Recent progress in the synthesis of carbohydrate-based amphiphilic materials: the examples of sucrose and isomaltulose

Synthesis of homologous series of surfactants from renewable resources, structure-properties relationship, surface active performance, evaluation of their antimicrobial and anticancer potentialities

Sugar esters display surface-active properties, wetting, emulsifying, and other physicochemical phenomena following their amphipathic nature and recognize distinct biological activity. The development of nutritional pharmaceuticals and other applications remains of great interest. Herein, three novel homologous series of several N-mono-fatty acyl amino acid glucosyl esters were synthesized, and their physicochemical properties and biological activities were evaluated. The design and preparation of these esters were chemically performed via the reaction of glucose with different fatty acyl amino acids as renewable starting materials, with the suggestion that they would acquire functional characteristics superior and competitive to certain conventional surfactants. The synthesized products are characterized using FTIR, 1H-NMR, and 13C-NMR spectroscopy. Further, their physicochemical properties, such as HLB, CMC, Γmax, γCMC, and Amin, were determined. Additionally, their antimicrobial and anticancer efficiency were assessed. The results indicate that the esters' molecular structure, including the acyl chain length and the type of amino acid, significantly influences their properties. The measured HLB ranged from 8.84 to 12.27, suggesting their use as oil/water emulsifiers, wetting, and cleansing agents. All esters demonstrate promising surface-active characteristics, with moderate to high foam production with good stability. Notably, compounds 6-O-(N-dodecanoyl, tetradecanoyl cysteine)-glucopyranose (34, 35), respectively and 6-O-(N-12-hydroxy-9-octadecenoyl cysteine)-glucopyranose (38) display superior foamability. Wetting efficiency increased with decreasing the chain length of the acyl group. The storage results reveal that increasing the fatty acyl hydrophobe length enhances the derived emulsion's stability for up to 63 days. Particularly, including cysteine in these glucosyl esters improves wetting, foaming, and emulsifying potentialities. Furthermore, the esters exhibit antibacterial activity against several tested Gram-positive and Gram-negative bacteria and fungi. On the other hand, they show significant antiproliferative effects on some liver tumor cell lines. For instance, compounds 6-O-(N-12-hydroxy-9-octadecenoylglycine)-glucopyranose (28), 6-O-(N-dodecanoyl, hexadecanoyl, 9-octadecenoyl and 12-hydroxy-9-octadecenoylvaline)- glucopyranose (29, 31, 32 and 33), respectively in addition to the dodecanoyl, hexadecanoyl, 9-octadecenoyl and 12-hydroxy-9-octadecenoyl cysteine glucopyranose (34, 36, 37 and 38), respectively significantly inhibit the examined cancer cells.

Carbohydrate-DNA Conjugation Enabled by Glycosyl Radicals Generated from Glycosyl Sulfinates

Herein, we report a method that enables the synthesis of carbohydrate-DNA conjugates by radical addition. Key to the success is the use of readily available, bench-stable, and unprotected glycosyl sulfinates as precursors to glycosyl radicals. The redox neutral reaction proceeds under mild and simple conditions and tolerates a broad substrate scope. A small library of carbohydrate-DNA conjugates was prepared.

Sugar-Based Monoester Surfactants: Synthetic Methodologies, Properties, and Biological Activities

Glycolipids are biocompatible and biodegradable amphiphilic compounds characterized by a great scientific interest for their potential applications in various technological areas, including pharmaceuticals, cosmetics, agriculture, and food production. This report summarizes the available synthetic methodologies, physicochemical properties, and biological activity of sugar fatty acid ester surfactants, with a particular focus on 6-O-glucose, 6-O-mannose, 6-O-sucrose, and 6'-O-lactose ones. In detail, the synthetic approaches to this class of compounds, such as enzymatic lipase-catalyzed and traditional chemical (e.g., acyl chloride, Steglich, Mitsunobu) esterifications, are reported. Moreover, aspects related to the surface activity of these amphiphiles, such as their ability to decrease surface tension, critical micelle concentration, and emulsifying and foaming ability, are described. Biological applications with a focus on the permeability-enhancing effect across the skin or mucosa, antimicrobial and antifungal activities, as well as antibiofilm properties, are also presented. The information reported here on sugar-based ester surfactants is helpful to broaden the interest and the possible innovative applications of this class of amphiphiles in different technological fields in the future.

