Amounts Of Free Sterols Research Articles

Effects ofSchistosoma mansoniand high temperature on the lipid composition ofBiomphalaria glabrataas determined by high-performance thin-layer chromatography and densitometry

Silica gel high-performance thin-layer chromatography (HPTLC) was used to study the effects of both Schistosoma mansoni infection and high temperatures on the neutral and polar lipid content of whole bodies of Biomphalaria glabrata snails. Neutral lipids were determined using petroleum ether-diethyl ether-glacial acetic acid (80:20:1) mobile phase, phosphomolybdic acid detection reagent, densitometry at 610 nm, and polar lipids with chloroform-methanol-water (65:25:4) mobile phase, cupric sulfate-phosphoric acid reagent, and scanning at 370 nm. The high-temperature experiments were done at ambient (22–24°C), 28°C, and 34°C. Snails were maintained at these temperatures for 7 days prior to necropsy. Extracts of their bodies were then analyzed by HPTLC to determine changes that occurred in the lipid content as a function of temperature and to compare unexposed to exposed cultures at each temperature. At 4 weeks postinfection (PI), the 34°C exposed snails had significantly lower amounts of free sterols than t...

THE INFLUENCE OF CONTROLLED ATMOSPHERE STORAGE ON PHYTOSTEROLS IN BROCCOLI HEADS

The objective of this study was to analyze changes in sterols content during storage of broccoli. Broccoli heads of “Marathon” and “Cezar” cultivars were stored for 6 weeks in a cold store, under normal (0% CO2 + 21% O2) and controlled atmosphere conditions (CA, 5% CO2 + 2% O2) at the temperature of 0–1C. Sterols, in the forms of free sterols and glucosides, were determined by high-performance liquid chromatography. Color parameters of broccoli were determined spectrophotometrically using CIE L*a*b* system. Amount of free sterols in the freshly harvested heads reached 54.3 mg/100 g dw and was the highest in the heads of “Marathon.” The dominant free sterol was b-sitosterol. During the storage of broccoli, sterol content decreased but was higher in the heads stored in CA. The broccoli showed smaller changes of color when stored in CA than in normal atmosphere.

Lipophilic extractives from several nonwoody lignocellulosic crops (flax, hemp, sisal, abaca) and their fate during alkaline pulping and TCF/ECF bleaching

The fate of lipophilic extractives from several nonwoody species (flax, hemp, sisal and abaca) used for the manufacturing of cellulose pulps, was studied during soda/anthraquinone (AQ) pulping and totally chorine free (TCF) and elemental chlorine free (ECF) bleaching. With this purpose, the lipophilic extracts from the raw materials and their unbleached and bleached industrial pulps, were analyzed by gas chromatography–mass spectrometry. Aldehydes, hydroxyfatty acids and esterified compounds such as ester waxes, sterol esters and alkylferulates strongly decreased after soda/AQ pulping while alkanes, alcohols, free sterols and sterol glycosides survived the cooking process. Among the lipophilic extractives that remained in the unbleached pulps, some amounts of free sterols were still present in the TCF pulps whereas they were practically absent in the ECF pulps. Sterol glycosides were also removed after both TCF and ECF bleaching. By contrast, saturated fatty acids, fatty alcohols and alkanes were still present in both bleached pulps.

