Sugar Headgroup Research Articles

Sugar-Based Surfactants: Effects of Structural Features on the Physicochemical Properties of Sugar Esters and Their Comparison to Commercial Octyl Glycosides.

Two series of sugar esters with alkyl chain lengths varying from 5 to 12 carbon atoms, and with a head group consisting of glucose or galactose moieties, were synthesized. Equilibrium surface tension isotherms were measured, yielding critical micellar concentration (CMC) surface tensions at CMC (γcmc) and minimum areas at the air-water interface (Amin). In addition, Krafft temperatures (Tks) were measured to characterize the ability of molecules to dissolve in water, which is essential in numerous applications. As a comparison to widely used commercial sugar-based surfactants, those measurements were also carried out for four octyl d-glycosides. Impacts of the linkages between polar and lipophilic moieties, alkyl chain lengths, and the nature of the sugar head group on the measured properties were highlighted. Higher Tk and, thus, lower dissolution ability, were found for methyl 6-O-acyl-d-glucopyranosides. CMC and γcmc decreased with the alkyl chain lengths in both cases, but Amin did not appear to be influenced. Both γcmc and Amin appeared independent of the ester group orientation. Notably, alkyl (methyl α-d-glucopyranosid)uronates were found to result in noticeably lower CMC, possibly due to a closer distance between the carbonyl function and the head group.

Phase behavior of lyotropic alkyl thioglycolipid surfactants: Effects of sugar headgroup and alkyl tail length

AbstractThe lyotropic properties of alkyl thioglycosides with varying sugar headgroup (lactose, cellobiose, maltose, galactose, or glucose) and alkyl chain length (octyl, decyl, or dodecyl chains) are investigated by surface tensiometry, visual observation, and fluorescence spectroscopy. The results substantiate that the glycosidic S‐linkage confers considerably different solution aggregation behavior on these surfactants relative to their O‐linked counterparts, where the properties of the latter are known. The materials properties of the aggregated structures from the alkyl thioglycosides vary considerably. Micelles are formed by octyl thiocellobioside and all alkyl thiomaltosides. Turbid aggregate solutions are formed by the alkyl thioglucosides and octyl thiogalactoside, whereas the longer chain alkyl thiogalactosides are minimally soluble. Fluorescence spectroscopy of these systems confirms their aggregation in lamellar‐like structures. The alkyl thiocellobiosides and alkyl thiolactosides form hydrogels from these low‐molecular weight materials at concentrations almost an order of magnitude lower than gels using other low‐molecular weight materials. Here, hydrogels form at concentrations <0.3 wt% with some forming hydrogels at concentrations as low as 0.03 wt% from alkyl thiocellobiosides and thiolactosides, with hydrogel properties differing significantly with this slight change in the sugar headgroup. Alkyl thiocellobiosides form a nanofiber network and alkyl thiolactosides form globular hydrogels. Overall, these results clearly document materials properties that can readily be controlled and designed depending on molecular structure.

Aqueous self-assembly of a wide range of sophorolipid and glucolipid microbial bioamphiphiles (biosurfactants): Considerations on the structure-properties relationship

Sophorolipids are well-known scaled-up microbial glycolipid biosurfactants with a strong potential for commercialization due to their biological origin and mildness in contact with the skin and the environment compared to classical surfactants. However, their association properties in water are still poorly understood, they cannot be predicted and their behavior in solution challenges half a century of knowledge generated in the field of surfactant science. By studying forty different types of sophorolipids and sophorosides in water using small angle X-ray scattering, and optical and cryogenic transmission electron microscopy, this work provides better understanding of their structure-property relationship and identifies which chemical groups in their molecular structure have a critical influence on their self-assembly properties. Structural features like the number of sugar headgroups, acetylation, end-chain functional group, (un)saturation, lactonization and length of chain are adjusted to both rationalize their impact and understand their effect on self-assembly. The number of sugar groups, pH, (un)saturation and lactonization were found to have a critical impact on sophorolipid self-assembly. The chemical nature of the end-chain functional group and chain length were also found to have a possibly critical impact, depending on the specific type of chemical function (COOH and long chains are critical). Mono- and diacetylation, as well as the position of sophorose in the fatty acid (ω, ω-1), are not critical, i.e., they did not significantly influence sophorolipid self-assembly.

