Sugar Fatty Acid Esters Research Articles

Integrated Process for the Enzymatic Production of Fatty Acid Sugar Esters Completely Based on Lignocellulosic Substrates.

Lignocellulose can be converted sustainably to fuels, power and value-added chemicals like fatty acid esters. This study presents a concept for the first eco-friendly enzymatic synthesis of economically important fatty acid sugar esters based on lignocellulosic biomass. To achieve this, beech wood cellulose fiber hydrolysate was applied in three manners: as sugar component, as part of the deep eutectic solvent (DES) reaction system and as carbon source for the microbial production of the fatty acid component. These fatty acids were gained from single cell oil produced by the oleaginous yeast Cryptococcus curvatus cultivated with cellulose fiber hydrolysate as carbon source. Afterwards, an immobilized Candida antarctica lipase B was used as the biocatalyst in DES to esterify sugars with fatty acids. Properties of the DES were determined and synthesized sugar mono- and di-esters were identified and characterized using TLC, MS, and NMR. Using this approach, sugar esters were successfully synthesized which are 100% based on lignocellulosic biomass.

Synthesis and antibacterial activity of water-dispersible silver nanoparticles via micellar nanoreactors

We have synthesized silver nanoparticles (AgNPs) using micelles of sugar fatty acid ester by dissolving the surfactant in a mixture of iso-octane and n-butanol, with solid-liquid extraction. Highly concentrated, water-dispersible AgNPs were obtained after thorough washing with alcohol, to remove excess of sucrose fatty acid ester DK SS and salt, followed by drying. The particles were characterized for their size, morphology and crystallinity using UV-Visible spectrophotometry, Transmission Electron Microscopy and x-ray diffractometry. Antibacterial study, confirmed the activity of nanoparticles against E. coli, P. aeruginosa and S. aureus, which causes diseases including diarrhoea and several life-threatening infections. Antibacterial activity of E. coli and P. aeruginosa was found to be 2.5 fold and for S. aureus 1.6 fold compared to 50 ppm conc. of Silver Nitrate. Our method of producing nanoparticles is employed as a platform technology for synthesizing other inorganic nanoparticles. This is the first report discussing the use of micellar carriers for obtaining silver nanopowder, to the best of our knowledge, which has the potential to overcome limitations during fabrication of AgNPs using reverse/inverse micelles. Our method yielded nano-sized, water-dispersible AgNPs via an easy and economic approach. The one-pot approach possesses advantages in terms of cost and simplicity, as compared with traditional methods of producing powdered AgNPs using energy intensive and expensive techniques like lyophilisation. The developed method, thus, possesses immense potential for commercial synthesis of AgNPs.

Enzymatic Preparation of a Homologous Series of Long-Chain 6- O-Acylglucose Esters and Their Evaluation as Emulsifiers.

Sugar fatty acid esters are nonionic surfactants that are widely exploited in the food and cosmetics industries, as well as in the oral care and medical supply fields. Accordingly, new methods for their selective synthesis and the "tuning" of their emulsifying properties are of considerable interest. Herein we report simple and irreversible enzymatic esterifications of d-glucose with seven fatty acid vinyl esters. The foaming and emulsifying effects of the resulting 6- O-acylglucose esters were then evaluated. In accord with expectations, when the length of the alkyl side chain associated with the 6- O-acylglucose esters increases, then their hydrophilic-lipophilic balance (HLB) values decrease, while the stabilities of the derived emulsions improve. In order to maintain good foaming properties, alkyl side chains of at least 9 to 11 carbons in length are required. In the first such assays on 6- O-acylglucose esters, most of those described herein are shown to be nontoxic to the HepG2, MCF-7, LNacp, SW549, and LO-2 cell lines.

