Carbohydrate Research最新文献

This study aimed to evaluate the impact of carboxymethylation on the structural and functional properties of β-glucan derived from the pathogenic oomycete Pythium insidiosum. β-Glucan was extracted and subjected to carboxymethylation (CM-glucan), with structural changes analyzed using ¹³C and ¹H NMR spectroscopy. The modified β-glucan's ability to adsorb mycotoxins, specifically deoxynivalenol (DON) and T2 toxin, was assessed through in vitro adsorption assays. Results demonstrated that the adsorption of DON by CM-glucan increased from 0 % to 59.11 %, corresponding to the adsorption of approximately 1.18 μg of DON from the initial concentration (2 μg/mL). Similarly, the adsorption of T2 toxin increased slightly from 0 % to 4.54 %, corresponding to 0.09 μg of T2 toxin adsorbed from the initial concentration (2 μg/mL). These findings underscore the potential of chemical modifications to enhance the functional properties of natural polysaccharides, suggesting future applications in mycotoxin adsorption and other biological properties across various areas.

Seaweeds are natural sources of sulfated polysaccharides (SPs), biopolymers with remarkable pharmacological properties, including biological actions capable of attenuating components of the inflammatory process such as edema, cytokines, cell migration and pain. Our results confirm that SPs obtained from Gracilaria domingensis (SP-GD) are agarans, primarily composed of residues of β-d-galactopyranose 6-sulfate and 3,6-anhydro-α-l-galactopyranose. Specifically, SP-GD at a dose of 10 mg/kg was effective in significantly reducing paw edema induced by carrageenan or histamine, serotonin, bradykinin, 48/80 and prostaglandin E2. SP-GD (10 mg/kg) was also able to reduce neutrophil migration and the activity of the myeloperoxidase enzyme in carrageenan-induced peritonitis, as well as conserve glutathione concentration and reduce malondialdehyde levels in the animals' peritoneal fluid. Furthermore, it showed antinociceptive action in the abdominal writhing test induced by acetic acid and in the paw licking test induced by formalin. Thus, the results obtained allow us to infer that SPs extracted from G. domingensis at a dose of 10 mg/kg have anti-inflammatory effects by reducing neutrophil migration and modulating the activity of vasoactive mediators and antinociceptive effects by acting, at least in part, through a peripheral mechanism dependent on the negative modulation of inflammatory mediators.

The mucus layer on epithelial cells is an essential barrier, as well as a nutrient-rich niche for bacteria, forming a dynamic, functional and symbiotic ecosystem and first line of defense against invading pathogens. Particularly bacteria in biofilms are very difficult to eradicate. The extensively O-glycosylated mucins are the main glycoproteins in mucus that interact with microbes. For example, mucins act as adhesion receptors and nutritional substrates for gut bacteria. Mucins also play important roles in immune responses, and they control the composition of the microbiome, primarily due to the abundance of complex O-glycans. In inflammation or infection, the structures of mucin O-glycans can change and thus affect mucin function, impact biofilm formation and the induction of virulence pathways in bacteria. In turn, bacteria can support host cell growth, mucin production and can stimulate changes in the host immune system and responses leading to healthy tissue function. The external polysaccharides of bacteria are critical for controlling adhesion and biofilm formation. It is therefore important to understand the relationships between the mucus layer and microbes, the mechanisms and regulation of the biosynthesis of mucins, of bacterial surface polysaccharides, and adhesins. This knowledge can provide biomarkers, vaccines and help to develop new approaches for improved therapies, including antibiotic treatments.

Synthetic and natural polymers are widely used for constructing drug delivery systems. Biocompatibility, water solubility and non-toxicity make polymers a convenient matrix for encapsulation, delivery and release of bioactive compounds. Coupling of a drug with a biodegraded polymer matrix is a promising way for a controlled drug delivery. Along this line, the degradation of the four polymers in the presence of two enzymes in aqueous solutions was investigated. The following polymers were used: natural polysaccharides, sodium alginate and sodium hyaluronate, artificial (modified) sodium carboxymethylcellulose and synthetic sodium polyacrylate (control); their degradation was caused by the addition of alginate lyase and hyaluronidase. The first enzyme only cleaved the specific alginate substrate and left three other intact. Contrastingly, the second enzyme degraded all three polysaccharides, including artificial carboxymethylcellulose, but did not degrade synthetic polyacrylate. The biodegradation of polymers was accompanied by decreasing the size of polymer particles in solution from 100 to 200 nm down to 20-30 nm; the latter are capable of removing from the body through the kidneys. The initial polysaccharides showed the negative surface charge in aqueous solution, which changed but retained negative after biodegradation. The initial and biodegraded polysaccharides demonstrated negligible cytotoxicity during long exposure period. The obtained results are valuable for the development of polymer carriers for drug encapsulation and delivery.

