Characterization of an arabinogalactan isolated from gum exudate of Odina wodier Roxb.: Rheology, AFM, Raman and CD spectroscopy

Structural elucidation and immunomodulatory activities in vitro of type I and II arabinogalactans from different origins of Astragalus membranaceus

Astragalus membranaceus polysaccharide (APS) possesses excellent immunomodulatory activity. However, there are several studies on the structural characterization of APS. Here, we aimed to elucidate the repeating units of polysaccharides (APS1, 106.5 kDa; APS2, 114.5 kDa) obtained from different Astragalus membranaceus origins and further investigated their immunomodulatory activities. Based on structural analysis, types of the two polysaccharides were identified as arabinogalactan-I (AG-I) and arabinogalactan-II (AG-II), and co-elution of arabinogalactans (AGs) and α-glucan was observed. The backbone of AG-I was 1,4-linked β-Galp occasionally substituted by α-Araf at O-2 and/or O-3. AG-II was a highly branched polysaccharide with long branches of α-Araf, which were attached to the O-3 of 1,6-linked β-Galp of the backbone. The presence of AGs in A. membranaceus was confirmed for the first time. The two polysaccharides could promote the expression of IL-6, IL-1β and TNF-α in RAW264.7 cells via MAPKs and NF-κB signaling pathways. The constants for APS1 and APS2 binding to Toll-like receptor 4 (TLR4) were 1.83 × 10-5 and 2.08 × 10-6, respectively. Notably, APS2 showed better immunomodulatory activity than APS1, possibly because APS2 contained more AGs. Hence, the results suggested that AGs were the vital components of APS in the immunomodulatory effect.

Employing Atomic Force Microscopy (AFM) for Microscale Investigation of Interfaces and Interactions in Membrane Fouling Processes: New Perspectives and Prospects

Membrane fouling presents a significant challenge in the treatment of wastewater. Several detection methods have been used to interpret membrane fouling processes. Compared with other analysis and detection methods, atomic force microscopy (AFM) is widely used because of its advantages in liquid-phase in situ 3D imaging, ability to measure interactive forces, and mild testing conditions. Although AFM has been widely used in the study of membrane fouling, the current literature has not fully explored its potential. This review aims to uncover and provide a new perspective on the application of AFM technology in future studies on membrane fouling. Initially, a rigorous review was conducted on the morphology, roughness, and interaction forces of AFM in situ characterization of membranes and foulants. Then, the application of AFM in the process of changing membrane fouling factors was reviewed based on its in situ measurement capability, and it was found that changes in ionic conditions, pH, voltage, and even time can cause changes in membrane fouling morphology and forces. Existing membrane fouling models are then discussed, and the role of AFM in predicting and testing these models is presented. Finally, the potential of the improved AFM techniques to be applied in the field of membrane fouling has been underestimated. In this paper, we have fully elucidated the potentials of the improved AFM techniques to be applied in the process of membrane fouling, and we have presented the current challenges and the directions for the future development in an attempt to provide new insights into this field.

Polysaccharides from exudate gums of plants and interactions with the intestinal microbiota: A review of vegetal biopolymers and prediction of their prebiotic potential

Polysaccharides in plant-exuded gums are complex biopolymers consisting of a wide range of structural variability (linkages, monosaccharide composition, substituents, conformation, chain length and branching). The structural features of polysaccharides confer the ability to be exploited in different industrial sectors and applications involving biological systems. Moreover, these characteristics are attributed to a direct relationship in the process of polysaccharide enzymatic degradation by the fermentative action in the gut microbiota, through intrinsic interactions connecting bacterial metabolism and the production of various metabolites that are associated with regulatory effects on the host homeostasis system. Molecular docking analysis between bacterial target proteins and arabinogalactan-type polysaccharide obtained from gum arabic allowed the identification of intermolecular interactions provided bacterial enzymatic mechanism for the degradation of several arabinogalactan monosaccharide chains, as a model for the study and prediction of potential fermentable polysaccharide. This review discusses the main structural characteristics of polysaccharides from exudate gums of plants and their interactions with the intestinal microbiota.

