Au@h-Al2O3 Analogic Yolk–Shell Nanocatalyst for Highly Selective Synthesis of Biomass-Derived D-xylonic Acid via Regulation of Structure Effects

Selective oxidation of biomass-based monosaccharides into value-added sugar acids is highly desired, but limited success of producing D-xylonic acid has been achieved. Herein, we report an efficient catalyst system, viz., Au nanoparticles anchored on the inner walls of hollow Al2O3 nanospheres (Au@h- Al2O3), which could catalyze the selective oxidation of D-xylose into D-xylonic acid under base-free conditions. The mesoporous Al2O3 shell as the adsorbent first adsorbed D-xylose. Then, the interface of Au nanoparticles and Al2O3 as active sites spontaneously dissociated O2, and the exposed Au nanoparticle surface as the catalytic site drove the transformation. With this catalyst system, the valuable D-xylonic acid was produced with excellent yields in the aerobic oxidation of D-xylose. Extensive investigation showed that Au@h- Al2O3 is an efficient catalyst with high stability and recyclability

GLP-1 receptor agonist as a modulator of innate immunity

Glucagon-like peptide-1 (GLP-1) is a 30-amino acid hormone secreted by L cells in the distal ileum, colon, and pancreatic α cells, which participates in blood sugar regulation by promoting insulin release, reducing glucagon levels, delaying gastric emptying, increasing satiety, and reducing appetite. GLP-1 specifically binds to the glucagon-like peptide-1 receptor (GLP-1R) in the body, directly stimulating the secretion of insulin by pancreatic β-cells, promoting proliferation and differentiation, and inhibiting cell apoptosis, thereby exerting a glycemic lowering effect. The glycemic regulating effect of GLP-1 and its analogues has been well studied in human and murine models in the circumstance of many diseases. Recent studies found that GLP-1 is able to modulate innate immune response in a number of inflammatory diseases. In the present review, we summarize the research progression of GLP-1 and its analogues in immunomodulation and related signal pathways

Interferon-Inducible Cholesterol-25-Hydroxylase Inhibits Hepatitis C Virus Replication via Distinct Mechanisms

Cholesterol 25-hydroxylase (CH25H) as an interferon-stimulated gene (ISG) has recently been shown to exert broad antiviral activity through the production of 25-hydroxycholesterol (25HC), which is believed to inhibit the virus-cell membrane fusion during viral entry. However, little is known about the function of CH25H on HCV infection and replication and whether antiviral function of CH25H is exclusively mediated by 25HC. In the present study, we have found that although 25HC produced by CH25H can inhibit HCV replication, CH25H mutants lacking the hydroxylase activity still carry the antiviral activity against HCV but not other viruses such as MHV-68. Further studies have revealed that CH25H can interact with the NS5A protein of HCV and inhibit its dimer formation, which is essential for HCV replication. Thus, our work has uncovered a novel mechanism by which CH25H restricts HCV replication, suggesting that CH25H inhibits viral infection through both 25HC-dependent and independent events

Microwave-assisted Extraction of Polysaccharides from Bamboo (Phyllostachys acuta) Leaves and their Antioxidant Activity

Polysaccharides were isolated from Phyllostachys acuta leaves by microwave-assisted extraction under various temperatures and time. The obtained polysaccharides were characterized by acid hydrolysis, the Folin-Ciocalteu method, and Fourier transform infrared spectroscopy (FTIR). The major monosaccharides presented in the extracts were arabinose (258.0 mg/g to 414.5 mg/g), galactose (167.0 mg/g to 289.2 mg/g), and glucose (157.4 mg/g to 246.7 mg/g) along with some mannose, fructose, and xylose. The total phenol yield of the bamboo leaves was 0.31 mg/g to 0.73 mg/g. The FTIR spectra revealed that the polysaccharides mostly consisted of β-glycosidic linkages. For the cytotoxicity, the presence of polysaccharides considerably elevated the multiplication of HepG2 cells and showed no growth inhibition for the samples. For the antioxidant activities, the polysaccharides exhibited excellent abilities both in the diphenyl picrylhydrazyl radical potential (DPPH) assay and ferric reducing antioxidant potential (FRAP) assay. The results suggest that bamboo leaf polysaccharides have great potential to be applied in the food, healthcare, and pharmaceutical fields

Xylan-Derived Light Conversion Nanocomposite Film

A new type of sustainable light conversion nanocomposite film was fabricated by using carboxymethyl xylan as matrix and xylan-derived carbon dots (CDs) as both light conversion regents and nano reinforcements. The results demonstrate that CDs can not only significantly enhance the mechanical strength of the nanocomposite film because of chemical reaction between CDs and carboxymethyl xylan, but also impart the film with excellent optical properties. With 1.92 wt% CDs, the tensile strength and elastic modulus of the film are increased by 114.3% and 90.7%, respectively. Moreover, the film has typical excitation and emission spectra, enabling the efficient absorption of UV and the conversion of UV to blue light. This xylan-derived light conversion nanocomposite film is expected to be used in agricultural planting and food packaging

Novel hydrophobic hemicelluloses: Synthesis and characteristic

Novel hydrophobic hemicelluloses possessing hydrophobic groups were prepared by the benzylation of wheat straw hemicelluloses with benzyl chloride under the presence of catalyst in an ethanol/water system. In particular, the progress of the benzylation reaction was studied as a function of the volume ratio of ethanol/water from 4:1 to 6:4, the molar ratio of NaOH/anhydroxylose unit in hemicelluloses from 0.6:1 to 1.5:1, the molar ratio of benzyl chloride/anhydroxylose unit in hemicelluloses from 0.5:1 to 2.0:1, reaction temperature 50-80 degrees C, and reaction time 4-20h. Benzylated hemicelluloses with the low degree of substitution from 0.09 to 0.35 were obtained depending on the experimental conditions. The incorporation of benzyl groups into the backbone of hemicelluloses was confirmed by FT-IR and C-13 NMR spectroscopies. The thermal stability increased after the modification of hemicelluloses due to the introduction of benzyl groups. The introduction of benzyl groups endows hemicelluloses with the hydrophobicity, which could be potentially applied in plastic industries. (C) 2012 Elsevier Ltd. All rights reserved