Acylated Steryl Glycosides Research Articles

Analysis of lipid composition and characterization of acyl steryl glycosides in rose petals by using nontargeted LC/MS

Analysis of lipid composition and characterization of acyl steryl glycosides in rose petals by using nontargeted LC/MS

Increase in steryl glycoside levels and stimulation of lipid raft formation in azuki bean epicotyls under hypergravity conditions

Sterols are the main components of the plasma membrane and are involved in various plant membrane functions. Azuki bean (Vigna angularis (Wild.) Ohwi et Ohashi) seedlings were cultivated under hypergravity conditions, and changes in the levels and composition of membrane sterols in their epicotyls were analyzed. Under hypergravity conditions at 300 g, the levels of steryl glycosides and acyl steryl glycosides per unit length and per gram fresh weight greatly increased, which accounted for an increase in the total sterol levels. Stigmasterol, β-sitosterol, and campesterol were the most abundant sterols. Hypergravity decreased the proportion of stigmasterol but increased that of β-sitosterol. The fatty chains of acyl steryl glycosides mainly consisted of palmitic acid (C16:0), stearic acid (C18:0), linoleic acid (C18:2), and α-linolenic acid (C18:3), and their proportions were not modified under hypergravity conditions. In addition, the density of membrane microdomains, visualized with anti-Flotillin 1 antibody per unit area, increased by hypergravity, suggesting that lipid raft formation was stimulated. These results support the hypothesis that lipid rafts are involved in plant response and resistance to gravity.

Phytochemical investigation of unripe banana (Musa AAB) cv. Nendran and its novel ‘Banana Grits’

Novel ‘Banana Grits’ (BG) was prepared from the pulp of unripe banana (Musa AAB) cv. Nendran, and their detailed phytochemical investigation is described. The present work serves as a first report of isolation and identification of glycolipids by exhaustive NMR and HR-ESI-MS analysis from Nendran that include glycolipids viz. monogalactosyldiacylglycerols, digalactosyldiacylglycerols, acyl steryl glycosides, glucocerebrosides, and sterylglycoside. Proximate analysis, estimation of total carotenoid content, and the resistant starch content in BG are also reported. In vitro starch digestion pattern indicated that out of 80% of total starch in BG, 21% is slowly digestible starch (SDS) and 42% is resistant starch (RS). The presence of SDS and RS indicates that they may contribute to gut health and glycaemic control.

Industrial applications of selected JFS articles

Industrial applications of selected <i>JFS</i> articles

Insights Into Oxidized Lipid Modification in Barley Roots as an Adaptation Mechanism to Salinity Stress.

Lipidomics is an emerging technology, which aims at the global characterization and quantification of lipids within biological matrices including biofluids, cells, whole organs and tissues. The changes in individual lipid molecular species in stress treated plant species and different cultivars can indicate the functions of genes affecting lipid metabolism or lipid signaling. Mass spectrometry–based lipid profiling has been used to track the changes of lipid levels and related metabolites in response to salinity stress. We have developed a comprehensive lipidomics platform for the identification and direct qualification and/or quantification of individual lipid species, including oxidized lipids, which enables a more systematic investigation of peroxidation of individual lipid species in barley roots under salinity stress. This new lipidomics approach has improved with an advantage of analyzing the composition of acyl chains at the molecular level, which facilitates to profile precisely the 18:3-containing diacyl-glycerophosphates and allowed individual comparison of lipids across varieties. Our findings revealed a general decrease in most of the galactolipids in plastid membranes, and an increase of glycerophospholipids and acylated steryl glycosides, which indicate that plastidial and extraplastidial membranes in barley roots ubiquitously tend to form a hexagonal II (HII) phase under salinity stress. In addition, salt-tolerant and salt-sensitive cultivars showed contrasting changes in the levels of oxidized membrane lipids. These results support the hypothesis that salt-induced oxidative damage to membrane lipids can be used as an indication of salt stress tolerance in barley.

