Free Sterol Composition Research Articles

Free and esterified sterols of Macoma balthica (L.)

1. 1. The Baltic Sea bivalve mollusc Macoma balthica was investigated for the content and composition of free and esterified sterols. 2. 2. Sterols in M. balthica occurred mainly in the free form. 3. 3. Cholest-5,24-dien-3β-ol has been found only in the esterified form, and seems to be an indication of the processes of transformation of dietary sterols in M. balthica.

Chilling and age related changes in the free sterol composition of Phaseolus vulgaris L. primary leaves

Chill-stressed or aged bean ( Phaseolus vulgaris cv. 194) plants showed relative increase in the campesterol content of the primary leaves. Sitosterol/stigmasterol ratio declined significantly 24 h following transfer of chilled plants to warmer conditions. Sitosterol/stigmasterol varied markedly according to plant age, showing a decline during the leaf greening phase but an increase by the senescent (leaf-yellowing) phase.

Sterol composition of chitosomes from yeast cells ofMucor rouxii: Comparison with whole cells

The free sterol composition of chitosomes and whole yeast cells of Mucor rouxii was determined by gas-liquid chromatography (GLC). The results obtained showed that, in contrast to whole cells, chitosomes are particularly rich in ergosterol: 87% vs. 29% of total free sterols. Three other sterols were present in varying amounts in both chitosomes and whole cells. These were identified by GLC as cholesterol, stigmasterol and sitosterol. These results indicate that the yeast cells preferentially accumulate ergosterol in chitosomes providing these microvesicles with a unique composition that may be important for the structure of the organelle.

Phospholipid, galactolipid and free sterol composition of fibrous roots from citrus genotypes differing in chloride exclusion ability

Phospholipid, galactolipid and free sterol composition of fibrous roots from citrus genotypes differing in chloride exclusion ability

Phospholipid, galactolipid and free sterol composition of fibrous roots from citrus genotypes differing in chloride exclusion ability

Abstract Fibrous roots of four citrus hybrids and parent rootstocks from which the hybrids were generated, all selected for their different Cl− exclusion abilities, were assayed for phospholipid, galactolipid and free 4‐desmethylsterol content. There was no correlation between a plant's ability to exclude Cl− and the level of either phospholipid, galactolipid, or total free sterol in the roots of control plants. However, an inverse correlation was established between the ratio of phospholipid to free sterol in control roots and total leaf Cl− levels of plants treated with 50 mol m−3 NaCl for 56 d.With the exception of a significant decrease in hybrid 80‐05‐05, galactolipid levels were unaffected by salt treatment. Phospholipid levels were significantly increased in two parent rootstocks viz. Trifoliate orange (Poncirus trifoliata (L.). Raf.) and Carrizo citrange (Citrus sinensis (L.) Osbeck ×P. trifoliata) and one hybrid (80‐02‐08) but were otherwise unchanged by salt treatment. Free sterol levels were significantly increased by salt treatment in all of the better Cl− excluders except Carrizo citrange i.e. in Rangpur lime (Citrus reticulata Blanco var. austera hybrid?), Cleopatra mandarin (Citrus reticulata Blanco) and all hybrids except 80–05–13. In all genotypes examined, salt‐treatment resulted in a significant decrease in the ratio of sitosterol to stigmasterol reflecting, primarily, an increase in the stigmasterol level. The two poorer Cl− excluders (Trifoliate orange and hybrid 80–05–13) both underwent a significant decrease in the ratio of ‘more planar’ to ‘less planar’ sterols.The inverse correlation between the phospholipid to free sterol ratio of control plants and leaf Cl− level of salt treated plants suggests that this ratio has the potential to be used as a biochemical marker of Cl− exclusion ability in citrus.

Sterol composition of chitosomes from yeast cells of Mucor rouxii: Comparison with whole cells

The free sterol composition of chitosomes and whole yeast cells of Mucor rouxii was determined by gas-liquid chromatography (GLC). The results obtained showed that, in contrast to whole cells, chitosomes are particularly rich in ergosterol: 87% vs. 29% of total free sterols. Three other sterols were present in varying amounts in both chitosomes and whole cells. These were identified by GLC as cholesterol, stigmasterol and sitosterol. These results indicate that the yeast cells preferentially accumulate ergosterol in chitosomes providing these microvesicles with a unique composition that may be important for the structure of the organelle.

Sterols from some black sea ulvaceae

The free and esterified sterol composition of Ulva rigida and Enteromorpha linza (Ulvaceae) from the Black Sea was investigated. The main sterol component of Ulva rigida was identified as fucosterol. The influence of the season and water pollution on the sterol composition was investigated. The origin of the C 26,- and C 25-sterols and of saringasterol in these seaweeds is discussed.