Regioselective Synthesis of Novel Galactose, Fucose and Lactose Fatty Acid Esters as Glycomimetics of Bile Acid 1-O-acyl Galactoside and Bacterial Glycolipids

Background: Carbohydrate fatty acid esters are found in important biological molecules such as bile acid 1-O-acyl galacto and bacterial glycolipids. The synthesis of glycomimetics of those biomolecules is required to study their structure-activity relationship. Method: In this work a series of carbohydrate fatty acid esters were regioselectively prepared mainly via protection and deprotection and tin-mediated strategies of partially benzyl-protected sugars, followed by hydrogenolysis of the benzyl groups. Results: We report here the regioselective synthesis of galactose palmitoyl esters along with other fatty acyl galactose glycomimetics namely fucose and lactose fatty esters. 1-O-palmitoyl-, 1,6-di-Opalmitoyl- D-galactose and 1-O-palmitoyl-L-fucose derivatives were prepared via a low-temperature esterification of the partially benzyl-protected galactose and fucose derivatives, respectively, followed by hydrogenolysis of the benzyl groups. The regioselective synthesis of 3'-O-acyl-D-lactosides of palmitic and nitrobenzoic acids was accomplished using a dibutyltin oxide activation strategy of partially protected lactoside derivatives. Conclusion: The regioselective synthesis of galactose, fucose and lactose fatty acid esters as glycomimetics of biological molecules containing the 1-O-fatty acyl-D-galactose moiety is reported in this work. Keywords: Glycolipid, glycomimetics, sugar fatty acid esters, regioselective esterification, dibutyltin oxide, bile acid.

Emulsification Properties of Lactose Fatty Acid Esters

Sugar fatty acid esters (SFAE) are a class of synthetic emulsifiers used in the food, pharmaceutical, and personal care industries. The influence of the fatty acid chain length on the emulsification properties of lactose fatty acid esters (LFAE) including lactose monooctanoate (LMO), lactose monodecanoate (LMD), lactose monolaurate (LML) and lactose monomyristate (LMM) was investigated in this study. The stability of the emulsions as well as the oil droplet size distribution in 20% soybean oil-in-water emulsions was measured at 0.1%, 0.25% and 0.5% of LFAE concentrations. In order of LFAE with the strongest emulsion stabilization characteristics were LML, LMD, LMO and LMM. Oil droplet distributions resulted in the same trend, with LML and LMD maintaining the smallest droplet sizes and thus the most stable emulsion. The hydrophilic-lipophilic balance (HLB) and critical micelle concentrations were determined for each LFAE. An increase in HLB value was seen with an increased CMC value for each LFAE, showing the strength of the linear relationship between these two measured values. Additionally, there was a decrease in HLB and CMC values with a decrease in the fatty acid chain length of each LFAE. This research showed that LML and LMD formed more stable emulsions, even with HLB and CMC values higher than those of LMM suggesting HLB and CMC values alone do not predict emulsifier effectiveness.

Lactose oleate as new biocompatible surfactant for pharmaceutical applications

Sugar fatty acid esters are an interesting class of non-ionic, biocompatible and biodegradable sugar-based surfactants, recently emerged as a valid alternative to the traditional commonly employed (e.g. polysorbates and polyethylene glycol derivatives). By varying the polar head (carbohydrate moiety) and the hydrophobic tail (fatty acid), surfactants with different physico-chemical characteristics can be easily prepared. While many research papers have focused on sucrose derivatives, relatively few studies have been carried out on lactose-based surfactants. In this work, we present the synthesis and the physico-chemical characterization of lactose oleate. The new derivative was obtained by enzymatic mono-esterification of lactose with oleic acid. Thermal, surface, and aggregation properties of the surfactant were studied in detail and the cytotoxicity profile was investigated by MTS and LDH assays on intestinal Caco-2 monolayers. Transepithelial electrical resistance (TEER) measurements on Caco-2 cells showed a transient and reversible effect on the tight junctions opening, which correlates with the increased permeability of 4 kDa fluorescein-labelled dextran (as model for macromolecular drugs) in a concentration dependent manner. Moreover, lactose oleate displayed a satisfactory antimicrobial activity over a range of Gram-positive and Gram-negative bacteria. Overall, the obtained results are promising for a further development of lactose oleate as an intestinal absorption enhancer and/or an alternative biodegradable preservative for pharmaceutical and food applications.