Beneficial Effects of Fructooligosaccharides Esterified with Lauric Acid in a Metabolic Syndrome Model Induced by a High-Fat and High-Carbohydrate Diet in Wistar Rats

Metabolic syndrome (MS) is a group of abnormalities in which obesity, insulin resistance (IR), oxidative stress, and dyslipidemia stand out. This pathology predisposes to the development of cardiovascular diseases and diabetes. The ingestion of linear fructooligosaccharides (FOS) such as inulin reduces conditions such as hyperinsulinemia, increased body fat, and triglyceridemia. When FOS are esterified with fatty acids, they present emulsifying and surfactant properties; however, there are no reports of their function at the biological level. The purpose of this investigation was to evaluate the effect of Agave tequilana Weber's FOS (AtW-FOS) and FOS esterified with lauric acid (FOS-LA) in MS markers in a rat model induced by a HFHC diet. Supplementation with AtW-FOS and FOS-LA decreased IR, improved glucose tolerance, reduced liver weight (19%), plasma triglycerides (24%), and blood pressure (16%) when compared with the untreated MS group. In conclusion, the ingestion of AtW-FOS and FOS-LA has beneficial effects in the prevention of MS alterations, showing a high potential for their application in functional foods.

Analysis of the Structure and Antigenicity in Ovalbumin Modified with Six Disaccharides Through Liquid Chromatography-High-Resolution Mass Spectrometry

Melibiose, cellobiose, maltose, lactose, turanose, and isomaltulose were selected to be glycated with OVA. The number of free amino groups of OVA modified with different disaccharides decreased, and the secondary and tertiary structures of the modified OVA also changed greatly. Moreover, the glycation sites detected by HPLC-HCD-MS/MS were all on the sensitized epitopes of OVA, which reduced the binding ability of IgG and IgE of glycated OVA. In addition, the glycation sites with the highest DSP in different samples were located in the irregular coil region of OVA. Among the six disaccharides, the glycation reaction between melibiose and OVA was the most obvious. Through the analysis of disaccharide configuration, it was found that the glycation efficiency of the reducing disaccharide linked by a 1 → 6 glycoside bond was higher than that by a 1 → 4 glycoside bond, and reducing sugar with β type was better than that with α type. These findings would provide a theoretical reference for the use of different sugars in food production.

Fast and selective synthesis of mono-substituted sucrose methacrylate ester monomer

Sucrose methacrylate (SM) is a key monomer for synthesizing biocompatible polymers with a carbohydrate core. However, controlled SM synthesis is challenging due to the possible formation of regio-isomers. This study describes SM synthesis that involves ultrasound irradiation of a homogeneous basic medium. The selectivity for mono-substituted SM was 86% within 30 min of reaction. The newly developed methodology is faster and more selective than that of mono-substituted SM synthesis already described in the literature.

Enzymatically-synthesized xylo-oligosaccharides laurate esters as surfactants of interest

Lipase-catalyzed synthesis of xylo-oligosaccharides esters from pure xylobiose, xylotriose and xylotetraose in the presence of vinyl laurate was investigated. The influence of different experimental parameters such as the loading of lipase, the reaction duration or the use of a co-solvent was studied and the reaction conditions were optimized with xylobiose. Under the best conditions, a regioselective esterification occurred to yield a monoester with the acyl chain at the OH-4 of the xylose unit at the non-reducing end. Surface-active properties of these pure xylo-oligosaccharides fatty esters have been evaluated. They display interesting surfactant activities that differ according to the degree of polymerization (DP) of the glycone moiety.

Sucrose fatty acid esters: synthesis, emulsifying capacities, biological activities and structure-property profiles

The notable physical and chemical properties of sucrose fatty acid esters have prompted their use in the chemical industry, especially as surfactants, since 1939. Recently, their now well-recognized value as nutraceuticals and as additives in cosmetics has significantly increased demand for ready access to them. As such a review of current methods for the preparation of sucrose fatty acid esters by both chemical and enzymatic means is warranted and is presented here together with an account of the historical development of these compounds as surfactants (emulsifiers). The somewhat belated recognition of the antimicrobial, anticancer and insecticidal activities of sucrose esters is also discussed along with a commentary on their structure-property profiles.

