Lactose oleate as new biocompatible surfactant for pharmaceutical applications

Recent advances in sugar-fatty acid esters and their analogs: antimicrobial properties, structural-functional relationships and potential mechanisms

Sugar-fatty acid esters and their analogs (SFAEA) exhibit broad-spectrum antimicrobial activities. The article comprehensively outlined their inhibitory potential against key pathogenic and spoilage bacteria as well as fungal species. Antibacterial efficacy is quantitatively assessed using minimum inhibitory concentration (MIC), and antifungal activity is typically characterized by inhibition zones or mycelial growth inhibition rates. Research highlighted that sugar esters incorporating medium- to long-chain fatty acids, particularly those derived from sucrose, galactose, and mannose, demonstrated superior antibacterial properties. The lauric acid and myristic acid moieties were found to be exceptional compared to other length in the fatty acid portion. The chain length of the hydrophobic group, the glycosyl structure and the substitution level and type of the hydrophobic group in the sugar ester and other factors all have an impact on the antibacterial effect. It was found that the disruption of cell envelope, the generation of reactive oxygen species, the interactions with cytoplasmic contents and the influences on metabolic pathways were major reasons leading to cell death. Omics technologies and molecular docking also suggested some potential mechanisms. Additionally, future research directions regarding the application in food and mechanistic studies were presented.

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.

The influence of mannose-based esters on the mesophase behaviour of lyotropic liquid crystalline nanosystems as drug delivery vectors

Lyotropic Liquid Crystalline (LLC) nanoparticles represent an emerging class of smart, biocompatible, and biodegradable systems for the delivery of drugs. Among these, structures with complex 3D architectures such as cubosomes are of particular interest. These are non- lamellar assemblies having hydrophobic and hydrophilic portions able to carry drugs of different nature. They can further be modulated including suitable additives to control the release of the active payload, and to promote an active targeting. Starting from monoolein (GMO) cubic phase, different concentrations of mannose-based esters were added, and the eventual structural modifications were monitored to ascertain the effects of the presence of glycolipids. Moreover, the structural properties of these nanosystems loaded with Dexamethasone (DEX), a very well-known anti-inflammatory steroid, were also studied. Experiments were carried out by synchrotron Small Angle X-ray Scattering (SAXS), Raman Microspectroscopy (RMS) and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) measurements. The drug delivery potential (i.e. entrapment efficiency and release properties) of the obtained nanoparticles was evaluated. Finally, in vitro cytocompatibility and anti-inflammatory activity studies of the prepared formulations were carried out. Inclusion of mannose-based surfactants up to 10 mol% influenced the structural parameters of Im3m cubic phase and swollen cubic phases were obtained with the different glycolipids with lattice parameters significantly higher than GMO. A complete cytocompatibility and an increased DEX activity were observed, thus suggesting the possibility to use GMO/glycolipids nanoparticles to formulate innovative drug delivery systems.

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.

Starch ester film properties: The role of the casting temperature and starch its molecular weight and amylose content

Oleic acid and 10-undecenoic acid were used to esterify corn, tapioca, potato and a waxy potato starch, with a maximum degree of substitution of 2.4 and 1.9 respectively. The thermal and mechanical properties were investigated as a function of the amylopectin content and M_w of starch, and by the fatty acid type. All starch esters had an improved degradation temperature regardless of their botanical origin. While the T_g did increase with increasing amylopectin content and M_w, it decreased with increasing fatty acid chain length. Moreover, films with different optical appearances were obtained by varying the casting temperature. SEM and polarized light microscopy showed that films cast at 20 °C had porous open structures with internal stress, which was absent when cast at higher temperatures. Tensile test measurements revealed that films had a higher Young's modulus when containing starch with a higher M_w and amylopectin content. Besides that, starch oleate films were more ductile than starch 10-undecenoate films. In addition, all films were resistant to water at least up to one month, while some light-induced crosslinking took place. Finally, starch oleate films showed antibacterial properties against Escherichia coli, whereas native starch and starch 10-undecenoate did not.

Antimicrobial Preservatives for Protein and Peptide Formulations: An Overview

Biological drugs intended for multi-dose application require the presence of antimicrobial preservatives to avoid microbial growth. As the presence of certain preservatives has been reported to increase protein and peptide particle formation, it is essential to choose a preservative compatible with the active pharmaceutical ingredient in addition to its preservation function. Thus, this review describes the current status of the use of antimicrobial preservatives in biologic formulations considering (i) appropriate preservatives for protein and peptide formulations, (ii) their physico-chemical properties, (iii) their in-/compatibilities with other excipients or packaging material, and (iv) their interactions with the biological compound. Further, (v) we present an overview of licensed protein and peptide formulations.

