Structural characterisation of a novel polysaccharide from pseudostellaria heterophylla fibrous root and its anti-inflammatory and antioxidant activities in vitro.

A novel water-soluble polysaccharide, named PF90-1, with a molecular weight of 1.8 kDa, was isolated and purified from the fibrous root of Pseudostellaria heterophylla. PF90-1 is composed of Gal, Glc and Man in a molar ratio of 73.61: 19.11: 7.28. Methylation analysis revealed that PF90-1 comprises of T-Galp, 1,4-Galp, 1,3,4-Galp, 1,2,3,4-Galp, T-Glcp and 1,3-Manp in a molar ratio of 37.89: 9.37: 17.01: 12.01: 15.88: 7.83. Bioactivity experiments showed that PF90-1 significantly improved lipopolysaccharide (LPS)-induced inflammatory damage in RAW264.7 cells by inhibiting nitric oxide (NO) production and reducing the levels of pro-inflammatory factors (IL-1ß and TNF-α). In addition, PF90-1 exhibited strong antioxidant effects, protecting PC12 cells from H2O2-induced oxidative damage. This findings suggest that PF90-1 holds potential therapeutic value for the treatment of inflammatory and oxidative injuries.

Isolation, purification, and biological activities of polysaccharides from Amorpha fruticosa flowers.

The extraction, isolation, structural characterisation and biological activities of polysaccharides from Amorpha fruticosa flowers were investigated. First, the crude polysaccharide AFP was extracted, and two major purified polysaccharide fractions AFP-2 and AFP-3 were isolated. The molecular weight and monosaccharide compositions of AFP-2 and AFP-3 were determined. Then the antioxidant activities of AFP, AFP-2 and AFP-3 were assessed by DPPH radical, ß-Carotene bleaching and hydroxyl radical assays. All three tested polysaccharides showed good antioxidant activity while AFP was the strongest one. The study also showed that AFP, AFP-2 and AFP-3 have good tyrosinase inhibition, moisture absorption and retention activities. The results will provide a helpful reference for the application of polysaccharide from Amorpha fruticosa flowers as a natural cosmetic ingredient.

A new perspective on structural characterisation and immunomodulatory activity of arabinogalactan in Larix kaempferi from Qinling Mountains.

In this study, crude polysaccharide (LAG-C) and homogeneous arabinogalactan (LAG-W) were isolated from Qinling Larix kaempferi of Shaanxi Province. Bioactivity assays showed that LAG-W and LAG-C enhanced the phagocytic ability, NO secretion, acid phosphatase activity, and cytokine production (IL-6, IL-1ß, and TNF-α) of RAW264.7 macrophages. Notably, LAG-W exhibited a significantly stronger immunomodulatory effect than LAG-C. The primary structure of LAG-W was characterised by chemical methods (monosaccharide composition, methylation analysis, and alkali treatment) and spectroscopic techniques (gas chromatography-mass spectrometry, high-performance liquid chromatography-mass spectrometry, and 1D/2D nuclear magnetic resonance). LAG-W was identified as a 22.08 kilodaltons (kDa) neutral polysaccharide composed of arabinose and galactose at a 1:7.5 molar ratio. Its backbone consisted of repeated →3)-ß-Galp-(1→ residues. Side chains, connected at the O-6 position, were mainly composed of T-ß-Galp-(1→ and T-ß-Galp-(1→6)-ß-Galp-(1→ residues. And it also contained small amounts of T-ß-Arap-(1→, T-α-Araf-(1→6)-ß-Galp-(1→6)-ß-Galp-(1→, and T-α-Araf-(1→3)-α-Araf-(1→6)-ß-Galp-(1→ residues. By structurally and functionally characterising L. kaempferi polysaccharides, this study opens the way for the valorisation of this species.

Characterisation of a capsular polysaccharide from Moraxella nonliquefaciens CCUG 348T.

