Release Of Unsaturated Fatty Acids Research Articles

Effects of gamma irradiation on the nutritional quality and physicochemical properties of Morchella angusticeps

This study aimed to evaluate the effects of gamma irradiation on the storage quality of Morchella angusticeps. The results indicated that different irradiation doses had varying effects on the nutritional quality and physicochemical properties of Morchella angusticeps during storage. The polyphenol content of mushrooms irradiated by 1 kGy and 2 kGy were 0.86 and 0.83 OD325/g mf, which had significant difference compared with CK (P < 0.05). The flavonoid content of the CK was 0.059 OD325/g mf, which was significantly lower than that of the 1 kGy and 2 kGy irradiation treatment groups (P < 0.05), the soluble protein content of 1 kGy and 2 kGy irradiated increased by 43.25% and 43.72% compared with CK, the Malondialdehyde (MDA) content of 1 kGy and 2 kGy irradiated decreased by 10.025% and 77.98% compared with CK, respectively. After irradiation, cis-9-myristylic acid, stearic acid and petrovic acid increased by 5%, 20% and 15%, respectively, and the volatile compounds were most abundant in the group irradiated by 2 kGy. With the storage time increasing, soluble protein content of all groups exhibited a downward trend, the soluble protein content of 1 kGy and 2 kGy irradiated samples increased by 43.25% and 43.72% compared with CK, so 1 and 2 kGy irradiation doses effectively reduced the decomposition of soluble protein. To identify the volatile components of Morchella angusticeps, headspace solid-phase microextraction was employed. The analysis revealed the presence of 49 volatile components. During the storage period, irradiation could promote the release of unsaturated fatty acids, and the dose of 1 kGy was found to effectively maintain cell morphology. The experimental results demonstrated that treatment with 1 and 2 kGy irradiation doses effectively delayed the quality loss of the fruiting body and inhibited browning-related enzyme activities. This study highlights the potential of irradiation as a helpful method to preserve the storage quality of Morchella angusticeps.

Preharvest chitooligosaccharide spray alleviates chilling injury in harvested muskmelon fruit by regulating membrane lipid metabolism and activating antioxidant enzyme activity

Chitooligosaccharide (COS), a degradation product of chitosan, can reduce chilling injury (CI) in postharvest fruit by increasing antioxidant enzyme activity. However, whether preharvest COS spray alleviates CI in muskmelon fruit after harvest by regulating membrane lipid metabolism and increasing antioxidant enzyme activity has not been reported. In this study, muskmelon plants and fruit were sprayed with 2 mL L−1 of COS at four developmental stages: young fruit, early enlargement, late enlargement, and mature stage. The expression of key genes involved in membrane lipid metabolism, fatty acid content, phospholipid component content and antioxidant enzyme activity in muskmelon fruit were measured, and the CI symptoms and index of the fruit were observed during cold storage. The results illustrated that the preharvest COS spray up-regulated the expression of CmPLA2, promoted the release of unsaturated fatty acids, and increased the value of the double bond index (DBI). However, the spray down-regulated the expression of CmPLC and CmPLD, increased the levels of phosphatidylcholine (PC) and phosphatidylinositol (PI), and decreased the levels of phosphatidic acid (PA). COS spray increased superoxide dismutase (SOD) and catalase (CAT) activity, decreased O2-· and H2O2 levels, maintained cell membrane permeability, and decreased MDA levels in fruit during chilling. In addition, the spray reduced peroxidase (POD) activity and alleviated fruit pericarp browning during cold storage. Taken together, preharvest COS spray alleviated CI in muskmelon fruit by stimulating membrane lipid metabolism and improving the activities of antioxidant enzymes.