Extractives in bark of different conifer species growing in Pakistan

AbstractThe amount and composition of lipophilic and hydrophilic extractives, including proanthocyanidins, has been analysed as a first screening in the bark of six Pakistani coniferous tree species, namelyPinus wallichiana,Pinus roxburghii,Pinus gerardiana,Abies pindrow,Taxus fuanaandCedrus deodara. The predominant lipophilic extractives were common fatty and resin acids, fatty alcohols and sterols. In all bark samples, short-chain fatty acids were more abundant than long-chain fatty acids. Generally, the amount of free fatty acids was also larger than the amount of triglycerides. Oleic acid was the most common fatty acid, except inC. deodara, where lignoceric acid dominated. The largest amounts of fatty acids and fatty alcohols were found inP. wallichianaandP. gerardiana.P. gerardianacontained an exceptionally large amount of resin acids, approximately 3% of the bark weight, compared to the other species. The amount of free sterols was approximately at the same level or larger than the amount of steryl esters in most samples. In addition to proanthocyanidins, different known lignans, stilbenes, ferulates and flavonoids were generally predominant amongst the hydrophilic extractives. Resveratrol glycoside was abundant inP. wallichiana, whileC. deodaraandP. gerardianacontained large amounts of lignans and lignan derivatives. All bark extracts contained large amounts of proanthocyanidin-related catechin and its derivatives. Furthermore,C. deodaraandP. roxburghiicontained quite large amounts of taxifolin. In particular,P. wallichianaandA. pindroware potential rich sources of proanthocyanidins, representing approximately 16% and 5% of the bark weight, respectively.

Effects of natural and artificial defoliation on the content and composition of extractive substances in birch leaves

Qualitative and quantitative compositions of extracts of birch (Betula pendula Roth.) leaves after natural and artificial defoliations were studied. Composition of the fraction of total lipids was determined. Overall, 11 fatty acids were identified. Differences between the fatty acid compositions of total lipids in the trees subjected to defoliation, consisting in the increase in quantities of short-chain saturated fatty acids and trienoic acids, were detected. Nine individual compounds--six flavones, two flavanones, and one flavanonol--were isolated from the flavonoid fraction by column chromatography. It was found that the total content of extractive substances in birch leaves as well as amounts of free sterols, triterpene compounds, and flavones decreased 1 year after an artificial defoliation and 1 month after depredation of 75% of birch stands by gypsy moth. On the contrary, the contents of flavanones and flavanonol increased. The assay method proposed may be used for studying the compositions of plant extracts.

Effects of moderately enhanced levels of ozone on the acyl lipid composition and dynamical properties of plasma membranes isolated from garden pea (Pisum sativum)

Plasma membranes were isolated from leaves of 16‐day‐old garden pea, Pisum sativum L., that had been grown in the absence or presence of 65 nl l−1 ozone for 4 days prior to membrane isolation. Plasma membranes from ozone‐fumigated plants contained significantly more acyl lipids per protein than those from leaves of plants grown in filtered air on a molar/weight ratio. The ratio between the major acyl lipids, phosphatidylethanolamine (PE) and phosphatidylcholine (PC), also increased due to the ozone fumigation, while the fatty acid unsaturation level was unaltered in total plasma membrane acyl lipids, as well as in PC and PE. The amount of free sterols per protein was unaltered, but the percentage of campesterol increased, concomitant with a decrease in stigmasterol. The dynamical properties of the isolated plasma membranes were assessed using Laurdan fluorescence spectroscopy, which monitors water penetration and mobility at the hydrophilic‐hydrophobic interface of the membrane. At 0°C, the molecular mobility was slightly lower in plasma membranes from ozone‐fumigated plants than in plasma membranes from control plants, possibly reflecting the increased PE/PC, campesterol/stigmasterol and lipid/protein ratios, and suggesting that ozone‐fumigated pea plants may be more susceptible to freezing injuries.

The effect of reduced activity of phytoene synthase on isoprenoid levels in tomato pericarp during fruit development and ripening

