Showing papers on "Stigmasterol published in 2007"

Phytosterol, Squalene, Tocopherol Content and Fatty Acid Profile of Selected Seeds, Grains, and Legumes

Abstract: The unsaponifiable lipid fraction of plant-based foods is a potential source of bioactive components such as phytosterols, squalene, and tocopherols. The objective of the present study was to determine the levels of phytosterols, and squalene, as well as tocopherols (α and β + γ) in selected grains, seeds, and legumes. The method comprised acid hydrolysis and lipid extraction followed by alkaline saponification, prior to analysis by HPLC. In addition, the fatty acid profile of the foods was determined via total lipid extraction, fatty acid derivitisation and GC analysis. In general, β-sitosterol was the most prevalent phytosterol, ranging in concentration from 24.9 mg/100 g in pumpkin seed to 191.4 mg/100 g in peas. Squalene identified in all foods examined in this study, was particularly abundant in pumpkin seed (89.0 mg/100 g). The sum of α- and β+ γ-tocopherols ranged from 0.1 mg/100 g in rye to 15.9 mg/100 g in pumpkin seeds. Total oil content ranged from 0.9% (w/w) in butter beans to 42.3% (w/w) in pumpkin seed and the type of fat, in all foods examined, was predominantly unsaturated. In conclusion, seeds, grains, and legumes are a rich natural source of phytosterols. Additionally, they contain noticeable amounts of squalene and tocopherols, and in general, their fatty acid profile is favorable.

Stigmasterol, a soy lipid-derived phytosterol, is an antagonist of the bile acid nuclear receptor FXR.

Abstract: Phytosterols, components of soy-derived lipids, are among the proposed exacerbants of parenteral nutrition-associated cholestasis (PNAC). We investigated whether phytosterols contribute to bile acid (BA)-induced hepatocyte damage by antagonizing a nuclear receptor (NR) critically involved in hepatoprotection from cholestasis, FXR (farnesoid X receptor, NR1H4). In HepG2 cells, stigmasterol acetate (StigAc), a water-soluble Stig derivative, suppressed ligand-activated expression of FXR target genes involved in adaptation to cholestasis (i.e. BSEP, FGF-19, OSTalpha/beta). Furthermore, StigAc antagonized BA-activated, FXR target genes SHP and BSEP in FXR+/+, but not in FXR-/- mouse hepatocytes. Both Stig and StigAc inhibited BA-activated, FXR-dependent reporter gene expression in transfected HepG2 cells, whereas the most prevalent phytosterol in lipids, beta-sitosterol, had no inhibitory effect. Finally, among six ligand-activated NR-ligand binding domains (LBDs) tested, antagonism by StigAc was specific to only two (FXR and PXR, pregnane X receptor, NR1I2). We demonstrate that Stig, a phytosterol prevalent in soy-derived PN lipid solutions, is a potent in vitro antagonist of the NR for bile acids FXR.

Plant sterols in "rafts": a better way to regulate membrane thermal shocks

Abstract: Specialized lipid domains (rafts) that are generally enriched in sterols and sphingolipids, are most likely present in cell membranes of animals, plants and fungi. While cholesterol and ergosterol are predominant in vertebrates and fungi, plants possess complex sterol profiles, dominated by sitosterol and stigmasterol in Arabidopsis thaliana. Fully hydrated model membranes of composition approaching those found in rafts of mammals, fungi and plants were investigated by means of solid-state 2H-NMR, using deuterated dipalmitoylphosphatidylcholine (2H(62)-DPPC). The dynamics of such membranes was determined through measuring of membrane ordering or disordering properties. The presence of the liquid-ordered, lo, phase, which may be an indicator of rigid sterol-sphingolipid domains, was detected in all binary or ternary mixtures of all sterols investigated. Of great interest, the dynamics of ternary mixtures mimicking rafts in plants (phytosterol/glucosylcerebroside/DPPC), showed a lesser temperature sensitivity to thermal shocks, on comparing to systems mimicking rafts in mammals and fungi. This effect was particularly marked with sitosterol. The presence of an ethyl group branched on the alkyl chain of sitosterol and stigmasterol is proposed as reinforcing the membrane cohesion by additional attractive van der Waals interactions with the alkyl chains of sphingolipids and phospholipids. As a side result, the elevated resolution of NMR spectra in the presence of sitosterol also suggests domains of smaller size than with other sterols. Finally, the role of phytosterols in maintaining plant membranes in a state of dynamics less sensitive to temperature shocks is discussed.