Anionic Polysaccharide Cryogels: Interaction and In Vitro Behavior of Alginate-Gum Arabic Composites

In the present study, polysaccharide-based cryogels demonstrate their potential to mimic a synthetic extracellular matrix. Alginate-based cryogel composites with different gum arabic ratios were synthesized by an external ionic cross-linking protocol, and the interaction between the anionic polysaccharides was investigated. The structural features provided by FT-IR, Raman, and MAS NMR spectra analysis indicated that a chelation mechanism is the main process linking the two biopolymers. In addition, SEM investigations revealed a porous, interconnected, and well-defined structure suitable as a scaffold in tissue engineering. The in vitro tests confirmed the bioactive character of the cryogels through the development of the apatite layer on the surface of the samples after immersion in simulated body fluid, identifying the formation of a stable phase of calcium phosphate and a small amount of calcium oxalate. Cytotoxicity tests performed on fibroblast cells demonstrated the non-toxic effect of alginate-gum arabic cryogel composites. In addition, an increase in flexibility was noted for samples with a high gum arabic content, which determines an appropriate environment to promote tissue regeneration. The newly obtained biomaterials that exhibit all these properties can be successfully involved in the regeneration of soft tissues, wound management, or controlled drug release systems.

A Comparison between the Molecularly Imprinted and Non-Molecularly Imprinted Cyclodextrin-Based Nanosponges for the Transdermal Delivery of Melatonin

Melatonin is a neurohormone that ameliorates many health conditions when it is administered as a drug, but its drawbacks are its oral and intravenous fast release. To overcome the limitations associated with melatonin release, cyclodextrin-based nanosponges (CD-based NSs) can be used. Under their attractive properties, CD-based NSs are well-known to provide the sustained release of the drug. Green cyclodextrin (CD)-based molecularly imprinted nanosponges (MIP-NSs) are successfully synthesized by reacting β-Cyclodextrin (β-CD) or Methyl-β Cyclodextrin (M-βCD) with citric acid as a cross-linking agent at a 1:8 molar ratio, and melatonin is introduced as a template molecule. In addition, CD-based non-molecularly imprinted nanosponges (NIP-NSs) are synthesized following the same procedure as MIP-NSs without the presence of melatonin. The resulting polymers are characterized by CHNS-O Elemental, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric (TGA), Differential Scanning Calorimetry (DSC), Zeta Potential, and High-Performance Liquid Chromatography (HPLC-UV) analyses, etc. The encapsulation efficiencies are 60-90% for MIP-NSs and 20-40% for NIP-NSs, whereas melatonin loading capacities are 1-1.5% for MIP-NSs and 4-7% for NIP-NSs. A better-controlled drug release performance (pH = 7.4) for 24 h is displayed by the in vitro release study of MIP-NSs (30-50% released melatonin) than NIP-NSs (50-70% released melatonin) due to the different associations within the polymeric structure. Furthermore, a computational study, through the static simulations in the gas phase at a Geometry Frequency Non-covalent interactions (GFN2 level), is performed to support the inclusion complex between βCD and melatonin with the automatic energy exploration performed by Conformer-Rotamer Ensemble Sampling Tool (CREST). A total of 58% of the CD/melatonin interactions are dominated by weak forces. CD-based MIP-NSs and CD-based NIP-NSs are mixed with cream formulations for enhancing and sustaining the melatonin delivery into the skin. The efficiency of cream formulations is determined by stability, spreadability, viscosity, and pH. This development of a new skin formulation, based on an imprinting approach, will be of the utmost importance in future research at improving skin permeation through transdermal delivery, associated with narrow therapeutic windows or low bioavailability of drugs with various health benefits.

