Steryl Glucoside Research Articles

Rice bran extract containing acylated steryl glucoside fraction decreases elevated blood LDL cholesterol level in obese Japanese men.

People who frequently consume whole grains show a lower incidence of arteriosclerotic disease than people who consume primarily refined grains. We examined whether or not rice bran extract containing the acylated steryl glucosides (ASG) fraction decreases blood LDL cholesterol levels in obese Japanese men with high blood levels of LDL cholesterol. The study utilized a randomized, double-blind design. A total of 51 subjects were randomly allocated to either a rice bran extract containing ASG fraction (RB-ASG) group or a placebo group. Subjects in the RB-ASG group received 30-50 mg/day of RB-ASG, and the placebo group took 9 capsules/day for 12 weeks. Before and after intake, height, weight, body fat percentage, systolic and diastolic blood pressure were measured, blood was collected, and visceral fat area, subcutaneous fat area, and abdominal circumference were determined based on umbilical computed tomography. Percentage decreases in blood LDL cholesterol, non-HDL cholesterol, LDL/HDL ratio, abdominal circumference and subcutaneous fat area were significantly better in the RB-ASG group than in the placebo group. These findings suggest that RB-ASG fraction may reduce blood LDL cholesterol levels and the risk of arteriosclerosis in obese Japanese men with high LDL cholesterol levels.

Functional diversification of two UGT80 enzymes required for steryl glucoside synthesis in Arabidopsis.

Steryl glucosides (SG) are abundant steroid conjugates in plant membranes. Beyond structural roles in lipid bilayers, functions in sugar transport, storage, and/or signalling are predicted. UDP-glucose:sterol glucosyltransferase 80A2 (UGT80A2) and UGT80B1, which share similarity to fungal counterparts, are implicated in SG synthesis in Arabidopsis thaliana. A third related enzyme, which seems specific to the plant lineage, is encoded by UGT713B1/At5g24750. Genetic and biochemical approaches were employed to determine the role of each UGT gene in the production of specific SGs and acyl SGs (ASGs). Using direct infusion electrospray ionization tandem mass spectrometry (ESI-MS/MS), SG and acyl SG (ASG) contents of ugt80 and ugt713 mutants, and triple and double mutants were profiled in seeds. In vitro enzyme assays were performed to assay substrate preferences. Both UGT80A2 and UGT80B1, but not UGT713B1 were shown to be coordinately down-regulated during seed imbibition when SG levels decline, consistent with similar functions as UGT80 enzymes. UGT80A2 was found to be required for normal levels of major SGs in seeds, whereas UGT80B1 is involved in accumulation of minor SG and ASG compounds. Although the results demonstrate specific activities for UGT80A2 and UGT80B1, a role for UGT713B1 in SG synthesis was not supported. The data show that UGT80A2, the more highly conserved enzyme, is responsible for the bulk production of SGs in seeds, whereas UGT80B1 plays a critical accessory role. This study extends our knowledge of UGT80 enzymes and provides evidence for specialized functions for distinct classes of SG and ASG molecules in plants.

Lipid Classes and Subclasses of Cold‐Pressed and Solvent‐Extracted Oils from Commercial Indian Niger (Guizotia abyssinica (L.f.) Cass.) Seed

AbstractLipid classes and subclasses of cold‐pressed and solvent‐extracted (hexane and ethanol) oils from commercially available niger (Guizotia abyssinica (L.f.) Cass.) seeds were investigated. The oil yield of niger seeds obtained by cold pressing was 28.3 g/100 g while by hexane and ethanol extractions was 38.3 and 29.7 g/100 g respectively. The lipid classification of the extracted niger seed oils showed neutral lipids (65.9–95.5 %), glycolipids (2.7–24.6 %) and phospholipids (1.8–9.5 %). The acylglycerol composition of neutral lipids of extracted niger seed oils showed triacylglycerols (76.9–91.6 %), diacylglycerols (3.9–7.3 %) and monoacylglycerols (0.6–2.5 %). The fatty acid composition of tri‐, di‐, and monoacylglycerols of extracted niger seed oils showed linoleic acid (66.7–71.6 %) as the major fatty acid. The triacylglycerol composition of neutral lipids of extracted niger seed oils showed trilinolein (39.2–40.3 %) as the major triacylglycerol. The extracted niger seed oils contained 1289.9–6215.8 ppm of total phytosterols with β‐sitosterol (41.9–43.7 %) as the major phytosterol. Acylated steryl glucoside (39.5–52.2 %) was the major glycolipid in extracted niger seed oils. Phosphatidylcholine (49.6 and 47.9 %) was the major phospholipid in cold‐pressed and hexane‐extracted niger seed oils and phosphatidylethanolamine (57.1 %) was the major phospholipid in ethanol‐extracted niger seed oil. This is probably the first report on the variations in lipid classes and subclasses of Indian niger seed oil as affected by different modes of oil extraction.