Process design for green and selective production of bio-based surfactant with heterogeneous resin catalyst

The aim of this study was to construct an environmentally and eco-friendly production process of a bio-based surfactant, namely a sugar fatty acid ester (SE), using a heterogeneous catalyst. A strongly basic resin was found to show a fairly high catalytic activity in the transesterification of sucrose and a fatty acid methyl ester to produce an SE under mild conditions, i.e., 60 °C and atmospheric pressure, especially when sufficient sucrose was adsorbed on the resin active sites. In a continuous process using a flow reactor packed with the resin, an appropriate combination of sucrose adsorption and sucrose supply during the reaction enabled to maintain the sucrose concentration at high levels. As a result, continuous SE production succeeded in a short residence time of 1.5 h without saponification to form soap for the first time. In this process, the downstream operations to separate the soap and the catalyst from the product were unnecessary. This heterogeneous resin catalyst enables simple, efficient, and environmentally friendly SE production and this process has potential commercial applications.

Raising the enzymatic performance of lipase and protease in the synthesis of sugar fatty acid esters, by combined ionic exchange -hydrophobic immobilization process on aminopropyl silica support

A sustainable industrial application of the enzymes requires their reuse and stability. These objectives are accomplished here for the Thermomyces lanuginosus lipase and Bacillus subtilis protease, by immobilization in porous silica modified with (3-aminopropyl) triethoxysilane. This silylation leaves aminopropyl groups on the silica surface, leading to a heterofunctional support, with amine and alkyl entities that participate in ionic exchange-hydrophobic interactions, respectively, with the enzyme. In this work, the silica surface is effectively modified, as it is shown by FTIR and 29Si- and 13C-ssNMR spectroscopic techniques. The characteristics of the support surface explain the changes of the catalytic properties of the two immobilized enzymes. This support promotes the homogeneous orientation and stabilization of the enzyme during the one-pot immobilization process, without the costs of other heterofunctiontal materials obtained by multiple functionalization steps. Both immobilized enzymes show thermal stabilization in aqueous solution (25 mM sodium phosphate buffer, pH 7.0) at 60 °C and in 100% acetone at 40 °C, without addition of stabilizers. Both biocatalysts exhibit high performance on the synthesis of sugar fatty acid esters, in comparison with others, reported under similar reaction conditions. Due to the characteristic of the lipase/aminopropyl silica and protease/aminopropyl silica biocatalysts, they are promisors in applications that need high mechanical and enzymatic stability.

Porcine pancreatic lipase hydrophobically adsorbed on octyl-silica: A robust biocatalyst for syntheses of xylose fatty acid esters

This work describes the immobilization of porcine pancreatic lipase (PPL), obtained from crude extract, on silica coated with octyl groups (OS) by interfacial adsorption, a simple and low-cost immobilization protocol. The biocatalyst PPL-OS was employed to the enzymatic preparation of fatty acid esters of d-xylose, a product used especially in the field of cosmetics and pharmacy, especially dermatology, improving the functionality of epidermal cells. The yields of the immobilization in terms of enzymatic activity and protein concentration (98% and 75%, respectively) suggested that PPL present in the crude extract was selectively immobilized on the octyl-silica support, which allowed the hyperactivation of the biocatalyst (recovered activity, 144%), a phenomenon that may be attributed to the interfacial activation of the enzyme on hydrophobic surfaces. The biocatalyst PPL-OS showed to be very robust in organic medium and at high temperature, which is an extremely important characteristic to produce sugar fatty acid esters from the industrial point of view. The syntheses of xylose fatty esters (oleate, caprylate and butyrate) yielded conversions around 70% after short reaction period (2 h) at 60 °C in tert-butyl alcohol. The biocatalyst, even after incubation at 60 °C for 24 h, could be reused in four esterification cycles of 2-h reaction at 60 °C, maintaining 100% of its catalytic activity.

