Molecular structure and baking performance of individual glycolipid classes from lecithins

Extraction Optimization, UHPLC-Triple-TOF-MS/MS Analysis and Antioxidant Activity of Ceramides from Sea Red Rice Bran

As a new type of salt-tolerant rice, sea red rice contains more minerals, proteins, and lipid compounds, and, in particular, its by-product rice bran may be used to replace other commercial rice brans as the main source of ceramides (Cers). However, the extraction rate of Cers is generally low, and it is crucial to seek an efficient extraction method. This study optimized the ultrasonic-assisted extraction of Cers from sea red rice bran using response surface methodology (RSM) and obtained a Cers yield of 12.54% under optimal conditions involving an extraction temperature of 46 °C, an extraction time of 46 min, and a material-to-liquid ratio of 5 g/mL. The Cers content in sea red rice bran was preliminarily analyzed using thin-layer chromatography, and the Cers content was determined via UHPLC-Triple-TOF-MS/MS after purification and separation using silica column chromatography. Forty-six different types of Cers were identified in sea red rice bran, of which Cer 18:0/24:0 (2OH), Cer 18:0/26:0, Cer 18:0/26:0 (2OH), and Cer 18:0/24:0 accounted for 23.66%, 17.54%, 14.91%, and 11.96%. Most of the Cers structures were mainly composed of sphingadienine. A biological activity assay indicated that Cers extracted from sea red rice bran had significant antioxidant and anti-aging properties. These findings indicate that the extracted Cers show great potential for applications in the cosmetic and pharmaceutical industries.

Investigation on the surface-active and antimicrobial properties of a natural glycolipid product

Glycolipids are a group of sugar-containing lipids with versatile functions. In this study, a natural glycolipid product was obtained from soy lecithin, and its emulsifying, oil-gelling, antibacterial and antiviral properties were investigated. A silica-based extraction method on a preparative scale was used to recover the glycolipid product (GLP) from soy lecithin. The GLP consisted of three different glycolipid classes: acylated sterol glucoside (64.16%), sterol glucoside (25.57%) and cerebroside (6.71%). As an emulsifier, the GLP was able to form a stable water-in-oil emulsion. The GLP exhibited a good oil-gelling property, capable of gelling rapeseed oil at a concentration of 6%. For the investigated microorganisms (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus), the GLP did not show any antibacterial effects. The GLP exerted antiviral activity against lentivirus, but not adenovirus. The results of this study help in enriching the knowledge on the properties of naturally occurring glycolipids, which may find potential applications in the food, pharmaceutical and related industries.

Oil-gelling properties of soy lecithin fractions

Lecithin is a mixture of amphiphilic lipids with health benefits. In this study, four different fractions (ethanol soluble, ethanol insoluble, phospholipid and glycolipid fractions) from soy lecithin were obtained and evaluated as oleogelators. As with the parent lecithin, the ethanol insoluble fraction (EIF) was unable to function as an oleogelator. The ethanol soluble fraction (ESF) and phospholipid fraction (PLF) formed oleogels at 30% (wt%), while the glycolipid fraction (GLF) formed oleogels at 15%. ESF resulted in an oleogel with a similar appearance and microstructure, but a harder and less cohesive texture than the PLF-supported oleogel. The oleogels formed with GLF were different from those formed with ESF and PLF in appearance and microstructure. GLF at 20% formed an oleogel with better texture characteristics (in the light of hardness) and oil-holding capacity than those formed with 30% of ESF and PLF. This is the first study to investigate the oil-gelling properties of fractions from soy lecithin. Our results show that the naturally occurring glycolipids from soy lecithin exhibit great potential as oleogelators.