Isolation of stigmasterol and beta-sitosterol from methanolic extract of root bark of Calotropis gigantea (Linn).

Abstract: Aim of this study is to identify and characterize the bioactive principles from the root bark of Calotropis gigantea. It has wide folk medicinal use. For isolation of the compounds, the dried root bark's powder of Calotropis gigantea were subjected to hot extraction and then the crude methanol (MeOH) extract was fractionated with petroleum ether, chloroform and ethyl acetate. Two compounds were isolated and purified from petroleum ether fraction of crude methanol extract and the structures were determined as stigmasterol and beta-sitosterol by analysis of physical, chemical and spectral characteristics (1D NMR and mass spectrometry).

Overexpression of CYP710A1 and CYP710A4 in transgenic Arabidopsis plants increases the level of stigmasterol at the expense of sitosterol

Abstract: Sitosterol and stigmasterol are major sterols in vascular plants An altered stigmasterol:sitosterol ratio has been proposed to influence the properties of cell membranes, particularly in relation to various stresses, but biosynthesis of stigmasterol is poorly understood Recently, however, Morikawa et al (Plant Cell 18:1008-1022, 2006) showed in Arabidopsis thaliana that synthesis of stigmasterol and brassicasterol is catalyzed by two separate sterol C-22 desaturases, encoded by the genes CYP710A1 and CYP710A2, respectively The proteins belong to a small cytochrome P450 subfamily having four members, denoted by CYP710A1-A4, and are related to the yeast sterol C-22 desaturase Erg5p acting in ergosterol synthesis Here, we report on our parallel investigation of the Arabidopsis CYP710A family To elucidate the function of CYP710A proteins, transgenic Arabidopsis plants were generated overexpressing CYP710A1 and CYP710A4 Compared to wild-type plants, both types of transformant displayed a normal phenotype, but contained increased levels of free stigmasterol and a concomitant decrease in the level of free sitosterol CYP710A1 transformants also displayed higher levels of esterified forms of stigmasterol, cholesterol, 24-methylcholesterol and isofucosterol The results confirm the findings of Morikawa et al (Plant Cell 18:1008-1022, 2006) regarding the function of CYP710A1 in stigmasterol synthesis, and show that CYP710A4 also has this capacity Furthermore, our results suggest that an increased stigmasterol level alone is sufficient to stimulate esterification of other major sterols

The chemical composition of fruits of Pistacia atlantica desf. subsp. atlantica from Algeria

Abstract: The chemical composition of the fruits of the north algerian ecotype Pistacia atlantica subsp. atlantica was determined and compared to other fruits of different species in the genus growing in south Algeria and other Mediterranean regions. These fruits were analyzed for their dry matter, protein, crude oil, ash, fatty acids, and phytosterol content. The main fatty acids identified by gas chromatography were oleic (54.15%), linoleic (28.84%), and palmitic (12.21%) acids. The fruits of the north ecotype were found to be rich in protein, oil, fiber, and unsaturated fatty acids, suggesting that they may be valuable for food uses. The sterols isolated were campesterol, stigmasterol, β-sitosterol, and Δ5-avenasterol with β-sitosterol as the major constituent (85%±0.85). The biochemical data indicated an elevated MUFA rate (∼56%) in pistacia oil which may be important against certain pathologies for its nutritional and preventive virtues.

