A series of glycolipid crown ether analogs was prepared by bis-propargylation of lauryl glycoside followed by subsequent click-coupling with ethylene glycol-based diazides. The triazole-linked macrocycles were obtained in remarkable high yields. While the surfactant assembly was affected by presence of sodium ions, suggesting the formation of complexes, no ion-selectivity was observed for the macrocylic ligands. Computational studies suggest a low but significant cation-binding activity of the macrocycle, involving coordination at both oxygen and nitrogen atoms.
Aiming for new glycolipids with enhanced chemical stability and close structural similarity to natural cell membrane lipids for the development of a drug delivery system, we have synthesized double amide analogs of glyco-glycerolipids. The synthesis applied a Staudinger reaction based coupling of a 1,3-diazide with fatty acid chlorides. While the concept furnished the desired glucosides in reasonable yields, the corresponding lactosides formed a tetrahydropyrimidine based 1:1 coupling product instead. This unexpected coupling result likely originates from steric hindrance at the iminophosphorane intermediate and provides an interesting core structure for potentially bioactive surfactants. The assembly behavior of both glycolipid types was investigated by optical polarizing microscopy, DSC and surface tension studies.
Anomers and epimers α- and β-gluco and -galactosides are expected to behave differently. However, recent results on a series of Guerbet glycosides have indicated similar liquid crystal clearing temperatures for pure β-glucosides and the corresponding α-galactosides. This observation has led to speculation on similarities in the self-assembly interactions between the two systems, attributed to the trans-configuration of the 4-OH group and the hydrophobic aglycon. Previous simulations on related bilayers systems support this hypothesis, by relating this clearing transition temperature to intralayer (sugar-sugar) hydrogen bonding. In order to confirm the hypothesis, the comparison was expanded to include the cis-configurated pair, that is, α-gluco/β-galactoside. A set of α-configurated Guerbet glucosides as well as octyl α-galactoside were prepared and their thermotropic phase behavior studied. The data obtained enabled a complete comparison of the isomers of interest. While the results in general are in line with a pairing of the stereo-isomers according to the indicated cis/trans-configuration, differences within the pairs can be explained based on the direction of hydrogen bonds from a simple modeling study.
Immobilized Candida antarctica lipase B-catalyzed esterification of xylitol and two fatty acids (capric and caproic acid) were studied in a solvent-free system. The Taguchi orthogonal array method based on three-level-four-variables with nine experiments was applied for the analysis and optimization of the reaction parameters including time, substrate molar ratio, amount of enzyme, and amount of molecular sieve. The obtained conversion was higher in the esterification of xylitol and capric acid with longer chain length. The optimum conditions derived via the Taguchi approach for the synthesis of xylitol caprate and xylitol caproate were reaction time, 29 and 18h; substrate molar ratio, 0.3 and 1.0; enzyme amount, 0.20 and 0.05g, and molecular sieve amount of 0.03g, respectively. The good correlation between the predicted conversions (74.18% and 61.23%) and the actual values (74.05% and 60.5%) shows that the model derived from the Taguchi orthogonal array can be used for optimization and better understanding of the effect of reaction parameters on the enzymatic synthesis of xylitol esters in a solvent-free system.
A series of surfactants combining carbohydrate and imidazolium head groups were prepared and investigated on their assembly behavior. The presence of the imidazolium group dominated the interactions of the surfactants, leading to high CMCs and large molecular surface areas, reflected in curved rather than lamellar surfactant assemblies. The carbohydrate, on the other hand, stabilized molecular assemblies slightly and reduced the surface tension of surfactant solutions considerably. A comparative emulsion study discourages the use of pure alkyl imidazolium glycosides owing to reduced assembly stabilities compared with APGs. However, the surfactants are believed to have potential as component in carbohydrate based surfactant mixtures.