Hexahydrofarnesyl as an original bio-sourced alkyl chain for the preparation of glycosides surfactants with enhanced physicochemical properties

Five new bio-based surfactants have been synthetized by coupling hexahydrofarnesol with mono and di-saccharides. Hexahydrofarnesol (3,7,11-trimethyl-dodecan-1-ol) is a by-product of the industrial production of farnesane, a sustainable aviation fuel obtained by a fermentation process from sugar feedstocks. Using hexahydrofarnesol as the lipophilic starting material allows obtaining 100% bio-based surfactants while valorizing an industrial by-product. Moreover, the C₁₅-branched alkyl chain brings unique properties to the surfactants. This paper presents a physicochemical characterization of these new surfactants including their behaviors in water (water solubility, critical micellar concentration and surface tension) and in oil/water systems (interfacial tension against model oil and ternary phase behavior). Their hydrophilicities have been determined thanks to the PIT-slope method and compared to the ones of standard surfactants with linear alkyl chains, in order to distinguish the contributions of the sugar polar heads and of the branched hexahydrofarnesyl lipophilic chain. This novel class of surfactants combines the properties of sugar-based surfactants (low sensitivity to temperature and salinity, ability to form Winsor III microemulsion systems over a wide range of salinity), along with specificities linked to the branched alkyl chain (lower Krafft temperature, low surface tension).

The novelty of this work lies in the valorization of an original by-product into new sugar-based surfactants presenting effective properties.

Synthesis, Surface and Antimicrobial Activity of New Lactose-Based Surfactants

This work presents a synthesis method for new surfactants based on lactose. The compounds obtained belong to the homologous series of O-β-D-Galactopyranosyl-(1→4)-N-alkyl-(3-sulfopropyl)-D-glucosamine hydrochloride, containing 12 and 14 carbon atoms in the alkyl chain, and they may serve as an example of cationic surfactants. The newly synthesized compounds exhibit good surface properties, low value of CMC (Critical Micelle Concentration) and good wetting properties. These surfactants' ability to produce foam is considerably higher than in the commercial surfactants. Moreover, antibacterial and fungistatic activity was carried out by well diffusion assay against the selected bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa), yeasts (Candida albicans) and filamentous fungi (Fusarium graminearum, F. avenaceum, F. oxysporum, F. culmorum, F. equiseti, Alternaria alternata and Botrytis cinerea). It was shown that the resulting quaternary salts significantly inhibit the growth of tested microorganisms. Antibacterial and fungistatic activity of the surfactant compounds varied depending on the species of bacteria or fungi. The results of antimicrobial activity of new lactose derivatives indicate that the compounds exhibit larger or similar antagonistic activity against tested bacteria and fungi than typical cationic surfactant cetylpyridinium chloride.

Solvent issues in the Baylis-Hillman reaction of 5-hydroxymethyl furfural (HMF) and 5-glucosyloxymethyl furfural (GMF). Towards no-solvent conditions

The possibility to apply solventless conditions for the Baylis-Hillman reaction of 5-hydroxymethyl furfural (HMF) and its glucosylated analog, glucosyloxymethyl furfural (GMF) has been investigated. This study shows that highly functionalized adducts can be obtained in fair to good yields, under the conditions combining the renewability of the substrates, the straightforwardness of the strategy, and the lowered cost and toxicity of the solvent conditions. The issue of the polarity of the furanic substrate is addressed by comparing HMF with furfural and GMF.

Comparative Study of the Emulsifying Properties of a Homologous Series of Long-Chain 6'- O-Acylmaltose Esters

Emulsifiers derived from renewable resources such as sucrose and fatty acids are high volume commodity chemicals and currently produced by traditional chemical synthesis techniques that lack the capacity to form the most desirable monoesters (of sucrose) in a selective and efficient fashion. The development of new emulsifiers (surfactants) from alternate, structurally simpler but nevertheless abundant disaccharides such as maltose represents a possible solution to this problem. Herein, we report the facile enzymatic preparation of a homologous series of 6'- O-acylmaltose esters and an in-depth evaluation of them revealing that their surfactant properties and thermal stabilities are largely determined by the length of the fatty acid chain. In the first such comparison, we show that the foaming and emulsifying effects of certain of these maltose monoesters are superior to those of their sucrose-derived and commercially exploited counterparts. As such, maltose esters have considerable potential as emulsifiers for use in, for example, the food industry.