SYNTHESIS, PHYSICAL AND BIOLOGICAL STUDY OF SOME NEW GLUCOSE BASED GLYCOLIPIDS

New glycolipids on glucose have been synthesized according to well-known sequencing reactions. The series of reactions started with peracetylation of glucose to produce mainly β-anomer, which is reacted directly with long chain alcohol in presence of Lewis acid as catalyst. The deacetylation of sugar head group was achieved under basic conditions. The resulting glycolipids have been modified in more three reaction steps to get the final products. The modified glycolipids have been studied under POM and DSC to confirm the phase behavior of these type of amphiphilic molecules, which is indicate that most of them form lamellar phase. These materials were also studied against two types of cancer cells to confirm their ability to interfere the bi-layer membrane of the living cell.

Microbial Surfactants: Bright Prospects for Innovation, New Product Categories, and Commercialization

Microbial Surfactants: Bright Prospects for Innovation, New Product Categories, and Commercialization

Emulsifying properties of sugar-based surfactants prepared by chemoenzymatic synthesis

Sugar Fatty Acid Esters (SFAEs) are a class of non-ionic surfactants that can be synthesized from inexpensive natural resources. Depending on carbon chain length and nature of the sugar head group, SFAEs cover a wide range of hydrophilic–lipophilic balance (HLB) values, which result in tunable tenside properties and in turn relevant for a wide variety of industrial applications. Three sugar-based surfactants (6-O-lauroyl-, 6-O-palmitoyl- and 6-O-stearoyl-1-O-butyl glucopyranosides) have been prepared by a lipase-catalyzed esterification of isomeric mixture of n-butyl glucosides. Specifically, their interfacial features together with W/O emulsifying properties and stability over time have been finely evaluated (interfacial tension (IFT) values, W/O emulsion turbidity and water droplet size distribution), resulting 6-O-palmitoyl- and 6-O-stearoyl-1-O-butyl glucopyranosides as the most efficient ones.

Ball milled glyco-graphene oxide conjugates markedly disrupted Pseudomonas aeruginosa biofilms

The engineering of the surface of nanomaterials with bioactive molecules allows controlling their biological identity thus accessing functional materials with tuned physicochemical and biological profiles suited for specific applications. Then, the manufacturing process, by which the nanomaterial surface is grafted, has a significant impact on their development and innovation. In this regard, we report herein the grafting of sugar headgroups on a graphene oxide (GO) surface by exploiting a green manufacturing process that relies on the use of vibrational ball mills, a grinding apparatus in which the energy is transferred to the reacting species through collision with agate spheres inside a closed and vibrating vessel. The chemical composition and the morphology of the resulting glyco-graphene oxide conjugates (glyco-GO) are assessed by the combination of a series of complementary advanced techniques (i.e. UV-vis and Raman spectroscopy, transmission electron microscopy, and Magic Angle Spinning (MAS) solid-state NMR (ssNMR) providing in-depth insights into the chemical reactivity of GO in a mechanochemical route. The conjugation of monosaccharide residues on the GO surface significantly improves the antimicrobial activity of pristine GO against P. aeruginosa. Indeed, glyco-GO conjugates, according to the monosaccharide derivatives installed into the GO surface, affect the ability of sessile cells to adhere to a polystyrene surface in a colony forming assay. Scanning electron microscopy images clearly show that glyco-GO conjugates significantly disrupt an already established P. aeruginosa biofilm.

Biosurfactants - Nature's Solution for Today's Cleaning Challenges.

Biosurfactants are surface-active molecules, developed by nature through evolution and naturally produced by different microorganisms. The most prominent examples are rhamnolipids and sophorolipids, molecules which contain hydrophilic sugar head groups and hydrophobic alkyl residues leading to an amphiphilic behavior with unique properties. Recent developments in the field of biotechnology enable the large-scale production of these biological molecules. The raw material basis is 100% renewable since sugars and oils are used as major raw materials. Additionally, biosurfactants are fully biodegradable, which allows the path back into the natural cycles. In comparison to established standard surfactants like SLES/SLS (sodium laureth (ether) sulfates) or betaines, rhamnolipids are much milder and, at the same time, show similar or even better performance in household or personal care applications. Foam behavior, solubilization and cleaning effectiveness are examples where these natural substances give excellent results compared to the synthetic benchmarks. The commercialization of biosurfactants at industrial scale now offers alternatives to consumers seeking sustainable solutions, without compromising performance. Biosurfactants combine both and set a new standard for surfactant applications.