Extending ‘Granny Smith’ apple superficial scald control following long-term ultra-low oxygen controlled atmosphere storage

Superficial scald is an apple postharvest peel browning disorder that contributes to annual losses of susceptible cultivars, principally where crop protectants that control the disorder are restricted. Controlled atmosphere (CA) storage reduces or eliminates superficial scald while apples remain in storage, especially when pO2 is maintained below 1 kPa. However, symptoms often develop during the post-storage cold chain, which can last beyond a month. Diphenylamine (DPA) or 1-methylcyclopropene (1-MCP) treatment can be used to control scald, but application is required within the first weeks of cold air storage following harvest. After this period, treatments are no longer effective due to irreversible physiological changes, hereby referred to as “scald induction”. As a recent report indicates, apple flesh softening can be reduced by 1-MCP treatment following ultra-low oxygen CA (ULO-CA) storage (pO2 ≤ 1.0 kPa). Here, we sought to determine if ULO-CA would also preserve the capacity to control scald with post-CA treatments. To determine this, ‘Granny Smith’ apples were treated with hot water and 1-MCP at harvest or following long-term (>3 months) in-house and commercial ULO-CA for two consecutive years. Different CA storage environments (2.0 kPa and 1.0 kPa O2) and delays in ULO-CA establishment were used in combinations with delayed DPA and 1-MCP treatments to reveal the scald induction timeline and how different storage practices may impact the effectiveness of post-CA scald control measures. Taken together, results indicate that scald induction is effectively delayed during ULO-CA storage and resumes upon return to air storage. 1-MCP and hot water treatments applied after four months of ULO-CA storage were equally effective at controlling scald during subsequent air storage as treatments applied at harvest. However, the efficacy of post-storage treatments relied on the rapid establishment and maintenance of ULO conditions and immediate treatment upon removal from ULO-CA storage. Scald induction resulted from cumulative oxygen exposure occurring prior to, during (pO2) and following CA storage. Conjugated trienol and acylated steryl glycoside levels at the end of ULO-CA storage reflected how much scald induction had occurred and, likewise, the efficacy of post-storage scald mitigation treatments.

Augmentation of systemic resistance and secondary metabolites by chitinolytic microbes in Withania somnifera against Meloidogyne incognita

ABSTRACTAshwagandha (Withania somnifera L. Dunal), a therapeutically imperative herb is known for its useful steroidal lactones (withanolide and withaferin) and acyl steryl glycosides. The plant is a highly susceptible host for the plant parasitic nematode, Meloidogyne incognita. Selected chitinolytic microbes, namely Cellulosimicrobium cellulans MTN13, Flavobacterium johnsoniae MTN 20, Chitiniphilus sp. MTN22 and Streptomyces sp. MTN14, alone and in combination for M. incognita management and enhancement of secondary metabolites in W. somnifera cv. Poshita were evaluated. A significant enhancement in biomass yield (1.9-fold) and disease diminution (2.7-fold) was found in the dual microbial treatment Streptomyces sp. and Chitiniphilus sp. with respect to the untreated inoculated control plants. A significant augmentation (2.7- and 2.0-fold, respectively) in withanolide A and withaferin A was also found in the same treatment. The studies revealed increment of defence variables 1.1- to 1.3-fold and 1.6- to 2.1-fold in single- and dual-microbe treatments, respectively, than the untreated inoculated plants. The stimulation of the phenylpropanoid pathway and phenolics accumulation was the maximum at 5 days post inoculation (dpi), whereas antioxidant enzymes activities were the highest at 7 dpi. The results thus highlight a possible new function of chitinolytic microbes alone and in combinations that can effectively manage M. incognita-induced stress along with enhanced active molecules of W. somnifera.

Gene expression and metabolism preceding soft scald, a chilling injury of 'Honeycrisp' apple fruit.

