Acid-Base Cascades in Zeotype Single Crystal for Sugar Conversion.

The chemically catalyzed production of fructose syrup from high concentrations of glucose is crucial for the food industry and biorefining. In this work, a single crystal catalyst was synthesized via protective desilication of zeolite while incorporating indium. Glucose was isomerized in methanol at concentrations as high as 33 wt % before being hydrolyzed with water. The final fructose production was 54.9 %, with 89.1 % selectivity and 93.3 % sugar recovery, the highest isomerization rate at the highest concentration ever reported. Indium was present in the single-crystal catalyst as oxide nanoparticles and boundary framework atoms, and it achieved intelligent cooperation in the production of fructose syrup in methanol by catalyzing isomerization and selective glycosidation, minimizing degradation due to fructose accumulation and eliminating side reactions. This study contributed to the advancement of the industrial practice of chemically catalyzed glucose isomerization.

Rational Positioning of Metal Ions to Stabilize Open Tin Sites in Beta Zeolite for Catalytic Conversion of Sugars.

Via hydrothermal synthesis of Sn-Al gels, mild dealumination and ion exchange, a bimetallic Sn-Ni-Beta catalyst was prepared which can convert glucose to methyl lactate (MLA) and methyl vinyl glycolate (MVG) in methanol at yields of 71.2 % and 10.2 %, respectively. Results from solid-state magic-angle spinning nuclear magnetic resonance, X-ray photoelectron spectroscopy, transmission electron microscopy, spectroscopic analysis, probe-temperature-programmed desorption, and density functional theory calculations conclusively reveal that the openness of the Sn sites, such as by the formation of [(SiO)3 -Sn-OH] entities, is governed by an adjacent metal cation such as Ni2+ , Co2+ , and Mn2+ . This relies on the low structure-defective pore channel, provided by the current synthesis scheme, and the specific silica hydroxyl anchor point is associated with the incorporation of Sn for additional and precise metal ion localization. The presence of metal cations significantly improved the catalytic performance of Sn-Ni-Beta for glucose isomerization and conversion to MLA of sugar compared with Sn-Beta.

Preliminary characterization and antioxidant and hypoglycemic activities in vivo of polysaccharides from Huidouba.

Here, the antioxidant and hypoglycemic activities of polysaccharides from Huidouba were preliminarily characterized. Two novel polysaccharides, HDBP-1 and HDBP-2 (127.33 kDa and 9.703 kDa, respectively), were purified by ultrafiltration using a Sephadex G-200 column and then characterized by high-performance gel permeation chromatography (HPGPC), high-performance liquid chromatography (HPLC), infrared spectroscopy (FT-IR), GC-MS, NMR and the Congo red test. HDBPs (crude Huidouba polysaccharide (CHDBP), HDBP-1 and HDBP-2) exhibited significant antioxidant and α-glucosidase inhibitory activities in vitro. In addition, in vivo hypoglycemia experiments in mice revealed that CHDBP, HDBP-1 and HDBP-2 demonstrated active roles in reversing diabetic symptoms. These polysaccharides decreased the serum triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels and significantly improved oral glucose tolerance (OGT), indicating that HDBPs suppressed obesity and alleviated insulin resistance. Moreover, HDBP-2 with lower molecular weight performed better in antioxidant capacity, α-glucosidase-inhibiting activity and hypoglycemic activity. These results suggest that HDBPs have the potential to be functional foods with hypoglycemic properties.