Moraxella nonliquefaciens is a commensal of the human upper respiratory tract (URT) but on rare occasions is recovered in cases of ocular, septic and pulmonary infections. Hence there is interest in the pathogenic determinants of M. nonliquefaciens, of which outer membrane (OM) structures such as fimbriae and two capsular polysaccharide (CPS) structures, →3)-ß-D-GalpNAc-(1→5)-ß-Kdop-(2→ and →8)-α-NeuAc-(2→, have been reported in the literature. To further characterise its surface virulence factors, we isolated a novel CPS from M. nonliquefaciens type strain CCUG 348T. This structure was elucidated using NMR data obtained from CPS samples that were subjected to various degrees of mild acid hydrolysis. Together with GLC-MS data, the structure was resolved as a linear polymer composed of two GalfNAc residues consecutively added to Kdo, →3)-ß-D-GalfNAc-(1→3)-α-D-GalfNAc-(1→5)-α-(8-OAc)Kdop-(2→. Supporting evidence for this material being CPS was drawn from the proposed CPS biosynthetic locus which encoded a potential GalfNAc transferase, a UDP-GalpNAc mutase for UDP-GalfNAc production and a putative CPS polymerase with predicted GalfNAc and Kdo transferase domains. This study describes a unique CPS composition reported in Moraxella spp. and offers genetic insights into the synthesis and expression of GalfNAc residues, which are rare in bacterial OM glycans.

Differences in the Chromogenic Effect of Corn Starch and Potato Starch on Paprika Red Pigment and Structural Characterisation.

The present study aims to investigate the chromogenic effect and the interaction between starch-pigment complexes of corn starch (CS) and potato starch (PS) complexed with paprika red pigment. Compared to PS, CS showed 12.5 times higher adsorption capacity for paprika red pigment. Additionally, the a* value of CS-P (26.90 ± 0.23) was significantly higher than that of PS-P (22.45 ± 1.84), resulting in a corn starch-paprika red pigment complex (CS-P) with a more intense red colour. The addition of paprika red pigment significantly decreased the particle size and porosity of CS by 48.14 ± 5.29% and 17.01 ± 3.80%, respectively. Conversely, no significant impact on PS was observed. Additionally, the Fourier transform infrared (FT-IR) spectroscopy results revealed that the starch molecules and paprika red pigment were bound to each other through strong hydrogen bonds. X-diffraction (XRD) results indicated that the starch-paprika red pigment complexes have a V-shaped structure. Furthermore, the relative crystallinity of the complexes between starch and red pepper pigment showed an increasing trend, however, the relative crystallinity of CS increased significantly by 11.77 ± 0.99-49.21 ± 3.67%. Consequently, the CS-P colouring was good.

Moraxella ovis and Moraxella bovoculi lipooligosaccharide biosynthesis genes, and structural characterisation of oligosaccharide from M. ovis 354T.

Moraxella ovis is a Gram-negative bacterium isolated from sheep conjunctivitis cases and is a rare isolate of infectious bovine keratoconjunctivitis (IBK). This species is closely related to M. bovoculi, another species which can also be isolated from IBK, or cattle upper respiratory tract (URT). Prior to molecular identification techniques, M. bovoculi was frequently misclassified as M. ovis. We previously described the structure of two oligosaccharides (lipooligosaccharide-derived, minor and major glycoforms) from M. bovoculi 237T (type strain, also ATCC BAA-1259T). Here, we have identified the genetic loci for lipooligosaccharide synthesis in M. ovis 354T (NCTC11227) and compared it with M. bovoculi 237T. We identified genes encoding the known glycosyltransferases Lgt6 and Lgt3 in M.ovis. These genes are conserved in Moraxella spp., including M bovoculi. We identified three further putative OS biosynthesis genes that are restricted to M. ovis and M. bovoculi. These encode enzymes predicted to function as GDP-mannose synthases, namely a mannosyltransferase and a glycosyltransferase. Adding insight into the genetic relatedness of M.ovis and M. bovoculi, the M. ovis genes have higher similarity to those in M. bovoculi genotype 2 (nasopharyngeal isolates from asymptomatic cattle), than to M. bovoculi genotype 1 (isolates from eyes of IBK-affected cattle). Sequence analysis confirmed that the predicted mannosyltransferase in M. bovoculi 237T is interrupted by a C>T polymorphism. This mutation is not present in other M. bovoculi strains sequenced to date. We isolated and characterised LOS-derived oligosaccharide from M. ovis 354T. GLC-MS and NMR spectroscopy data revealed a heptasaccharide structure with three ß-D-Glcp residues attached as branches to the central 3,4,6-α-D-Glcp, with subsequent attachment to Kdo. This inner core arrangement is consistent with the action of Lgt6 and Lgt3 glycosyltransferases. Two α-D-Manp residues are linearly attached to the 4-linked ß-D-Glcp, consistent with the presence of the two identified glycosyltransferases. This oligosaccharide structure is consistent with the previously reported minor glycoform isolated from M. bovoculi 237T.