Carotenoids, gibberellins (GAs), sterols, abscisic acid and β-amyrins were analysed in tomato (Lycopersicon esculentum Mill.) pericarp during fruit development and ripening. The contents of these isoprenoids in wild-type (cv. Ailsa Craig) fruit were compared with those in fruit of the carotenoid-deficient R-mutant and a transgenic plant containing antisense RNA to a phytoene synthase gene. In both carotenoid-deficient genotypes, a 14-fold reduction in carotene and twofold decrease in xanthophyll content, compared to the wild type, was found in ripe fruit. Immature green fruit from wild type and R-mutant plants contained similar amounts of the C19-GAs, GA1, and GA20, and their C20 precursor, GA19. Immature fruit from the transgenic plants contained three- to fivefold higher contents of these GAs. In wild-type fruit at the mature green stage the contents of these GAs had decreased to < 10% of the levels in immature fruit. A similar decrease in GA19 content occurred in the other genotypes. However, the contents of GA1 and GA20 in fruit from phytoene synthase antisense plants decreased only to 30% between the immature and mature green stages and did not decrease at all in R-mutant fruit. At the breaker and ripe stages, the contents of each GA were much reduced for all genotypes. The amount of abscisic acid was the same in immature fruit from all three genotypes, but, on ripening, the levels of this hormone in antisense and R-mutant fruit were ca. 50% of those in the wild type. Quantitative differences in the amounts of the triterpenoid β-amyrins, total sterols, as well as individual sterols, such as campesterol, stigmasterol and sitosterol, were apparent between all three genotypes during development. Amounts of free sterols of wild type and antisense fruit were greatest during development and decreased during ripening, whereas the opposite was found in the R-mutant. This genotype also possessed less free sterol and more bound sterol in comparison to the other varieties. These data provide experimental evidence to support the concept of an integrated metabolic relationship amongst the isoprenoids.

The effects of excess exogenous mevalonic acid on sterol and steryl ester biosynthesis in celery (Apium graveolens) cell suspension cultures

Cell suspension cultures of celery ( Apium graveolens) have been used to investigate the fate of excess added mevalonic acid and the effects on the amounts of free sterols and steryl esters in the cells. Radiolabelling studies using [2- 14C] MVA showed that the main effect of excess MVA (5 mM) was an increase in the synthesis of steryl esters. Further analysis revealed that esterified 4,4-dimethylsterols were more highly labelled than 4-mono- and 4-desmethylsterols in MVA-treated cells, suggesting a restriction in the flow of carbon downstream from cycloartenol and 24-methylenecycloartanol, and thus indicating the presence of a post-mevalonic acid control point in the sterol biosynthesis pathway. The total fatty acids recovered from the celery cell lipids showed a very low incorporation of radioactivity from the [2- 14C] mevalonate, indicating that a limited breakdown of excess mevalonate to acetate may occur in these cells, possibly by the operation of the mevalonate shunt. However, this does not appear to be a major route for the disposal of excess mevalonate. Analysis of the free sterols and steryl esters showed that the administration of excess exogenous MVA (5 mM) to Apium graveolens cells caused a two-fold increase in the steryl ester content when compared with control cells, although there was little effect on the free sterol content or composition. When excess MVA was administered in conjunction with the sterol biosynthesis inhibitor paclobutrazol (50 μM), the steryl ester content increased almost three-fold. It is possible that, as well as providing a means of storage of excess sterols, the esterification of sterols may have a regulatory role in sterol biosynthesis, by controlling the rate of C-4 demethylation of precursor 4,4-dimethylsterols.

Influence of Clarification and Suspended Grape Solid Materials on Sterol Content of Free Run and Pressed Grape Musts in the Presence of Growing Yeast Cells

Clarified and unclarified free run and pressed musts were left in contact with suspended solid materials and natural growing yeast cells for 16 hours at room temperature. Free and bound sterols (after saponification) were extracted and analyzed by gas chromatography and GC/MS. Unlike unclarified free run and pressed musts, both clarified musts completely lacked sterols, with the exception of ergosterol which was present at about 10 % of the amount found in the non-clarified must. Free grape sterol content increases proportionately to the time contact of must with grape solid materials in the first four hours; after that, there was a constant decrease in the amount of free sterols, until they almost disappeared at 16 hours. Generally, bound grape sterols decreased during the first two hours, after which they increased. The content of yeast sterols (ergosterol and lanosterol) increased over time and according to the number of viable cells. These changes could be explained by the existence of two processes having antithetic effects: the first due to enzymatic factors of musts and/or yeasts releasing sterols from solid materials and the second due to yeasts uptaking sterols for growth at the same time.

