Carbohydrate Research最新文献

Chitosan is a widely used linear biopolymer composed mainly of glucosamine and to a lesser extent of N-acetylglucosamine units. Many biological activities of chitosan are attributed to its shorter oligomeric chains, which consist of chitosan prepared either by enzyme activity (lysozyme, bacterial chitinase) or chemically by acid-catalyzed hydrolysis (e.g. in the stomach). However, these processes always result in a mixture of shorter chitooligosaccharides with varying degrees of acetylation whereas for relevant results of biological studies it is necessary to work with a precisely defined material. In this review, we provide an overview and comparison of analytical methods leading to the determination of the degree of polymerization (DP), the degree of acetylation (DA), the fraction of acetylation (FA) and the acetylation patterns (PA) of chitooligosaccharide chains and of the current state of knowledge on chitooligosaccharide separation. This review aims to present the most promising routes to well-defined low molecular weight chitosan with low dispersity.

Chitosan is a natural polymer that can degrade in the environment and support green chemistry. It displays superior biocompatibility, easy access, and easy modification due to the reactive amino groups to transform or improve the physical and chemical properties. Chitosan can be chemically modified to enhance its properties, such as water solubility and biological activity. Modified chitosan is the most effective functional biomaterial that can be used to deliver the drugs to the targeted site. With diverse and versatile characteristics, it can be fabricated into various drug delivery systems such as membranes, beads, fibers, microparticles, composites, and scaffolds, for different drug delivery methods. Integrating nanotechnology with modified chitosan enhanced the delivery attributes of antibacterial, antifungal, antiviral, anticancer, anti-inflammatory, protein/peptides, and nucleic acids for intended use toward desired therapeutic outcomes. The review brings out an overview of the research regarding drug delivery systems utilizing modifying chitosan detailing the properties, functionality, and applications.

We investigated the transglycosylation reaction of two types of oligosaccharide acceptors, i.e., β-cyclodextrin (CD) derivatives 1 and 2 conjugated with multiple glucose (Glc) units, catalyzed by endo-β-N-acetyl-glucosaminidase from Mucor hiemalis (Endo-M) using the oligosaccharide donor sialoglycopeptide (SGP). The acceptor specificity of the enzyme transglycosylation of 1 and 2 having seven Glc moieties within small nanoscale spatial regions on the β-CDs was investigated on the basis of the effect of the molar ratios of SGP to acceptors 1 or 2 with different spatial configurations on the transglycosylation behavior. The formation of the corresponding CD-based oligosaccharide clusters from Endo-M was also evaluated.

Chitooligosaccharides (CHOS) or chitosan oligosaccharides (COS) are oligomers mainly composed of d-glucosamine (GlcN) units and structured in a positively charged, basic, amino molecule obtained from the degradation of chitin/chitosan through physical, chemical, or enzymatic methods. CHOS display physicochemical properties attractive to applications from the food to the biomedical field, such as non-toxicity to humans, high water solubility, low viscosity, biocompatibility, and biodegradability. These properties also allow CHOS to exert important biological activities, for example, antioxidant, antimicrobial, anti-inflammatory, immunomodulatory, antitumor, and hypocholesterolemic ones, besides to exhibit applications in food systems, technological, and nutraceutical potential. Therefore, this study summarized the synthesis and chemical structure, biological functions, and mechanisms of action of CHOS; with this, we aimed to contribute to the knowledge about the application of CHOS from the food to the biomedical industries.

In the present study, we designed to link the coumarin molecule to chitosan via a triazole group and synthesized chitosan-coumarin derivatives, which were further quaternized in one step in order to further improve their solubility to obtain a second series of chitosan-coumarin ammonium salt derivatives. The structures of these chitosan derivatives were verified by FT-IR and ¹H NMR. They were tested for their antioxidant activities. The experimental results showed that the derivatives had excellent free radical scavenging ability. The introduction of the coumarin moiety significantly improved the antioxidant activity, and the scavenging capacity was much higher than that of the chitosan feedstock in all three antioxidant tests. Overall, the scavenging capacity of chitosan-coumarin ammonium salt derivatives was slightly higher than that of chitosan-coumarin derivatives, with the highest scavenging rates in all three tests. Compound 8B scavenged 98.74 % (0.01 mg/mL) of superoxide anion radicals, compound 8D scavenged 95.5 % (0.3 mg/mL) of DPPH radicals and compound 8A scavenged 92.97 % (0.2 mg/mL) of hydroxyl radicals. Toxicity assays used L929 cells demonstrated that there was no significant toxicity of the derivatives. The results indicated that the chitosan derivatives described herein were safe and non-toxic and have good antioxidant activity.