Background‘Honeycrisp’ is an apple cultivar that is susceptible to soft scald, a chilling injury expressed as necrotic patches on the peel. Improved understanding of metabolism associated with the disorder would improve our understanding of soft scald and contribute to developing more effective management strategies for apple storage. It was expected that specific gene expression and specific metabolite levels in the peel would be linked with soft scald risk at harvest and/or specific time points during cold storage.ResultsFruit from nine ‘Honeycrisp’ apple orchards that would eventually develop different incidences of soft scald between 4 and 8 weeks of cold air storage were used to contrast and determine differential transcriptomic and metabolomic changes during storage. Untargeted metabolic profiling revealed changes in a number of distinct pathways preceding and concurrent with soft scald symptom development, including elevated γ-aminobutryic acid (GABA), 1-hexanol, acylated steryl glycosides, and free p-coumaryl acyl esters. At harvest, levels of sesquiterpenoid and triterpenoid acyl esters were relatively higher in peel of fruit that did not later develop the disorder. RNA-seq driven gene expression profiling highlighted possible involvement of genes and associated metabolic processes with soft scald development. These included elevated expression of genes involved in lipid peroxidation and phenolic metabolism in fruit with soft scald, and isoprenoid/brassinosteroid metabolism in fruit that did not develop soft scald. Expression of other stress-related genes in fruit that developed soft scald included chlorophyll catabolism, cell wall loosening, and lipid transport while superoxide dismutases were up-regulated in fruit that did not develop the disorder.ConclusionsThis study delineates the sequential transcriptomic and metabolomic changes preceding soft scald symptom development. Changes were differential depending on susceptibility of fruit to the disorder and could be attributed to key stress related and mediating pathways.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3019-1) contains supplementary material, which is available to authorized users.

Cholesteryl esters stabilize human CD1c conformations for recognition by self-reactive T cells

Cluster of differentiation 1c (CD1c)-dependent self-reactive T cells are abundant in human blood, but self-antigens presented by CD1c to the T-cell receptors of these cells are poorly understood. Here we present a crystal structure of CD1c determined at 2.4 Å revealing an extended ligand binding potential of the antigen groove and a substantially different conformation compared with known CD1c structures. Computational simulations exploring different occupancy states of the groove reenacted these different CD1c conformations and suggested cholesteryl esters (CE) and acylated steryl glycosides (ASG) as new ligand classes for CD1c. Confirming this, we show that binding of CE and ASG to CD1c enables the binding of human CD1c self-reactive T-cell receptors. Hence, human CD1c adopts different conformations dependent on ligand occupancy of its groove, with CE and ASG stabilizing CD1c conformations that provide a footprint for binding of CD1c self-reactive T-cell receptors.

Characterization of Arabidopsis sterol glycosyltransferase TTG15/UGT80B1 role during freeze and heat stress

Sterol glycosyltransferases regulate the properties of sterols by catalyzing the transfer of carbohydrate molecules to the sterol moiety for the synthesis of steryl glycosides and acyl steryl glycosides. We have analyzed the functional role of TTG15/UGT80B1 gene of Arabidopsis thaliana in freeze/thaw and heat shock stress using T-DNA insertional sgt knockout mutants. Quantitative study of spatial as well as temporal gene expression showed tissue-specific and dynamic expression patterns throughout the growth stages. Comparative responses of Col-0, TTG15/UGT80B1 knockout mutant and p35S:TTG15/UGT80B1 restored lines were analyzed under heat and freeze stress conditions. Heat tolerance was determined by survival of plants at 42°C for 3 h, MDA analysis and chlorophyll fluorescence image (CFI) analysis. Freezing tolerance was determined by survival of the plants at -1°C temperature in non-acclimatized (NA) and cold acclimatized (CA) conditions and also by CFI analysis, which revealed that, p35S:TTG15/UGT80B1 restored plants were more adapted to freeze stress than TTG15/UGT80B1 knockout mutant under CA condition. HPLC analysis of the plants showed reduced sterol glycoside in mutant seedlings as compared to other genotypes. Following CA condition, both β-sitosterol and sitosterol glycoside quantity was more in Col-0 and p35S:TTG15/UGT80B1 restored lines, whereas it was significantly less in TTG15/UGT80B1 knockout mutants. From these results, it may be concluded that due to low content of free sterols and sterol glycosides, the physiology of mutant plants was more affected during both, the chilling and heat stress.