In vitro antioxidant activity of the polysaccharide from Auricularia auricula and its structural characterisation.

A new polysaccharide (AAP) was extracted from Auricularia auricula by water extraction and alcohol precipitation. The antioxidant activity in vitro showed that AAP had a good scavenging effect on ABTS free radicals. Then AAP was purified by DEAE-52 ion exchange chromatography to obtain the purified component pAAP. The structure analysis showed that the molecular weight (Mw) of pAAP was 96.768 kDa, which was composed of rhamnose (Rha), arabinose (Ara), fucose (Fuc), xylose (Xyl), mannose (Man), glucose (Glu) and galactose (Gal), with the ratio of 0.1:0.157:0.33:2.797:2.881:2.988:0.587, and contained α-pyranose configuration and ß-pyranose configuration. Field emission scanning electron microscopy and atomic force microscopy revealed the special conformation of pAAP in the ring and chain shape.

Structural characterisation and structure-antioxidant activity relationship of polysaccharides from Dendrobium catenatum Lindl.

Dendrobium catenatum Lindl. has been long used in China as a functional food and traditional Chinese medicine and polysaccharides from Dendrobium catenatum Lindl. (DOP) exhibited extensive bioactivities. However, studies on the structure-activity relationship of DOP are rarely reported. Here, two polysaccharides named DOP-1 and DOP-2 were obtained, which differed in the ratio of monosaccharide composition and molecular weight. Structural characteristics were elucidated by spectral and chemical analysis. The main structures of DOPs were the linkage of ß-(1→4)-D-Manp, with some attached 2-O- or 3-O-acetylated groups. Additionally, the DPPH, hydroxyl and superoxide radicals scavenging assays of DOP-1 and DOP-2 showed that DOP-2 exhibited the higher antioxidant activity, which might be related to its lower molecular weight, higher mannose proportion and lower degree of acetylation, and higher phenolic content. Our results provide a more accurate basis for the application of DOPs in the pharmaceutical and food industries.

Insights into the Stability of Graphene Oxide Aqueous Dispersions.

Understanding graphene oxide's stability (or lack thereof) in liquid solvents is critical for fine-tuning the material's characteristics and its potential involvement in future applications. In this work, through the use of structural and surface investigations, the alteration of the structural and edge-surface properties of 2D graphene oxide nanosheets was monitored over a period of eight weeks by involving DLS, zeta potential, XRD, XPS, Raman and FT-IR spectroscopy techniques. The samples were synthesized as an aqueous suspension by an original modified Marcano-Tour method centred on the sono-chemical exfoliation of graphite. Based on the acquired experimental results and the available literature, a phenomenological explanation of the two underlying mechanisms responsible for the meta-stability of graphene oxide aqueous dispersions is proposed. It is based on the cleavage of the carbon bonds in the first 3-4 weeks, while the bonding of oxygen functional groups on the carbon lattice occurs, and the transformation of epoxide and hydroxyl groups into adsorbed water molecules in a process driven by the availability of hydrogen in graphene oxide nanosheets.