Characterization on structure and bioactivities of an exopolysaccharide from Lactobacillus curvatus SJTUF 62116

This study aimed to investigate the chemical structure, physicochemical properties, antioxidant capacity, antibacterial ability and anti-biofilm formation activity of an exopolysaccharide (EPS) produced by Lactobacillus curvatus SJTUF 62116 from the fish Gymnocypris przewalskii. The purified EPS, denoted as EPS-1, was mainly composed of glucose and mannose at a relative molar ratio of 1:1.05 with molecular weight of 31.9 kDa. The chemical structure of EPS-1 was consisted of →2)-α-D-Manp-(1→, →4)-α-D-Manp-(1→, →3,6)-α-D-Manp-(1→, T-β-D-Glcp-(1→, →6)-β-D-Glcp-(1→, and →3)-β-D-Glcp-(1→ glycosidic bonds. A sheet-like structure of dried EPS-1 was determined by scanning electron microscope (SEM), whilst a peak-shaped structure of EPS-1 was observed by atomic force microscope (AFM). The degradation temperature of EPS-1 was determined as 300.21 °C using thermogravimetric analysis (TGA). Moreover, the antioxidant capacity of EPS-1 at a concentration of 5.0 mg/mL against DPPH and ABTS was 84.50% and 92.53%, respectively. Furthermore, EPS-1 exhibited acceptable bacteriostatic efficacy against S. Enteritidis, E. coli, and S.aureus with significant inhibition of S. Enteritidis biofilm formation.

Isolation and identification of an arabinogalactan extracted from pistachio external hull: Assessment of immunostimulatory activity

This work studies the extraction and purification of a novel arabinogalactan from pistachio external hull. It was extracted with a simple method from pistachio hull which is considered as unexploited waste. Based on the results of sugar analysis by GC-FID, glycosidic linkage by GC-MS, NMR spectroscopy, and molecular weight by Size Exclusion Chromatography, pistachio hull water soluble polysaccharides (PHWSP) were identified as a type II arabinogalactan (AG), with characteristic terminally linked α-Araf, (α1 → 5)-Araf, (α1 → 3,5)-Araf, terminally linked β-Galp, (β1 → 6)-Galp, and (β1 → 3,6)-Galp. DEPT-135, HSQC, HMBC and COSY NMR data suggested the presence of (β1 → 3)-Galp mainly branched at O-6 with (β1 → 6)-Galp chains, α-Araf chains, and terminally linked α-Araf. These AG from pistachio external hulls showed in vitro stimulatory activity for B cells, suggesting their possible use as an immunological stimulant in nutraceutical and biomedical applications.

Defensive strategies of Norway spruce and Kurile larch heartwood elucidated on the micron-level

To decarbonize the building sector, the use of durable wood materials must be increased. Inspiration for environmentally benign wood protection systems is sought in durable tree species depositing phenolic extractives in their heartwood. Based on the hypothesis that the micro-distribution of extractives influences durability, we compared the natural impregnation patterns of non-durable, but readily available Norway spruce to more durable Kurile larch by mapping the distribution of heartwood extractives with Confocal Raman Imaging and multivariate data decomposition. Phenolics of both species were associated with hydrophobic oleoresin, likely facilitating diffusion through the tissue. They accumulated preferentially in lignin-rich sub-compartments of the cell wall. Yet, the distribution of extractives was found not to be the same. The middle lamellae contained flavonoids in larch and aromatic waxes in spruce, which was also found in rays and epithelial cells. Spruce-lignans were tentatively identified in all cell types, while larch-flavonoids were not present in resin channels, hinting at a different origin of synthesis. Larch-oleoresin without flavonoids was only found in lumina, indicating that the presence of phenolics in the mixture influences the final destination. Together our findings suggest, that spruce heartwood-defense focuses on water regulation, while the more efficient larch strategy is based on antioxidants.