Resistance of young versus old tobacco leaves to necrotrophs, fusaric acid, cell wall-degrading enzymes and autolysis of membrane lipids

Infection with necrotrophs, Alternaria alternata or Botrytis cinerea caused more severe symptoms on old than young tobacco leaves. Much higher amounts of fusaric acid were required to induce necrosis in young leaves compared with older leaves. Similarly fusaric acid caused higher leakage of ions from older leaf discs than from younger discs. Leaf slices from younger leaves were more resistant to pectinase and cellulase enzymes. Protoplasts from younger leaves were more tolerant to the toxic effect of cell wall-degrading enzymes than protoplasts from older leaves. These differences were related to lipid content. The amount of phospho- and galactolipids was higher while the amount of free sterols was lower in juvenile leaf tissues. The autolysis of phospholipids was much higher in homogenates from older leaves, suggesting that infection caused cell decompartmentalization resulting from a more rapid degradation of membranes in senescent tissues compared to young leaves.

Influence of defoliating agents on the level of some secondary metabolites in cotton-plant leaves

The change in the composition of the secondary metabolites (SMs) of cotton-plant leaves under the influence of two modifications of defoliating agents in the period of leaf fall has been studied. It has been shown that, in contrast to the dynamics of the SMs in genetic deciduous lines, up to the period of leaf-fall the amount of free sterols in the petioles decreases, while in the leaf blades it remains unchanged. In experiments with cotyledons, the opposite effect was observed. In all cases, the amount of polyprenols decreased substantially.

Amount of sterols and triterpenoids in leaves and petioles of leaf-shedding and standard lines of cotton plant

The amount of free and bound sterols and triterpenoids in the leaf blades and petioles of the variety Tashkent-1 and the deciduous lines L-275 and L-470 in the budding-flowering, maturing, and leaf-fall phases have been compared. In the leaf blades, the maximum accumulation of free sterols in the deciduous lines is observed in an earlier phase than in the variety Tashkent-1, and this is most characteristic for sterols saturated in the C-17 side chain. The dynamics of the change in the content of unsaturated sterols is individual for each line. The nature of the change in the amount of free sterols in the petioles is typical for each line and does not depend on the nature of the sterol for the variety Tashkent-1 this index falls sharply in the leaf-fall phase while for L-275 the process is retarded between the second and third phases, and for L-470 in the same period the amount of these substances rises sharply. In the leaf blades, as a rule, the level of sterol esters changes in parallel with the levels of free sterols, and in the petioles in the antiparallel direction between the first and second phases. In all the samples free and bound amyrin was detected. The dynamics of the change in the amounts of these substances in the three lines were different.

Concentration gradients of free sterols, steryl esters and lipid phosphorus in the trunkwood of Scot's pine (Pinus sylvestris L.)

The amounts of free sterols, steryl esters and lipid phosphorus were determined in the sapwood and heartwood of mature, and in the outer and inner sapwood of young Pinus sylvestris trees. In the mature trees (up to 70 years old) the heartwood contains significantly higher amounts of free sterols than the sapwood. No radial gradient can be demonstrated in the amounts of steryl esters. Lipids extracted from the sapwood contain higher amounts of phosphorus than those from the heartwood. Stems of young Pinus sylvestris trees (up to 13 years old) show in the inner sapwood higher amounts of both free sterols and steryl esters than the peripheral younger wood zone. The inner sapwood of the young stems shows slightly higher amounts of lipid phosphorus than the outer sapwood. The results indicate that Pinus sylvestris accumulates both free sterols and steryl esters in the stems at a very early stage of the life cycle. Sterol accumulation in the innermost parts of the stems seems not to depend on heartwood formation.

