Jinhong Wu

Structural analysis of a pectic polysaccharide from boat-fruited sterculia seeds

The chemical structure of a water-soluble pectic polysaccharide (sterculia APS) isolated from boat-fruited sterculia seeds (Semen Sterculiae Lychnophorae) was elucidated using partial acid hydrolysis, methylation analysis and 1D/2D nuclear magnetic resonance (NMR) spectroscopy. The results of partial acid hydrolysis revealed that sterculia APS contained galacturonic acids and rhamnose units in the backbone, and arabinose, galactose and xylose residues in the branched chains. Combined the methylation analysis results with NMR spectroscopy, a possible structure of APS was proposed as follow: the backbone consisted of the homogalacturonan (HG) named smooth regions by linear linkage of 1,4-α-D-GalpA, and the rhamnogalacturonan-I (RG-I) called hairy ones by the linkage of →4)-α-D-GalpA-(1→2)-α-L-Rhap-(1→partially substituted at O-4 of rhamnose units. The GalpA residues were partially methyl esterified and O-acetylated on C-2 and/or C-3. The side chains were mainly composed of araban and arabinogalactan by the linkages of T-, 1,3-, 1,5-L-Araf and T-, 1,4-, 1,6-, 1,3,6-, 1,3,4-D-Galp, attached to O-4 of the backbone rhamnose units.

Extraction, partial characterization and bioactivity of polysaccharides from boat-fruited sterculia seeds

Three polysaccharides (water-soluble (WSP), alkali-soluble (ASP) and insoluble (IMP)) from boat-fruited sterculia seeds were obtained using different extraction methods. Moisture, ash, protein and total carbohydrate content of WSP, ASP and IMP were analyzed. WSP was rich in glucose, rhamnose, arabinose and galactose while small amount of xylose was also detected. The monosaccharide composition as well its relative content for WSP and ASP were similar. The intrinsic viscosity results demonstrated that ASP had much lower intrinsic viscosity than WSP, indicating partial polysaccharides were degraded into low molecular weight polymers during alkaline extraction. The acute anti-inflammatory bioactive results of polysaccharides indicated that WSP demonstrated an inhibitive effect toward acute inflammation.

Potential of lignin from Canna edulis ker residue in the inhibition of α-d-glucosidase: Kinetics and interaction mechanism merging with docking simulation

In this study, we extracted lignin from Canna edulis ker residue. Its chemical structure, inhibitory activity on α-d-glucosidase, and kinetics as well as interaction mechanism were investigated by using spectrum analysis and docking simulation. The isolated lignin was composed by guaiacyl and syringal units, and exhibited stronger inhibition on α-d-glucosidase than acarbose with the half maximal inhibitory concentration at 5.3±0.3μM. It was a non-competitive inhibitior with Km and Ki values of 0.53±0.02mM and 0.92±0.12μM, respectively. It could quench the intrinsic fluorescence of α-d-glucosidase through a static quenching mode. The calculated values of enthalpy and entropy change were 20.8±2.5kJmol-1 and 172.7±0.8Jmol-1K-1, respectively. There was a single binding site on α-d-glucosidase for lignin, and the binding distance was 3.2nm. The molecular docking analysis exhibited that the hydrogen bonds, hydropholic interaction, and van der Waals forces were the main forces for lignin bind to α-d-glucosidase. This work provides a new insight into the interaction between the lignin and α-d-glucosidase, which might be beneficial to type 2 diabetes with the application of lignin in functional food and pharmacy fields.

Functional Properties and Morphological Characters of Soluble Dietary Fibers in Different Edible Parts of Angelica Keiskei

This study comparatively investigated the functional properties, chemical compositions, and morphological characters of soluble dietary fibers (SDFs) from the root, stem, and leaf of Angelica keiskei. The SDFs showed relevant functional properties, with the root SDF (RSDF) exhibiting the highest water-holding capacity (22.6 g/g), oil-holding capacity (6.29 mL/g), swelling capacity (36.6 mL/g), emulsion stability, and fat adsorption (5.66 g/g). Stem SDF (SSDF) gave the highest foam stability, toxic ions adsorption (Pb: 1.12 mg/g; As: 3.22 mg/g), and bile acid salts adsorption (sodium cholate: 85.6 mg/g; sodium glycocholate: 93.1 mg/g; sodium taurocholate: 125.7 mg/g). RSDF and SSDF presented similar monosaccharide compositions, thermal property, chemical bonds and groups, and irregular, rough, and porous surfaces. It can be concluded that the obtained SDFs, especially for RSDF and SSDF, can be used in the food industry as fiber-rich functional ingredients.

Optimized extraction and molecular characterization of polysaccharides from Sophora alopecuroides L. seeds

Optimized extraction of crude polysaccharides from Sophora alopecuroides L. seeds (CSAP) was firstly investigated, and the results were extraction time 4.15 h, extraction temperature 70.68°C and water/seed ratio 50.99:1 ml/g. At this proximal point, highest yield (10.88%) and relative viscosity (1.2952) were obtained for CSAP, which contained 78.40% sugar, 6.08% protein, 9.71% ash, 7.16% moisture and 1.88% uronic acid. Neutral fractions of F15, F25, F35 and F60 were further obtained via stepwise alcohol precipitation. Results of monosaccharide composition indicated that CSAP and its neutral fractions mainly consisted of mannose and galactose (79.45-97.52%) with M/G ratios of 0.94-1.48, typical for galactomannans, which were demonstrated by FT-IR. Weight-average molecular weight, radius of gyration and hydrodynamic radius were in the same order (F15>F25>F35>F60), whereas the highest intrinsic viscosity was observed for F25. Multiple analyses, including Mark-Houwink-Sakurada exponent (0.48-0.80), persistence length (1.45-3.93 nm), conformation zoning (random coil) and power-law exponent (b>1), showed flexible coils for all neutral fractions. Concerning viscometry, there were no aggregates (K″ 0.60) or coil overlaps (master curve) of F25 in dilute solutions. Relatively weak surface activity of F25 was probably related to its particular chemical structure and proteinaceous moieties closely conjoined.

