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PubMed1979

Utilization of various sterols by lecithin-cholesterol acyltransferase as acyl acceptors.

Highly purified lecithin-cholesterol acyltransferase of human plasma was used to study the utilization of various sterols as the acyl acceptor. The esterification of sterols was facilitated by the presence of a 3beta-hydroxyl group and the trans configuration of the A/B rings, as was evident from the lack of acceptor activity of all 3 alpha-hydroxy sterols tested and coprostanol. Cholesterol analogs in which the side chain is modified, such as campesterol, beta-sitosterol, desmosterol and stigmasterol, were less effective than cholesterol as acyl acceptors. However, androstan-3 beta-ol, which completely lacks the side chain, was found to be more active than cholesterol. The transfer of the acyl group to all effective sterols required the presence of the cofactor peptide apolipoprotein A-I.

Cholesterol↗
PubMed1979

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.

Esters↗
PubMed1982

Herbal remedies of the Maritime indians: sterols and triterpenes of Tanacetum vulgare L. (Tansy).

Plant sterols and triterpenes exhibit a wide range of pharmacological activities. As part of our ongoing studies of the medicinal aspects of Maritime flora, particularly the herbal remedies of the Micmac and Malecite Indians, we determined the nature of the sterols and triterpenes of Tanacetum vulgare L. (Compositae)-a widely used herbal remedy usually referred to as tansy. By using thin layer and gas chromatographics, nuclear magnetic resonance (NMR) spectroscopy and combined gas chromatography-mass spectrometry, we were able to identify beta-sitosterol as the major sterol and alpha-amyrin as the major triterpene of tansy. We also identified the sterols stigmasterol, campesterol and cholesterol, and the triterpenes beta-amyrin and taraxasterol. A fourth triterpene was tentatively identified as pseudo-taraxasterol. The successful therapeutic application of this herb may be due partly to the presence of one or more of these compounds. The sterols and triterpenes of tansy have not been previously reported; neither, to our knowledge, have the NMR spectra of the amyrins and the NMR and mass spectra of taraxasterol.

Chromatography, Thin Layer↗
PubMed1994

The lipids of slugs and snails: evolution, diet and biosynthesis.

There is a considerable gap in current knowledge of the lipid composition of snails and slugs, both of which belong to the phylum Mollusca. We have therefore analyzed the sterol and fatty acid compositions of three species of slugs and three species of snails. The sterols of slugs included eight different sterols: cholesterol contributed 76-85% of the total sterols, brassicasterol accounted for 4-13%; other sterols we identified were lathosterol, 24-methylene cholesterol, campesterol, stigmasterol, sitosterol and sitostanol. In contrast, snails contained two additional sterols, desmosterol and cholestanol. Of the polyunsaturated fatty acids in slugs, linoleic (18:2n-6) and arachidonic acids (20:4n-6) were the major n-6 fatty acids, while linoleic (18:3n-3) and eicosapentaenoic acids (20:5n-3) were the predominant n-3 fatty acids. Docosahexaenoic acid (22:6n-3), the end product in the n-3 fatty acid synthetic pathway and an important membrane fatty acid of mammals, fish and birds, was absent in both slugs and snails. However, the analogous product of n-6 fatty acid synthesis, 22:5n-6, was found in both snails and slugs. This raises speculation about preference for n-6 fatty acid synthesis in these species. Our data show the unique sterol and fatty acid compositions of slugs and snails, as well as similarities and differences in sterol composition between the two. The results between the two land mollusks are contrasted with those of marine mollusks, such as oysters, clams and scallops.

Animals↗
PubMed2005

Inhibitory constituents against cyclooxygenases from Aralia cordata Thunb.