Genomic Analysis of Surfactant-Producing Bacillus vallismortis TIM68: First Glimpse at Species Pangenome and Prediction of New Plipastatin-Like Lipopeptide

Surfactants are applied in several industrial processes when the modification of interface activity and the stability of colloidal systems are required. Lipopeptides are a class of microbial biosurfactants produced by species of the Bacillus genus. The present study aimed at assembling and analyzing the genome of a new Bacillus vallismortis strain, TIM68, that was shown to produce surfactant lipopeptides. The draft genome was also screened for common virulence factors and antibiotics resistance genes to investigate the strain biosafety. Comparative genomics analyses, i.e., synteny, average nucleotide identity (ANI), and pangenome, were also carried out using strain TIM68 and publicly available B. vallismortis complete and partial genomes. Three peptide synthetase operons were found in TIM68 genome, and they were surfactin A, mojavensin, and a novel plipastatin-like lipopeptide named vallisin. No virulence factors that render pathogenicity to the strain have been identified, but a region of prophage, that may contain unknown pathogenic factors, has been predicted. The pangenome of the species was characterized as closed, with 57% of genes integrating the core genome. The results obtained here on the genetic potential of TIM68 strain should contribute to its exploration in biotechnological applications.

Synthesis and Properties of Sucrose- and Lactose-Based Aromatic Ester Surfactants as Potential Drugs Permeability Enhancers

The delivery of therapeutics across biological membranes (e.g., mucosal barriers) by avoiding invasive routes (e.g., injection) remains a challenge in the pharmaceutical field. As such, there is the need to discover new compounds that act as drug permeability enhancers with a favorable toxicological profile. A valid alternative is represented by the class of sugar-based ester surfactants. In this study, sucrose and lactose alkyl aromatic and aromatic ester derivatives have been synthesized with the aim to characterize them in terms of their physicochemical properties, structure-property relationship, and cytotoxicity, and to test their ability as permeability enhancer agents across Calu-3 cells. All of the tested surfactants showed no remarkable cytotoxic effect on Calu-3 cells when applied both below and above their critical micelle concentration. Among the explored molecules, lactose p-biphenyl benzoate (URB1420) and sucrose p-phenyl benzoate (URB1481) cause a reversible ~30% decrease in transepithelial electrical resistance (TEER) with the respect to the basal value. The obtained result matches with the increased in vitro permeability coefficients (Papp) calculated for FTIC-dextran across Calu-3 cells in the presence of 4 mM solutions of these surfactants. Overall, this study proposes sucrose- and lactose-based alkyl aromatic and aromatic ester surfactants as novel potential and safe permeation enhancers for pharmaceutical applications.

Synthesis and Biological Evaluation of 6-O-Sucrose Monoester Glycolipids as Possible New Antifungal Agents

A small library of 6-O-sucrose monoester surfactants has been synthesized and tested against various microorganisms. The synthetic procedure involved a modified Mitsunobu reaction, which showed improved results compared to those present in the literature (higher yields and larger scope). The antifungal activities of most of these glycolipids were satisfactory. In particular, sucrose palmitoleate (URB1537) showed good activity against Candida albicans ATCC 10231, Fusarium spp., and Aspergillus fumigatus IDRAH01 (MIC value: 16, 32, 64 µg/mL, respectively), and was further characterized through radical scavenging, anti-inflammatory, and biocompatibility tests. URB1537 has been shown to control the inflammatory response and to have a safe profile.

Review on Metal-Based Theranostic Nanoparticles for Cancer Therapy and Imaging

Theranostic agents are promising due to their ability to diagnose, treat and monitor different types of cancer using a variety of imaging modalities. The advantage specifically of nanoparticles is that they can accumulate easily at the tumor site due to the large gaps in blood vessels near tumors. Such high concentration of theranostic agents at the target site can lead to enhancement in both imaging and therapy. This article provides an overview of nanoparticles that have been used for cancer theranostics, and the different imaging, treatment options and signaling pathways that are important when using nanoparticles for cancer theranostics. In particular, nanoparticles made of metal elements are emphasized due to their wide applications in cancer theranostics. One important aspect discussed is the ability to combine different types of metals in one nanoplatform for use as multimodal imaging and therapeutic agents for cancer.

Lipase-Mediated Mechanoenzymatic Synthesis of Sugar Esters in Dissolved Unconventional and Neat Reaction Systems

Mechanochemical and biocatalytic approaches in modern research are two major assets to develop greener processes. In the present study, these modular tools of sustainability are pointed toward the production of versatile and daily employed compounds such as surfactants. Toward this aim, glycolipids, a class of nonionic surfactants composed of ubiquitous and primary metabolites such as sugar and fatty acid moieties, represent a promising alternative to petroleum-derived surface-active agents. Therefore, the combination of biocatalysis with mechanochemistry aiming at glycolipid synthesis seemed a logical step that was taken in this study for the first time. The monoacylated model compound glucose-6-O-decanoate was synthesized with the help of a bead mill apparatus using two different unconventional dissolved reaction systems, namely, menthol-based hydrophobic deep eutectic solvents and 2-methyl-2-butanol, thus reaching up to 12% yield in the latter based on the conversion of vinyl decanoate, after only 90 min of reaction. In addition, a neat reaction system using an excess of vinylated fatty ester as an adjuvant allowed a 27 mM/h space-time yield. The overall significant increase in productivities, up to 6 times, compared to standard heating and shaking methods, shows the tremendous potential of mechanoenzymatic synthesis.