Identification of β‐sitosterol, stigmasterol and ergosterin in A. roxburghii using supercritical fluid extraction followed by liquid chromatography/atmospheric pressure chemical ionization ion trap mass spectrometry

Abstract: β-Sitosterol and stigmasterol are the most common phytosterols in traditional Chinese medicine. They have been proved to have many important bioactivities. To the best of our knowledge, this is the first report that β-sitosterol, stigmasterol and ergosterol coexisting in A. roxburghii herbs can be simultaneously extracted by a supercritical fluid extraction (SFE) procedure; then a simple high-performance liquid chromatography/atmospheric pressure chemical ionization ion trap mass spectrometry (HPLC/APCI/MS) method was developed for simultaneous identification and determination of these three compounds. The ion trap MS/MS detector was equipped with an atmospheric pressure chemical ionization source operating in the positive ion mode, APCI(+). The linear responses were obtained in the concentration range of 0.50–150 µg/mL (r = 0.9999) for ergosterol, 5–400 µg/mL (r = 0.9999) for stigmasterol, and 10–2000 µg/mL (r = 0.9998) for β-sitosterol. An orthogonal L9 (33) test design was employed for optimization of the SFE process. Under the optimized conditions, i.e. pressure of 25 mPa, temperature of 45°C and ethanol as modifier, the concentrations of sterols in the extract were found to be 2.89% (g/g) for β-sitosterol, 3.56% (g/g) for stigmasterol and 2.96% (g/g) for ergosterin. The SFE method was also compared with a previously developed Soxhlet extraction. The SFE method produced higher yields of sterols than that of the Soxhlet extraction. The proposed method has been successfully used for identification and quantitation of β-sitosterol, stigmasterol and ergosterin in a real A. roxburghii sample. Copyright © 2007 John Wiley & Sons, Ltd.

Phytochemical and biological investigations of erythrina variegata

Abstract: Five compounds were isolated from the n-hexane and chloroform soluble fractions of a methanol extract of the stem bark of Erythrina variegata. The structures of the isolated compounds were elucidated as alpinum isoflavone (1), epilupeol (2), 6-hydroxygenistein (3), 3β, 28dihydroxyolean-12-ene (4) and stigmasterol (5) by extensive spectroscopic studies, including high field NMR analyses. Different partitionates of the methanol extract exhibited mild to moderate antimicrobial activity and varying degrees of cytotoxicity. Although, alpinum isoflavone (1) has previously been reported from E. variegata, this is the first report of isolation of compounds 2-4 and stigmasterol from this plant species.

Determination of Campesterol, Stigmasterol, and Beta-Sitosterol in Saw Palmetto Raw Materials and Dietary Supplements by Gas Chromatography: Collaborative Study

Abstract: An interlaboratory study was conducted to evaluate a method for the determination of campesterol, stigmasterol, and beta-sitosterol in saw palmetto raw materials and dietary supplements at levels >1.00 mg/100 g based on a 2-3 g sample. Test samples were saponified at high temperature with ethanolic KOH solution. The unsaponifiable fraction containing phytosterols (campesterol, stigmasterol, and beta-sitosterol) was extracted with toluene. Phytosterols were derivatized to trimethylsilyl ethers and then quantified by gas chromatography with hydrogen flame ionization detection. Twelve blind duplicates, one of which was fortified, were successfully analyzed by 10 collaborators. Recoveries were obtained for the sample that was fortified. The results were 99.8, 111, and 111% for campesterol, stigmasterol, and beta-sitosterol, respectively. For repeatability, the relative standard deviation (RSDr) ranged from 3.93 to 17.3% for campesterol, 3.56 to 22.7% for stigmasterol, and 3.70 to 43.9% for beta-sitosterol. For reproducibility, the RSDR ranged from 7.97 to 22.6%, 0 to 26.7%, and 5.27 to 43.9% for campesterol, stigmasterol, and beta-sitosterol, respectively. Overall, the Study Director approved 5 materials with acceptable HorRat values for campesterol, stigmasterol, and beta-sitosterol ranging from 1.02 to 2.16.