Seven diterpenes, four polyacetylenes, a lipid glycerol, and two sterols were isolated from the methylene chloride fraction of the root of Aralia cordata. Their chemical structures were determined as (-)-pimara-8(14),15-dien-19-oic acid (2), pimaric acid (3), (-)-kaur-16-en-19-oic acid (4), 17-hydroxy-ent-kaur-15-en-19-oic acid (9), 7alpha-hydroxy-(-)-pimara-8(14),15-dien-19-oic acid (10), 16alpha,17-dihydroxy-(-)-kauran-19-oic acid (11), 16-hydroxy-17-isovaleroyloxy-ent-kauran-19-oic acid (12), falcarindiol (5), dehydrofalcarindiol (6), dehydrofalcarindiol-8-acetate (7), falcarindiol-8-acetate (8), alpha-mono palmitin (13), stigmasterol (1), and daucosterol (14) by the spectral evidences. These compounds were tested with COX-1 and COX-2 inhibition assays. This study found that compounds 2, 4, 5, 6, 7, 8, and 10 inhibited COX-1 dependent conversion of the exogenous arachidonic acid to PGE2 in a dose-dependent manner with IC50 values of 134.2 microM, 121.6 microM, 170 microM, 50.4 microM, 11.7 microM, 99.6 microM, and 69.6 microM, respectively. But, most of these compounds weakly inhibited COX-2 dependent PGE2 generation. Among them, only compound 4 showed relatively significant inhibitory activity (IC50: 127.6 microM).

Aralia↗
PubMed2000

Identification of metabolites of phytosterols in rat feces using GC/MS.

Beta-sitosterol, campesterol and stigmasterol have been known to the phytosterols the most frequently found in plants. Metabolism of phytosterols was investigated using rat feces and liver microsomes. Feces were collected after phytosterols (a well characterized mixture of beta-sitosterol 40%, campesterol 30% and dihydrobrasicasterol) were administered orally (0.5 g/kg) to rats. Metabolites of phytosterols were identified using GC/MS. Three peaks were eluted at 12.47, 12.65, 12.87 min and had characteristic molecular ions m/z 428, 430, 432, respectively. Three fecal metabolites were identified as androstadienedione, androstenedione, and androstanedione. No metabolites could be detected in the rat liver microsomal reaction mixture. The results suggest that the metabolites of phytosterols in rat feces are formed by oxidation at 3- position, saturation at 5- and 6- position, and 17- side chain cleavage in the rat large intestine.

Animals↗
PubMed2004

Constituents of the halophyte Salicornia herbacea.

Four compounds were isolated from Salicornia herbacea by repeated column chromatography. Their structures were identified as beta-sitosterol (1), stigmasterol (2), uracil (3), and isorhamnetin-3-O-beta-D-glucopyranoside (4) by spectral analysis and comparison with the published data.

Chenopodiaceae↗
PubMed1999

Composition and role of tapetal lipid bodies in the biogenesis of the pollen coat of Brassica napus.

The composition of the two major lipidic organelles of the tapetum of Brassica napus L. has been determined. Elaioplasts contained numerous small (0.2-0.6 micron) lipid bodies that were largely made up of sterol esters and triacylglycerols, with monogalactosyldiacylglycerol as the major polar lipid. This is the first report in any species of the presence of non-cytosolic, sterol ester-rich, lipid bodies. The elaioplast lipid bodies also contained 34- and 36-kDa proteins which were shown by N-terminal sequencing to be homologous to fibrillin and other plastid lipid-associated proteins. Tapetosomes contained mainly polyunsaturated triacylglycerols and associated phospholipids plus a diverse class of oleosin-like proteins. The pollen coat, which is derived from tapetosomes and elaioplasts, was largely made up of sterol esters and the C-terminal domains of the oleosin-like proteins, but contained virtually no galactolipids, triacylglycerols or plastid lipid-associated proteins. The sterol compositions of the elaioplast and pollen coat were almost identical, consisting of stigmasterol > campestdienol > campesterol > sitosterol >> cholesterol, which is consistent with the majority of the pollen coat lipids being derived from elaioplasts. These data demonstrate that there is substantial remodelling of both the lipid and protein components of elaioplasts and tapetosomes following their release into the anther locule from lysed tapetal cells, and that components of both organelles contribute to the formation of the lipidic coating of mature pollen grains.

Amino Acid Sequence↗
PubMed2006

The extracellular pollen coat in members of the Brassicaceae: composition, biosynthesis, and functions in pollination.