Molecular dynamics simulations support the hypothesis that the brGDGT paleothermometer is based on homeoviscous adaptation

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids that are ubiquitous in the environment. Although the exact source organism is unknown, the distribution of brGDGTs in mineral soils, peats, and lake sediments is correlated with temperature through a decrease in the degree of methylation with increasing temperature. This empirical observation forms the basis of the brGDGT paleothermometer, one of the most important and widely used organic proxies to reconstruct terrestrial temperatures in the past. However, a mechanistic understanding to underpin this empirical correlation between the degree of methylation of brGDGT lipids and temperature is lacking, hindering a holistic understanding of the brGDGT paleothermometer as well as the membrane dynamics of their bacterial producers. To address this, here we present the first molecular dynamics simulations of membranes consisting of brGDGTs. Using intact polar lipid (IPL) brGDGTs with two sugar headgroups, our simulations demonstrate that increasing the degree of methylation modulates membrane order and packing, rendering the membrane less rigid and more fluid. These results indicate that the empirically observed correlation between the degree of methylation and temperature allows brGDGT-producing bacteria to maintain adequate membrane fluidity. Our simulations provide the first molecular simulation data to support the hypothesis that the brGDGT paleothermometer is based on homeoviscous adaptation.

Recent Development in the Design of Neoglycoliposomes Bearing Arborescent Architectures

This brief review highlights systematic progress in the design of synthetic glycolipid (neoglycolipids) analogs evolving from the conventional architectures of natural glycosphingolipids and gangliosides. Given that naturally occurring glycolipids are composed of only one hydrophilic sugar head-group and two hydrophobic lipid tails embedded in the lipid bilayers of the cell membranes, they usually require extraneous lipids (phosphatidylcholine, cholesterol) to confer their stability. In order to obviate the necessity for these additional stabilizing ingredients, recent investigations have merged dendrimer chemistry with that of neoglycolipid syntheses. This singular approach has provided novel glycoarchitectures allowing reconsidering the necessity for the traditional one to two hydrophilic/hydrophobic ratio. An emphasis has been provided in the recent design of modular arborescent neoglycolipid syntheses coined glycodendrimersomes.

Structural Analysis of Glycosylglycerolipids Using NMR Spectroscopy.

Glycosylglycerolipids are essential components of plant and bacterial membranes. These lipids exert central roles in physiological processes such as photosynthesis in plants or to maintain membrane stability in bacteria. They are composed of a glycerol backbone esterified with two fatty acids at the sn-1 and sn-2 positions, and carbohydrate moieties connected via a glycosidic bond at the sn-3 position. Nuclear magnetic resonance (NMR) spectroscopy is a state-of-the-art technique to determine the nature of the bound carbohydrates as well as their anomeric configurations. Here we describe the analysis of intact glycosylglycerolipids by NMR spectroscopy to determine structural details of their sugar head groups without the need of chemical derivatization.

Glycolipids: Lipids with a Carbohydrate Attached Glycosidic Bond

Glycolipids are amphiphilic components of cell films, composed of a hydrophilic polar sugar head group and a hydrophobic a polar lipid moiety securing the atom within the layer. The sugar portion may change from little saccharide units to exceptionally expansive polysaccharide chains. Agreeing to their point by point chemical structure, in specific of the sugar portion, these compounds may satisfy a assortment of natural capacities imperative for numerous forms in life. To these functions have a place forms of acknowledgment, attachment and cell flagging as well as impact on film parameters such as smoothness and space arrangement . specific mammalian glycolipids may serve as transmitter and capacity component of data, and others from bacterial root have a place to the most grounded activators of the human resistant framework.

X‐Shaped Sugar‐Derived Emulsifiers From ‘Click Chemistry’ ‐ A New Gemini Surfactant Type for Oil‐in‐Water Systems

AbstractThree sugar‐based surfactants containing a double hydrophobic chain and two side‐by‐side arranged sugar head groups were synthesized by a click‐chemistry approach and investigated on assembly and surface active behavior. The surfactants exhibited higher packing parameters and lowered the surface tension more effectively than previously investigated Y‐shaped surfactants. However, although the surface tension was lower and found in the range of 32–36 mNm−1, the surfactants were less effective emulsifiers than the Y‐shaped surfactants, indicating that the shape of a surfactant is affecting its emulsifying abilities more than its ability to lower the surface tension. The surfactant exhibited good oil‐in‐water emulsion stabilities, requiring five days for the separation of an emulsion in the absence of a polymeric stabilizer. Surfactant 14 show a fine crystal needle is a formation in contact with water and 1‐undecanol, based on the texture the latter was identified as an inverted hexagonal phase.