The behavior of the inclusion behavior of guanosine (GU) with beta-cyclodextrin (β-CD) in the liquid, solid and virtual state were investigated. The absorption and fluorescence spectral were used to determine the inclusion behavior in liquid state. FT-IR, NMR, TGA, DSC, PXRD and FESEM techniques were used to investigate the inclusion behavior in solid-state, meanwhile the virtual state studies are done by molecular docking. The solid inclusion complex (GU: β-CD) was prepared by using the co-precipitation method. The binding constant (K) of (GU: β-CD) was calculated by using Benesi-Hildebrand. Besides that, the 1:1 stoichiometric ratio of inclusion complex was confirmed by using the Benesi-Hildebrand plot and Job's plot of continuous variation method. The most preferable model of GU: β-CD that suggested via molecular docking studies was in good agreement with experimental results. The inclusion complex of GU: β-CD exerted its toxicity effects towards HepG2 cell lines based on the reduced number of cell viability and lowest IC50 value compared to the GU and β-CD viability.
The total syntheses of natural products Prelactone-V and Prelactone-B have been accomplished by a novel Chiron approach starting from d-glucose. The synthesis involves isopropylidene acetal formation of d-glucose using Poly(4-vinylpyridine) supported iodine as a catalyst, Tebbe olefination, Grignard reaction, Wittig olefination, selective mono deprotection of acetal using PMA/SiO2, hydrogenation and anti-1,3-diol formation are as key steps.
Two azide-terminated oligoethylene oxide spacered glycolipids have been synthesized, and their assembly behavior has been studied in comparison to the corresponding base surfactants. The results suggest potential of the Guerbet lactoside-based compound for targeted drug delivery, while a coiling of the ethylene oxide linker disfavors the application of the glucoside.
Cellulose acetate (CA) is a remarkable biomaterial most extensively used in biomedical applications due to their properties. This review highlighted the synthesis and chemical structure of CA polymer as well as focused on the mechanical, chemical, thermal, biocompatible, and biodegradable properties of electrospun CA nanofibers. These properties are essential in the evaluation of the CA nanofibers and provide information as a reference for the further utilization and improvement of CA nanofibers. Moreover, we have summarized the use of electrospun CA nanofibers in the drug delivery system as a carrier for drugs and classify them according to the drug class, including anti-inflammatory, anticancer, antioxidant, antimicrobial agents, vitamins and amino acids. Our review has been concluded that CA nanofibers cannot wholly be biodegraded within the human body due to the absence of cellulase enzyme but degraded by microorganisms. Hence, the biodegradation of CA nanofibers in vivo has addressed as a critical challenge.
Dysregulation of glycosylation pathways has been well documented in several types of cancer, where it often participates in cancer development and progression, especially cancer metastasis. Hence, inhibition of glycosidases such as mannosidases can disrupt the biosynthesis of glycans on cell surface glycoproteins and modify their role in carcinogenesis and metastasis. Several reviews have delineated the role of N-glycosylation in cancer, but the data regarding effective inhibitors remains sparse. Golgi α-mannosidase has been an attractive therapeutic target for preventing the formation of ß1,6-branched complex type N-glycans. However, due to its high structural similarity to the broadly specific lysosomal α-mannosidase, undesired co-inhibition occurs and this leads to serious side effects that complicates its potential role as a therapeutic agent. Even though extensive efforts have been geared towards the discovery of effective inhibitors, no breakthrough has been achieved thus far which could allow for their use in clinical settings. Improving the specificity of current inhibitors towards Golgi α-mannosidase is requisite in progressing this class of compounds in cancer chemotherapy. In this review, we highlight a few potent and selective inhibitors discovered up to the present to guide researchers for rational design of further effective inhibitors to overcome the issue of specificity.
The development of hybrid polysaccharide-protein complexes as Pickering emulsion stabilizers has attracted increasing research interest in recent years. This work presents an eco-friendly surface modification strategy to functionalize hydrophilic cellulose nanocrystals (CNC) using hydrophobic soy protein isolate (SPI) via mussel adhesive-inspired poly (l-dopa) (PLD) to develop improved nanoconjugates as stabilizers for oil-in-water Pickering emulsion. The physicochemical properties of the CNC-PLD-SPI nanoconjugate were evaluated by solid-state 13C NMR, FT-IR, TGA, XRD, contact angle analysis, and TEM. The modified CNC (conjugation content of 38.22 ± 1.21%) had lowered crystallinity index, higher thermal stability, and more hydrophobic than unmodified CNC, with an average particle size of 309.9 ± 8.0 nm. Use of amphiphilic CNC-PLD-SPI nanoconjugate with greater conformational flexibility as Pickering stabilizer produced oil-in-water emulsions with greater physical stability.