I have used cellular and molecular genetic and bioinformatic approaches to characterise the components of the pollen coat in plants of the family Brassicaceae, including Arabidopsis thaliana and several brassicas including Brassica napus, B. oleracea, and B. rapa. The pollen coat in these species is mostly made up of a unique mixture of lipids that is highly enriched in acylated compounds, such as sterol esters and phospholipids. These acyl lipids are characterised by an unusually high degree of saturation. The fatty acids typically contain 70-90% saturated acyl residues such as myristate, palmitate, and stearate. The major sterol components of the pollen coat are saturated fatty acyl esters of stigmasterol, campesterol, and campestdienol. In addition to lipids, the second major component of the pollen coat is a specific group of proteins that is dominated by a family of proteins that we term pollenins. Although pollenins are by far the major protein components of the pollen coat of members of the Brassicaceae, proteomic analysis reveals that there are several additional protein components, including lipases, protein kinases, a pectin esterase, and a caleosin. The biosynthesis of these lipids and proteins and their significance for overall pollen function are reviewed and discussed.

Brassicaceae↗
PubMed2006

A very efficient bioconversion of soybean phytosterols mixtures to androstanes by mycobacteria.

The production of several high value steroid drugs, used as progestational, adrenocortical, estrogenic and contraceptive agents, is mostly derived from 4-androstene-dione (AD) and 1,4 androsta-diene-3,17-dione (ADD). Three Vietnamese phytosterols mixtures named VN-1, VN-2 and VN-3, isolated from soybean oil may be efficiently converted into these key compounds by mycobacterial cells. Their general phytosterol composition was 55.39, 70.55, 70.19% for VN-1, VN-2 and VN-3, respectively. Moreover, values of campesterol, beta-sitosterol and stigmasterol were determined. After 120 h of shaking in suitable culture media and temperature, maximal yield conversion to ADD was higher than 70% and up to 64% to AD, for the various phytosterols mixtures assays. These results may be better when scaling-up such a procedure of phytosterols conversion.

Androstanes↗
PubMed2026

Molecular mechanisms underlying low glycemic index in rice: Insights from Indian landrace diversity.

The rising prevalence of diabetes mellitus, especially among populations with high rice consumption, underscores the need for functional staple crops with a low glycemic index (GI). This review examines the molecular and genetic factors influencing low-GI traits in rice, highlighting the importance of diversity within Indian landraces. Traditional cultivars like Mappillai Samba, Karuppu Kavuni and Kattuyanam contains high level of Resistant starch, dietary fiber and bioactive phytochemicals. The Waxy (Wx) gene, which codes for granule-bound starch synthase I (GBSSI), is very important for controlling the production of amylose. For example, functional alleles like Wxa and Wxlv are linked to higher amylose levels and lower starch digestibility. Moreover, secondary metabolites, such as anthocyanins and phytosterols like stigmasterol, play a role in regulating blood sugar levels by stopping the activities of α-amylase and α-glucosidase. Interactions within the starch-dietary matrix, including starch-protein, starch-lipid, and starch-polyphenol complexes, further influence enzymatic hydrolysis and glucose release kinetics. Recent advancements in genomics, encompassing QTL mapping and gene editing techniques, offer innovative prospects for the creation of biofortified, low-GI rice cultivars. The integration of these molecular insights into rice breeding programs can facilitate the development of low-glycemic, nutritionally enhanced rice cultivars that contribute to improved metabolic health and food security.

Oryza↗
PubMed2002

Changes in lipid molecular species and sterols of microsomal membranes during aging of potato (Solanum tuberosum L.) seed-tubers.

Changes in sterols and the molecular species composition of polar lipids from microsomal membranes were characterized as a prerequisite to determining how lipid chemistry affects membrane susceptibility to peroxidation during aging of potato tubers. Polar lipid content of the microsomal fraction fell 17% (protein basis) as tubers aged from 22 to 38 mon at 4 degrees C. In younger seed-tubers, PC concentration (protein basis) was the highest, followed by digalactosyldiacylglycerol (DGDG), PE, monogalactosyldiacylglycerol (MGDG), and PI. PC and PE increased 14 and 27%, respectively, whereas glycolipids fell 64 and PI 43% with advancing age. These changes resulted in PC and PE dominating the microsomal membrane lipids of 38-mon-old tubers. Nonpositional analysis of lipid molecular species across lipid pools showed an increase in 16:0/18:3, 18:3/18:3, and 18:2/18:3 (PC and PE only), and a decline in 18:2/18:2 and 16:0/18:2 (except for MGDG) with advancing tuber age. The increase in 18:3-bearing species effected a linear increase in double-bond index (DBI) of PC and PE during aging. The DBI of DGDG did not change with age; however, it fell 65% for MGDG, resulting in an overall decrease in average microsomal DBI. In addition, A5-avenasterol and stigmasterol concentrations increased 1.6- and 3.3-fold, respectively, effecting a significant increase in the sterol/phospholipid ratio with advancing tuber age. The increase in sterol/phospholipid ratio and the possibility that the increased unsaturation of microsomal membranes reflects a compensatory response to maintain optimal membrane function in light of the age-induced loss of galactolipid and PI are discussed.