Multi-sulfonated ligands on gold nanoparticles as virucidal antiviral for Dengue virus

Dengue virus (DENV) causes 390 million infections per year. Infections can be asymptomatic or range from mild fever to severe haemorrhagic fever and shock syndrome. Currently, no effective antivirals or safe universal vaccine is available. In the present work we tested different gold nanoparticles (AuNP) coated with ligands ω-terminated with sugars bearing multiple sulfonate groups. We aimed to identify compounds with antiviral properties due to irreversible (virucidal) rather than reversible (virustatic) inhibition. The ligands varied in length, in number of sulfonated groups as well as their spatial orientation induced by the sugar head groups. We identified two candidates, a glucose- and a lactose-based ligand showing a low EC50 (effective concentration that inhibit 50% of the viral activity) for DENV-2 inhibition, moderate toxicity and a virucidal effect in hepatocytes with titre reduction of Median Tissue Culture Infectious Dose log10TCID50 2.5 and 3.1. Molecular docking simulations complemented the experimental findings suggesting a molecular rationale behind the binding between sulfonated head groups and DENV-2 envelope protein.

Biodegradability and Toxicity of Cellobiosides and Melibiosides.

In 2014, almost 16 million tons of surfactants were used globally for cleaning and industrial applications. As a result, massive quantities disperse into environmental compartments every day. There is great market interest in developing highly biodegradable, less-toxic, and renewable alternatives to currently used petroleum-based surfactants. Glycolipid surfactants, composed of a sugar head-group and lipid tail, are effective surfactants and emulsifiers with a high tolerance to electrolytes and are easily tailored to address specific needs. The green synthesis and surfactant characteristics of a suite of cellobiosides and melibiosides were recently described. The biodegradability and toxicity of 1°-alkyl-O-cellobiosides, 2°-alkyl-O-cellobiosides, and 1°-alkyl-O-melibiosides with straight-chain alkyl tails of 8, 10, and 12 are reported in this study. Biodegradability was assessed by quantifying mineralization (CO2 evolution). All of the glycosides were inherently biodegradable and most were readily biodegradable according to OECD and EPA definitions. The Microtox acute toxicity assay showed both chain length and head group had significant effects on toxicity, but most of the molecules were practically non-toxic according to EPA definitions with EC50 values > 100 mg L-1. Cytotoxicity to human lung (H1299) and keratinocyte cell lines (HaCaT) was measured by xCELLigence and MTS assays. Cytotoxicity values were comparable to similar glycosides previously reported. IC50 values were determined but, in general, exceeded surfactant concentrations that are found in the environment. These data demonstrate the promising nature of these molecules as green alternatives to petrochemical surfactants.

Heterocyte glycolipid diketones: A novel type of biomarker in the N2-fixing heterocytous cyanobacterium Microchaete sp.

The heterocyte (heterocyst) glycolipid (HG) content of heterocytous (heterocystous) cyanobacteria can principally be separated into two different types. In the first type, the aglycone moiety attached to the sugar headgroup exclusively contains hydroxyl functionalities resulting in the formation of HG diols and HG triols. In the second type, one of the hydroxyl groups is replaced by a ketone functionality giving rise to HG keto-ols and HG keto-diols. In the N2-fixing heterocytous cyanobacterium Microchaete sp. PCC 7126 both types of HGs were dominant and consisted primarily of two structural isomers each of the HG28 diol and HG28 keto-ol. In addition to these well-characterized HGs, Microchaete sp. PCC 7126 also contained a yet undescribed type of HG that based on comparison of retention times, molecular weight and mass spectrometry consisted of a hexose headgroup attached to an aglycone moiety with 28 carbon atoms at which two instead of one ketone functionalities were attached. Hence, the novel HG structure was identified as HG28 diketone. This study thus provides further evidence for the large structural diversity of HGs, which allows chemotaxonomic profiling of heterocytous cyanobacteria and in turn studying the community composition of these important diazotrophs in the geological rock record.