Antimicrobial loaded gum odina - gelatin based biomimetic spongy scaffold for accelerated wound healing with complete cutaneous texture

The main objective of this study was to assess the therapeutic activity of gum odina and gelatin based biomimetic scaffold which was previously established as an excellent wound dressing material. In the accelerated stability study, the changes in physicochemical properties were found to be negligible. The cytotoxicity studies were carried out in-vitro and the results showed that upto 90% of the cells remained viable in presence of the scaffold, confirming its biocompatibility. Moreover, results depicted the superior ability of the scaffold to promote cutaneous healing by increasing the rate of wound contraction (about 98%), granulation formation, collagen deposition and formation of an intact epidermis within 18 days. A satisfactory amount of hydroxyproline (240.2 ± 6.67 μg/100 mg tissue) in scaffold treated groups at 21 days ensured the significant deposition of collagen to re-epithelialization. Further it can be hypothesized that the controlled levels of antioxidant enzymes (SOD, CAT) to diminish the oxidative stress in the wounded sites were due to the innate antioxidant properties of both blank and drug loaded scaffold. These results strongly indicated that the prepared scaffolds have strong potential for biomedical applications and it may serve as promising candidate for the next generation of wound treatment systems.

Synthesis, characterization and use of enzyme cashew gum nanoparticles for biosensing applications

This research reports, for the first time, the immobilization of an enzyme - Rhus vernificera laccase - on cashew gum (CG) nanoparticles (NPs) and its application as a biological layer in the design and development of an electrochemical biosensor. Laccase-CG nanoparticles (LacCG-NPs) were prepared by the nanoprecipitation method and characterized by UV-Vis spectrophotometry, atomic force microscopy, scanning electron microscopy, attenuated total reflectance-Fourier-transform infrared spectroscopy, circular dichroism, cyclic voltammetry, and electrochemical impedance spectroscopy. The average size and stability of the NPs were predicted by DLS and zeta potential. The ATR-FTIR results clearly demonstrated an interaction between -NH and -OH groups to form LacCG-NPs. The average size found for LacCG-NPs was 280 ± 53 nm and a polydispersity index of 0.309 ± 0.08 indicated a good particle size distribution. The zeta potential shows a good colloidal stability. The use of a natural product to prepare the enzymatic nanoparticles, its easy synthesis and the immobilization efficiency should be highlighted. LacCG-NPs were successfully applied as a biolayer in the development of an amperometric biosensor for catechol detection. The resulting device showed a low response time (6 s), good sensitivity (7.86 μA μM^-1 cm^-2), wide linear range of 2.5 × 10^-7-2.0 × 10^-4 M, and low detection limit (50 nM).

In vitro fermentation characteristics of polysaccharide from Sargassum fusiforme and its modulation effects on gut microbiota

In this study, polysaccharides from Sargassum fusiforme (SFP) were obtained by cellulase assisted hot water extraction. The chemical composition, structural characteristics, and in vitro fermentation properties of SFP were investigated. Results showed that the contents of total carbohydrate, protein, uronic acid and sulfate in SFP were 83.25%, 1.42%, 12.80% and 7.81%, respectively. It mainly consisted of fucose glucose and galactose, with molecular weight of 255.83 kDa. UV spectrum, FTIR, SEM and AFM results showed that SFP was a typical sulfate polysaccharide with relative smooth surface and regular shape. After in vitro fermentation for 24 h, the pH value of fermentation medium declined significantly (p < 0.05), utilization of carbohydrate was 53.17%. The contents of total SCFAs increased by 10.77 times. Moreover, SFP fermentation could change obviously the microbiota composition. It significantly increased the abundance of Faecalibacterium (increased by 49.07% compared with the Blank24 group), Phascolarctobacterium (increased by 88.06%), Bifidobacterium (increased by 139.13%), Ruminococcaceae_UCG-014 (increased by 177.78%), and Lactobacillus (increased by 400.00%), decreased the abundance of Prevotella_9 (decreased by 34.54%) and Blautia (decreased by 40.79%) at genus level. These results showed that SFP could be utilized by microbiota in human feces, and may have the potential to improve intestinal health.