Change in interfacial properties of milk fat globules by homogenization and thermal processing plays a key role in their in vitro gastrointestinal digestion

The effects of homogenization, homogenization plus thermal processing including high temperature short time (HHTST) or ultra-high temperature (HUHT) treatment on digestion and interfacial properties of milk fat globules during simulated gastrointestinal digestion were investigated. Compared to raw milk fat globules, homogenization and thermal processing increased the initial digestion rate of milk fat globules. Homogenization increased the release of middle- and long-chain fatty acids, HHTST increased the release of unsaturated fatty acids, and HUHT increased the release of all types of fatty acids under gastrointestinal digestion. After homogenization, milk proteins (caseins and whey proteins) increased but glycosylated molecules decreased, both of which were at the surface of milk fat globules. The amount of glycosylated molecules at the surface of HHTST milk fat globules and the amount of denatured milk proteins at the surface of HUHT milk fat globules were higher than those of homogenized milk fat globules. During gastrointestinal digestion, fat globules in HHTST milk possessed higher amount of glycosylated molecules and more integrated phospholipid layers, and HUHT milk fat globules had more filamentous phospholipid layers, and less integrated phospholipid layers and glycosylated molecules than those of homogenized milk fat globules. Therefore, the changes in composition and microstructure of glycosylated molecules and phospholipid layers at the surface of milk fat globules induced by homogenization and thermal processing might contribute to the digestion difference of milk fat globules.

Impact of fatty acids unsaturation on stability and intestinal lipolysis of bioactive lipid droplets

Emulsions are complex mixtures of immiscible liquids that are widely spread in foods and considered as natural, efficient and cost effective tools to deliver lipophilic bioactives to the consumer. Many recent studies seek to elucidate the principles for formulating emulsions with novel bioactive ingredients, such as bovine lactoferrin or bioactive lipids, towards enhanced and extended emulsion functionality. This research evaluated the effects of droplet lipid unsaturation degree on emulsion properties, stability and susceptibility to intestinal lipolysis. For this purpose, emulsions were produced via high pressure homogenization using extra virgin olive oil (EVOO) rich in 18:1n9 oleic acid, hemp seed oil (HSO) rich in 18:2n6 linoleic acid and pomegranate seed oil (PSO) rich in 18:3n5 conjugated linolenic acids (CLnA). Droplet fatty acid composition was altered using glyceryl trioleate (TOLN) doping at varying concentrations (1%, 2%, 5% and 10% [w/w]) and found to temper emulsion stability, droplet size, droplet size distribution spans. In respect to intestinal lipolysis, TOLN did not affect EVOO lipolysis, had mild impact on HSO lipolysis and markedly accelerated and enhanced the lipolysis of PSO. Fatty acid profiling of intestinal digesta indicated the preferential liberation of saturated, then monounsaturated and lastly polyunsaturated fatty acids from the various lipid droplets. Overall, the results presented herein show a new possibility for smart design of emulsions with sustained and controlled release of unsaturated fatty acids in the human gut.

The circulating metabolome of human starvation.

The human adaptive starvation response allows for survival during long-term caloric deprivation. Whether the physiology of starvation is adaptive or maladaptive is context dependent: activation of pathways by caloric restriction may promote longevity, yet in the context of caloric excess, the same pathways may contribute to obesity. Here, we performed plasma metabolite profiling of longitudinally collected samples during a 10-day, 0-calorie fast in humans. We identify classical milestones in adaptive starvation, including the early consumption of gluconeogenic amino acids and the subsequent surge in plasma nonesterified fatty acids that marks the shift from carbohydrate to lipid metabolism, and demonstrate findings, including (a) the preferential release of unsaturated fatty acids and an associated shift in plasma lipid species with high degrees of unsaturation and (b) evidence that acute, starvation-mediated hypoleptinemia may be a driver of the transition from glucose to lipid metabolism in humans.

Incorporation of pig back fat in restructured dry cured ham to facilitate the release of unsaturated fatty acids and generation of volatile compounds