Phytochemical and biological investigation of Stevia rebaudiana Bertoni; 1-labdane-type diterpene

Abstract: Five labdane diterpenoids, austroinulin, iso-austroinulin, sterebin E, sterebin E acetate, and sterebin A acetate, along with hydrocarbons, aliphatic alcohols, β-amyrin, β-sitosterol and stigmasterol were isolated from the chloroform soluble fraction of the methanol extract of Stevia rebaudiana leaves. Chlorogenic and caffeic acids were isolated from the EtOAc fraction. All the isolated compounds were identified using spectral tools. The chloroform and methanol extracts proved significant anti-inflammatory effect and caused marked inhibition of carrageenan-induced paw oedema in rats.

Lipid Composition of Tobacco Seeds

Abstract: ZLATANOV, M., M. ANGELOVA and G. ANTOVA, 2007. Lipid composition of tobacco seeds. Bulg. J. Agric. Sci., 13: 539-544 The content and composition of lipids isolated from seeds of 7 Bulgarian tobacco species was investigated. 382-492g.kg -1 glyceride oil in the seed was founded to be. The biological active substances - fatty acids, phospholipids, sterols and tocopherols were studied. Palmitic (126367g.kg -1 ), oleic (152-263g.kg -1 ) and linoleic acid (176-627g.kg -1 ) predominated in the oils. The content of phospholipids, sterols and tocopherols in the oils was 2-15g.kg -1 , 3-8g.kg -1 and 2-195 mg/kg respectively. Phosphatidylcholine (247-405g.kg -1 ), phosphatidylinositol (215-276g.kg -1 ) and phosphatidylethanolamine (143-320g.kg -1 ) were found to be the main constituents. b-sitosterol (433-682g.kg -1 ), stigmasterol (102-188g.kg -1 ) and kampesterol (93-149g.kg -1 ) predominated in the sterol fraction. All of tocopherol derivatives were identified in the tocopherol fraction.

The Antibacterial Metabolites and Proacacipetalin from Acacia cochliacantha

Abstract: Chromatographic purification of the antibacterial hexane, ethyl acetate and methanol extracts from the aerial parts of Acacia cochliacantha provided twelve known antibacterial compounds: b- sitosterol, stigmasterol, b-sitosterol 3-O-b-D-glucoside, stigmasterol 3-O-b-D-glucoside, lupenone, taraxerone, apigenin, luteolin, querce- tin, gallic acid, methyl gallate and salicylic acid whose MIC values were determined. Additionally, proacacipetalin, squalene, (+)-pinitol, and palmitic, linoleic, oleic, stearic and myristic acids were isolated. These substances were fully characterized by 1D and 2D NMR spec- troscopy as well as by their physical properties. This is the first time that stigmasterol 3-O-b-D-glucoside and taraxerone are isolated from Acacia.

Constituintes químicos das cascas do caule de Cenostigma macrophyllum: ocorrência de colesterol

Abstract: Phytochemical investigation of the bark of Cenostigma macrophyllum (Leguminosae-Caesapinioideae) resulted in the isolation and identification of valoneic acid dilactone, ellagic acid, lupeol, alkyl ferulate, four free sterols (cholesterol, campesterol, stigmasterol and sitosterol), a mixture of sitosteryl ester derivatives of fatty acids, sitosterol-3-O-b-D-glucopyranoside, stigmasterol-3-O-b-D-glucopyranoside and saturated and unsaturated fatty acids. The structures of the isolated compounds were identified by 1H and 13C NMR spectral analysis and comparison with literature data. The mixtures of 3-b-hydroxysterols and fatty acids were analysed by GC/MS.

Fatty Acids, Triacylglycerols, and Sterols in Neem Oil (Azadirachta Indica A. Juss) as Determined by a Combination of Chromatographic and Spectral Techniques

Abstract: Quantitative thin‐layer chromatography in silver ion and reversed phase modes, gas chromatography, gas chromatography–mass spectrometry, and 13C nuclear magnetic resonance spectrometry were employed to determine the lipid composition in neem (Azadirachta indica A. Juss) kernel oil. Thirteen fatty acids and 25 triacylglycerols species were identified and quantified. The seven main triacylglycerols species were found in almost equal amounts in the range 7–10%. Saturated fatty moieties occupied positions 1‐ and 3‐ in the triacylglycerol molecule, oleic acid was almost equally distributed, and linoleic acid predominantly occupied position 2. Sitosterol, stigmasterol, campesterol, and fucosterol were the main components in free sterol and sterol ester fractions.