Application of lipid extracts from Solidago canadensis to phytomonitoring of PCB126 in transgenic Arabidopsis plants

The aim of this study is to elucidate the effect of lipid extracts from Solidago canadensis for phytomonitoring of polychlorinated biphenyl (PCB) 126 in the transgenic Arabidopsis plant XgD2V11-6 carrying the recombinant guinea pig (g) aryl hydrocarbon receptor (AhR)-mediated β-glucuronidase (GUS) reporter gene expression system. A lipid extract was prepared from S. canadensis and separated into simple lipid, glycolipid, and phospholipid fractions by silica gel column chromatography. Sterylglucoside (SG), monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and glucosyl ceramide were found in the glycolipid fraction. When the transgenic Arabidopsis plants were treated with the glycolipid fraction together with PCB126, PCB126-induced GUS activity significantly increased in the whole plant. Moreover, S. canadensis-derived SG, MGDG, and DGDG also significantly increased PCB126-induced GUS activity. These results indicated that glycolipids in S. canadensis enhanced the sensitivity of this monitoring assay.

On the glucoside analysis: Simultaneous determination of free and esterified steryl glucosides in olive oil. Detailed analysis of standards as compulsory first step

This work covers two important gaps in the field of micronutrient databases: herein we describe a short and easy protocol that allows the analysis of both free and esterified steryl gulcosides in olive oil. By utilising accurate quantitative methods we achieve a better understanding of olive oil composition and health promoting properties. The procedure consists of isolating the fraction of interest through solid phase extraction, and using gas chromatography–flame ionisation detection for both identification and quantification of the derivatised species. Additionally, mass-spectrometry detection has been utilised for confirming the identity of the individual esterified steryl glucosides in some cases.The method’s limit of detection has been set at 0.37mg/kg for each free steryl glucoside and 0.20mg/kg for each esterified steryl glucoside, whereas the recoveries are around 96% and 77%, respectively.Finally, we provide a complete analysis of the commercial standard for esterified steryl glucosides, since such information was not yet available.

Phenotypic Characteristics as Predictors of Phytosterols in Mature Cycas micronesica Seeds

The relationship between mature Cycas micronesica K.D. Hill seed sterol concentration and content and plant or seed phenotypic characteristics was established by multiple regression. Combined models were significant for free but not glycosylated sterols. Reduced models revealed leaf number as the only significant predictor. Free and glycosylated sterol concentrations were unaffected throughout the range of several predictors: tree height (1.7 to 5.8 m), seed fresh weight (48 to 120 g), seed load (one to 76 seeds per plant), and estimated tree age (32 to 110 years). The free and glycosylated sterol phenotypes were also not dependent on the presence/absence of developed embryos in mature seeds. The significant response to leaf number was subtle with an increase of 43 leaves associated with a 0.1-mg increase in free sterol per gram seed fresh weight. This is the first report for any cycad that discusses reproductive or physiological traits in the context of allometric relations. Results indicate a highly constrained phenotypic plasticity of Cycas gametophyte sterol and steryl glucoside concentration and seed content in relation to whole plant and organ size variation.