The aim of the present study was to evaluate the effects of incorporating pig back fat in restructured dry cured ham (RDH) on its free fatty acid profile (FFA) and the volatile compounds released. Fresh raw hams were skinned, boned, and cut into meat cubes (4–6 × 4–6 × 4–6 cm). The meat cubes were restructured with 0, 2, and 4% pig back fat paste into raw restructured ham. After 30 days of ripening, the FFA and volatiles in the RDH were identified using gas chromatography and gas chromatography mass spectrometry, respectively. The results showed that exogenous pig back fat incorporation from 2 to 4% gave rise to increased neutral lipase activity (p &lt; 0.05) and to enhanced lipid degradation and unsaturated fatty acid release in the RDH sample. A total of 63 volatile compounds were isolated from RDH. The most abundant volatiles were alcohols, followed by esters and aldehydes. The chromatographic areas of the total volatile amount, short chain esters, 3‐hydroxy‐2‐butanone, 2‐nonanone, long chain hydrocarbons, and pyrazines increased with pig back fat incorporation, suggesting that exogenous pig back fat incorporation could improve the sensorial quality of restructured dry cured ham.Practical application: Hams produced from genotypes with high intramuscular fat have more intense and persistent aroma, because intramuscular triacylglycerols are a good trap for most aroma compounds and also a source of volatile (aromatic) compounds. Nowadays, mixed diet feed systems or other specific feeding strategies could improve the fat content and composition of raw ham, but led to lower nutritional and sensory quality of hams. Perhaps, the major problem for the relatively poor quality of dry cured ham may be the leanness of modern genotypes, and the pigs from these genotypes are not suitable for dry cured ham production. Thus, thinking from another perspective, through incorporating exogenous pig back fat directly into raw ham, the present work have successfully improved the sensorial properties of dry cured hams.Restructured dry cured hams (RDH) with different pig back fat levels were successfully manufactured. This work shown that large differences in the free unsaturated fatty acid and volatile compounds of RDH can be caused by the exogenous pig back fat incorporation. An increase in pig back fat level from 2 to 4% in RDH significantly enhanced the release of unsaturated fatty acid, and facilitated the generation of volatile compounds including esters, ketones, aliphatic hydrocarbons, and aromatic hydrocarbons.

Role of sphingomyelin and ceramide in the regulation of the activity and fatty acid specificity of group V secretory phospholipase A 2

We previously showed that group V secretory phospholipase A 2 (sPLA 2V) is inhibited by sphingomyelin (SM), but activated by ceramide. Here, we investigated the effect of sphingolipid structure on the activity and acyl specificity of sPLA 2V. Degradation of HDL SM to ceramide, but not to ceramide phosphate, stimulated the activity by 6-fold, with the release of all unsaturated fatty acids being affected equally. Ceramide-enrichment of HDL similarly stimulated the release of unsaturated fatty acids. Incorporation of SM into phosphatidylcholine (PC) liposomes preferentially inhibited the hydrolysis of 16:0–20:4 PC. Conversely, SMase C treatment or ceramide incorporation resulted in preferential stimulation of hydrolysis of 16:0–20:4 PC. The presence of a long chain acyl group in ceramide was essential for the activation, and long chain diacylglycerols were also effective. However, ceramide phosphate was inhibitory. These studies show that SM and ceramide in the membranes and lipoproteins not only regulate the activity of phospholipases, but also the release of arachidonate, the precursor of eicosanoids.

Contribution of lipoxygenase metabolism to the brassinosteroid signaling pathway.

Brassinosteroids (BSs) are phytohormones, the chemical structure of which is closest to the chemical structure of animal steroid hormones. It was shown by a number of researchers that BSs contributed to plant growth and development [1]. It was also demonstrated that BS caused an increase in the plant resistance to pathogens [2] and adverse climatic factors [3]. Receptors of BS were found to be located in plasmalemma [4]. Phosphorylation of certain proteins was demonstrated to be an early BS-induced response [5]. These findings suggest that BSs are incorporated into the signaling systems of plant cells. However, it is still unclear which types of signaling systems may incorporate BSs. It was also suggested that BSs constituted a previously unknown signaling system [2]. Because it is well known that the lipoxygenase signaling system is involved in cell response to various pathogens, mechanical injuries, elicitors, and some other primary signals [6], the goal of this work was to study the possibility of the brassinosteroid-induced activation of this signaling system. Effects of 24-epibrassinosteroid (EPB), the most active form of BS, on concentrations of oxygenated derivatives of linoleic acid (indicators of lipoxygenase activity) and on the level of phosphorylation of soluble proteins of pea leaves (it is well known that reactions of protein phosphorylation/dephosphorylation are a very important component of signaling systems) were studied. It was suggested that the analysis of lipoxygenase activity and the use of phospholipase A 2 (PLA 2 ) inhibitor provided an opportunity to elucidate the contribution of the lipoxygenase metabolism to the initial phase of the EPB-induced response of the cells. Bromphenylacyl bromide (BPB) was used as a phospholipase A 2 inhibitor decreasing the rate of release of unsaturated fatty acids (lipoxygenase substrate). The lipoxygenase activity level was assessed using the methodological approach based on the appearance of two conjugated bonds and absorption maximum at 232 nm during the reaction of formation of oxygenated derivatives of linoleic acid.