Analysis of phytosterol contents in Chinese plant food and primary estimation of its intake of people

Abstract: Objective To analyze the phytosterol content in plant food commonly consumed in China, and to estimate the intake of phytosterols in Chinese people. Methods More than 160 types of plant food in 7 kinds were chosen as samples. The contents of beta-sitosterol, campesterol, stigmasterol, beta-sitostanol, campestanol were analyzed by GC methods and the total phytosterols were calculated. The intake of phytosteols in Chinese people was estimated using the data of "Survey on the Status of Nutrition and Health of the Chinese People" in 2002. Results The contents of phytosterols in edible oils, nuts, and soybeans were higher than those in other plant food. In cereals, phytosterol contents of wheat flour were much higher than those of rice, the refinements of cereals may decrease the phytosterol contents. The phytosterol contents in vegetables and fruits were lower. The total intake of phytosterols in Chinese people was estimated to be 322.41mg/day, in which 40% may be of edible oil origin and 40% may be of cereal origin. Conclusion The results indicated that in the current dietary pattern, increase the intake of wheat, soybean, vegetable and fruit would enhance the phytosterol intake in Chinese.

Prenylated Flavonoids and Flavonostilbenes from Sophora pachycarpa. Roots

Abstract: Seven known compounds including three prenylated flavonoids (sophoraisoflavanone A, sophoraflavanone G, and 3′-isoprenylgenistein), two flavonostilbenes (alopecurone A and alopecurone B), in addition to two steroid glucosides (sitosterol 3-O.-glucoside and stigmasterol 3-O.-glucoside), were isolated using silica gel column chromatography and preparative thin layer chromatography from the roots of Sophora pachycarpa. C. A. Mey. (Papilionaceae) for the first time. The structures were characterized by 1D and 2D NMR experiments.

HPTLC Determination of Stigmasterol and Tocopherol Acetate in Leptadenia reticulata and in its Formulation

Abstract: Leptadenia reticulata W and A (Jivanti) is a shrub of the Asclepiadaceae family with many medicinal uses. Two high-performance thin-layer chromatographic methods have been developed for separate quantitative analysis of stigmasterol and dl -α-tocopherol acetate, two marker compounds in Leptadenia reticulata . The methods are rapid, simple and accurate and can be used for routine quality testing.

Effect of membrane fluidity on photosynthetic oxygen production reactions.

Abstract: The effect of changes of membrane fluidity on the oxygen evolving capability of isolated thylakoids was investigated. Alteration of the lipid phase fluidity was achieved by incorporation of the plant sterol stigmasterol. Incorporation of stigmasterol in the lipid bilayer of thylakoid membranes results in rigidization of the hydrophobic phase of thylakoid membranes and decreases the degree of packing of the lipid head groups. These changes of lipid order are accompanied by a reduction of oxygen evolution, measured with 1,4-benzoquinone as an electron acceptor, and by a more pronounced inhibition of PSI-mediated electron transport. By analysis of the parameters of oxygen flash yields and oxygen burst under continuous illumination it was shown that after treatment with stigmasterol: 1.) the number of active oxygen-evolving centres decreased; 2.) the remaining active oxygen-evolving centres were not affected in respect to the oscillation pattern; 3.) the contribution of the slow oxygen-evolving centres in oxygen burst yield was increased. The effect of stigmasterol was compared with the well-studied effect of cholesterol. Results were discussed in terms of determining the role of lipid order for the organization and functioning of the photosynthetic machinery.