Sterols and frost hardening of winter rape

Winter rape (Brassica napus L., var. olifera cv. Górczanski) seedlings were exposed to hardening conditions and the content and composition of free sterols as well as the ratio of free sterols to total phospholipids were determined. There was a reduction in free sterol content in the leaves at the most advanced stage of hardening. The ratio of free sterol to total phospholipids was significantly reduced by hardening due to a decrease in the level of the former and an increase in that of the latter compounds. There was a negative correlation between this ratio and the temperature at which half of the seedlings died. Thus, adaptation of membranes to temperature takes place also at the level of sterol‐phospholipid interactions. Exposing seedlings already hardened to freezing temperatures caused injury higher than 50%, and brought about a drastic increase in the level of free sterols and an elevation in the ratio of free sterols to phospholipids. The results are discussed in terms of a possible role of the molecular architecture of membranes in surviving at subzero temperatures.

Temperature and Aging Effects on Leaf Membranes of a Cold Hardy Perennial, Fragaria virginiana

The lipid composition of leaves of wild strawberry (Fragaria virginiana Duchesne) was analyzed throughout an annual growth cycle in the field. Cellular hardiness to temperature stress was assessed concomitantly by a solute leakage technique. Leaves were shown to be very sensitive to an applied temperature of -5 degrees C during the summer months but insensitive to a 35 degrees C treatment. This general pattern was also seen in young overwintering leaves but was reversed after a period of low-temperature hardening of these same leaves. Associated with cold hardening of the overwintering leaves was a twofold increase in the phospholipid content of the leaf membranes with a proportionately smaller increase in free sterols. The large increase in phospholipids presumably is due primarily to the proliferation of a sterol-poor membrane fraction, probably the endoplasmic reticulum. These quantitative changes in membrane material may be important in increasing freezing tolerance in the overwintering leaf cells by enhancing the overall capacity of the cell for plasma membrane and tonoplast extension through vesicle fusion using components from this endomembrane pool. Analysis of electron micrographs of hardened leaf cells showed an increase in vesiculated smooth endoplasmic reticulum and tonoplast membrane over nonhardened leaf cells, the latter resulting in an enhanced tonoplast surface area to vacuolar volume ratio. During this same period, no changes in the fatty acid or free sterol composition were detectable, suggesting that regulation of membrane fluidity via these components is not required for cold acclimation in this species. During aging and senescence of both the overwintering and the summer leaves, the cellular membranes remained functionally intact but became progressively more vulnerable to temperature stress. Free sterol content increased during this time. This feature may be related to the inability of the older leaves to withstand environmental stress. Increasing sensitivity of the cellular membranes to stress may, in turn, be causally related to the actual onset of senescence in these leaves, thus explaining why only the older leaves senesce when the plant is challenged by periodic environmental stress.

Senescence-related Changes in the Composition of Free and Esterified Sterols and Alcohols in Sphagnum fuscum

Summary The content and composition of sterols, triterpenoid alcohols, n-aliphatic alcohols and hydrocarbons were studied by GC and GC/MS in the green (capitulum) and senescent parts of Sphagnum fuscum . The content of esterified sterols and triterpenoid alcohols, on a dry weight basis, was highest in the capitulum (740 μg · g -1 d.wt.) and very low in older parts (90 μg · g -1 d.wt. in the 3—6 cm segment and 20 μg · g -1 d.wt. in the 21—24 cm segment). Likewise the content of free sterols and triterpenoid alcohols was high in the capitulum (680 μg · g -1 d.wt.) and decreased with increased shoot age (380 μg and 240 μg · g -1 d.wt. in the 3—6 cm and 21—24 cm segments, respectively). The dominant components of the esterified sterols and triterpenoid alcohols were an unidentified component B (33.8%), cycloartenol (16.2%), methylene cycloartanol (9.5%), stigmasterol (16.2%) and campesterol (9.5%). At the depth of 21—24 cm esterified sitosterol was dominant. The major components among the free sterols and triterpenoid alcohols in the capitulum were stigmasterol (56.5%), campesterol (15.9%), sitosterol (10.9%) and an unidentified compound A (17.4%). The proportion of free sitosterol increased with increased shoot age (41.7% in the 21—24 cm segment) as did the proportion of free triterpenoid alcohols (cycloartenol and methylene cycloartanol), the level of which was extremely low in the capitulum. The contents of both free and esterified phytol (200 μg and 360 μg · g -1 d.wt., respectively) were highest in the capitulum and decreased with increased shoot age. At the depth of 21—24 cm only traces of free phytol and very small amounts of esterified phytol (20 μg · g -1 d.wt.) were found. The contents of hydrocarbons and n-alcohols of the esters were at about the same level in the capitulum and the 3—6 cm segment (i.e. 360 μg and 340 μg · g -1 d.wt. n-alcohols and 260 μg and 230 μg · g -1 d.wt. hydrocarbons, respectively), but distinctly lower in the 21—24 cm segment (170 μg · g -1 d.wt. n-alcohols and 100 μg · g -1 d.wt. hydrocarbons). The content of free n-alcohols was highest in the 3—6 cm segment (230 μg · g -1 d.wt.). The first signs of decay of S. fuscum shoots at the microscopic level ( i.e. occasionally damaged stem centre) were observed at the depth of 21—24 cm.

Free sterols of the rabbit optic nerve and cerebral white matter during ontogenic development.