Hybrid emulsifier systems: Alkyl imidazolium lactoside surfactants derived from natural resources

A new series of hybrid surfactants comprising an imidazolium as a cation and a disaccharide as a non-ion were synthesized, and their aggregation behavior was also investigated. The synthetic approach used alkylation as an easily accessible route on an imidazole to attempt an economic production followed by coupling with bromoethyl lactoside to form lacto-imidazolium salts surfactants. The coupled surfactants were obtained in almost quantitative yield over several steps. The surfactant surface properties in aqueous media were investigated, including critical micelle concentration (CMC), Krafft temperature, and emulsion stability were studied. The CMC measurements of the alkyl imidazolium lactoside surfactants are significantly lower than normal imidazolium surfactants, while the emulsion investigations encourage the use of alkyl imidazolium lactoside surfactants owing to stabilized assemble behavior as good as APGs.

Synthesis and Biological Characterization of the New Glycolipid Lactose Undecylenate (URB1418)

As a follow-up to our previous studies on glycolipid surfactants, a new molecule, that is lactose 6′-O-undecylenate (URB1418), was investigated. To this end, a practical synthesis and studies aimed at exploring its specific properties were carried out. URB1418 showed antifungal activities against Trichophyton rubrum F2 and Candida albicans ATCC 10231 (MIC 512 μg/mL) and no significant antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. At the same time, it presented anti-inflammatory properties, as documented by the dose-dependent reduction in LPS-induced NO release in RAW 264.7 cells, while a low antioxidant capacity in the range of concentrations tested (EC50 > 200 µM) was also observed. Moreover, URB1418 offers the advantage of being more stable than the reference polyunsaturated lactose esters and of being synthesized using a “green” procedure, involving an enzymatic method, high yield and low manufacturing cost. For all these reasons and the absence of toxicity (HaCaT cells), the new glycolipid presented herein could be considered an interesting compound for applications in various fields.

A combination of sugar esters and chitosan to promote in vivo wound care

In recent years, researchers are exploring innovative green materials fabricated from renewable natural substances to meet formulation needs. Among them, biopolymers like chitosans and biosurfactants such as sugar fatty acid esters are of potential interest due to their biocompatibility, biodegradability, functionality, and cost-effectiveness. Both classes of biocompounds possess the ability to be efficiently employed in wound dressing to help physiological wound healing, which is a bioprocess involving uncontrolled oxidative damage and inflammation, with an associated high risk of infection. In this work, we synthesized two different sugar esters (i.e., lactose linoleate and lactose linolenate) that, in combination with chitosan and sucrose laurate, were evaluated in vitro for their cytocompatibility, anti-inflammatory, antioxidant, and antibacterial activities and in vivo as wound care agents. Emphasis on Wnt/β-catenin associated machineries was also set. The newly designed lactose esters, sucrose ester, and chitosan possessed sole biological attributes, entailing considerable blending for convenient formulation of wound care products. In particular, the mixture composed of sucrose laurate (200 µM), lactose linoleate (100 µM), and chitosan (1%) assured its superiority in terms of efficient wound healing prospects in vivo together with the restoring of the Wnt/β-catenin signaling pathway, compared with the marketed wound healing product (Healosol®), and single components as well. This innovative combination of biomaterials applied as wound dressing could effectively break new ground in skin wound care.

6'-O-Lactose Ester Surfactants as an Innovative Opportunity in the Pharmaceutical Field: From Synthetic Methods to Biological Applications

Glycolipid surfactants are biocompatible and biodegradable compounds characterized by potential applications in various sectors including pharmaceuticals, cosmetics, agriculture, and food production. A specific overview regarding synthetic methodologies and properties of 6′-lactose-based surfactants is presented herein, particularly all the synthetic approaches to this class of lactose esters, such as enzymatic and traditional organic syntheses. Moreover, detailed descriptions of physicochemical data and biocompatibility properties of these molecules, that is, surface tension, critical micelle concentration, emulsifying ability, foaming, particle size distribution, biocompatibility, and safety, are described. Biological applications with a focus on permeability enhancing, antimicrobial activity, and antibiofilm properties of 6′-lactose-based esters are also reported.