Inhibition and interactions of alpha-amylase by daucosterol from the peel of Chinese water chestnut (Eleocharis dulcis)

The alpha-amylase inhibitory effect of daucosterol purified from the peel of Chinese water chestnut (CWC), a common Chinese vegetable, was assessed. The alpha-amylase inhibitory properties were elucidated by enzyme inhibition, fluorescence quenching and molecular docking experiments. It was found that three saponins from CWC peel exhibited potent inhibitory activity on alpha-amylase and daucosterol was found to be the main inhibitory factor against alpha-amylase with a mixed-type mode. Strong fluorescence quenching of alpha-amylase was observed under static fluorescence quenching with hydrophobic interactions with daucosterol. Molecular docking revealed that the conformation of daucosterol in the high-affinity sites I and II of alpha-amylase was optimum, and hydrophobic interactions were produced by daucosterol aglycone, and hydrogen bonding by the β-D-glucopyranosyl residue. Ingested daucosterol suppressed the elevation of blood glucose levels through inhibition of alpha-amylase in the small intestine in starch-loaded mice. This study provides data supporting the potential benefit of daucosterol from CWC peel in the treatment of diabetes.

Galactosyldiacylglycerols: From a Photosynthesis-Associated Apparatus to Structure-Defined In Vitro Assembling

Being ubiquitously present in plants, microalgae, and cyanobacteria and as the major constituents of thylakoid membranes, monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) make up approximately 52 and 26%, respectively, of chloroplast lipids. Thylakoid membranes harbor the photosynthetic complexes and numerous essential biochemical pathways where MGDG and DGDG play a central role in facilitating photosynthesis light reaction, maintaining chloroplast morphology, and responding to abiotic stresses. Furthermore, these galactolipids are also bioactive compounds with antitumor, antimicrobial, antiviral, immunosuppressive, and anti-inflammatory activities and important nutritional value. These characteristics are strictly dependent upon their fatty acyl chain length, olefinic nature, and stereoconfiguration. However, their application potentials are practically untapped, largely as a result of the fact that their availability in large quantity and high purity (structured galactolipids) is challenging. In addition to laborious extraction from natural sources, in vitro assembling of these molecules could be a promising alternative. Thus, this review updates the latest advances in elucidating biosynthesis paths of MGDG and DGDG and related enzyme systems, which present invaluable inspiration to design approaches for a retrosynthesis of galactolipids. More critically, this work summarizes recent developments in the biological and enzymatic syntheses of galactolipids, especially the strategic scenarios for the construction of in vitro enzymatic and/or chemoenzymatic synthesis routes. Protein engineering of enzymes involved in the synthesis of MGDG and DGDG to improve their properties is highlighted, and the applications of galactolipids in foods and medicine are also discussed.

Inhibitory properties of saponin from Eleocharis dulcis peel against α-glucosidase

The inhibitory properties towards α-glucosidase in vitro and elevation of postprandial glycemia in mice by the saponin constituent from Eleocharis dulcis peel were evaluated for the first time. Three saponins were isolated by silica gel and HPLC, identified as stigmasterol glucoside, campesterol glucoside and daucosterol by NMR spectroscopy. Daucosterol presented the highest content and showed the strongest α-glucosidase inhibitory activity with competitive inhibition. Static fluorescence quenching of α-glucosidase was caused by the formation of the daucosterol–α-glucosidase complex, which was mainly derived from hydrogen bonds and van der Waals forces. Daucosterol formed 7 hydrogen bonds with 4 residues of the active site and produced hydrophobic interactions with 3 residues located at the exterior part of the binding pocket. The maltose-loading test results showed that daucosterol inhibited elevation of postprandial glycemia in ddY mice. This suggests that daucosterol from Eleocharis dulcis peel can potentially be used as a food supplement for anti-hyperglycemia.

Daucosterol from Eleocharis dulcis peel exhibits potent inhibitory activity against α-glucosidase.