Intracellular Membranes↗
PubMed2005

Simultaneous quantification of free fatty acids, free sterols, squalene, and acylglycerol molecular species in palm oil by high-temperature gas chromatography--flame ionization detection.

This paper discusses a rapid GC-FID technique for the simultaneous quantitative analysis of FFA, MAG, DAG, TAG, sterols, and squalene in vegetable oils, with special reference to palm oil. The FFA content determined had a lower SE compared with a conventional titrimetric method. Squalene and individual sterols, consisting of beta-sitosterol, stigmasterol, campesterol, and cholesterol, were accurately quantified without any losses. This was achieved through elimination of tedious conventional sample pretreatments, such as saponification and preparative TLC. With this technique, the separation of individual MAG, consisting of 16:0, 18:0, and 18:1 FA, and the DAG species, consisting of the 1,2(2,3)- and 1,3-positions, was sufficient to enable their quantification. This technique enabled the TAG to be determined according to their carbon numbers in the range of C44 to C56. Comparisons were made with conventional methods, and the results were in good agreement with those reported in the literature.

Chromatography, Gas↗
PubMed1997

Sterol utilization and metabolism by Heliothis zea.

Heliothis zea (corn earworm), an insect that fails to synthesize sterols de novo, was reared on an artificial diet treated with 18 different sterol supplements. Larvae did not develop on a sterol-less medium. delta 5-Sterols with a hydrogen atom, a methylene group, an E- or Z-ethylidene group, or an alpha- or beta-ethyl group (cholesterol, ostreasterol, isofucosterol, fucosterol, sitosterol, and clionasterol, respectively) at position C-24, and delta 5-sterols doubly substituted in the side chain at C-24 with an alpha-ethyl group and at C-22 with a double bond (stigmasterol) supported normal larval growth to late-sixth instar (prepupal: maturity). The major sterol isolated from each of these sterol treatments was cholesterol, suggesting that H. zea operates a typical 24-dealkylation pathway. The sterol requirement of H. zea could not be met satisfactorily by derivatives of 3 beta-cholestanol with a 9 beta, 19-cyclopropyl group, gem dimethyl group at C-4, a delta 5,7-bond or delta 8-bond, or by side chain modified sterols that possessed a delta 25(27)-24 beta-ethyl group, delta 23(24)-24-methyl group or 24-ethyl group, or delta 24(25)-24-methyl or 24-ethyl group. The major sterol recovered from the larvae (albeit developmentally arrested larvae) treated with a nonutilizable sterol was the test compound. Sterol absorption was related to the degree of sterol utilization. The most effective sterols absorbed by the insect ranged from 27 to 66 micrograms per insect, whereas the least effective sterols absorbed by the insect ranged from 0.6 to 6 micrograms per insect. Competition experiments using different proportions of cholesterol and 24-dihydrolanosterol (from 9:1 to 1:9 mixtures) indicated that abnormal development of H. zea may be induced on less than a 1 to 1 mixture of utilizable (cholesterol) to nonutilizable (24-dihydrolanosterol) sterols. The results demonstrate new structural requirements for sterol utilization and metabolism by insects, particularly with respect to the position of double bonds in the side chain and functionalization in the nucleus. The novel sterol specificities observed in this study appear to be associated with the dual role of sterols as membrane inserts (nonmetabolic) and as precursors to the ecdysteroids (metabolic).

Animals↗
PubMed1987

Lipid composition of plasma membranes isolated from light-grown barley (Hordeum vulgare) leaves: identification of cerebroside as a major component.