Enzymatic Synthesis of Glucose-Based Fatty Acid Esters in Bisolvent Systems Containing Ionic Liquids or Deep Eutectic Solvents

Sugar fatty acid esters (SFAEs) are biocompatible nonionic surfactants with broad applications in food, cosmetic, and pharmaceutical industries. They can be synthesized enzymatically with many advantages over their chemical synthesis. In this study, SFAE synthesis was investigated by using two reactions: (1) transesterification of glucose with fatty acid vinyl esters and (2) esterification of methyl glucoside with fatty acids, catalyzed by Lipozyme TLIM and Novozym 435 respectively. Fourteen ionic liquids (ILs) and 14 deep eutectic solvents (DESs) were screened as solvents, and the bisolvent system composed of 1-hexyl-3-methylimidazolium trifluoromethylsulfonate ([HMIm][TfO]) and 2-methyl-2-butanol (2M2B) was the best for both reactions, yielding optimal productivities (769.6 and 397.5 µmol/h/g, respectively) which are superior to those reported in the literature. Impacts of different reaction conditions were studied for both reactions. Response surface methodology (RSM) was employed to optimize the transesterification reaction. Results also demonstrated that as co-substrate, methyl glucoside yielded higher conversions than glucose, and that conversions increased with an increase in the chain length of the fatty acid moieties. DESs were poor solvents for the above reactions presumably due to their high viscosity and high polarity.

Immobilized lipase catalyzing glucose stearate synthesis and their surfactant properties analysis.

Sugar fatty acid esters are practical importance and have a variety of applications that include surfactants and as an emulsifying agent. In this study, we report glucose stearate synthesis using lipase-Fe3O4 nanoparticles catalyst. The influence of various reaction factors, such as silica gel concentration, molar ratio of sugar/acid, reaction temperature and speed of agitation on esterification by immobilized enzyme was analyzed. The glucose stearate esterification degree of 87.2 % was obtained under the optimized condition: 1:2 molar ratio of glucose/stearic acid, 2 % (w/v) of silica gel at 120 rpm and 40 °C. Glucose esters were characterized according to their surfactant activity like emulsification index, oil displacement activity and antimicrobial activity. The results indicated glucose stearate acts as biosurfactant, with emulsification index of 66 % in mustard oil and oil displacement activity of 19.64 cm2.

Tetraalkylammonium Ionic Liquids as Dual Solvents–Catalysts for Direct Synthesis of Sugar Fatty Acid Esters

AbstractAs nonionic surfactants derived from naturally renewable resources such as sugars and fatty acids, sugar fatty acid esters have been widely utilized in food, cosmetic and pharmaceutical industries. Our present study has demonstrated that the inexpensive and halogen‐free tetraalkylammonium salts (e.g., [Bu4N][Ac], [Et4N][Ac] and [Me4N][Ac]) can act as dual solvents–catalysts for regioselective acylation to produce glucose laurate. This non‐enzymatic synthesis can proceed under mild conditions with high specificity, and the conversions obtained were superior to that when an enzyme catalyst (lipase, EC 3.1.1.3) was added. A higher yield was obtained in the ammonium salt with a longer alkyl chain on the cation, while no product was obtained in [Bu4N][HSO4] and [Bu4P][Ac]. A reaction mechanism has been proposed, which is supported by phase‐transfer catalysis and law of matching water affinity.

Aspergillus oryzae lipase-catalyzed synthesis of glucose laurate with excellent productivity

As nonionic surfactants derived from naturally renewable resources, sugar fatty acid esters (SFAEs) have been widely utilized in food, cosmetic, and pharmaceutical industries. In this study, six enzymes were screened as catalyst for synthesis of glucose laurate. Aspergillus oryzae lipase (AOL) and Aspergillus niger lipase (ANL) yielded conversions comparable to the results obtained by commercial enzymes such as Novozyme 435 and Lipozyme TLIM. The productivity obtained by AOL catalysis in anhydrous 2–methyl–2–butanol (2M2B) (38.7 mmol/L/h and 461.0 μmol/h/g) was much higher than the other literature results. Factors affecting the synthetic reaction were investigated, including water content, enzyme amount, substrate concentrations and reaction temperature. The process was greatly improved by applying the Box-Behnken design of response surface methodology (RSM). Solubilities of glucose in 14 different organic solvents were determined, which were found to be closely associated with the polarity of the solvents. Aspergillus oryzae lipase is a promising enzyme capable of efficiently catalyzing the synthesis of sugar fatty acid esters with excellent productivity.