Enzymatic Synthesis and Characterization of Sucrose Erucate

The enzyme catalyzed synthesis is a environmentally friendly route compared to traditional syntheses. The lipase-catalyzed synthesis of sucrose erucate was achieved in a solvent mixture of t-butanol and dimethyl sulfoxide (4: 1) by esterification of sucrose with erucic acid using the immobilized Thermomyces lanuginosus lipase. Various process parameters like temperature, substrate molar ratio, solvent, time, and enzyme loading were studied. The optimal conditions for the esterification reaction obtained were 10 %(w/w) enzyme loading, a molar ratio sucrose/fatty acid 1: 1, mild reaction conditions (50 °C and atmospheric pressure) and reaction time (40 h with 55.6 % conversion). The sugar esters were characterized for surfactant properties at different concentration. Sucrose erucate showed a surface tension of (32.73 ± 0.01) mN m−1at a critical micellar concentration of 9.8 × 10−5 mol L−1 and good emulsification power.

Lipase-catalyzed synthesis of sucrose monoester: Increased productivity by combining enzyme pretreatment and non-aqueous biphasic medium

Sucrose monocaprate was synthesized by carrying out a lipase-catalyzed transesterification in a non-aqueous biphasic medium. Vinyl caprate was mechanically dispersed into a solution of sucrose in DMSO. The use of DMSO allowed increasing sucrose concentration up to 0.7M (in DMSO). The denaturing effect of DMSO on lipase was avoided by pretreatment of lipase by pH adjustment in the presence of crown ether. This pretreatment maintained a significant catalytic activity which led to 0.2M sucrose monoester within 1h at 50°C, which represented higher productivity than already reported. Detailed structural characterization revealed that only monoester was recovered and the 2-O-acylated sucrose monocaprate was the major isomer in the final product.

Switching chirality in the assemblies of bio-based amphiphiles solely by varying their alkyl chain length

Chirality inversion in the nanotubes of bio-based amphiphiles could be realized solely by increasing the alkyl chain length.

Sugar ester surfactants: enzymatic synthesis and applications in food industry

Sugar esters are non-ionic surfactants that can be synthesized in a single enzymatic reaction step using lipases. The stability and efficiency of lipases under unusual conditions and using non-conventional media can be significantly improved through immobilization and protein engineering. Also, the development of de novo enzymes has seen a significant increase lately under the scope of the new field of synthetic biology. Depending on the esterification degree and the nature of fatty acid and/or sugar, a range of sugar esters can be synthesized. Due to their surface activity and emulsifying capacity, sugar esters are promising for applications in food industry.

Glucosyloxymethylfurfural (GMF): a creative renewable scaffold towards bioinspired architectures

Glucosyloxymethylfurfural (GMF) is the glucosylated analogue of hydroxymethylfurfural (HMF), and is obtained in one step from the very available disaccharide isomaltulose. This account gives an overview on the preparation and the uses of GMF towards architectures containing a carbohydrate moiety and shows that rather elaborated targets can be synthesized from GMF in very short sequences. A special focus is made on carbon–carbon formation on the aldehyde group leading to new biobased acrylic derivatives by the Baylis–Hillman reaction.

Improvement of efficiency in the enzymatic synthesis of lactulose palmitate

Sugar esters are considered as surfactants due to its amphiphilic balance that can lower the surface tension in oil/water mixtures. Enzymatic syntheses of these compounds are interesting both from economic and environmental considerations. A study was carried out to evaluate the effect of four solvents, temperature, substrate molar ratio, biocatalyst source, and immobilization methodology on the yield and specific productivity of lactulose palmitate monoester synthesis. Lipases from Pseudomonas stutzeri (PsL) and Alcaligenes sp. (AsL), immobilized in porous silica functionalized with octyl groups (adsorption immobilization, OS) and with glyoxyl-octyl groups (both adsorption and covalent immobilization, OGS), were used. The highest lactulose palmitate yields were obtained at 47 °C in acetone, for all biocatalysts, while the best lactulose:palmitic acid molar ratio differed according to the immobilization methodology, being 1:1 for AsL-OGS biocatalyst (20.7 ± 3%) and 1:3 for the others (30-50%).