Comparative study on interfacial and foaming properties of glycolipids in relation to the gas applied for foam generation

Glycolipids are biosurfactants with a wide range of structural diversity. They are biodegradable, based on renewables, ecocompatible and exhibit high surface activity. Still, studies comparing glycolipids and conventional surfactants in terms of interfacial properties and foaming performance are lacking. Here, we compared interfacial and foaming properties of microbial and enzymatically synthesized glycolipids to those of the widely-used, conventional surfactant sodium dodecyl sulfate (SDS). The enzymatically produced sorbose monodecanoate, as well as microbially produced di-rhamno-di-lipids exhibited high foam stabilizing properties, similar to those of SDS. However, sophorolipid and mono-rhamno-di-lipids did not produce metastable foams. An appropriate selection of head and tail groups depending on the application of interest is therefore necessary. Then, glycolipids can serve as an ecofriendly and efficient alternative to petroleum-based surfactants, even at substantially lower concentrations than e.g. SDS. Moreover, the influence of three foaming gases on the foaming properties of the glycolipids was evaluated. Slightly higher foam stability and lower coarsening rates were determined for sorbose monodecanoate when using nitrogen as the foaming gas instead of air. Foams generated with carbon dioxide were not metastable, no matter which surfactant was used.

Surface Properties and Liquid Crystal Properties of Alkyltetra(oxyethyl) β-d-Glucopyranoside

Hydrophilic alkyl polyglycosides (APGs) and alkyl glycosides (AGs) with anomeric pure are a class of important substitutes for petroleum-based surfactants. Improving their water solubility should make such hydrophilic glycosurfactants have more excellent potential application value. To solve the inherent problem of poor water solubility of traditional alkyl β-d-glucopyranoside (5), a series of alkyltetra(oxyethyl) β-d-glucopyranosides (4a-4g, n = 7-18) were successfully synthesized by introducing tetra(oxyethylene) fragments to carry out the structural modification. The relationship between the related structure and the physicochemical properties was further investigated, including their hydrophilic-lipophilic balance (HLB), water-solubility, foaming performance, emulsification, hygroscopicity, surface activity, and thermotropic/lyotropic liquid crystal phase behavior. The results showed that the water solubility gradually decreased as the alkyl chain length increased due to the gradual decrease of their HLB number. Octadecyltetra(oxyethyl) β-d-glucopyranoside (4g, n = 18) was found to be insoluble in water at 25 °C. Taken together, long-chain alkyl glycosides had good foaming properties and excellent emulsifying properties. Among them, dodecyltetra(oxyethyl) β-d-glucopyranoside (4d, n = 12) had the best foaming performance. In the rapeseed oil/water system, cetyltetra(oxyethyl) β-d-glucopyranoside (4f, n = 16) had the best emulsifying ability. With the increase of the alkyl chain length, the critical micelle concentration (C_cmc), γ_cmc, Γ_max, and hygroscopicity of this series of glycosides showed a downward trend. Differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) showed that the thermal stability increased with the increase of the alkyl chain length, and alkyltetra(oxyethyl) β-d-glucopyranosides (4d-4g, n = 12-18) had the corresponding melting points and clearing points. Alkyltetra(oxyethyl) β-d-glucopyranosides (4b-4g, n = 8-18) formed a smectic phase with a typical fan-shaped and focal conic texture during the cooling process. In the water contact experiments, it was found that glycosides (4b-4g, n = 8-18) at high concentrations transformed into various lyotropic liquid crystal including hexagonal phase, bicontinuous cubic phase, and lamellar phase phases. Therefore, such green nonionic glycosurfactants alkyltetra(oxyethyl) β-d-glucopyranosides should have potential practical application prospects.

Parameters Influencing Lipase-Catalyzed Glycolipid Synthesis by (Trans-)Esterification Reaction

Glycolipids are biodegradable, non-toxic surfactants with a wide range of applications. Enzymatic esterification or transesterification facilitated in reaction media of low water activity is a reaction strategy for the production of tailor-made glycolipids as a high structural diversity can be achieved. Organic solvents, ionic liquids, and deep eutectic solvents have been applied as reaction media. However, several challenges need to be addressed for efficient (trans-)esterification reactions, especially for the lipophilization of polar substrates. Therefore, crucial parameters in (trans-)esterification reactions in conventional and non-conventional media are discussed and compared in this review with a special focus on glycolipid synthesis.

The beauty of biocatalysis: sustainable synthesis of ingredients in cosmetics

Covering: 2015 up to July 2021The market for cosmetics is consumer driven and the desire for green, sustainable and natural ingredients is increasing. The use of isolated enzymes and whole-cell organisms to synthesise these products is congruent with these values, especially when combined with the use of renewable, recyclable or waste feedstocks. The literature of biocatalysis for the synthesis of ingredients in cosmetics in the past five years is herein reviewed.