Selective Synthesis of Glycoside Fatty Acid Esters and Their Antibacterial Structure‐activity Relationship against Bacterial Staphylococcus Aureus and Salmonella Agona

AbstractFatty acid esters of glycosides and glucopyranosiduronides were regioselectively synthesized with tin‐mediated method using dibutyltin dimethoxide as the stannylating agent, these novel esters were investigated for their antibacterial activities against bacterial Staphylococcus Aureus and Salmonella Agona, the essential structural feature as antibacterial agents was probed. Antimicrobial tests showed that some laurates of trans‐ol glycosides are effective inhibitors against S. Aureus, while some laurates and myristates of cis‐ol glycosides are moderate inhibitors against both S. Aureus and S. Agona. Studies on antimicrobial structure‐activity relationship of sugar fatty acid esters showed that both the carbohydrate moiety and the length of fatty acid played a vital role on the antibacterial effect.

Enzymatic production and functional characterization of d-sorbitol monoesters with various fatty acids

Sugar fatty acid esters are surfactants that are widely used in food, cosmetics, and pharmaceutical industries. In this study, enzymatic production of d-sorbitol monoesters with various fatty acids (C10–C18) was assessed. Reactions were performed in tert-butanol at 40°C, catalyzed by Candida sp. 99–125 lipase. Dissolution of the substrates was found to be the limiting step of the reaction, and hence preheating was performed to increase the solubility of d-sorbitol. Thus, the yield of d-sorbitol palmitate was increased from 7.34 to 31.6mM. The results demonstrated that the specific lipase preferred long-chain fatty acids. The surface-active properties of the products were also determined.

Impacts of ionic liquids on enzymatic synthesis of glucose laurate and optimization with superior productivity by response surface methodology

As biosurfactants derived from naturally renewable resources, sugar fatty acid esters have broad applications in food, cosmetic and pharmaceutical industries. Glucose laurate was synthesized by a lipase-catalyzed acylation of glucose with vinyl laurate in ionic liquid (IL) systems. 16 ILs were screened for investigating the impact of the IL’s compositions on both the solvent properties of the IL and the synthetic process. The conversions obtained in ILs showed a bell-shaped relationship with their log P values. ILs that carry hydrophobic cations and hydrophilic anions seemed to favor the sugar ester synthesis. 1-Hexyl-3-methylimidazolium trifluoromethylsulfonate ([HMIm][TfO]) was selected both as a pure solvent and as a co-solvent with 2-methyl-2-butanol (2M2B) for this application, and the influence of the affecting factors (such as reaction temperature, enzyme amount, molar ratio of the two substrates, and reaction time) has been studied. Response surface methodology (RSM) was applied to optimize the [HMIm][TfO]/2M2B bisolvent system, and an optimal productivity of 14.2mmol/L/h was achieved, which is superior to other literature results.

Lipase catalyzed synthesis of glucose palmitate in ionic liquid

Esterification of glucose and palmitic acid catalyzed by Novozyme 435 was carried out in three ionic liquids (IL): Cyphos 104, Cyphos 109 and [bmim][PF6]. To our knowledge this product has not been obtained in these ILs from these substrates up to now. The equilibrium conversion, as well as the amount of produced ester, were the highest in [bmim][PF6], i.e. X = 77%, 0.115 mmol g−1 of ester. Hence, this IL was chosen for further experiments. The enzyme was reused four times at 50 and 70 °C to evaluate its stability in [bmim][PF6]. It was found that the enzyme activity slowly decreases at both temperatures. The reaction conditions in [bmim][PF6] were optimized to achieve the best reaction yield using the factorial design of experiments. The highest concentration of ester that could be achieved in the investigated variable range after 48 h was 0.205 mmol g−1 at 70 °C, equimolar concentrations of substrates of 0.5 mmol g−1 and 0.5% of water. Since it takes more than 48 h to achieve equilibrium, the equilibrium ester concentration at optimal conditions is even higher, i.e. 0.254 mmol g−1. The novelty of the present work lies in the use of IL as a solvent for the synthesis of sugar fatty acid ester, and particularly in the use of palmitic acid as an acyl donor in esterification with glucose in this solvent.