The total lipid composition of highly purified plasma membranes from light-grown barley (Hordeum vulgare) leaves was investigated. The plasma membranes were separated from intracellular membranes by subfractionation of the microsomal fraction using aqueous polymer two-phase partitioning. A novel finding was that glucocerebroside was a major lipid of the plasma membrane (23 mol%). The most abundant lipid class in the plasma membrane was phospholipid (42 mol%), consisting mainly of phosphatidylcholine and phosphatidylethanolamine, together with free sterols at a level of 28 mol%. The only free sterols of the plasma membrane were campesterol (15%), stigmasterol (23%), and sitosterol (62%). The plasma membrane contained a relatively high proportion of saturated fatty acids compared to the bulk of intracellular membranes, the major components of the plasma membrane being palmitic (16:0), linoleic (18:2), and linolenic (18:3) acids in approximately equal amounts.

Cell Membrane↗
PubMed1982

The influence of sterols on pentachlorophenol-induced charge transfer across lipid bilayers studied by alternating current methods.

The frequency dependence of membrane admittance has been determined for a series of phosphatidylcholine/sterol/n-decane bilayers in the presence of an aqueous environment containing pentachlorophenol. Variations in the results among membranes can be related to differences in the kinetic parameters of a kinetic model of pentachlorophenol-induced charge transport by characterizing both measurements and model behavior in terms of a common equivalent circuit. The kinetic model assumes a three-layer structure for the membrane and immediate environment. Data from membranes formed with beta-hydroxysterols having a flat ring structure and an intact side-chain (cholestanol, cholesterol, 7-dehydrocholesterol), after correction for sterol-induced membrane thinning, suggest that these sterols affect charge translocation by altering both interior fluidity and surface dipolar fields. The effects almost cancel for the case of cholesterol. These sterols also affect interfacial processes, either by inhibiting proton exchange between the aqueous and lipid environments, or by suppressing the adsorption of pentachlorophenol anions. Stigmasterol, coprostanol and epicholesterol cause only minor alterations in both translocation and interfacial processes. None of the sterols investigated has a significant influence on the capacitance of the interfacial region.

Animals↗
PubMed1975

Lipids in plant tissue cultures. IV. The characteristic patterns of lipid classes in callus cultures and suspension cultures.

Lipids from callus cultures and suspension cultures of higher plants constitute 5 to 8% of the dry tissue's weight. The predominant lipid classes are the sterols, steryl esters, steryl glycosides and esterified steryl glycosides. Considerable amounts of a variety of sterylglycolipids, whose structures are not completely elucidated, are also present. Triglycerides and phospholipids occur in small proportions, whereas monogalactosyl diglycerides, digalactosyl diglycerides and sulfoquinovosyl diglycerides are present only in traces, if at all. Beta-Sitosterol is the predominant constituent sterol, stigmasterol and campesterol as well as a variety of as yet unidentified sterols occur in smaller proportions. The major constituent fatty acids are palmitic, oleic, linoleic and linolenic acids. Saturated very long-chain fatty acids are found in smaller proportions. Unusual fatty acids, such as epoxy acids, which occur in the seed lipids of certain plants, are not found in tissue cultures derived from these plants. Clucose and traces of galactose are the only sugars obtained by acid hydrolysis of the glycolipids occurring in plant tissue cultures.

Cell Division↗
PubMed1991

Palmitoyl diol S- and O-phosphoroamidates of some sterols.

The hexamethylphosphorus triamide activated by the addition of iodine at the optimum molar ratio 1.05:0.05 was used as a phosphorylating reagent to synthesize 1-palmitoyloxyethyl-2-O-, 1-palmitoyloxypropyl-3-O- and 1-palmitoyloxybutyl-4-O-(N,N-dimethylamido)thiophosphate and -phosphate derivatives of beta-sitosterol, cholesterol and stigmasterol in a one-pot procedure with overall yields of 80-87%. 1-Palmitoyloxypropyl-3-O-(cholesteryl-3-O)-(N,N-dimethylamido++ +) phosphite was used as a model synthon for the preparation of transamidated morpholido-thiophosphate and -phosphate analogues with final yields of 82-86%.

Amides↗