DFT Based Pharmacokinetic, Molecular Docking, and ADMET Studies of Some Glucopyranoside Esters

Monosaccharide esters (MEs) are getting more attention from bioorganic chemists due to their biodegradable and drug-likeness properties. As a consequence, carbohydrate derivatives (sugar-based esters, SEs) are an essential part of medicinal chemistry. In this context, density functional theory (DFT) with B3LYP/ 3-21G has been employed to optimize the methyl 4,6-O-benzylidene-α-D-glucopyranoside (3) of methyl α-D-glucopyranoside (2) and its protected acyl esters 4-6. The prediction of activity spectra for substances (PASS) of these compounds showed better antifungal functionalities than the antibacterial potentiality. Thermodynamic properties and molecular electrostatic potential (MEP) of these MEs indicated their stability and both the electrophilic and nucleophilic attack sites. Due to their better antifungal potentiality, molecular docking was conducted against fungal protein lanosterol 14α-demethylase (3JUS), and SARS-CoV-2 main protease (6LU7) along with absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies. The study indicated a better binding affinity of some esters compared to the standard antifungal and COVID-19 related drug hydroxychloroquine (HCQ).

Synthesis, PASS Predication, Antimicrobial, DFT, and ADMET Studies of Some Novel Mannopyranoside Esters

Due to the biodegradability and drug-likeness properties sugar esters (SEs) are getting especial attention to the synthetic and bioorganic chemists. In this context, we have synthesized several 6-O-pentanoyl mannopyranoside esters (5-9) with alkanoyl and sylfonyl chains reasonably in good yields. Both the prediction of activity spectra for substances (PASS) and in vitro tests indicated that these mannopyranoside esters possess better potentiality against fungal pathogens than the bacterial organisms. These SEs were also optimized with quantum chemical density functional theory (DFT), and various thermodynamic properties like frontier molecular orbital, and molecular electrostatic potential (MEP) were calculated and discussed. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) calculations indicated that these SEs can pass through blood brain barrier and less toxic. Drug-likeness results indicated good conditions for alkanoyl esters rather than sulfonyl esters despite their promising antifungal results. All the in vitro and in silico results indicated that the combination of pentanoyl (C5) and lauroyl (C12) chains in mannopyranoside framework, as in 9, might be a potential candidate for novel antifungal agent.

Synthesis and property of alkyl dioxyethyl α-D-xyloside

Due to the inherent defects of the long alkyl chain in the related hydrophilicity and water solubility, alkyl α-D-xylosides (7) had hardly the practical application as sugar-based surfactants and should be reconstructed to obtain alkyl dioxyethyl α-D-xylosides (5) with dioxyethylene fragment (-(OCH2CH2)2-)) as the hydrophilic spacer to increase the related TPSA value. With D-xylose as the raw material, 1,2-cis alkyl dioxyethyl α-D-xylosides (5a-5f, n = 6-12) were stereoselectively synthesized. Their physicochemical properties including water solubility, surface tension, foamability, emulsification, thermotropic liquid crystal, and hygroscopicity had been investigated. Their water solubility was found to decrease gradually whereas their calculated HLB numbers were 14.72 → 11.67 (n = 6 → 12) with increasing alkyl chain length (n). Dodecyl dioxyethyl α-D-xyloside (5f) had not water solubility because the HLB number was low. Furthermore, their CMC values decreased with increasing the alkyl chain length, and the CMC value of decyl dioxyethyl α-D-xyloside (5e) was as low as 9.21 × 10-5 mol·L-1. Octyl dioxyethyl α-D-xyloside (5c) had the lowest surface tension (27.25 mN·m-1) at the CMC. Both of nonyl and decyl dioxyethyl α-D-xylosides (5d & 5e) possessed good foaming power and foam stability. Decyl dioxyethyl α-D-xyloside (5e) had the strongest emulsifying property either in the toluene/water system or in the octane/water system. Nonyl dioxyethyl α-D-xylosides (5d) had the most stylish SA texture. Hexyl dioxyethyl α-D-xyloside (5a) possessed the strongest hygroscopicity. Therefore, the alkyl dioxyethyl α-D-xylosides as a class of novel sugar-based surfactants will be widely considered as promising candidates for various practical applications.

Interfacial and Foaming Properties of Tailor-Made Glycolipids-Influence of the Hydrophilic Head Group and Functional Groups in the Hydrophobic Tail