Characterization of Sterol Lipids in Kluyveromyces lactis Strain M-16 Accumulating a High Amount of Steryl Glucoside

Kluyveromyces lactis strain M-16 isolated from raw milk accumulates a high amount of steryl glucoside in the cells. Under high temperature or in the presence of NaCl, this strain did not show better growth than other K. lactis strains that hardly accumulated steryl glucoside. Heat shock elevated the content of steryl glucoside 3.2-fold, which accounted for 27% of the total sterol lipids, and simultaneously reduced that of acyl sterol. Both strains, M-16 and NBRC 1267, contained ergosterol as a principal component, and dihydroergosterol was also included in steryl glucoside of strain M-16. Lanosterol was a major component second to ergosterol in free sterols. In acyl sterol of strain M-16, the proportion of 4,4-dimethylzymosterol was higher than that of ergosterol. Excess synthesis of steryl glucoside in strain M-16 consumes ergosterol and dihydroergosterol in the pool of free sterols, and acyl sterol may inevitably take in 4,4-dimethylzymosterol and 4-methylfecosterol, the intermediates in the biosynthetic pathway to ergosterol, as a component sterol.

Identification and quantification of steryl glucosides in biodiesel

AbstractThis paper discusses the nature and the chemical identification of a white, solid and insoluble residue isolated during the production of biodiesel, using palm or soybean oil as starting material. Using different isolation, purification and characterisation techniques, the solid was identified as a mixture of phytosteryl glucosides. A simple method for the quantitative evaluation of steryl glucoside (SG) concentrations in biodiesel samples is presented and discussed. Some preliminary results about the average concentration in biodiesel and about the solubility limits of SG are presented. The final section of this paper is dedicated to the impact of different crude oil refining techniques before the biodiesel synthesis reaction on the final SG concentration in biodiesel.

Metabolism of conjugated sterols in eggplant. Part 2. Phospholipid : steryl glucoside acyltransferase.

A membrane-bound phospholipid : steryl glucoside acyltransferase from Solanum melongena leaves was partially purified and its specificity and molecular as well as kinetic properties were defined. Among the steryl glycosides tested (e.g. typical plant steryl glucosides, steryl galactosides and cholesteryl xyloside) the highest activity was found with cholesteryl glucoside, but some structurally related compounds such as sito- and stigmasteryl glucoside or galactoside as well as cholesteryl galactoside were also acylated, albeit at lower rates. The investigated enzyme was able to use all classes of phosphoglycerolipids (phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol) as an acyl source for biosynthesis of acylated steryl glucoside. Among them 1,2-dimirystoylphosphatidylic acid appeared to be the best acyl donor. Apart from phosphoglycerolipids, 1,2-diacylglycerols were also used as acyl donor for steryl glucoside acylation, although at a distinctly lower rate. The acyl moiety was transferred from the C-1 position of phospholipid molecule. The investigated acyltransferase activity was stimulated by 2-mercaptoethanol, Triton X-100, 1-monoacylglycerols and inhibited in the presence of divalent cations such as Ca(2+), Mn(2+), Zn(2+) or Co(2+), some lipids (MDGD, ceramide), detergents (Tween 20, 40, 60 and 80, Tyloxapol, sodium deoxycholate) and high ionic strength.

Selection of lactic yeast producing glucosylceramide from cheese whey

From 2150 isolates from raw milk and milk products, yeast strains were surveyed to produce glucosylceramide from cheese whey. Most of the 54 strains that had accumulated a detectable amount of glucosylceramide were identified as Kluyveromyces lactis var. lactis. The cells of K. lactis var. lactis strain M-11 derived from domestic raw milk accumulated glucosylceramide 2.5-fold higher than K. lactis var. lactis NBRC 1267, the reference strain selected from the culture collections. Strain M-16 of K. lactis var. lactis derived from the same origin was found to synthesize a considerable amount of steryl glucoside in addition to glucosylceramide. Sequence analysis of ribosomal DNA intergenic spacer two regions revealed that strains M-11 and M-16 were diverged from a type strain of K. lactis var. lactis in the same species.