In this study, we prepared granulated chitosan (G-CS)/catechin tablets with excellent disintegration properties. We then compared their physical properties, dissolution behavior, and pharmacokinetic profile to non-granulated chitosan (N-CS)/catechin tablets. During the tableting process, the G-CS/catechin tablets demonstrated significantly higher compatibility and superior manufacturability, as evidenced by lower ejection and detachment stress than the N-CS/catechin tablets. This resulted in more robust tablets with better physical properties. The dissolution of catechin from the G-CS/catechin tablets occurred significantly faster than from the N-CS/catechin tablets, resulting in a significantly higher 2,2'-azino-bis(3 ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity. Similarly, the primary catechin components of the tablets, epigallocatechin gallate (EGCG) and caffeine, showed faster dissolution and membrane uptake from the G-CS/catechin tablets. These indicate a more efficient tablet formulation than N-CS/catechin tablets. Furthermore, the absorption and bioavailability of EGCG and caffeine in rats were significantly higher after oral administration of the G-CS/catechin tablets than the N-CS/catechin tablets. These findings suggest that G-CS/catechin tablets, having better disintegration properties than N-CS/catechin tablets, could allow for combination with other supplements, leading to the design of highly efficient supplement combination tablets.

Capsular polysaccharides (CPS) of Acinetobacter baumannii is a virulence factor with diverse structures. CPS are produced by the CPS biosynthesis gene cluster in their K locus (KL). However, CPS variations may occur due to insertion of additional genes from external sources, e.g., prophages. Recently, the CPS structure from a clinical isolate, BAL062 which includes KL58 locus, was found to have a pseudaminic acid isomer (8ePse5NAc7NAc) as a result of prophage inserted epaA/epaB genes. Here, we report a CPS structure produced by A. baumannii strain MRSN31468 which also belongs to a KL58 type. The K58 CPS structure was determined by 1D and 2D NMR analysis of the oligosaccharides derived from the CPS by a phage depolymerase, and supported by the sugar composition analysis. The K58 CPS structure has the following tetra saccharide repeating unit. The K58 CPS differs from the CPS from BAL062 only by replacing 8-epimerized β-8ePse5NAc7NAc with β-Pse5NAc7NAc.

Chitosan derivatives, including O-carboxymethyl chitosan (CMC), N-(2-hydroxypropyltrimonium chloride)-O-carboxymethyl chitosan (QCMC), and N-(2-hydroxypropyltrimonium chloride)-O-dodecylylpyridine chitosan quaternary ammonium salt (DQCMC), were synthesized and characterized using Fourier transform infrared (FTIR) spectroscopy, ¹H nuclear magnetic resonance (¹H NMR) spectroscopy, Ultraviolet-visible (UV-vis) spectroscopy, and element analysis (EA). The antibacterial activities of chitosan and chitosan derivatives against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were evaluated through the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antibacterial rate assays. Results demonstrated that DQCMC exhibited significantly higher antibacterial efficacy compared to chitosan, CMC, and QCMC. The MIC of DQCMC against E. coli and S. aureus were 31 μg/mL and 7 μg/mL, respectively, with a 100 % antibacterial rate at a concentration of 0.5 mg/mL. Furthermore, assessment of mouse fibroblast (L929) cell viability using cell counting kit-8 (CCK-8) methods revealed no toxicity associated with the material.

Photoredox catalysis has recently emerged as a powerful approach for preparing oligosaccharides because it uses mild conditions, is compatible with partially or completely unprotected carbohydrate substrates, and exhibits impressive regio- and stereo-selectivity and high functional group tolerance. However, most catalytic photoredox reactions require an external photocatalyst (organic dye or expensive transition-metal complex) to deliver key glycosyl radicals. Several photocatalyst-free photocatalytic reactions that avoid the use of expensive metal salts or organic-dye additives have received significant attention. In this review, we highlight the most recent developments in photocatalyst-free light-promoted carbohydrate synthesis and modification, which is expected to inspire broad interest in further innovations in the green synthesis of saccharides.

Methyl 5-thio-α-d-galactopyranoside was synthesized and found to have a more favorable enthalpy of binding to Jacalin than methyl α-d-galactopyranoside, which is attributed to the greater magnitude of sulfur-π over oxygen-π interactions. This increase in enthalpy, however, was offset by a less favorable entropy of binding, arising from the need to constrain the more flexible thiosugar, thereby highlighting the complexities inherent in the design of effective sugar mimetics.