Optimization of the silica-gel adsorption technique for the extraction of phytosterol glycosides from soybean lecithin powder using response surface methodology and artificial neural network models

Phytosterol glycosides (PGs), comprising both acylated steryl glycosides (ASGs) and steryl glycosides (SGs), are active ingredients with benefits for human use. Here, we aimed to optimize the silica-gel adsorption technique for the extraction of PGs from soybean lecithin powder, which contains 5 to 10% of these glycolipids. Both response surface methodology (RSM) and artificial neural networks (ANNs) were applied to optimize the PG extraction parameters (X1 = silica-gel dosage, X2 = adsorption temperature, and X3 = lecithin concentration) for high-purity phospholipid and PG production, and their prediction and optimization accuracies were compared. Although both models fitted well with the experimental data, the ANN model demonstrated better accuracy for predicting and optimizing the conditions using four interrelated dependent variables (Y1 = phospholipid yield, Y2 = ASG recovery, Y3 = SG recovery, and Y4 = PG purity) and had a higher coefficient of determination and lower root mean square error and absolute average deviation. After digitally setting the percentages of the four dependent variables for phospholipid and PG production, the ANN-optimized phospholipid product (Y1 = 88.07%, Y2 = 98.89%, Y3 = 100%, and Y4 = 49.03%) was acquired at X1 = 3.54 g/g, X2 = 26 °C, and X3 = 43 mg/mL, whereas the PG product (Y1 = 83.83%, Y2 = 97.64%, Y3 = 100%, and Y4 = 59.21%) was obtained at X1 = 2.00 g/g, X2 = 28.38 °C, and X3 = 41 mg/mL. In conclusion, the ANN method was better than RSM for the optimization of the silica-gel adsorption technique for PG extraction from soybean lecithin powder. PRACTICAL APPLICATION: This paper lays a theoretical foundation for the optimization of the industrial production of phytosterol glycosides and the comprehensive utilization of lecithin resources.

Genetic variation in wheat grain quality is associated with differences in the galactolipid content of flour and the gas bubble properties of dough liquor

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A QTL for breadmaking quality is associated with more galactolipids in flours.

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Dough liquor fractions from the same flours also have higher galactolipid contents.

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The dough liquor fractions with higher galactolipids exhibit increased elasticity.

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These increases indicate a mechanism of action for the quality QTL.

Lipids affect the quality of wheat flour for breadmaking. One possible mechanism is stabilization of the gas cells which are formed during dough mixing and expanded during fermentation, leading to a greater loaf volume and evenness of texture. We therefore compared the lipidomic profiles of flour and dough liquor fractions (which contain surface-active components present at the gas bubble interface) from two sets of wheat lines differing in allelic variation at a QTL for loaf volume. Analyses of fractions from three field trials showed consistent increases in the contents of galactolipids (monogalactosyl diglyceride and digalactosyl diglyceride) in flour and dough liquor of the lines with the increasing (good quality) allele. Biophysical analysis showed that this was associated with greater elasticity of the dough liquor fraction. This is consistent with published studies reporting a relationship between galactolipids and breadmaking quality and suggests a mechanism of action for the QTL.

Evaluation system construction and factor impact analysis of silica-gel adsorption to extract phytosterol glycosides from soybean lecithin powder

BACKGROUND

Soybean lecithin powders are good sources of phytosterol glucosides (PGs) containing acyl-sterylglycosides (ASGs) and sterylglucosides (SGs), but PG extraction from soybean lecithin powder is difficult due to the solubilizing property of phospolipids. To comprehensively utilize soybean lecithin resources, an evaluation system construction and factor impact analysis of PG extraction by silica-gel adsorption was investigated in this article.

RESULTS

With high-performance liquid chromatography (HPLC) as the main experimental analysis method, software such as SIMICA and SPSS were applied to construct an evaluation system of PG extraction. Different from scores plot in SIMICA for distinguishing samples in chloroform from others, the loading plot and binary variant correlation analysis of all indicators in PG extraction were brought to confirm four evaluation indicators containing PG purity, ASG recovery, SG recovery and phospholipid recovery. In the factor impact analysis, four times elution from silica-gel sediment was enough to achieve a PG product with least reagent waste, while SPW in petroleum ether at 50 mg mL-1 with 1:3 silica-gel dosage (lecithin/silica-gel, w/w) was then determined as the optimum of single factors.

CONCLUSION

All studies in this article were of great significance, as they laid foundations for research of PG extraction procedure, as well as PG industrial production, facilitating the comprehensive utilization of lecithin resources. © 2019 Society of Chemical Industry.