Lipids and sterols of Pinus sylvestris L. sapwood and heartwood

The lipid and sterol content and composition of three lipid fractions (free fatty acids/ sterols, triacylglycerols and sterol/triterpenoid esters) extracted from three stem discs of Pinus sylvestris were assessed to investigate metabolic changes related to heartwood formation. The wood was separated into (1) cambial zone, (2) outer sapwood, (3) inner sapwood, (4) transition zone, (5) outer heartwood and 6) inner heart-wood. The fractions were separated by thin-layer chromatography (TLC) and analysed by gas-liquid chromatography (GLC). The amount of fatty acids of sapwood triacylglycerols was about 1.5% (dry wt.) but a large reduction occurred in the transition zone. In contrast, noticeable amounts of free fatty acids were present only in the heart-wood. The most important fatty acids in the sapwood fractions were 16:0, 18:0, 18:1, 18:2 (the dominant fatty acid in all fractions), 18:3 and 20:3. Together 18:1 and 18:2 formed about 70% of the total triacylglycerol fatty acids. Of the sterol/ triterpenoid esters, 18:2 and 18:3 were predominant. The fatty acid composition of all fractions changed in the transition zone. The sterols found were sitosterol, stigmastanol, campesterol and campestanol. The amount of sterol esters increased towards the heartwood, and the amount of free sterols was lowest in the inner sapwood. Sitosterol was the dominant sterol in both free sterols and sterol esters.

Free Sterols and Steryl Esters in the Trunkwood of Picea abies (L.) Karst.

Summary Free sterols and steryl esters were analyzed in discs from mature xylem in four trunks of Picea abies (L.) Karst. (77–86 years old). The wood of the individual discs was separated into a) outer sapwood, b) rest of the sapwood, c) sapwood-heartwood transition zone, d) outer heart-wood and e) innermost heartwood. After extraction of the wood with acetone, free sterols and steryl esters were separated by column chromatography and quantitated by color reaction. In all trunks analyzed the innermost heartwood contains the highest amounts of free sterols and steryl esters. Lipid-phosphorus, on the other hand, decreases from the younger to the older parts of the trunks. The heartwood of all trunks contains only trace amounts of lipid-phosphorus. The free sterols are made up of cholesterol, desmosterol, campesterol and sitosterol. Desmosterol was absent in the steryl ester fraction. Sitosterol was dominant in both free sterols and steryl esters. The percentage of cholesterol and desmosterol to the total free sterols decreased from the younger to the older trunkwood while campesterol and sitosterol showed no gradient in the trunks. In the steryl ester fraction, the percentage of cholesterol decreased, campesterol seemed to increase and sitosterol showed no gradient towards the center of the trunks. Calculated on dry weight basis, only cholesterol had the tendency to decrease from the younger to the older trunkwood zones.

Effects of the hypocholesteremic agent trifluperidol on the sterol, steryl ester, and fatty acid metabolism of Saccharomyces cerevisiae

Trifluperidol (TFP), at a concentration of 100 muM, inhibited the 24-h growth of Saccharomyces cerevisiae by about 30%. Effects on lipid metabolism were investigated by monitoring the incorporation of [1-14C]sodium acetate into various lipid fractions after 4 and 24 h of growth in the presence of several concentrations of TFP. Although little effect was noted on the amount of free sterols, 24-h incorporation of label into steryl esters was increased two- to fourfold by 100 muM TFP. Major sterol components of the steryl ester fraction isolated from an untreated culture were zymosterol (48%) and ergosterol (24%), whereas from the TFP-treated culture delta8,24(28)-ergostadienol (66.6%) and delta8-ergostenol (14.7%) were most abundant. Free sterols present in the highest concentration in the untreated culture were ergosterol (78.2%) and lanosterol (13%); whereas delta8,22-ergostadienol (38.5%), delta8-ergostenol (35.4%), and delta8,24(28)-ergostadienol (25.4%) were the most abundant free sterols obtained from the TFP-treated culture. Thus, the major block in the sterol biosynthetic pathway in yeast appears to be delta8 leads to delta7 isomerization. In these same cultures the relative amounts of C12 and C14 acids isolated from both steryl ester and miscellaneous lipid fractions were increased more than threefold over controls.