Pharmacokinetics and Pharmacodynamics of Sterylglucoside-Modified Liposomes for Levonorgestrel Delivery via Nasal Route

For emergency contraceptive, the rapid delivery of levonorgestrel (LNG) to plasma is desirable, furthermore, a sustained delivery of LNG along with rapid absorption will be necessary. The pharmacokinetics and pharmacodynamics of LNG entrapped in different kinds of liposome formulations via nasal administration in rats were evaluated and compared with LNG suspension via the oral route. The relative bioavailabilities of these liposome formulations via nasal administration were 100% or higher than 100%. The Cmax and Tmax values of sterylglucoside (SG) and chitosan-contained formulations by nasal administration were 416.84 ng/mL and 1.02 hr, 227.97 ng/mL and 2.02 hr, respectively, compared with that of 334.94 ng/mL and 1.89 hr of oral suspension. Fully 100% contraception was observed for all the formulations. SG could promote the absorption of LNG via the nasal route and may provide a rapid onset of action of LNG for emergency contraception. Chitosan could retain LNG in the nasal cavity for long contact time to sustain delivery of LNG. The rapid onset and sustained delivery of LNG can be achieved via the nasal route using liposomes as the vehicle.

Steryl glucoside concentration declines with Cycas micronesica seed age.

Neurotoxins contained in the seeds of Cycas micronesica K.D. Hill have been implicated in the Guam neurological disease cluster, amyotrophic lateral sclerosis-parkinsonism dementia complex (ALS-PDC). Some of these neurotoxins remain in the washed cycad seed flour that was historically an important part of the Chamorro diet. Of these, variant steryl glucosides have been identified by us as a possible etiological factor in the disease. In vitro and in vivo animal studies have strongly supported a role for these molecules in some forms of neurodegeneration. As part of a series of studies, we have now determined the concentrations of several steryl glucosides and their sterol precursors as affected by the age of C. micronesica seeds. The concentration of these molecules declined with seed age from 2.0 to 30.5 months. Following log-transformation of both axes, the decline was linear. Similarly, concentration of all but one of the molecules declined with age when samples were restricted to gametophyte tissue. Factors suspected of influencing phenotypic plasticity must be addressed when interpreting plant physiology data. Our results confirm for the first time that tissue age must be documented and reported in cycad seed biochemistry studies to remove ambiguities from results. Past studies in this important area of research have failed to account for the potential impact of seed age, rendering previous outcomes and interpretations of cycad neurotoxins in their impact on ALS-PDC ambiguous.

Spatial Variation of Steryl Glucosides in Cycas micronesica Plants: Within- and Among-plant Sampling Procedures

Amyotrophic lateral sclerosis–parkinsonism dementia complex (ALS–PDC) of the Western Pacific has been linked to the consumption of washed Cycas micronesica seed tissue. The search for a causal toxin in the seed tissue has generated decades of research, yet none of the published reports include an adequate description of sampling methods. We set out to design and conduct a study to serve as a model for future research. We used three populations of plants with similar recent plant life history, size, shade, seed load, and co-occurring species to determine intra- and interplant variation of four steryl glucoside variants. Variation was greatest among tissue types within seeds, intermediate among plants, and least among locations within plants. Results demonstrate the need of adhering to appropriate sampling protocols in cycad biochemistry research. Uses of appropriate sampling scheme and sample size are clearly required to avoid artifacts as this important area of research progresses.

ANALYSIS OF STERYL GLUCOSIDES IN FOODS AND DIETARY SUPPLEMENTS BY SOLID‐PHASE EXTRACTION AND GAS CHROMATOGRAPHY

ABSTRACT A method to quantify β‐sitosterol (BSS) and β‐sitosteryl glucoside (BSSG) in dietary supplements containing added BSS and BSSG was developed and also validated for the analysis of naturally occurring free and esterified sterols and steryl glucosides in foods. Steryl glucosides were extracted with hexane‐diethyl ether (1 : 1, v/v) after the alkaline saponification of a powdered supplement or of total lipid extracts of whole wheat flour, granola bars, soybeans, flaxseed, dried figs, peanut butter, lyophilized mixed vegetables, almonds, pine nuts and a diet homogenate. An oil‐based supplement was analyzed directly. Steryl glucosides were isolated by solid‐phase extraction, derivatized and quantified as trimethylsilyl ethers using capillary gas chromatography (GC) with a 5% diphenyl−95% dimethylpolysiloxane column. Recovery studies using a commercially available mixed steryl glucoside standard and gas chromatography‐mass spectrometry (GC‐MS) analyses validated the method. Approximately 2–36 mg/100 g (9–37%) of total sitosterol, campesterol and stigmasterol in the foods was contributed by the glucosides.