Nanoencapsulation of green tea extract using maltodextrin and its characterisation.

Nano-particles of green tea extract were prepared by ultrasonication, encapsulated in maltodextrin and were subjected to freeze drying to produce nanoencapsulated powders. Different proportions of 30 % solution of maltodextrin and dry tea extract (1:5; 1:10, 1:15) were combined with a small molecule surfactant (Tween 40). Average particle size of 1:5, 1:10, 1:15 based nano-particles were 380.34, 390.26 and 520.45 nm with encapsulation efficiency of 41.27, 45.92 and 57.51% and with negative surface charge of -22.04, -16.40 and -14.91, respectively. Scanning electron microscopy revealed irregular shapes of nanoencapsulated freeze dried powders with variation in appearance. X-ray diffraction patterns showed very low degree of crystanillity after encapsulation. The nanoencapsulated powders showed characteristic bands in infra-red spectra at âˆ¼ 3200, ∼1600 and âˆ¼ 1140 cm1. Nanocapsules displayed controlled release when compared to free green tea extract under simulated intestinal conditions and all the data showed good correlation with zero order kinetics.

Structural Insight of MOFs under Combined Mechanical and Adsorption Stimuli.

External control over the pore size of flexible metal-organic frameworks (MOFs) has recently emerged as an intriguing concept, with possible applications to gas storage and separation. In this work we present a new pressure cell capable for the first time of monitoring through in situ X-ray powder diffraction an adsorbent powder under combined uniaxial applied mechanical stress (up to 1 GPa) and gas pressure (up to 20 bar). The combined stress-pressure clamp (CSPC) cell was successfully exploited to follow the evolution of the CO2 breathing behaviour of the prototypical complex breathing MIL-53(Al) system under mechanical compression obtaining structural evidence that this MOF can be maintained in its closed pore state upon compression, precluding its re-opening at high gas pressure (>7 bar). This novel setup shows potential for the in-operando exploration of flexible systems, in equilibrium and flow configurations.

The use of optical differential scanning calorimetry to investigate ibuprofen miscibility in polymeric films for topical drug delivery.

Understanding drug miscibility in pharmaceutically relevant systems is essential for the development and optimisation of pharmaceutical dosage forms. This is particularly true for film forming systems which are designed to become supersaturated with drug, following application on the skin surface, whilst maintaining the physical stability of the drug for a suitable period to enhance drug delivery. For such formulations, chemical penetration enhancers as well as the drug are absorbed from the formulation into the skin, making understanding drug delivery from the films challenging. This study investigated the use of an optical differential scanning calorimetry (DSC) to understand drug miscibility in polymeric film forming systems and explain drug transport behaviour from film forming formulations, containing ibuprofen, a copolymer based on dimethylaminoethyl methacrylate, butyl methacrylate, and methyl methacrylate (Eudragit® E, EuE), a copolymer based on ethyl acrylate, methyl methacrylate and methacrylic acid ester with quaternary ammonium groups (Eudragit® RS, EuRS) and a copolymer based on methacrylic acid and methyl methacrylate (Eudragit® S, EuS), with and without the chemical penetration enhancer propylene glycol, across a model membrane. The optical DSC enabled the rapid screening of not only drug-polymer miscibility, but also drug-vehicle miscibility, while considering both the melting-point depression and melting enthalpy of the drug due to the presence of the polymer/polymer-based vehicle, obtained via thermal analysis by structural characterisation (TASC) and DSC analysis, respectively. The results obtained enable the polymers studied to be ranked in the order of EuE > EuRS > EuS, with EuE being more miscible with ibuprofen, and the incorporation of a penetration enhancer in the film forming system formulation was found to increase ibuprofen solubility in EuE- and EuRS- based films. The drug-polymer/vehicle miscibility information obtained via optical DSC provided understanding of drug transport from film forming systems with the higher miscibility of ibuprofen with EuE reducing drug transport through decreasing drug saturation in the film. The higher drug transport from films containing EuRS and EuS could also be linked to drug miscibility with the polymer and showed dependence on ibuprofen loading in the formulation. Overall optical DSC has been demonstrated to be a valuable tool for determining drug-vehicle miscibility for pharmaceutical product development.