Cytotoxic activity of triazole-containing alkyl β-D-glucopyranosides on a human T-cell leukemia cell line

BACKGROUND

Simple glycoside surfactants represent a class of chemicals that are produced from renewable raw materials. They are considered to be environmentally safe and, therefore, are increasingly used as pharmaceuticals, detergents, and personal care products. Although they display low to moderate toxicity in cells in culture, the underlying mechanisms of surfactant-mediated cytotoxicity are poorly investigated.

RESULTS

We synthesized a series of triazole-linked (fluoro)alkyl β-glucopyranosides using the copper-catalyzed azide-alkyne reaction, one of many popular "click" reactions that enable efficient preparation of structurally diverse compounds, and investigate the toxicity of this novel class of surfactant in the Jurkat cell line. Similar to other carbohydrate surfactants, the cytotoxicity of the triazole-linked alkyl β-glucopyranosides was low, with IC50 values decreasing from 1198 to 24 μM as the hydrophobic tail length increased from 8 to 16 carbons. The two alkyl β-glucopyranosides with the longest hydrophobic tails caused apoptosis by mechanisms involving mitochondrial depolarization and caspase-3 activation.

CONCLUSIONS

Triazole-linked, glucose-based surfactants 4a-g and other carbohydrate surfactants may cause apoptosis, and not necrosis, at low micromolar concentrations via induction of the intrinsic apoptotic cascade; however, additional studies are needed to fully explore the molecular mechanisms of their toxicity. Graphical AbstractTriazole-linked, glucose-based surfactants cause apoptosis, and not necrosis, at low micromolar concentrations via induction of the intrinsic apoptotic cascade.

Green recyclable SO3H-carbon catalyst for the selective synthesis of isomannide-based fatty acid monoesters as non-ionic bio-surfactants

Solvent free one-pot synthesis of isomannide-based fatty acid monoesters as non-ionic bio-surfactants employing a green recyclable SO₃H-carbon catalyst was demonstrated.

Supramolecular glycolipid based on host-enhanced charge transfer interaction

Supramolecular glycolipid has been fabricated based on ternary complex system, which is composed of naphthyl glucosamine (GlcNap), alkyl viologen (RV8), and cucurbit[8]uril (CB[8]). CB[8] plays a key role to connect the other two building blocks together, and the process is driven by host-enhanced charge transfer interaction. Compared with the classic glycolipids, supramolecular glycolipids display redox responsiveness. Supramolecular glycolipids are able to self-assemble in water to form spherical aggregations, such as vesicle like structure. In addition, spherical aggregations can specifically interact with Concanavalin A, indicating that the carbohydrate groups are available on the surfaces of the aggregates.

Self-assembly of 6-O- and 6'-O-hexadecylsucroses mixture under aqueous conditions

In this paper, we report the self-assembly of 6-O- and 6'-O-hexadecylsucroses mixture under aqueous conditions. The mixture was synthesized by a five-step sequence from sucrose. The SEM image of a sample prepared by drying a dispersion of the mixture in water showed nanoparticles with the diameter of ∼50nm and aggregates that were formed by further assembly of them. The XRD measurement of the sample exhibited the diffraction pattern assignable to face-centered cubic (FCC) structure and the diameter of a sphere, which took part in the FCC structure, was calculated to be 5.1nm. This value was relatively close to that observed in the DLS measurement of a dispersion of the mixture in water and estimated for a spherical micelle based on the molecular sizes of the two sucrose ethers. On the basis of the above findings, the following self-assembly process of the mixture under aqueous conditions was proposed. The mixture formed the spherical micelles with the diameter of ∼5-7nm in water. The micelles regularly organized according to the FCC structure during the drying process from the aqueous dispersion to construct the nanoparticles with the diameter of ∼50nm. Several numbers of the nanoparticles further assembled to form the aggregates.