Direct saponification preparation and analysis of free and conjugated phytosterols in sugarcane (Saccharum officinarum L.) by reversed-phase high-performance liquid chromatography

A simple method based on direct saponification followed by RP-HPLC analysis was developed for quantification of free and conjugated sterols in sugarcane. Acid hydrolysis prior to alkaline saponification was used to determined acylated steryl glycoside and steryl glycoside in sugarcane. The applicability and generality of this method were improved with intensive investigation. Compared to traditional solvent extraction method, this method was more time saving and appropriate for characterization of sterol fractions in sugarcane. This method was successfully applied for determination of free and conjugated sterols in different sugarcane samples. The results exhibited that stigmasterol (varied from 883.3±23.5 to 1823.9±24.5μg/g dry weigh) and β-sitosterol (varied from 117.6±19.9 to 801.4±33.5μg/g dry weight) were major phytosterols in the sugarcane sample, and their glycosylated forms accounted for almost 87.0% of stigmasterol and 87.5% of β-sitosterol in sugarcane, respectively. In addition, among other parts of sugarcane, tips contained the greatest amount of phytosterols.

Antioxidative Effects of Germinated Brown Rice-Derived Extracts on H2O2-Induced Oxidative Stress in HepG2 Cells.

The antioxidant properties of germinated brown rice (GBR) are likely mediated by multiple bioactives. To test this hypothesis, HepG2 cells pretreated with GBR extracts, rich in acylated steryl glycoside (ASG), gamma amino butyric acid GABA), phenolics or oryzanol, were incubated with hydrogen peroxide (H2O2) and their hydroxyl radical (OH•) scavenging capacities and thiobarbituric acid-reactive substances (TBARS) generation were evaluated. Results showed that GBR-extracts increased OH• scavenging activities in both cell-free medium and posttreatment culture media, suggesting that the extracts were both direct- and indirect-acting against OH•. The levels of TBARS in the culture medium after treatment were also reduced by all the extracts. In addition, H2O2 produced transcriptional changes in p53, JNK, p38 MAPK, AKT, BAX, and CDK4 that were inclined towards apoptosis, while GBR-extracts showed some transcriptional changes (upregulation of BAX and p53) that suggested an inclination for apoptosis although other changes (upregulation of antioxidant genes, AKT, JNK, and p38 MAPK) suggested that GBR-extracts favored survival of the HepG2 cells. Our findings show that GBR bioactive-rich extracts reduce oxidative stress through improvement in antioxidant capacity, partly mediated through transcriptional regulation of antioxidant and prosurvival genes.

Conjugated and free sterols from black bean (Phaseolus vulgaris L.) seed coats as cholesterol micelle disruptors and their effect on lipid metabolism and cholesterol transport in rat primary hepatocytes

Phytosterols have been widely studied for their cholesterol-lowering effect. Conjugated phytosterol forms have been found more active than free moieties. There are no reports about the sterol profile of black bean seed coats neither its effects on cholesterol metabolism. The aim of this research was to identify and quantify phytosterols from black bean seed coats and to determine their effects on cholesterol micellar solubility and on mRNA and key protein levels involved in lipid/cholesterol metabolism and cholesterol transport in primary rat hepatocytes. Free phytosterols, acylated steryl glycosides, and steryl glycosides were extracted from black bean seed coats. They were identified through HPLC-MS-TOF and quantified through HPLC equipped with UV-visible and evaporative light-scattering detectors. Free and conjugated phytosterols from the coats significantly increased the inhibitory effect of cholesterol micelle formation compared with stigmasterol, which was used as control (P<0.05). In addition, phytosterols of black bean seed coat decreased lipogenesis by the downregulation of lipogenic proteins such as sterol regulatory element-binding protein 1 and fatty acid synthesis (FAS) in primary rat hepatocytes. Regarding β-oxidation, phytosterols upregulated the expression of carnitine palmitoyltransferase I and promoted the β-oxidation of long-chain fatty acids. Phytosterols inhibited cholesterol micellar solubility and reduced the activation of the liver X receptor, decreasing hepatic FAS and promoting hepatic β-oxidation of long-chain fatty acids.