Structural characterisation of the oligosaccharide from Moraxella bovoculi type strain 237 (ATCC BAA-1259) lipooligosaccharide.

The Gram-negative bacterium Moraxella bovoculi is associated with infectious bovine keratoconjunctivitis (IBK), colloquially known as 'pink-eye'. IBK is an extremely contagious ocular disease of cattle. We report here the structure of the oligosaccharide derived from the lipooligosaccharide from M. bovoculi type strain 237 (also known as ATCC BAA-1259T). GLC-MS and correlation NMR analysis of the oligosaccharide revealed 5 sugar residues, with a notable central branched 3,4,6-α-D-Glcp. An additional α-D-Manp was present ~30% on the sub-terminal α-D-Manp of the 4-linked branch. This oligosaccharide structure was consistent with other members of the Moraxellaceae where no heptose was present and 5-linked Kdo was directly attached to the central 3,4,6-α-D-Glcp.

Formation mechanisms and characterisation of the typical polymers in melanoidins from vinegar, coffee and model experiments.

Melanoidins, are of increasing interest for their potential biological activities. However, little knowledge is available on their structure. In the present study, vinegar, coffee and model melanoidins were degraded by NaBH4, and the resultant reaction products were characterised by chromatography, mass spectrometry and spectrometry methods to elucidate the mechanism of formation of melanoidin skeleton molecules. The study identified a typical polymer with a molecular weight (MW) interval of 74 Da, which was polymerised by aldol condensation and reduced by NaBH4, followed by intermolecular dehydration. MW of the theoretically derived typical polymers matched the detected polymers, validating the speculated pathway involved in the formation of melanoidins skeleton molecules. The study also revealed that melanoidins from different sources contain polymers with the same MW and different binding preferences, contributing to the heterogeneity of melanoidins. Overall, these findings indicated that the identified polymers could be used as potential candidate biomarkers for melanoidins.

Recent Advances in the Engineering of Single-Atom Catalysts Through Metal-Organic Frameworks.

This mini-review highlights some recent progress in the engineering of single-atom catalysts (SACs) through metal-organic frameworks (MOFs) and derivatives. The inherent molecular and chemical specificities within the MOFs and derivatives can offer stabilisation of the SACs with high atomic isolation and dispersion. As MOFs are often considered an infinite array of self-assembled molecular catalysts, specifically designed structures can provide further functionalities to suit the needs of different catalytic applications. In brief, we can divide the preparation approaches into three main categories: (1) fabrication onto functional groups of the ligands, (2) fabrication onto Lewis acid sites of nodal centres, and (3) synthesis via a pyrolysis-mediated technique. Through these approaches, strong metal-support interactions can be established to aid the fine-tuning of the catalytic properties. We also discuss how recent progress in the development of state-of-the-art microscopic, spectroscopic, and crystallographic techniques has enabled scientists to elucidate the structure-activity relationship.

Recent progress in solid-state nuclear magnetic resonance of half-integer spin low-γ quadrupolar nuclei applied to inorganic materials.

An overview is presented of recent progress in the solid-state nuclear magnetic resonance (NMR) observation of low-γ nuclei, with a focus on applications to inorganic materials. The technological and methodological advances in the last 20 years, which have underpinned the increased accessibility of low-γ nuclei for study by solid-state NMR techniques, are summarised, including improvements in hardware, pulse sequences and associated computational methods (e.g., first principles calculations and spectral simulation). Some of the key initial observations from inorganic materials of these nuclei are highlighted along with some recent (most within the last 10 years) illustrations of their application to such materials. A summary of other recent reviews of the study of low-γ nuclei by solid-state NMR is provided so that a comprehensive understanding of what has been achieved to date is available.