Molecular species determination of oligosaccharides and glycoconjugates in soybean lecithin powders

BACKGROUND

Oligosaccharides and glycoconjugates in soybean lecithin powder are very important for the properties and functions of the materials that contain it. Oligosaccharides can trigger infusion reactions and color changes in soybean lecithin during medical injections; glycoconjugates in the form of glycolipids can also change the physical behavior of lecithin. The molecular components of oligosaccharides and glycoconjugates in soybean lecithin powder were studied in this paper.

RESULTS

Three oligosaccharides and 21 glycoconjugates were verified in soybean lecithin powders for the first time. Raffinose, sucrose, and stachyose were detected as the principal components of oligosaccharides by high-performance liquid chromatography (HPLC). Twenty-one glycoconjugates, including four steryl glucosides (SG), 13 acyl steryl glucosides (ASG), one digalactosyl diacylglycerol (DGDG), one monogalactosyl diacylglyceride (MGDG), one glucocerebroside (Glucer), and one glucose palmitate were analyzed by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and RP-UPLC-Q-TOF-ESI-MS. Glycoconjugates were constructed in soybean lecithin powder after separation by column chromatography, thin-layer chromatography, and color reactions.

CONCLUSION

The determination of molecular species of oligosaccharides and glycoconjugates provided a new direction for the exploration of novel functions and uses of soybean lecithin powder. © 2018 Society of Chemical Industry.

Lipases as Processing Aids in the Separation of Wheat Flour into Gluten and Starch: Impact on the Lipid Population, Gluten Agglomeration, and Yield

Three lipases with different hydrolysis specificities were tested in a laboratory-scale dough-batter wheat flour separation process in two concentrations. Lipolase specifically hydrolyzed nonpolar flour lipids. At the highest concentration tested, it significantly improved gluten agglomeration and yield, also when combined with a xylanase with hydrolysis specificity toward water-extractable arabinoxylan. We hypothesize that its action is due to the release of adequate levels of free fatty acids, which, because at least a part of them is dissociated, act as anionic surfactants. Lipolase at the lowest concentration, Lecitase Ultra, hydrolyzing both nonpolar and polar lipids, and YieldMAX, which specifically hydrolyzed phospholipids, had no or a negative impact on gluten agglomeration and yield. In conclusion, this study demonstrated that lipases with hydrolysis specificity toward nonpolar lipids can be used as processing aids in wheat flour separation in the absence or presence of added xylanases to maximize gluten agglomeration and yield.

Synthesis and in vitro antioxidant and antimicrobial studies of novel structured phosphatidylcholines with phenolic acids

Novel phenoylated phosphatidylcholines were synthesized from 1,2-dipalmitoyl phosphatidylcholine/egg 1,2-diacyl phosphatidylcholine and phenolic acids such as ferulic, sinapic, vanillic and syringic acids. The structures of phenoylated phosphatidylcholines were confirmed by spectral analysis. 2-acyl-1-lyso phosphatidylcholine was synthesized from phosphatidylcholine via regioselective enzymatic hydrolysis and was reacted with hydroxyl protected phenolic acids to produce corresponding phenoylated phosphatidylcholines in 48-56% yields. Deprotection of protected phenoylated phosphatidylcholines resulted in phenoylated phosphatidylcholines in 87-94% yields. The prepared compounds were evaluated for their preliminary in vitro antimicrobial and antioxidant activities. Among the active derivatives, compound 1-(4-hydroxy-3,5-dimethoxy) cinnamoyl-2-acyl-sn-glycero-3-phosphocholine exhibited excellent antioxidant activity with EC₅₀ value of 16.43μg/mL. Compounds 1-(4-hydroxy-3-methoxy) cinnamoyl-2-acyl-sn-glycero-3-phosphocholine and 1-(4-hydroxy-3,5-dimethoxy) cinnamoyl-2-palmitoyl-sn-glycero-3-phosphocholine exhibited good antioxidant activity with EC₅₀ values of 36.05 and 33.35μg/mL respectively. Compound 1-(4-hydroxy-3-methoxy) cinnamoyl-2-palmitoyl-sn-glycero-3-phosphocholine exhibited good antibacterial activity against Klebsiella planticola with MIC of 15.6μg/mL and compound 1-(4-hydroxy-3-methoxy) benzoyl-2-acyl-sn-glycero-3-phosphocholine exhibited good antifungal activity against Candida albicans with MIC of 15.6μg/mL.