Soluble phospholipase A2 activity is induced before oxylipin accumulation in tobacco mosaic virus-infected tobacco leaves and is contributed by patatin-like enzymes.

Recent evidence suggests that oxidized lipid-derived molecules play significant roles in inducible plant defence responses against microbial pathogens, either by directly deterring parasite multiplication, or as signals involved in the induction of sets of defence genes. The synthesis of these oxylipins was hypothesized to be initiated by the phospholipase A2-mediated release of unsaturated fatty acids from membrane lipids. Here, we demonstrate that, in tobacco leaves reacting hypersensitively to tobacco mosaic virus, a strong increase in soluble phospholipase A2 (PLA2) activity occurs at the onset of necrotic lesion appearance. This rapid PLA2 activation occurred before the accumulation of 12-oxophytodienoic and jasmonic acids, two fatty acid-derived defence signals. Three PLA2 isoforms were separated and the most active enzyme was partially purified, its N-terminal sequence displaying similarity with patatin, the major storage protein in potato tubers. Three related tobacco patatin-like cDNAs, called NtPat1, NtPat2 and NtPat3, were cloned, with NtPat2 encoding the PLA2 isolated from infected leaves. RT-PCR experiments showed a rapid transcriptional activation of the three NtPat genes in virus-infected leaves, preceding the increase in PLA2 activity. Recombinant NtPat1 and NtPat3 enzymes were active in an assay using labelled bacterial membranes, and also displayed high bona fide PLA2 activity on phosphatidylcholine substrate. These results point to a possible new role of patatin-like phospholipases in inducible plant defence responses. The induction kinetics together with the enzymatic activity data indicate that the NtPat proteins may provide precursors for oxylipin synthesis during the hypersensitive response to pathogens.

Phospholipase A2-Mediated Activation of Phospholipase D in Rat Heart Sarcolemma

The effect of phospholipase A2(PLA2)-dependent release of unsaturated fatty acids (FA) on phospholipase D (PLD) function was examined in purified sarcolemmal (SL) membranes isolated from rat heart. PLD hydrolytic activity was determined by measuring either [14C] phosphatidic acid formation from exogenous [14C] phosphatidylcholine (PtdCho) or [3H] choline release from prelabelled SL Ptd[3H]choline. SL membranes with endogenous [3H] PtdCho that were prelabelled with [3H] myristic acid were used for testing PLD transphosphatidylation activity. Exogenouscis-unsaturated FA, arachidonate and oleate, significantly enhanced the [3H] choline formation at 50 and 100μm, respectively; their effect was maximal at 250μmand declined at higher concentrations. Use of melittin (which stimulates membrane-bound PLA2, thus releasing FA) or exogenous PLA2reproduced the stimulatory effect of added arachidonate and oleate. Under melittin, PLA2-dependent FA release was strongly correlated (r=0.99) to the PLD-dependent phosphatidic acid formation. Arachidonate- or melittin-enhanced PLD transphosphatidylation activity confirmed the augmented catalytic rate of PLD by these agents. Melittin-evoked PLD activation was completely blocked by 1μmE-6-(bromomethylene) tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one, a selective inhibitor of Ca2+-independentvCa2+-dependent PLA2, thus indicating that PLD stimulation under melittin occurred via PLA2. Activity measurement and Western blotting studies revealed the presence of a Ca2+-independent, high molecular weight (110 kDa) PLA2in the SL membrane, and its immunoprecipitation by monoclonal antibodies significantly reduced the melittin-related PLD stimulation. These results suggest that Ca2+-independent PLA2and subsequent endogenous mobilization ofsn-2 unsaturated FA modulate PLD activity in heart SL membranes. This event may occur in physiological conditions via hormonal stimulation of membranal PLA2as well as in heart diseases characterized by PLA2pathological dysfunction.