Free sterol composition of the developing rabbit optic nerve was compared with that of the homologous cerebral white matter at corresponding stages of ontogeny. The sterols were detected and identified by means of combined gas-chromatography and mass spectrometry. The following free sterols were found in both the optic nerve and cerebral white matter: cholesterol, desmosterol, lanosterol, two dimethylsterols, which are probably 4,4-dimethyl-5 alpha-cholest-8,24-diene-3 beta-ol, with a molecular weight of 412, and 4 alpha, 14 alpha-dimethyl-5 alpha-cholest-7-ene-3 beta-ol, with a molecular weight of 414 and probably cholestene, with a molecular weight of 368. The sterol spectrum of the developing optic nerve differed not only from that of the mature nerve but also from that of age-matched white matter of the rabbit brain. The tri- and dimethyl-sterols, detected for the first time in the rabbit optic nerve and cerebral white matter, are natural components of the developing nervous tissue but they were not found in the mature nerve nor in cerebral white matter.

The Effect of processing on the content and composition of free sterols and sterol esters in soybean oil

AbstractThe content and composition of free sterols and sterol esters in crude soybean oil and in oils from different stages of two continuous refining systems were determined. The sterols were isolated by preparative thin layer chromatography and analyzed by gas chromatography with cholesterol as an internal standard. The free sterols in one of the degummed oils amounted to 3.1 mg/g and were diminished to 1.8 mg/g oil by the De Laval Short‐Mix refining process. The content of free sterols of the other degummed oil was reduced from 3.4 to 1.6 mg/g oil by the Zenith process. The greatest reduction of sterol content was caused by the treatment with bleaching earth. The sterol esters accounted for 0.6 mg/g of the degummed oil, and only very small changes were observed during the processes. However, changes in the composition of fatty acids of the sterol esters were found. These changes might indicate a selective deacylation of sterol esters or an interesterification during the refining processes. The composition of sterols in free and esterified form were different. Campesterol, stigmasterol and sitosterol were obtained in both free and esterified form, but Δ7 stigmasterol was only found in esterified form. Only small changes in the percentage distribution of the sterols occurred during the processes.

The content and composition of sterols and sterol esters in sunflower and poppy seed oils

The composition and proportion of free sterols and sterol esters in crude sunflower and poppy seed oils were determined, using preparative thin layer chromatography followed by gas chromatography with cholesterol as an internal standard. Free sterols and sterols esters were also isolated in a liquid fraction obtained by low temperature crystallization (-80 C) of the oils and enriched with minor lipid classes. This enrichment procedure provided a liquid fraction suitable for studies of minor components in the oils. However, selectivity towards sterol esters was observed since sterols esterified to very long chain fatty acids (C20-C24) were preferentially retained in the precipitate. The proportion of free and esterified sterols were found to be 0.34% and 0.28%, respectively, in the sunflower oil, whereas the corresponding figures for poppy seed oil were 0.33% and 0.05%. Sunflower oil was characterized by a relatively high percentage of delta 7-sterols, preferentially obtained in the esterified fraction, and by very long chain saturated fatty acids of sterol esters. The sterols in poppy seed oil were composed almost entirely of campesterol, stigmasterol, sitosterol and delta 5-avenasterol, although their percentage distributions were remarkably different in the free and esterified fraction.

Symptom Expression and Free Sterol and Fatty Acid Composition of Flue-cured Tobacco Plants Exposed to Ozone

Symptom Expression and Free Sterol and Fatty Acid Composition of Flue-cured Tobacco Plants Exposed to Ozone

The effect of triparanol on the composition of free and esterified sterols of Saccharomyces cerevisiae

Triparanol altered the sterol composition of Saccharomyces cerevisiae and promoted an increase in the steryl ester and total sterol per organism. The accumulation of Δ 8 sterols, both free and esterified, in the presence of triparanol indicates that a major effect of the compound in yeast is the inhibition of the Δ 8→7 isomerase. Isolation of ergosta-5,8(9),22-trien-3 β-ol, hitherto detected only in ergosterol-deficient yeast mutants, further supports the concept that all of the other metabolic alterations required for the conversion of lanosterol to ergosterol can occur without the necessity of Δ 8→7 isomerization.

On the biosynthesis and composition of sterols and sterolesters in some sea anemones (Anthozoa)

1. 1. The incorporation of radioactivity from either sodium acetate-1- 14C or dl-mevalonate-2- 14C into some classes of lipids in Metridium senile, Anemonia sulcata and Cerianthus membrananaceus is investigated. 2. 2. Lipid contents in these animals are relatively very high. Structural lipids make up a relatively small portion of these lipids, suggesting that part of the lipids is stored and functions as a reserve. This is also reflected in the composition of the neutral lipids. 3. 3. It is demonstrated that these animals utilize the injected precursor for the biosynthesis of lipids. The high incorporation of radioactivity from mevalonate into phospholipids is rather enigmatic. 4. 4. There was only a slight incorporation of radioactivity into the sterols and it is supported that likely sea anemones can synthesize sterols. 5. 5. Sterols with twenty-seven carbon atoms were predominant, cholesterol in all cases being the main sterol. 6. 6. The composition of free and esterified sterols of each species, but also the sterol compositions of the different species closely resembled each other.