Application of Sterylglucoside-Containing Particles for Drug Delivery

Recent advances in biotechnology have promoted biomolecular targeting of drugs, peptides and genes in the treatment and management of major diseases and infections. Therapeutic development of drugs and delivery systems may have various objectives: Systemic drugs require optimal delivery and uptake at target sites; peptide drugs require alternative routes of administration, such as nasal or intestinal absorption; gene medicines need to be delivered efficiently, safely and selectively to diseased areas. The propensity of ligand-modified liposomes to carry drugs and genes to desirable sites has been extensively examined and current reports show considerable progress in this field. Sterylglucoside (SG) is a novel absorption-enhancer of peptide drugs across nasal and intestinal mucosae. Physico-chemical properties and biodistribution of liposomes incorporating SG were studied and compared against the profiles of aglycon and sitosterol derivatives of SG. It was shown that SG particles aided colon drug delivery and increased bioavailability of peptide drugs after nasal and intestinal administration. In addition, they were able to enhance anticancer effects in liver cancer chemotherapy. Biological fate and interaction of SG with hepatocytes support the novel proposition of liver-targeting SG-liposomes.

Plants Express a Lipid Transfer Protein with High Similarity to Mammalian Sterol Carrier Protein-2

This is the first report describing the cloning and characterization of sterol carrier protein-2 (SCP-2) from plants. Arabidopsis thaliana SCP-2 (AtSCP-2) consists of 123 amino acids with a molecular mass of 13.6 kDa. AtSCP-2 shows 35% identity and 56% similarity to the human SCP-2-like domain present in the human D-bifunctional protein (DBP) and 30% identity and 54% similarity to the human SCP-2 encoded by SCP-X. The presented structural models of apo-AtSCP-2 and the ligand-bound conformation of AtSCP-2 reveal remarkable similarity with two of the structurally known SCP-2s, the SCP-2-like domain of human DBP and the rabbit SCP-2, correspondingly. The AtSCP-2 models in both forms have a similar hydrophobic ligand-binding tunnel, which is extremely suitable for lipid binding. AtSCP-2 showed in vitro transfer activity of BODIPY-phosphatidylcholine (BODIPY-PC) from donor membranes to acceptor membranes. The transfer of BODIPY-PC was almost completely inhibited after addition of 1-palmitoyl 2-oleoyl phosphatidylcholine or ergosterol. Dimyristoyl phosphatidic acid, stigmasterol, steryl glucoside, and cholesterol showed a moderate to marginal ability to lower the BODIPY-PC transfer rate, and the single chain palmitic acid and stearoyl-coenzyme A did not affect transfer at all. Expression analysis showed that AtSCP-2 mRNA is accumulating in most plant tissues. Plasmids carrying fusion genes between green fluorescent protein and AtSCP-2 were transformed with particle bombardment to onion epidermal cells. The results from analyzing the transformants indicate that AtSCP-2 is localized to peroxisomes.

Stability and antitumor effects of all- trans retinoic acid-loaded liposomes contained sterylglucoside mixture

The aim of this study was to develop an intravenous delivery of all- trans retinoic acid (ATRA) for the treatment of cancer. Two kinds of liposomes composed of dipalmitoylphosphatidylcholine and cholesterol with sterylglucoside (SG) mixture (SG liposomes) or without SG (non-SG liposomes) were prepared. A limited amount of ATRA was incorporated into liposomes approximately 3 mol%. ATRA-loaded SG liposomes were more stable at 4 °C with light protection for 24 days than non-SG liposomes; maintaining 83.1% ATRA and the average diameter 198.5 nm (36 days), and in 80% rat serum for 120 min. SG seems to increase the ATRA-loaded efficiency in liposomes and stability of liposomes compared with cholesterol. The mean survival time of mice given SG liposomes (18.2 days) indicated a greater antitumor activity than saline (14.1 days) ( P<0.001) without change of mean body weight. It is concluded that the current ATRA-loaded SG liposomes are potentially applicable for hepatic metastasis of M5076 tumor.