Plant sterol metabolism with emphasis on glycoalkaloid biosynthesis in potato

Abstract: Glycoalkaloids are secondary metabolites present within species of the family Solanaceae. They are toxic to humans and animals, and it is important to keep the levels in potato (Solanum tuberosum L.) tubers below the safe limit for consumption. Glycoalkaloids are derived from sterols, which are important components of cell membranes. The sterol composition in plants is complex, and varies between species. For instance, cholesterol is a minor sterol in most plants, but a major one in the Solanaceae. Cholesterol has been suggested as a metabolic precursor to the glycoalkaloids in potato, although the biosynthetic pathway is largely unknown. To investigate the role of sterols in glycoalkaloid biosynthesis, potato plants overexpressing a type 1 sterol methyltransferase (SMT1) were generated. SMT1 plants displayed an increased level of alkylated sterols, while the level of the non-alkylated sterol cholesterol was decreased. Along with this there was a reduction of glycoalkaloid levels. To gain more insight into the sterol biosynthesis in plants, Arabidopsis lines were generated overexpressing CYP710A1 and CYP710A4, encoding enzymes potentially involved in stigmasterol synthesis. Both transformants contained increased levels of stigmasterol and a decrease in the level of sitosterol. CYP710A1 transformants also displayed increased levels of esterified sterols, suggesting that an increased stigmasterol level alone is sufficient to stimulate esterification of other sterols. The possibility of downregulating cholesterol and glycoalkaloid levels by increasing cholesterol catabolism was investigated in plants by expression of four mouse cDNAs encoding enzymes hydroxylating cholesterol. In Arabidopsis, plant growth and sterol/steroid levels were altered, indicating that the introduced hydroxysterol synthesis affected regulatory steps in steroid homeostasis. However, an increased level of hydroxylated cholesterol in potato had no effect on glycoalkaloid levels. A sterol Δ24-reductase was downregulated in transgenic potato. Transformants displayed increased levels of Δ24-sterols, while the levels of 24-saturated sterols such as cholesterol were decreased, as was their glycoalkaloid level. This reveals a new role for this type of enzymes in plant steroid metabolism. Taken together, the results show that both cholesterol and glycoalkaloid biosynthesis can be downregulated in transgenic plants, and support the view of cholesterol as a metabolic precursor in glycoalkaloid biosynthesis.

Thermal and Photooxidation Reactions of the Steroids : β-Sitosterol, Stigmasterol and Diosgenin

Abstract: Phytosterols β-sitosterol (1) and stigmasterol (2) were extracted from Nigella sativa which were collected from Al Qaseem’s area in the Kingdom of Saudi Arabia. Steroidal sapogenin diosgenin (3) was extracted from Balanites aegyptiaca (Zygopyllaceae), which was collected from Khamis al Bahr in theKingdom of Saudi Arabia. They have been fully characterized. Stigmasterol (2) and diosgenin (3) were acetylated to give stigmasterol and diosgenin acetate derivatives 4 and 5. Epoxidation of 1-5 gave exo and endo epoxide derivatives 6a, b; 10a, b; 11a, b; 16a, b and 17a, b as precursors of the brassinosteroidal compounds. On the other hand, photooxygenation of 1-5 gave hydroperoxysitosterol derivatives 7 and 9, hydroperoxystigmasterol derivatives 12 and 13, hydroperoxystigmasterol acetate derivatives 14 and 15, hydroperoxydiosgenin derivatives 18 and 19, and hydroperoxydiosgenin acetate derivatives 20 and 21.

Chemical constituents from Carthamus tinctorius L.

Abstract: Aim To study the chemical constituents of Carthamus tinctorius L.Methods The compounds were separated and purified by column chromatography and their structures were established by spectroscopic methods.Results and conclusion Six compounds were isolated from the ethyl acetate,n-butanol extracts of Carthamus tinctorius L.The structures were determined as benzyl-O-β-D-glucopyranoside(1),syringarenol(2),lirioresinol-A(3),5-hydroxymethyl-2-furaldehyde(4),β-sitosterol(5),and stigmasterol(6).Compounds 1-4 were isolated from this genus for the first time.

8-Methoxycapnolactone and stigmasterol From Micromelum minutum

Abstract: The coumarin, 8-methoxycapnolactone and stigmasterol were isolated from the leaves of Micromelum minutum (Rutaceae) which collected from Sepilok, Sabah, Malaysia and their structures were characterized by spectroscopic methods. Key words: Micromelum minutum ; Coumarin; 8-Methoxycapnolactone, Stigmasterol