Glycolipids are a class of biodegradable surfactants less harmful to the environment than petrochemically derived surfactants. Here we discuss interfacial properties, foam stability, characterized in terms of transient foam height, gas volume fraction and bubble diameter as well as texture of seven enzymatically synthesized surfactants for the first time. Glycolipids consisting of different head groups, namely glucose, sorbitol, glucuronic acid and sorbose, combined with different C10 acyl chains, namely decanoate, dec-9-enoate and 4-methyl-nonanoate are compared. Equilibrium interfacial tension values vary between 24.3 and 29.6 mN/m, critical micelle concentration varies between 0.7 and 3.0 mM. In both cases highest values were found for the surfactants with unsaturated or branched tail groups. Interfacial elasticity and viscosity, however, were significantly reduced in these cases. Head and tail group both affect foam stability. Foams from glycolipids with sorbose and glucuronic acid derived head groups showed higher stability than those from surfactants with glucose head group, sorbitol provided lowest foam stability. We attribute this to different head group hydration also showing up in the time to reach equilibrium interfacial adsorption. Unsaturated tail groups reduced whereas branching enhanced foam stability compared to the systems with linear, saturated tail. Moreover, the tail group strongly influences foam texture. Glycolipids with unsaturated tail groups produced foams quickly collapsing even at smallest shear loads, whereas the branched tail group yielded a higher modulus than the linear tails. Normalized shear moduli for the systems with different head groups varied in a narrow range, with the highest value found for decylglucuronate.

Total Synthesis of Natural Disaccharide Sambubiose

A practical and robust synthetic method to obtain the natural disaccharide sambubiose (2-O-β-D-xylopyranosyl-D-glucopyranose) is reported, exploring the key step in the synthesis, i.e., stereoselective O-glycosylation. Specifically, the best combinations of glycoside donors and acceptors were identified, stereospecific control of the reaction was achieved by screening several catalysts and protection/deprotection steps were evaluated and improved. The best result was obtained by coupling allyl 3,5,6-tri-O-benzyl-β-D-glucofuranoside with 2,3,4-tri-O-acetyl-D-xylopiranosyl-α-trichloro acetimidate in the presence of trimethylsilyl triflate as a catalyst giving the corresponding protected target compound as a correct single isomer. The latter was transformed accordingly into the desired final product by deprotection steps (deallylation, deacetylation, and debenzylation). Sambubiose was synthesized into a satisfactory and higher overall yield than previously reported and was also characterized.

Quantification of 2- and 3-isopropylmalic acids in forty Italian wines by UHPLC-MS/MS triple quadrupole and evaluation of their antimicrobial, antioxidant activities and biocompatibility

2-Isopropylmalic acid (2-IPMA) and 3-isopropylmalic acid (3-IPMA), recently discovered in wines, were simultaneously quantified in forty wines by UHPLC-MS/MS triple quadrupole. Principal component analysis displayed that red wines were more correlated with high amounts of 2-IPMA (average content 31.60 mg/L); white wines were mostly characterized by low levels of both organic acids. No correlation of theirs levels to other wine features (wine ageing or alcoholic content) were found. 2-IPMA and 3-IPMA showed MICs values of 4096 mg/L and MBCs values of 8192 mg/L or higher against several food borne pathogens. In association, an interesting lower MIC and MBC values (2048 mg/L and 4096 mg/L respectively) were observed against Y. enterocolitica. Interestingly, 3-IPMA showed a mild antioxidant activity by DPPH assay (EC₅₀ = 3940 mg/L), higher than that of 2-IPMA (EC₅₀ > 4800 mg/L). No toxicity of these compounds against human colorectal and liver cells (TB assay) was observed.

Enzymatic Synthesis of Glucose Monodecanoate in a Hydrophobic Deep Eutectic Solvent

Environmentally friendly and biodegradable reaction media are an important part of a sustainable glycolipid production in the transition to green chemistry. Deep eutectic solvents (DESs) are an ecofriendly alternative to organic solvents. So far, only hydrophilic DESs were considered for enzymatic glycolipid synthesis. In this study, a hydrophobic DES consisting of (-)-menthol and decanoic acid is presented for the first time as an alternative to hydrophilic DES. The yields in the newly introduced hydrophobic DES are significantly higher than in hydrophilic DESs. Different reaction parameters were investigated to optimize the synthesis further. Twenty milligrams per milliliter iCalB and 0.5 M glucose resulted in the highest initial reaction velocity for the esterification reaction, while the highest initial reaction velocity was achieved with 1.5 M glucose in the transesterification reaction. The enzyme was proven to be reusable for at least five cycles without significant loss of activity.

Surfactant Self-Assembling and Critical Micelle Concentration: One Approach Fits All?

Critical micelle concentration (CMC) is the main chemical-physical parameter to be determined for pure surfactants for their characterization in terms of surface activity and self-assembled aggregation. The CMC values can be calculated from different techniques (e.g., tensiometry, conductivity, fluorescence spectroscopy), able to follow the variation of a physical property with surfactant concentrations. Different mathematical approaches have been applied for the determination of CMC values from the raw experimental data. Most of them are independent of the operator, despite not all of the fitting procedures employed so far can be applied in all techniques. In this experimental work, the second derivative of the experimental data has been proposed as a unique approach to determine the CMC values from different techniques (tensiometry, conductimetry, densimetry, spectrofluorimetry, and high-resolution ultrasound spectroscopy). To this end, the CMC values of five different surfactants, specifically three anionic (sodium dodecyl sulfate, sodium deoxycolate, and N-lauroyl sarcosinate) and two nonionic, such as polyethylene glycol ester surfactants [polyethylenglicol (8) monostearate and polyethylenglicol (8) monolaurate], have been determined by this approach. The "second-derivate" approach provides a reliable determination of the CMC values among all of the techniques investigated, which were comparable to those calculated by the other operator-free routinely methods employed, such as segmental linear regression or Boltzmann regression. This study also highlighted the strengths and shortcomings of each technique over the others, providing an overview of the CMC values of commonly used anionic and nonionic surfactants in the pharmaceutical field, determined by employing different experimental approaches.