Structural and Magnetic Properties of FePd Thin Film Synthesized by Electrodeposition Method.

Bimetallic nanomaterials in the form of thin film constituted by magnetic and noble elements show promising properties in different application fields such as catalysts and magnetic driven applications. In order to tailor the chemical and physical properties of these alloys to meet the applications requirements, it is of great importance scientific interest to study the interplay between properties and morphology, surface properties, microstructure, spatial confinement and magnetic features. In this manuscript, FePd thin films are prepared by electrodeposition which is a versatile and widely used technique. Compositional, morphological, surface and magnetic properties are described as a function of deposition time (i.e., film thickness). Chemical etching in hydrochloric acid was used to enhance the surface roughness and help decoupling crystalline grains with direct consequences on to the magnetic properties. X-ray diffraction, SEM/AFM images, contact angle and magnetic measurements have been carried out with the aim of providing a comprehensive characterisation of the fundamental properties of these bimetallic thin films.

2-furyl(phenyl)methanol isolated from Atractilis gummifera rhizome exhibits anti-leishmanial activity.

We report for the first time the isolation of 2-furyl(phenyl)methanol (5) from the chloroform extracts of the Atractylis gummifera roots. A. gummifera is a thistle belonging to the Asteraceae family that produces the ent-kaurane diterpenoid glycoside atractyloside (ATR). ATR (1) was isolated and chemically modified to obtain its aglycone atractyligenin (2) and the methylated derivatives ATR-OMe (3) and genine-OMe (4). The compounds 1-5 were structurally characterised and evaluated against the intracellular amastigote, cultured within macrophages, and the extracellular promastigote of Leishmania donovani, the protozoan parasite responsible for the highly infective disease visceral leishmaniasis, which is fatal if untreated. The 2-furyl(phenyl)methanol 5 exhibited notable activity against the promastigote.

X-ray microfocus computed tomography: a powerful tool for structural and functional characterisation of 3D printed dosage forms.

One of the most promising advances in modern pharmaceutical technology is the introduction of three-dimensional (3D) printing technology for the fabrication of drug products. 3D printed dosage forms have the potential to revolutionise pharmacotherapy as streamlined production of structurally complex formulations with optimal drug releasing properties is now made possible. 3D printed formulations are derived as part of a process where a 'print-head' deposits, or sinters material under computer control to produce a drug carrier. However, this manufacturing route inherently generates objects that deviate from the ideal designed template for reasons specific to the 3D printing method used. This short opinion article discusses the potential of high-resolution nondestructive 3D (volume) imaging by means of X-ray microfocus Computed Tomography (µCT) as a Process Analytical Technology for the structural and functional characterisation of 3D printed dosage forms.

Membrane protein nanoparticles: the shape of things to come.

The use of styrene-maleic acid (SMA) for the purification of a wide range of membrane proteins (MPs) from both prokaryotic and eukaryotic sources has begun to make an impact in the field of MP biology. This method is growing in popularity as a means to purify and thoroughly investigate the structure and function of MPs and biological membranes. The amphiphilic SMA copolymer can effectively extract MPs directly from a native lipid bilayer to form discs ∼10 nm in diameter. The resulting lipid particles, or styrene-maleic acid lipid particles (SMALPs), contain SMA, protein and membrane lipid. MPs purified in SMALPs are able to retain their native structure and, in many cases, functional activity, and growing evidence suggests that MPs purified using SMA have enhanced thermal stability compared with detergent-purified proteins. The SMALP method is versatile and is compatible with a wide range of cell types across taxonomic domains. It can readily be adapted to replace detergent in many protein purification methods, often with only minor changes made to the existing protocol. Moreover, biophysical analysis and structural determination may now be a possibility for many large, unstable MPs. Here, we review recent advances in the area of SMALP purification and how it is affecting the field of MP biology, critically assess recent progress made with this method, address some of the associated technical challenges which may remain unresolved and discuss opportunities for exploiting SMALPs to expand our understanding of structural and functional properties of MPs.