Barrel assembly senses glycolipids

Sensors that selectively detect glycolipids—molecules that are involved in infection, inflammation, and cancer progression—are hard to make. Most sensors target either the hydrophilic sugar head group or the hydrophobic lipid tail. A new supramolecular sensor has components that bind both parts of the glycolipid, Timothy E. Glass of the University of Missouri reported at the ACS meeting last week. The work was also published earlier this month (Angew. Chem. Int. Ed. 2018, DOI: 10.1002/anie.201807221). Glass’s supramolecular sensor comprises a hydrophobic cavity made from a barrel-shaped cucurbituril molecule, a boronic acid-based carbohydrate receptor, and a fluorescent indicator dye. The receptor stays put in the cavity because a bis-pyridinium group anchors it there. This positively charged anchor region also quenches the dye, which accompanies the receptor in the cavity. When the boronic acid receptor binds the sugar head group of a glycolipid, the lipid tail displaces the dye, which is then free

A novel heterocyst glycolipid detected in a pelagic N2-fixing cyanobacterium of the genus Calothrix

Previous studies have shown that heterocyst glycolipids (HGs) are unique markers for N2-fixing heterocystous cyanobacteria. In this study, the HGs of a marine pelagic Calothrix sp. CCY1611 isolated from the tropical western North Atlantic were analyzed by ultra-high pressure liquid chromatography–high resolution mass spectrometry and it was shown that this organism contains an unusual C28 triol HG with a methylated C6 sugar (methyl-HG28 triol) head group. Gas chromatography–mass spectrometry analysis of the sugar released from the novel HG by acid methanolysis revealed that the sugar is likely 6-O-methyl-β-d-glucopyranose. We propose that this methyl-HG28 triol is a potential biomarker for pelagic members of the genus Calothrix.

Effects of GM1 on brain spectrin-aminophospholipid interactions

Spectrin, a major component of the membrane skeletal meshwork of metazoan cells, is implicated to associate with membrane domains and is known to act as a scaffold for stabilization and activation of different signalling modules. We have studied the effect of GM1 (monosialotetrahexosyl ganglioside), a well-known model ganglioside and a signalling moiety, on the interaction of non-erythroid brain spectrin with both saturated and unsaturated aminophospholipids by spectroscopic methods. We observe that GM1 modulates brain spectrin-aminophospholipid interaction to the greatest degree whereas its effect on erythroid spectrin is not as pronounced. Fluorescence quenching studies show that brain spectrin interacts with DMPC/DMPE-based vesicles with a 10-fold increased affinity in presence of very low amounts of 2% and 5% GM1, and the extent of quenching decreases progressively in presence of increasing amounts of GM1. Interaction of brain spectrin with unsaturated membrane systems of DOPC/DOPE weakens in presence GM1. Increase in the mean lifetime of the Trp residues of brain spectrin in presence of GM1 indicates change in the microenvironment of spectrin, without affecting the secondary structure of the protein significantly. Studies on pressure – area isotherm of Langmuir-Blodgett monolayer and Brewster's angle microscopy show that GM1 has an expanding effect on the aminophospholipid monolayers, and ordered regions in DMPC/DMPE mixed monolayers are formed and are stabilized at higher pressure. GM1-induced fluidization of the phospholipid membranes and probable physical contact between bulky sugar head group of GM1 and spectrin, may explain the modulatory role of GM1 on aminophospholipid interactions with nonerythroid brain spectrin.

Dry Thermotropic Glycolipid Self-Assembly:A Review

Also recognized as carbohydrate liquid crystals, glycolipids are amphiphiles whose basic unit comprises of a sugar group attached to an alkyl chain. Glycolipids are amphitropic, which means these materials form liquid crystal self-assemblies when dry (thermotropic) as well as when dissolved in solvents (lyotropic/surfactants) such as water. Many glycolipids are also naturally derived since these can be found in cell membranes. Their membrane and surfactant functions are largely understood through their lyotropic properties. While glycolipids are expected to play major roles as eco-friendly surfactants in the global surfactant market, their usefulness as thermotropic liquid crystal material is, to date, unknown, due to relatively lack of research performed and data reported in the literature. Understandably since glycolipids are hygroscopic with many hydroxy groups, removing the last trace water is very challenging. In recent time, with careful lyophilization and more consistent characterization technique, some researchers have attempted serious studies into "dry" or anhydrous glycolipids. Motivated by possible developments of novel thermotropic applications, some results from these studies also provide surprising new understanding to support conventional wisdom of the lyotropic systems. Here we review the dry state of glycosides, a family of glycolipids whose sugar headgroup is linked to the lipid chain via a glycosidic oxygen linker. The structure property relationship of both linear and anhydrous Guerbet glycosides will be examined. In particular, how the variation of sugar stereochemistry (e.g. anomer vs. epimer), the chain length and chain branching affect the formation of thermotropic liquid crystals phases, which not only located under equilibrium but also far from equilibrium conditions (glassy phase) are scrutinized. The dry glycolipid assembly has been subjected to electric and magnetic fields and the results show interesting behaviors including a possible transient current generation.