Optimization of Glycolipid Synthesis in Hydrophilic Deep Eutectic Solvents

Glycolipids are considered an alternative to petrochemically based surfactants because they are non-toxic, biodegradable, and less harmful to the environment while having comparable surface-active properties. They can be produced chemically or enzymatically in organic solvents or in deep eutectic solvents (DES) from renewable resources. DES are non-flammable, non-volatile, biodegradable, and almost non-toxic. Unlike organic solvents, sugars are easily soluble in hydrophilic DES. However, DES are highly viscous systems and restricted mass transfer is likely to be a major limiting factor for their application. Limiting factors for glycolipid synthesis in DES are not generally well understood. Therefore, the influence of external mass transfer, fatty acid concentration, and distribution on initial reaction velocity in two hydrophilic DES (choline:urea and choline:glucose) was investigated. At agitation speeds of and higher than 60 rpm, the viscosity of both DES did not limit external mass transfer. Fatty acid concentration of 0.5 M resulted in highest initial reaction velocity while higher concentrations had negative effects. Fatty acid accessibility was identified as a limiting factor for glycolipid synthesis in hydrophilic DES. Mean droplet sizes of fatty acid-DES emulsions can be significantly decreased by ultrasonic pretreatment resulting in significantly increased initial reaction velocity and yield (from 0.15 ± 0.03 μmol glucose monodecanoate/g DES to 0.57 ± 0.03 μmol/g) in the choline: urea DES. The study clearly indicates that fatty acid accessibility is a limiting factor in enzymatic glycolipid synthesis in DES. Furthermore, it was shown that physical pretreatment of fatty acid-DES emulsions is mandatory to improve the availability of fatty acids.

Structural Modifications of a Flaxseed Lignan in Pursuit of Higher Liposolubility: Evaluation of the Antioxidant and Permeability Properties of the Resulting Derivatives

While lignans and their biogenetic precursors can have various health benefits, the poor liposolubilities of such phenolic systems have restricted their application as antioxidants in the food industry. The research reported here was aimed at addressing these matters through derivatizing certain forms of such compounds and then assessing their properties as potential nutraceuticals. In particular, crude flaxseed lignan was purified to afford secoisolariciresinol diglucoside (SDG, 1) that was then subjected to structural modification. By such means, the SDG long-chain fatty acid esters 4-9 and 11-13, the fully acetylated SDG 10, secoisolariciresinol (SECO, 2), and anhydrosecoisolariciresinol (ASECO, 14) were obtained. The antioxidant activities of these derivatives were determined while their permeability properties were evaluated. Such studies revealed that certain SDG derivatives possessing useful liposolubilities also retained their antioxidative properties, as well as being capable of permeating Caco-2 cell monolayers while being nontoxic to them. SDG fatty acid esters 4-9 and 11-13 could be developed into emulsifiers with enhanced health benefits, especially considering their improved antioxidative (ca. <11 000 μmol Trolox/g) and permeability properties. This study thus highlights strategies for the structural modification of SDG so as to generate derivatives with superior properties in terms of their utility in the food and pharmaceutical industries.

Synthesis and Evaluation of Saccharide-Based Aliphatic and Aromatic Esters as Antimicrobial and Antibiofilm Agents

A small library of sugar-based (i.e., glucose, mannose and lactose) monoesters containing hydrophobic aliphatic or aromatic tails were synthesized and tested. The antimicrobial activity of the compounds against a target panel of Gram-positive, Gram-negative and fungi was assessed. Based on this preliminary screening, the antibiofilm activity of the most promising molecules was evaluated at different development times of selected food-borne pathogens (E. coli, L. monocytogenes, S. aureus, S. enteritidis). The antibiofilm activity during biofilm formation resulted in the following: mannose C10 > lactose biphenylacetate > glucose C10 > lactose C10. Among them, mannose C10 and lactose biphenylacetate showed an inhibition for E. coli 97% and 92%, respectively. At MICs values, no toxicity was observed on Caco-2 cell line for all the examined compounds. Overall, based on these results, all the sugar-based monoesters showed an interesting profile as safe antimicrobial agents. In particular, mannose C10 and lactose biphenylacetate are the most promising as possible biocompatible and safe preservatives for pharmaceutical and food applications.

