gills of fresh water-acclimatized Chinese crabs (Enocheir sinensis) has been analysed by two-dimensional TLC and GLC. All the phospholipids, especially PE and DPG, contain large amounts of long chain, polyunsaturated fatty acids. In PC and PE of both the anterior and posterior gills, polyenic fatty acids (particularly the ω-3-acid family) were found to be mainly incorporated in the 2-positon of the glycerol molecule. The ω-3-fatty acids/ω-6-fatty acids ratio in each class of phospholipids is higher in the posterior gills than in the anterior ones. The sum of polyunsaturated fatty acids and the unsaturation index of DPG are more important in the posterior gills than in the anterior ones. It is suggested that negatively charged unsaturated DPG and that the contrast of activities of ω-6- and ω-3-acids found in phospholipids provide a suitable lipid environment for optimal activity of the transport mechanisms at work in posterior gills of the Chinese crab.     

Effect of selenium supplementation on polyunsaturated fatty acids in rats

The purpose of this work was to study plasma, adipose tissue, and liver fatty acids percentages of Wistar rats that drank water supplemented with several levels of sodium selenite for 1, 3, and 6 mo. In a general way, percentages of saturated, monounsaturated, and polyunsaturated fatty acids of supplemented groups were not different from those obtained with nontreated animals in the analyzed tissues. However, in rats supplemented with 0.5 ppm Se, mainly in adipose tissue, a polyunsaturated fatty acids increase (p<0.005) was observed for all times of treatment. This could suggest that 0.5 ppm Se supplement probably exercises a protective role on polyunsaturated fatty acids in that tissue. Supplements of 6.0, 15.0, and 54.0 ppm Se did not change unsaturation levels of fatty acids in the analyzed tissues.     

Identification of fatty acids from Cladonia lichens

Fatty acids of eight lichen species belonging to the genus Cladonia were examined by GC-MS. Twenty-two saturated, 23 monoene, five diene, nine triene and eight tetra-, penta- and hexaene fatty acids were identified. Unusually for lichens, very long-chain fatty acids, 25:1, 26:0, 26:1, 26:3, 28:0, 28:1, and 30:1 were detected.     

Whey-derived free fatty acids suppress the germination of Candida albicans in vitro

Bovine whey from the cheese-making industry contains several bioactive factors that promote health and prevent disease. Although many efforts have been made over the years to show that immunoglobulins, lactoperoxidase, lactoferrin, lysosyme and small peptides present in whey have antimicrobial activities against several pathogenic microorganisms, such activities have not been investigated so far for the lipid fraction of whey. Here, we have used an in vitro assay-based fractionation procedure to show that free fatty acids derived from whey cream specifically inhibit the germination of Candida albicans, a morphologic change associated with pathogenicity. Further fractionation by HPLC demonstrated that this activity can be mainly attributed to lauric acid, myristoleic acid, linoleic acid and arachidonic acid.