Gynecological tumors are highly aggressive cancers in women, often treated with conventional treatments that can cause significant side effects. This study focuses on the preparation of chitosan nanoparticles from Nyctanthes arbor-tristis leaves, which possess anti-tumor properties, to address and overcome these issues. The successfully synthesized nanoparticles were characterized by UV-spectroscopy, DLS, TEM, and FTIR spectroscopy to analyze their physiochemical properties. In vitro studies, including cytotoxicity and scratch wound healing assays, along with staining and qRT-PCR, revealed the nanoparticles' anticancer efficacy against breast and ovarian cancer cells. The formation of Nat-CSNPs showed an absorbance peak at 221 nm, a particle size range of 41-56 nm with a spherical shape, polydispersity, and a positive surface charge. FTIR spectroscopy demonstrated the presence of functional groups associated with the synthesized Nat-CSNPs. It exhibited dose-dependent cytotoxicity, with IC₅₀ values of 62.40 μg/ml for MDA-MB-231 and 44.7 μg/ml for SKOV3 cells. Further assays such as wound healing assay, and DAPI/AO/EtBr staining demonstrated their antiproliferative and apoptotic effects on MDA-MB-231 and SKOV3 cells. Induction of apoptosis by the chitosan-nanoparticle via upregulation of the pro-apoptotic genes (Bax, Cas3, Cas9) and downregulation of antiapoptotic genes (Bcl2) was assessed using qRT-PCR analysis. In vivo acute toxicity assessments of Nat-CSNPs on Danio rerio revealed no significant impact on glucose levels or AST, ALT, and AChE activity, indicating low toxicity. These findings underscore the potent anticancer effects of Nat-CSNPs, particularly inducing apoptosis in MDA-MB-231 and SKOV3 cell lines. While demonstrating low toxicity in Danio rerio, Nat-CSNPs are considered a promising novel anti-cancer drug for breast and ovarian cancer treatment.

In this study, to address the issue of solvent selection in the chemical modification of starch, a method was developed for the efficient esterification of waxy maize starch (WMS) using an acidic deep eutectic solvent composed of choline chloride and acetic acid (CCHAc-ADES). The impact of different mass fractions of CCHAc-ADES on the degree of substitution and reaction efficiency of lauric acid starch esters was explored. It was found that under the conditions of 70 wt% CCHAc-ADES, starch esters with the highest degree of substitution of 0.161 were successfully prepared, achieving an esterification efficiency of 79.63 %. ¹³C and ¹H nuclear magnetic resonance spectroscopy, X-ray diffraction and gel permeation chromatography revealed that CCHAc-ADES acted within the surface voids of WMS particles without seriously damaging the WMS structure, making it a favorable solvent for chemical modification of WMS. By monitoring changes in the morphology, relative crystallinity, particle size, and hydrophobicity of esterified WMS in CCHAc-ADES, the formation mechanism of lauric acid starch esters was inferred, primarily related to the competitive hydrogen bonding of CCHAc-ADES with WMS. The method proposed in this study allows for the preparation of long-chain fatty acid starch esters without the use of any additional chemicals or enzymes, offering significant guidance for the application of deep eutectic solvents in green synthesis.

During a synthesis of the well-known and useful building block 6^A-F-hexa-O-tert-butyldimethylsilyl α-cyclodextrin (2) by silylation of α-cyclodextrin (1) we isolated as a byproduct the oversilylated 2^A,6^A-F-hepta-O-tert-butyldimethylsilyl α-cyclodextrin (3) where one 2-OH group has also been silylated. This unsymmetrical new compound has a remarkable ¹H NMR spectrum in CDCl₃ where all 11 alcohol groups are visible. We have analyzed the spectrum of 3 using 1D and 2D 800 MHz NMR and are able to assign all the 11 alcohol protons. The remarkable chemical shifts of these protons are interpreted as being due to a partial disruption of an otherwise efficient hydrogen bond network.

With the expanding use of phosphates as leaving groups in sialylations, little remains known about the C-5 effect towards their reactivity and stereoselectivity in the presence of a range of acceptors, and in different solvents. Herein we report the comparison between sialyl phosphate donors bearing N-acetyloxazolidinone and trifluoroacetamido functionalities at C-5. Excellent results and complete stereoselectivity were observed in several sialylations, but the outcome was influenced by the nature of the solvent and/or glycosyl acceptor.

Nickel, an essential transition metal, plays a vital role in biological systems and industries. However, exposure to nickel can cause severe health issues, such as asthma, dermatitis, pneumonitis, neurological disorders, and cancers of the nasal cavity and lungs. Due to nickel's toxicity and extensive industrial use, efficient sensors for detecting Ni²⁺ ions in environmental and biological contexts are essential. Carbohydrates, with their inherent water solubility and biocompatibility, are ideal for constructing chemosensors. Incorporating a pyridyl group enhances the selectivity and sensitivity of these sensors. We present a carbohydrate-derived colorimetric chemosensor 5-(2'-Pyridoylethene-1'-yl)-4-(2''-phenylethene-1''-yl)-2,3-O-isopropylidene-2,3-dihydrofuran-2,3-diol (7a) that exhibits a distinct colour change and significant fluorescence quenching upon binding with Ni²⁺ ions. The synthesis of receptor (7a) was validated by using ¹H, ¹³C NMR, HRMS, and single crystal X-ray analysis. Detection limit of receptor (7a) for Ni²⁺ was calculated to be 0.97 μM, which is below the standard (1.2 μM) set by the United States Environmental Protection Agency (EPA). The binding ratio of receptor (7a) to Ni²⁺ was determined to be 1:1 by using Job's plot. The binding constant of receptor (7a) and Ni²⁺ was calculated as 4.38 × 10⁴ M^-1 by using the Benesi-Hildebrand equation. This sensor demonstrates exceptional selectivity for Ni²⁺ ions over other metal cations. Receptor (7a) is stable and can be used to detect Ni²⁺ in the range of pH from 6 to 10. The sensor responded to Ni²⁺ ions selectively and a large number of coexisting ions showed almost no obvious interference with the detection. Our findings shed light on the potential of carbohydrate-derived chemosensors for nickel detection, paving the way for further exploration in this field. The binding mechanism of receptor (7a) to Ni²⁺ ions was proposed by Job's plot, UV-vis spectra and DFT (Density Functional Theory) calculations.