Nutrigenomic effects of germinated brown rice and its bioactives on hepatic gluconeogenic genes in type 2 diabetic rats and HEPG2 cells

Chronic sustained hyperglycemia underlies the symptomatology and complications of type 2 diabetes mellitus, and dietary components contribute to it. Germinated brown rice (GBR) improves glycemic control but the mechanisms involved are still the subject of debate. We now show one mechanism by which GBR lowers blood glucose. Effects of GBR, brown rice, and white rice (WR) on fasting plasma glucose and selected genes were studied in type 2 diabetic rats. GBR reduced plasma glucose and weight more than metformin, while WR worsened glycemia over 4 weeks of intervention. Through nutrigenomic suppression, GBR downregulated gluconeogenic genes (Fbp1 and Pck1) in a manner similar to, but more potently than, metformin, while WR upregulated the same genes. Bioactives (gamma-amino butyric acid, acylated steryl glycoside, oryzanol, and phenolics) were involved in GBR's downregulation of both genes. Plasma glucose, Fbp1 and Pck1 changes significantly affected the weight of rats (p = 0.0001). The fact that GBR downregulates gluconeogenic genes similar to metformin, but produces better glycemic control in type 2 diabetic rats, suggests other mechanisms are involved in GBR's antihyperglycemic properties. GBR as a staple could potentially provide enhanced glycemic control in type 2 diabetes mellitus better than metformin.

The Hypocholesterolemic Effect of Germinated Brown Rice Involves the Upregulation of the Apolipoprotein A1 and Low-Density Lipoprotein Receptor Genes

Germinated brown rice (GBR) is rich in bioactive compounds, which confer GBR with many functional properties. Evidence of its hypocholesterolemic effects is emerging, but the exact mechanisms of action and bioactive compounds involved have not been fully documented. Using type 2 diabetic rats, we studied the effects of white rice, GBR, and brown rice (BR) on lipid profile and on the regulation of selected genes involved in cholesterol metabolism. Our results showed that the upregulation of apolipoprotein A1 and low-density lipoprotein receptor genes was involved in the hypocholesterolemic effects of GBR. Additionally, in vitro studies using HEPG2 cells showed that acylated steryl glycoside, gamma amino butyric acid, and oryzanol and phenolic extracts of GBR contribute to the nutrigenomic regulation of these genes. Transcriptional and nontranscriptional mechanisms are likely involved in the overall hypocholesterolemic effects of GBR suggesting that it may have an impact on the prevention and/or management of hypercholesterolemia due to a wide variety of metabolic perturbations. However, there is need to conduct long-term clinical trials to determine the clinical relevance of the hypocholesterolemic effects of GBR determined through animal studies.

Phytosterol Variability in Almond Germplasm

Phytosterols are important dietary components that contribute to reducing serum cholesterol levels. The objective of this research was to assess genetic diversity for total content and profile of free and esterified phytosterols in a world germplasm collection of almond [Prunus amygdalus Batsch; syn. P. dulcis (Mill.) D.A. Webb]. Steryl glycosides and acylated steryl glycosides were not measured. Fruit from 160 almond accessions were collected in 2009 and 2010. Kernel phytosterol content ranged from 1126 to 2769 mg·kg−1 in 2009 and from 1191 to 2777 mg·kg−1 in 2010. The phytosterol fraction was mainly made up of β-sitosterol (from 59.1% to 84.1% in 2009 and from 55.9% to 84.6% in 2010) and Δ5-avenasterol (from 8.9% to 25.4% in 2009 and from 8.5% to 28.2% in 2010). Significant genotypic effects were observed for kernel phytosterol content and concentration of major phytosterols. Kernel oil content was positively correlated with kernel phytosterol content in both years. The results suggested that almond germplasm contains genetic variability for both phytosterol content and profile that can be used for developing cultivars with increased levels of phytosterols and contrasting phytosterol profiles. Positive correlation between kernel phytosterol content and kernel oil content suggests the feasibility of simultaneous selection for both traits.

Analysis of dietary phytochemicals needs to be applauded: Glycosylated plant sterols

AbstractIn this issue of European Journal of Lipid Science and Technology, Lampi and co‐workers [p. 656–669] report the content of glycosylated plant sterols (steryl glycosides and acylated steryl glycosides) as minor glycolipids found in common edible plants.See accompanying article http://dx.doi.org/10.1002/ejlt.201200033

Steryl glycosides and acylated steryl glycosides in plant foods reflect unique sterol patterns