In the attempt to create a delivery system for an alkali-cation stimulated drug release, a computational study was conducted, aiming for the evaluation of synthetic access towards glycolipid crown ethers analogs and their potential for coordination-induced changes of packing constraints for molecular assemblies. The results disfavor amide-linkages for the creation of macrocycles around the inter-glycosidic bond of a disaccharide. Conformational changes upon cation coordination of the macrocycle decrease the intersection area for easily accessible macrocycles based on lactose. This leads to shrinking intersection areas upon alkali complexation. Maltose-based analogs, on the other hand, exhibited the targeted increase of the glycolipid intersection area and, hence, may be considered as a promising resource.
Nanocellulose (NC) is a natural fiber that can be extracted in fibrils or crystals form from different natural sources, including plants, bacteria, and algae. In recent years, nanocellulose has emerged as a sustainable biomaterial for various medicinal applications including drug delivery systems, wound healing, tissue engineering, and antimicrobial treatment due to its biocompatibility, low cytotoxicity, and exceptional water holding capacity for cell immobilization. Many antimicrobial products can be produced due to the chemical functionality of nanocellulose, such disposable antibacterial smart masks for healthcare use. This article discusses comprehensively three types of nanocellulose: cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), and bacterial nanocellulose (BNC) in view of their structural and functional properties, extraction methods, and the distinctive biomedical applications based on the recently published work. On top of that, the biosafety profile and the future perspectives of nanocellulose-based biomaterials have been further discussed in this review.
This work presents the characterization of a novel naturally phosphorylated starch extracted from an unconventional and non-utilized source, the seeds of the stone fruit Syzygium malaccense. The morphology and chemical characteristics of the extracted starch were examined by scanning electron microscopy, FTIR, 1H/13C/31P NMR and 13C-CP/MAS-NMR, HPAEC-PAD chromatography, XRD, DSC, and RVA. The extraction yielded a highly pure starch (95.6 %) with an average granule size of 13 μm. The analysis of the starch components revealed an amylose content of 28.1 % and a predominance (65 %) of B-chains (B1-B3 65 %) in the amylopectin, as shown through HPAEC-PAD chromatography. The X-ray diffractogram was compatible with B-type starch, which was confirmed by the deconvolution of the C1 peak in the 13C-CP/MAS-NMR. X-Ray diffractogram also showed that S. malaccense has 28.5 % of crystallinity. DSC analysis showed values of 82.6 °C and -12.41 J g-1 for Tc and ΔH, respectively, which is compatible with a highly ordered starch granule structure. The values observed for peak (4678 mPa•s), trough (3055 mPa•s), and final viscosity (6526 mPa•s) indicated that S. malaccense may be used as a thickener in hot food.
PelQ1 from Saccharobesus litoralis is a Ca2+-dependent pectate lyase belonging to the polysaccharide lyase family 1 (PL1). Although being an endolytic enzyme, it degraded polygalacturonate into predominantly unsaturated trimer in an exolytic manner with delayed production of dimer, tetramer and pentamer. The enzyme harbours a C-terminal domain from the carbohydrate-binding module family 13 (CBM13), whose presence facilitated the production of dimer. PelQ1's homology model showed that it possessed a well-conserved catalytic cleft, with R232 acting as the general base and R203 as the general acid. Structural comparison with DcPelC, a similar trimer-generating pectate lyase from Dickeya chrysanthemi EC16, implied that both enzymes' catalytic clefts encompassed at least eight subsites, i.e. -5 to +3. The unequal distribution of the subsites between the reducing and non-reducing ends of the cleavage site might be responsible for the exolytic generation of the trimer. As all but the -1, +1 and + 2 subsites could accommodate methylated galacturonate, this subclass of PL1 pectate lyases may function to help break up methylated pectin.