Lipases in wheat breadmaking: analysis and functional effects of lipid reaction products

The baking activity of two different lipases was evaluated by a microbaking test on a 10 g flour basis, and the altered lipid composition of lipase-treated wheat lipids was quantitated. To identify and quantitate the various lipid classes, pure glycolipids and phospholipids were isolated from a wheat flour lipid extract by a silica gel batch procedure and silica gel column chromatography. These reference compounds were used to establish a high-performance liquid chromatographic method with evaporative light scattering detection, which was able to separate all of the wheat lipid classes and lipase reaction products. Wheat lipids, dough lipids, and dough lipids after lipase addition were quantitated using cholesterol as an internal standard. Especially digalactosyl diglycerides (-0.9 mmol/kg flour), monogalactosyl diglycerides (-0.4 mmol/kg), and N-acyl-phosphatidyl ethanolamine (-0.3 mmol/kg) were hydrolyzed, and a concomitant formation of digalactosyl monoglycerides (+0.6 mmol/kg), monogalactosyl monoglycerides (+0.6 mmol/kg), and N-acyl-lysophosphatidyl ethanolamine (+0.5 mmol/kg) was found. The lipase-induced changes of the lipid fraction caused increases in bread volume of 56-58%, depending on the type and concentration of the added lipase. The current results confirm the important relationship between the lipid fraction composition and the baking performance of flour.

A simple method for positional analysis of phosphatidylcholine

Simple and fast method of positional analysis of fatty acid composition of phosphatidylcholine (PC) from egg-yolk and soy has been elaborated. The key step of the procedure was complete ethanolysis of PC catalyzed by sn-1,3 specific lipase from Mucor miehei (Lipozyme). 2-Acyl-lysophosphatidylcholine (2-acyl LPC), fatty acids ethyl esters (FAEEs) and free fatty acids (FAs) were formed in this process. No acyl migration was observed during the reaction. The products were entirely separated from the products mixture by simple extraction in water:hexane (2:3 v/v) system. The hexane fraction containing free FAs and FAEEs was treated with BF(3)/Et(2)O in ethanol to obtain only FAEEs. The analysis of FAEEs by GC gave the composition of the FAs in the sn-1 position of the PC. 2-Acyl LPC from water fraction after precipitation in cold (-20°C) acetone was converted into FAEEs and analyzed by gas chromatography (GC) to determine FAs composition in the sn-2 position of the PC.

Effects of alkylresorcinols on volume and structure of yeast-leavened bread

BACKGROUND

Alkylresorcinols (AR) are amphiphilic phenolic compounds found in high amounts in wheat, durum wheat and rye, with different homologue composition for each cereal. The effect of different amounts of added AR from these cereals on bread volume, height, porosity and microstructure was studied. Breads with added rye bran (with high levels of AR) or acetone-extracted rye bran (with low levels of AR) were also baked, as well as breads with finely milled forms of each of these brans.

RESULTS

Breads with high amounts of added AR, irrespective of AR homologue composition, had a lower volume, a more compact structure and an adverse microstructure compared with breads with no or low levels of added AR. AR were also shown to inhibit the activity of baker's yeast. There was no difference in bread volume and porosity between bread baked with rye bran and acetone-extracted rye bran or with brans of different particle size.

CONCLUSION

Irrespective of homologue composition, AR had a negative effect on wheat bread properties when added in high amounts as purified extracts from wheat, durum wheat and rye. Natural levels of AR in rye bran, however, did not affect the volume and porosity of yeast-leavened wheat breads.