AbstractGlycosylated plant sterols (steryl glycosides, SG and acylated steryl glycosides, ASG) are minor glycolipids found in a variety of plants at different levels and in different compositions. They have until now been far less studied than other sterol conjugates, though they possess at least the same potential health benefits as free or esterified plant sterols. Additionally, due to the more hydrophilic conjugated part, they may possess further beneficial properties in forming water‐soluble structures. We studied the content and sterol profiles of glycosylated sterols in various plant foods to be able to better understand their levels in human diets, as well as to identify sources with high levels and/or unique sterol profile for possible extraction for ingredients. Glycosylated sterols contributed up to almost 60% of total sterols in e.g. potatoes, indicating that they indeed are an important group of sterols in plants. The ratio of ASG and SG varied from 0.4 to 3.6, indicating significant differences in the proportions of these two conjugates in various plants. Furthermore, extremely large differences were observed in the sterol profiles not only between but also within different plants, which indicates that the sterol profile of the glycosylated sterols does not always reflect the total sterol composition in the same plant tissue.Practical applications: Glycosylated sterols have hydrophilic properties owing to the carbohydrate moiety of the conjugate. As a consequence, they could potentially be introduced to water‐based functional foods (unlike the hydrophobic free sterols and sterol esters in current applications). Various plant materials or side streams of food processes were shown to be good sources of these glycosylated plant sterols, and could be used as sources for extraction of glycosylated sterols for food ingredients. Furthermore, the detailed compositional information reported here will provide a basis to select also the desired sterol composition for the product. Finally, the data presented in this paper is invaluable for estimating the contribution of different foods as sources of glycosylated sterols in the diet.See commentary by Jiménez‐Escrig [p. 615–616]

Ripening, storage temperature, ethylene action, and oxidative stress alter apple peel phytosterol metabolism

The chilling conditions of apple cold storage can provoke an economically significant necrotic peel disorder called superficial scald (scald) in susceptible cultivars. Disorder development can be reduced by inhibiting ethylene action or oxidative stress as well as intermittent warming. It was previously demonstrated that scald is preceded by a metabolomic shift that results in altered levels of various classes of triterpenoids, including metabolites with mass spectral features similar to β-sitosterol. In this study, a key class of phytosterol metabolites was identified. Changes in peel tissue levels of conjugates of β-sitosterol and campesterol, including acylated steryl glycosides (ASG), steryl glycosides (SG) and steryl esters (SE), as well as free sterols (FS), were determined during the period of scald development. Responses to pre-storage treatment with the ethylene action inhibitor, 1-methylcyclopropene, or an antioxidant (diphenylamine), rapid temperature elevation, and cold acclimation using intermittent warming treatments were evaluated. Diphenylamine, 1-MCP, and intermittent warming all reduced or prevented scald development. ASG levels increased and SE levels decreased in untreated control fruit during storage. Removing fruit from cold storage to ambient temperature induced rapid shifts in ASG and SE fatty acyl moieties from unsaturated to saturated. FS and SG levels remained relatively stable during storage but SG levels increased following a temperature increase after storage. ASG, SE, and SG levels did not increase during 6months cold storage in fruit subjected to intermittent warming treatment. Overall, the results show that apple peel phytosteryl conjugate metabolism is influenced by storage duration, oxidative stress, ethylene action/ripening, and storage temperature.

Glycosidic Bond Cleavage is Not Required for Phytosteryl Glycoside‐Induced Reduction of Cholesterol Absorption in Mice

Phytosteryl glycosides occur in natural foods but little is known about their metabolism and bioactivity. Purified acylated steryl glycosides (ASG) were compared with phytosteryl esters (PSE) in mice. Animals on a phytosterol-free diet received ASG or PSE by gavage in purified soybean oil along with tracers cholesterol-d(7) and sitostanol-d(4). In a three-day fecal recovery study, ASG reduced cholesterol absorption efficiency by 45±6% compared with 40±6% observed with PSE. Four hours after gavage, plasma and liver cholesterol-d(7) levels were reduced 86% or more when ASG was present. Liver total phytosterols were unchanged after ASG administration but were significantly increased after PSE. After ASG treatment both ASG and deacylated steryl glycosides (SG) were found in the gut mucosa and lumen. ASG was quantitatively recovered from stool samples as SG. These results demonstrate that ASG reduces cholesterol absorption in mice as efficiently as PSE while having little systemic absorption itself. Cleavage of the glycosidic linkage is not required for biological activity of ASG. Phytosteryl glycosides should be included in measurements of bioactive phytosterols.