Synergistic action of diacylglycerol and unsaturated fatty acid for protein kinase C activation: its possible implications.

Kinetic properties of the purified alpha, beta, and gamma subspecies of protein kinase C (PKC) to respond to diacylglycerol, phosphatidylserine (PtdSer), and Ca2+ were reinvestigated in the presence of several fatty acids. Although responses of these enzyme subspecies to the lipids slightly differed from one another, the reaction velocity of these subspecies was significantly enhanced by synergistic action of diacylglycerol and a cis-unsaturated fatty acid. Arachidonic, oleic, linoleic, linolenic, and docosahexaenoic acids were active in this role, whereas saturated fatty acids such as palmitic and stearic acids were inactive. Elaidic acid was also inactive. In the presence of both PtdSer and diacylglycerol, the cis-unsaturated fatty acids increased further an apparent affinity of PKC to Ca2+ and allowed the enzyme to exhibit almost full activation at nearly basal levels of Ca2+ concentration. The concentration of fatty acid giving rise to the maximum activation of enzyme was approximately 20-50 microM. The result presented herein implies that the receptor-mediated release of unsaturated fatty acids from phospholipids may take part, in synergy with diacylglycerol, in the activation of PKC even when the Ca2+ concentration is low. A possibility arises, then, that the activation of PKC is an integral part of the signal-induced degradation cascade of various membrane phospholipids, which is initiated by the actions of phospholipase C and phospholipase A2.

Activation of wheat embryo calcium-regulated protein kinase by unsaturated fatty acids in the presence and absence of calcium

Unsaturated fatty acids (oleic, linoleic and arachidonic acids) markedly activate extensively purified wheat embryo Ca 2+-regulated protein kinase in the absence of Ca 2+ or at very low free Ca 2+ levels (<0.4 μM). While oleic and linoleic acids also activate in the presence of Ca 2+ (10 −6−10 −4 M), arachidonic acid inhibits at free Ca 2+ greater than 10 −5 M. Phosphatidylserine does not substantially activate in the absence of Ca 2+ or the presence of high Ca 2+. Stearic and arachidic acids are less effective than the unsaturated fatty acids as activators in the absence of Ca 2+. This type of plant protein kinase may be regulated in vivo independently of Ca 2+ through release of unsaturated fatty acids.

Effects of delipidation on proton translocation and ATPase activity in beef heart electron transport particles.

Delipidation of beef heart electron transport particles with phospholipase A2 has been examined. When the particles were treated with the lipase and subjected to a low bovine serum albumin wash, ATPase activity was unaffected as was the lipid/protein ratio of the particles. However, energisation by ATP/Mg2+ was abolished. Furthermore, unsaturated but not saturated fatty acids discharged the steady-state ATP-driven membrane potential of control samples. When the phospholipase A2 hydrolysis products were removed, inhibition of energy-linked reactions in the lipid-depleted particles was still observed and was interpreted in terms of non-specific leaks in the vesicle membranes, and 'specific' leaks through impaired H+-ATPase complexes. ATPase activity was less susceptible to delipidation than energisation but was, nevertheless, strongly inhibited at 50 percent lipid depletion. Spin label studies indicated a decrease in the fluidity of particle membranes accompanying delipidation. Moreover, the discontinuity seen in Arrhenius plots of ATPase activity was shifted from 17 degrees C (control) to 22 degrees C at 50 percent phospholipid depletion. The data are consistent with a release of unsaturated fatty acids by phospholipase A2 rendering the transport particles both leakier and the membranes less fluid than controls.

Effects of lipid peroxidation on prostaglandin synthesis in rabbit kidney medulla slices

Ascorbic acid and Fe 2+ had a more powerful stimulatory effect on the lipid peroxidation of rabbit kidney medulla slices in 0.15 M KCl/0.02 M Tris-HCl buffer than in Krebs-Henseleit buffer. The lipid peroxidation induced by ascorbic acid and Fe 2+ enhanced the release of unsaturated fatty acids from tissue lipids, but inhibited medullary generation of prostaglandin E. These results suggest that the lipid peroxidation induced by ascorbic acid and Fe 2+ may inhibit the formation of prostaglandin E and that this inhibitory effect may be mediated by lipid peroxides via the inhibition of prostaglandin synthetase.