Investigating inhibitory activity of novel synthetic sericin peptide on α-D-glucosidase: kinetics and interaction mechanism study using a docking simulation

BACKGROUNDnWe synthesised a novel sericin peptide (SP-GI) with α-d-glucosidase inhibitory activity, which has a sequence of SEDSSEVDIDLGN. The kinetics of its peptide-induced inhibition on α-d-glucosidase activity and its interaction mechanism merging with molecular docking were both investigated.nnnRESULTSnSP-GI exhibited significant inhibitory activity with an IC50 of 2.9u2009±u20090.1u2009µmol L-1 and this inhibition was reversible and non-competitive with a Ki value of 1.0u2009±u20090.1u2009µmol L-1 . An interaction study with SP-GI revealed it bound to α-d-glucosidase at a single binding site, resulting in alterations in α-d-glucosidase secondary structure. This led to quenching of intrinsic α-d-glucosidase fluorescence by a static quenching mechanism. Molecular docking results showed that the SP-GI binding site on α-d-glucosidase differed from acarbose, with hydrogen bonding and van der Waals forces being the main binding drivers.nnnCONCLUSIONnThese findings suggest the potential use for SP-GI or other natural sericin peptides as dietary supplements for the treatment of type 2 diabetes.

Effects of high hydrostatic pressure and high pressure homogenization processing on characteristics of potato peel waste pectin

To better understand the effects of high pressure processing on potato peel waste pectins, the structural characteristics, physicochemical properties, and morphological features of the pectin treated with high hydrostatic pressure (HHP) and high pressure homogenization (HPH) at 200u202fMPa for 5u202fmin were studied. The potato peel waste pectins subjected to high pressure treatments exhibited increased galacturonic acid contents as well as decreased esterification degree, (Galu202f+u202fAra)/Rha ratio, and molecular weight. Furthermore, the potato peel waste pectins treated with high pressure had an increased viscosity and improved emulsifying properties. The morphological features, determined by atomic force microscopy, shown the degradation of side chains of the pectin induced by high pressure treatments. The results suggest that high pressure processing is an efficient technique to modify pectin from potato peel waste to a thickener or stabilizer agent, but high pressure homogenization shows a better effect.

The cryoprotective effects of antifreeze peptides from pigskin collagen on texture properties and water mobility of frozen dough subjected to freeze–thaw cycles

This study was to evaluate the effect of antifreeze peptides from pigskin collagen hydrolysates (CoAPPs) on the fermentation properties, texture properties, water distribution and water mobility of dough during freezing and freeze–thaw cycles. The fermentation properties of the frozen dough were more stable in the CoAPPs groups than those of control groups. The texture profile analysis showed that the hardness, gumminess and chewiness of the CoAPPs breads were significantly smaller (Pxa0<xa00.05) than controls. The NMR showed that addition of CoAPPs weakened the influence of the freeze–thaw treatment on water mobility and influenced the water distribution in frozen dough. The results suggest that CoAPPs could potentially serve as a food-origin cryoprotectant in the conventional dough products.

Application of two-phase lamellar model to study the ultrastructure of annealed canna starch: A comparison with linear correlation function

Canna starch was annealed at sub-gelatinization temperature (50°C) with different annealing time. Small angle X-ray scattering (SAXS) was used to estimate the ultrastructure of the annealed starches with the combined two-phase lamellar model and one-dimensional correlation function. The results showed that, upon annealing, water preferably swelled the amorphous regions of canna starch granules while maintained the part of crystalline region, resulted in an increase in amorphous thickness (da) and lamellar repeat distance (d). Power law plots indicates that a mass fractal (self-similar) structure was observed in canna starch, and annealing induces a less compact structure compared to native canna starch (NCS). Correlation analysis showed that no correlation was existed between annealing time and lamellar peak area, width of peak, and volume crystallinity. However, due to the initial degradation of the amorphous region, the volume crystallinity increased significantly with the increase of crystalline thickness (dc).

Investigating lignin from Canna edulis ker residues induced activation of α-amylase: Kinetics, interaction, and molecular docking

The lignin isolated from C. edulis ker residues showed a significant activating effect on α-amylase. Further studies revealed that the isolated lignin formed a 1:1 complex with α-amylase through hydrogen bonding and quenched fluorescence of α-amylase with a static quenching procedure. Binding with lignin led to conformational and granular size changes of α-amylase. Two-dimensional nuclear Overhauser spectroscopy (2D-NOESY) spectra suggested that OH in G units and β-O-4 structure were the major binding sites of lignin on the α-amylase molecule. Molecular docking studies indicated that the binding residue on α-amylase for lignin was not the same as for chloride ions, and the major binding force was hydrogen bonding. Furthermore, the docking results also showed the structural change of lignin induced by α-amylase. Thus, this work provided a new insight into the interaction between lignin from Canna edulis ker residues and α-amylase, which may be beneficial to apply lignin in the food industry.