Analysis of glycolipids from black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.) and niger (Guizotia abyssinica Cass.) oilseeds

Edible plant glycolipids (GL) are anticipated to play a role in human nutrition. Total glycolipids (TGL) were separated from black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.) and niger (Guizotia abyssinica Cass.) seed oils by silica gel chromatography. Different GL subclasses were then identified and separated using high-performance liquid chromatography with ultraviolet adsorption (HPLC/UV). Separation was accomplished using Zorbax-Sil (5 μm) column with an isocratic elution by mixed solvents of isooctane/2-propanol (1:1, v/v) and detection at 206 nm. Methods are described for the analysis of GL constituents, sugar and sterols (ST), using gas–liquid chromatography equipped with flame ionization detector (GLC/FID). A relatively high level of TGL was found in all studied oilseeds. Six GL subclasses were detected in black cumin seed oil, wherein diglucosyldiacylglycerol (DGD) was the prevalent component, followed by glucocerebroside (CER). Among the TGL from coriander and niger oilseeds, acylated steryl glucoside (ASG), steryl glucoside (SG) and CER were detected. The fatty acid profiles of GL fractions from black cumin and niger seed oils was generally similar, wherein linoleic acid C18:2n-6 was the dominating fatty acid, followed by oleic acid C18:1n-9. Petroselinic acid C18:1n-12 was the fatty acid marker in GL subclasses obtained from coriander seed oil, followed by linoleic acid C18:2n-6. Four ST moieties were identified in black cumin and coriander SG and ASG fractions, while the fractions from niger oilseeds showed only three distinct ST peaks. As component sugar, glucose was the only sugar detected in all samples.

Modulation of proton pumping across proteoliposome membranes reconstituted with tonoplast H(+)-ATPase from cultured rice (Oryza sativa L. var. Boro) cells by acyl steryl glucoside and steryl glucoside.

Tonoplast H(+)-ATPase purified from cultured rice cells (Oryza sativa L. var. Boro) was reconstituted into asolectin liposomes containing steryl glucoside (SG) or acyl steryl glucoside (ASG), and the effects of SG and ASG on proton pumping, ATP-hydrolysis activity and proton permeability of the proteoliposome membranes were investigated. In the proteoliposomes containing 10 mol% SG, proton pumping and ATP-hydrolysis activity were increased to around 140% of those in SG-free proteoliposomes. In the proteoliposomes containing ASG, proton pumping and ATP-hydrolysis activity were decreased to one-tenth of those in ASG-free proteoliposomes at 15 mol% ASG; however, activity increased again slightly in the range between 20 and 40 mol% ASG. The change in proton pumping across the proteoliposome membrane is not due to a change of proteoliposome size nor to the location of the catalytic site of the tonoplast H(+)-ATPase in the proteoliposomes. SG and ASG also reduced the passive proton permeability of the proteoliposomes. These results show that SG and ASG modulate proton pumping across the tonoplast toward stimulation and depression, respectively, and they reduce the passive proton permeability of the tonoplast.

Steryl glucoside is a lipid mediator in stress-responsive signal transduction.

We previously reported that steryl glucoside (SG) is rapidly induced in cells from molds to humans by exposure to environmental stress (Murakami-Murofushi et al. (1997) J. Biol. Chem., 272, 486-489, Kunimoto et al. (2000) Cell Stress & Chaperones, 5, 3-7), and in mold cells SG production is followed by activation of a certain protein kinase and induction of heat shock proteins (HSP) (Maruya et al. (1997) Cell Struct. Funct., 21, 533-538). To determine the biological significance of SG in stress responsive signal transduction, we added SG to the culture of human fibroblasts and examined its effect on HSP induction. We demonstrated a rapid activation of heat shock transcription factor 1 (HSF1) to bind to heat shock element (HSE) and induction of heat shock protein 70 (HSP70) in fibroblast cells by exposure to exogenously added human major SG, cholesteryl glucoside (CG). In addition, enzyme activity to form CG from cholesterol and UDP-glucose was detected in the homogenate of fibroblast cells. These results strongly suggest that CG acts as a mediator in the early stage of stress responsive signal transduction.