Lipids and lipolytic enzyme activities of rat heart mitochondria

The lipid composition and lipolytic enzyme activities in rat cardiac mitochondria were examined. Subsarcolemmal mitochondria were prepared by treatment of heart muscle with a Polytron tissue processor, while interfibrillar mitochondria were released by exposure of the remaining low-speed pellet to the protease, nagarse. These procedures are known to yield two functionally different populations of mitochondria. However, their phospholipid contents and compositions were identical, as were the positional distributions of the constituent fatty acids. Of the ethanolamine phospholipids, 20% were plasmalogens, and about 2% of the choline phospholipids consisted of this alkenylacyl species. Both subsarcolemmal and interfibrillar mitochondria contained a Ca 2+-activated phospholipase A 2, as evidenced by the Ca 2+-dependent release of unsaturated fatty acids and lysophosphatidylethanolamine from endogenous lipids. Ruthenium red prevented the activation of this enzyme by Ca 2+, indicating that the activity is located in the matrix space or associated with the inner surface of the inner membrane. Both mitochondrial fractions produced free fatty acids and lysophosphatidylethanolamine in the absence of free Ca 2+ apparently due to an outer membrane phospholipase A 1. The activity of this enzyme decreased with time, particularly in interfibrillar mitochondria, providing that Ca 2+ was absent. Nagarse treatment of subsarcolemmal mitochondria resulted in a preparation with the same phospholipase A 1 properties as interfibrillar mitochondria. The possibility that differences in phospholipase A 1 properties account for some of the functional variations between the two mitochondrial types is discussed.

Physical exercise and the prevention of atherosclerosis and cholesterol gall stones

Summary There is accumulating evidence in man and experimental animals that even mild exercise, if regularly repeated, may alter the metabolism of lipids. Exercise has been reported as decreasing peripheral tissue cholesterol in red blood cells, working muscle, lungs and the liver. During physical activity, the output of cholesterol and bile acids into the bile increases. This probably leads to higher faecal losses of sterols which may lead to lower cholesterol levels in the peripheral tissues and in the bile, when exercise is repeated regularly. Preferential release of unsaturated fatty acids from the adipose tissue during exercise and the linoleic acid-dependent LCAT enzyme (transporting plasma cholesterol) may be partly responsible for this effect of exercise. The experimental data reviewed provide supportive basis for epidemiological studies reporting on the beneficial effect of regular exercise. Physical activity is an important factor in the phylogeny of all animal species, secondary only to food intake and reproduction. Exercise is readily available to all population groups. There is good evidence that the amount of exercise required for a protective effect is easily accessible for time-pressured and older individuals. Short bursts of activity repeated several times a day may be equally or more beneficial than prolonged exhaustive exercise. Modified exercise is also beneficial for patients with coronary heart disease and for elderly patients, provided this is done under strict medical supervision. To be effective, physical exercise should be regular and continuous throughout life.

Release of prostaglandins and their precursors by bradykinin

Bradykinin induces a release of unsaturated fatty acids and of prostaglandins from the perfused rat lung. This release is inhibited by chloroquine, a phospholipase A inhibitor. Histamine has no stimulating effect on fatty acids production. It is suggested that prostaglandins release induced by bradykinin might depend on a phospholipase activation.

Plasma lipid changes induced by epinephrine: A study carried out in premature babies fed with formulas of different lipid composition

Formulas containing varying amounts of fat and qualitatively different patternsof fatty acids were fed to premature infants, and the effects on subcutaneous fat and plasma lipid composition were observed before and after administration of epinephrine. Composition of subcutaneous fat and plasma lipids, with the exception of phospholipids, resembled dietary fat within about 4 weeks. After administration of epinephrine, compositional changes were observed in all the fractions. There appeared to be a preferential release of unsaturated fatty acids; changes in esterified fractions are interpreted as due to enhancement of transesterification reactions following release of free fatty acids.