Utilization of a fattigation platform gelatin-oleic acid sodium salt conjugate as a novel solubilizing adjuvant for poorly water-soluble drugs via self-assembly and nanonization

Solubilizing adjuvants are commonly used to dissolve insoluble drugs by simply adding in a formulation. In this study, gelatin and oleic acid sodium salt (OAS), a generally recognized as safe-listed material were chosen and conjugated to develop a natural solubilizing adjuvant using the fattigation platform technology to enhance solubility and dissolution rate of poorly water-soluble drugs according to self-assembly and nanonization principle when simply mixed with poorly water-soluble drugs. We synthesized the gelatin and OAS conjugates (GOC) at three different ratios (1:1, 1:3, 1:5; GOC 1, GOC 2, and GOC 3, respectively) via the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide reaction using a spray dryer. This amphiphilic micronized GOC was self-assembled into nanoparticles. The synthesis of new amphiphilic conjugates was identified through Fourier transform-infrared (FT-IR) spectroscopy. The powder properties of the GOCs, such as angle of repose, bulk density, and tapped density were varied with the oleic acid bonding ratio. Then, GOCs were utilized to investigate the enhanced solubility and release rate of various poorly water-soluble drugs such as cilostazol (CSZ), coenzyme Q10, ticagrelor, telmisartan, aprepitant and itraconazole as model drugs. Based on the solubility studies by concentration and type of GOCs, 3% GOC 2 was selected. When this GOC was mixed with these model drugs by the physical mixing, wetting and hot melting methoods, the solubility was highly enhanced compared to the pure control drug, ranging from 20 to 150,000 times. In case of CSZ, all formulations were significantly improved release rate compared to the of CSZ alone and the reference tablet, cilostan® (Korea United Pharm) in simulated intestinal fluid containing 0.2% sodium lauryl sulfate. Differential scanning calorimetry and powder X-ray diffraction were conducted to confirm the crystal polymorphic structure of CSZ, and as a result they changed to diminutive peak intensity compared to CSZ alone. Field-emission scanning electron microscopy indicated that GOC was round with a reduced size of about 100 nm. The reduction of drug particles via nanonization and self-assembly of amphiphilic GOC in an aqueous media could be a key factor to improve poor water solubility by providing a favorable dispersion of drug molecules in an amphiphilic network.

Evaluation of a Methylcellulose and Hyaluronic Acid Hydrogel as a Vehicle for Rectal Delivery of Biologics

Biologics have changed the management of Inflammatory Bowel Disease (IBD), but there are concerns regarding unexpected systemic toxicity and loss of therapeutic response following administration by injection. Local delivery of biologics directly to the inflamed mucosa via rectal enema administration addresses the problems associated with systemic administration. Hydrogels are potentially useful delivery vehicles enabling rectal administration of biologics. Here, we prepared a hydrogel system based on methylcellulose (MC) and hyaluronic acid (HA), which possesses mucosal healing properties, incorporating a model macromolecular drug, namely (fluorescently-labeled) bovine serum albumin (BSA). The BSA-loaded MCHA hydrogel showed temperature-dependent gelation (liquid-like at 20 °C and gel-like at 37 °C) and shear thinning behavior, with these being important and desirable characteristics for rectal application (enabling easy application and retention). BSA release from the MCHA system at 37 °C was linear, with 50% of the loaded drug released within 2 h. The system demonstrated acceptable toxicity towards intestinal (colon) Caco-2 epithelial cells, even at high concentrations. Importantly, application of the BSA-loaded MCHA hydrogel to polarized Caco-2 monolayers, with or without an exemplar absorption enhancer, resulted in transintestinal permeability of BSA. The study therefore indicates that the MCHA hydrogel shows potential for topical (rectal) delivery of biologics in IBD.

Effect of Variations in the Fatty Acid Residue of Lactose Monoesters on Their Emulsifying Properties and Biological Activities

Lactose fatty acid esters are high-value-added derivatives of lactose and represent a class of biodegradable, non-ionic, low-molecular-weight surfactants (emulsifiers) that have considerable potential in the food, cosmetic, and pharmaceutical industries. Certain lactose esters have also garnered attention for their biological activities. In this work, we detail syntheses of a homologous series of 6'- O-acyllactose esters of varying alkyl chain length (from 6 to 18 carbons) and report on their activities as surfactants as well as their antimicrobial and cytotoxic properties. The structure-property profiles established in this work revealed that while the medium-chain esters displayed excellent emulsifying properties and moderate antimicrobial activities, their longer chain congeners exhibited the highest cytotoxicities. As such, we have established that certain 6'- O-acyllactose esters are superior to their sucrose-derived and commercially exploited counterparts. These results will serve as a useful guide for the development of lactose esters as, inter alia, emulsifiers in the food industry.