Free and bound sterol content of sunflower, soy bean and maize oils

The amounts of free sterols, steryl esters and steryl glycosides in sunflower, soya and maize oils as well as in the phosphatides of the same oils were determined. The refinement byproducts were enriched with sterols. The highest contents of total sterols and steryl glycosides (2,68 and 1,9%, respectively) were established in soya phosphatides followed by those in sunflower oil phosphatides (2,03 and 1,68%, respectively) and maize oil phosphatides (0,81 and 0,54%, respectively).

Biosynthesis of lipids in perfused dog aorta and coronary artery: I. Incorporation of [2- 14C]acetate into the lipids of three aortic layers and of the coronary artery in normal and hyperlipemic dogs

Dog aortas and coronary arteries were perfused with the animal's own native serum for 8 h using pulsatile pressures. Lipid synthesis from [2- 14C]acetate was compared with the corresponding lipid contents in three aortic layers and in coronary arteries. The influence of an atherogenic diet on the arterial lipids was studied in this system. In control animals, 14C-incorporation into the total lipids was highest and nearly identical in the coronary arteries and in the aortic intima including several layers of media (intima); incorporation into the lipids of the aortic adventitia and media was approximately one fifth, as compared to the intima. The percentage distribution of 14C label between the different lipids was identical in the intima and media. The intima contained the highest amount of unesterified fatty acids; the percentage 14C-incorporation was low and approximately the same in the aortic layers and in the coronary arteries (< 6%). The highest concentration of free sterols was found in the aortic media; they comprised approximately 90% of the total sterols in this tissue. The percentage radioactivity was low (< 5%) and within the same range in the aortic tissues and in coronary arteries. Sterolesters were mostly present in the coronary arteries paralleled by the highest percentage 14C-incorporation (3%); the low concentrations in the aortic layers were associated with low percentage redioactivities (< 1%). The diglyceride contents were low in both vessels; relatively high amounts and radioactivities (6%) of those lipids were found in the adventitia, as compared to the media (3%); 14C-activity was higher in the coronary arteries (10%). The triglyceride contents and the percentage 14C-activity were highest in the aortic adventitia (51%) and in the coronary arteries (25%); the concentrations were extremely low in the media and intima; radioactivity, however, was relatively high (11 and 14%). The smallest phosphatide amount was measured in the coronary arteries; 14C-incorporation was high in the intima and media (76%) and low in the adventitia (39%) and coronary arteries (53%). In animals fed on an atherogenic diet containing butter fat, sucrose, cholesterol and thiouracil as main constituents, a severe hyperlipemia was induced; glucose levels were unchanged. No morphological changes of the vessels and no alteration of the 14C-incorporation into the total lipids of aorta and coronary arteries were observed. However, the following significant changes of the lipid concentrations and the percentage 14C-distribution were demonstrated: The concentration of the unesterified fatty acids was reduced in the aortic intima; 14C-incorporation was only moderately diminished; the media responded reversely; the coronary arteries showed decreased radioactivities and slightly increased fatty acid contents. The amounts of free sterols were moderately elevated in the intima, and the corresponding percentage radioactivity was also increased. The sterol concentrations of the coronary arteries were unchanged, radioactivity, however, was diminished. Increased sterolester contents were seen in the intima and media; percentage radioactivity, however, was elevated in the adventitia and media. Augmented diglyceride concentrations were found in the media and in the coronary arteries; percentage 14C-activity was diminished in the adventitia and media. No relevant alterations were observed in the triglycerides and phosphatides of both vessels. In control animals, the [ 14C]acetate was mainly incorporated into the fatty acids of glycerides (98.5%) and phosphatides (94.6%); this difference was highly significant. The diet treated animals incorporated 100% radioactivity into the glyceride fatty acids, and 99% into the phosphatide fatty acids; this difference was also significant.