In vitro antibacterial activities and mechanism of sugar fatty acid esters against five food-related bacteria

The objective of this study was to evaluate the antibacterial activities of sugar fatty acid esters, with different fatty acid and saccharide moieties, against five food-related bacteria including Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. Sucrose monocaprate showed the strongest antibacterial activity against all tested bacteria, especially Gram-positive bacteria. The minimum inhibitory concentrations (MICs) for Gram-positive bacteria and Gram-negative bacteria were 2.5 and 10mM, respectively. The minimum bactericidal concentrations (MBCs) for Gram-positive bacteria were 10mM. Time-kill assay also showed that sucrose monocaprate significantly inhibit the growth of tested bacteria. The permeability of the cell membrane and intracellular proteins were both changed by sucrose monocaprate according to cell constituents’ leakage, SDS–PAGE and scanning electron microscope assays. It is suggested that sucrose monocaprate, with both emulsifying and antibacterial activities, have a potential to serve as a safe multifunctional food additive in food industries.

Lipase‐catalyzed synthesis of glucose‐6‐O‐hexanoate in deep eutectic solvents

Enzymatic synthesis of sugar fatty acid esters in organic solvents is a well‐described procedure to synthesize glycolipids. This study aims at replacing these solvents with deep eutectic solvents (DES), a group of solvents that gained more and more interest during the last years, since they can be easily produced from non‐toxic resources. Enzymatic glycolipid synthesis in deep eutectic solvents was investigated, employing Candida antarctica lipase B (Novozyme 435) in various deep eutectic solvents. A successful lipase‐catalyzed synthesis of glucose fatty acid esters gave proof of this concept, while using the two deep eutectic solvents consisting of choline chloride and urea (CC : U) and choline chloride and glucose (CC : Glc). Additionally the DES consisting of choline chloride and glucose was observed to act as solvent and substrate for the synthesis at the same time.Practical applicationsGlycolipids find applications in many everyday products like cosmetic and pharmaceutical formulations, food and classic cleaning products, utilizing their good detergent or emulsification properties. Glycolipids can, among other routes, be synthesized via lipase‐catalyzed reactions, which are often carried out in organic solvents. By replacing these organic solvents with more ecologically friendly solvents like deep eutectic solvents, the reaction might be improved and the amount of waste produced could be reduced.The lipase‐catalyzed synthesis of glucose‐6‐O‐hexanoate employing glucose and vinyl hexanoate in different deep eutectic solvents was demonstrated within the manuscript.

Ionic liquids as novel solvents for the synthesis of sugar fatty acid ester.

Sugar fatty acid esters are bio-surfactants known for their non-toxic, non-ionic, and high biodegradability . With great emulsifying and conditioning effects, sugar fatty acids are widely used in the food, pharmaceutical, and cosmetic industries. Biosynthesis of sugar fatty acid esters has attracted growing attention in recent decades. In this study, the enzymatic synthesis of sugar fatty acid esters in ionic liquids was developed, optimized, and scaled up. Reaction parameters affecting the conversion yield of lipase-catalyzed synthesis of glucose laurate from glucose and vinyl laurate (i.e. temperature, vinyl laurate/glucose molar ratio, and enzyme loads) were optimized by response surface methodology (RSM). In addition, production was scaled up to 2.5 L, and recycling of enzyme and ionic liquids was investigated. The results showed that under optimal reaction conditions (66.86 °C, vinyl laurate/glucose molar ratio of 7.63, enzyme load of 73.33 g/L), an experimental conversion yield of 96.4% was obtained which is close to the optimal value predicted by RSM (97.16%). A similar conversion yield was maintained when the reaction was carried out at 2.5 L. Moreover, the enzymes and ionic liquids could be recycled and reused effectively for up to 10 cycles. The results indicate the feasibility of ionic liquids as novel solvents for the biosynthesis of sugar fatty acid esters.