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Yan J.-K.,Jiangsu University | Wang W.-Q.,Hong Kong Polytechnic University | Ma H.-L.,Jiangsu University | Ma H.-L.,Physical Processing of Agricultural Products Key Laboratory of Jiangsu Province | Wu J.-Y.,Hong Kong Polytechnic University
Molecules | Year: 2013

EPS-1 was an exopolysaccharide produced by the medicinal fungus Cordyceps sinensis (Cs-HK1). In the present study, EPS-1 was sulfated with chlorosulfonic acid (CSA)-pyridine (Pyr) at different volume ratios, yielding four sulfated derivatives, SEPS-1A, B, C and D, with different degrees of substitution (DS: 0.25-1.38) and molecular weights (17.1-4.1 kDa). The sulfation of EPS-1 occurred most frequently at the C-6 hydroxyl groups due to their higher reactivity. In aqueous solution, the native EPS-1 formed random coils or aggregated networks, but the sulfated derivatives formed single helices. The antioxidant activities of the sulfated EPS-1 derivatives for scavenging hydroxyl radicals (·OH) and 2,2-Azinobis-3-ehtylbenzothiazolin-6-sulfonic acid radicals (ABTS·+) were significantly increased with increasing DS and decreasing molecular weight (MW). Sulfation has thus been shown to be an effective and favorable strategy for improving the physico-chemical properties and bioactivities of fungal polysaccharides. © 2013 by the authors. Source


Yan J.-K.,Jiangsu University | Yan J.-K.,Physical Processing of Agricultural Products Key Laboratory of Jiangsu Province | Ma H.-L.,Jiangsu University | Ma H.-L.,Physical Processing of Agricultural Products Key Laboratory of Jiangsu Province | And 6 more authors.
Food Chemistry | Year: 2014

Regioselective oxidation was applied to commercial curdlan for the preparation of its water-soluble derivatives with improved antioxidant activities, using a 4-acetamido-2, 2, 6, 6-tetramethylpiperidine-1-oxyl radical/NaClO/NaClO2 system at pH 4.8 and 40 °C. The structural features, molecular properties, and chain conformations of the oxidised curdlans were determined using Fourier transform (FT) infrared and FT Raman spectroscopy, carbon nuclear magnetic resonance, X-ray diffraction, and size-exclusion chromatography with multi-angle laser-light scattering analyses. The C6 primary hydroxyls of curdlan were successfully oxidised into carboxylate groups with less depolymerization, and no aldehyde groups were formed during oxidation. The crystalline region of curdlan was destroyed after oxidation. The oxidised curdlans formed random coils in aqueous solution, and the chain became more flexible and expanded with increasing carboxylate contents from 2.07 mmol/g to 4.87 mmol/g. The high polyglucuronic acid derivative (Cur-24) showed the best antioxidant activity in TEAC and FRAP assays, thus it could be explored as novel potential antioxidants for dietary and therapeutic applications. © 2013 Elsevier Ltd. All rights reserved. Source


Yan J.-K.,Jiangsu University | Yan J.-K.,Physical Processing of Agricultural Products Key Laboratory of Jiangsu Province | Yan J.-K.,South China University of Technology | Cai P.-F.,Jiangsu University | And 4 more authors.
Journal of Inorganic and Organometallic Polymers and Materials | Year: 2013

In the present work, the interaction between bovine serum albumin (BSA) and as-synthesized silver nanoparticles (Oc-AgNPs) by using 4-acetamido-TEMPO-oxidized curdlan (Oc), as a reducing and stabilizing agent, was studied through fluorescence quenching method, ultraviolet visible spectrum (UV-Vis), and circular dichroism measurement. The results presented clearly indicate that the intrinsic fluorescence of BSA molecule was effectively quenched after the interaction with Oc-AgNPs by a static mechanism, which is further confirmed by UV-Vis analysis. The apparent binding constant (K), number of binding sites (n), and dissociation equilibrium constant (KD) were calculated to be 7.5 × 105 M-1, 1.03, and 3.0 ± 0.6 μM, respectively. Furthermore, a conformational change of BSA was also observed when the Oc-AgNPs-BSA interactant formed. © 2013 Springer Science+Business Media New York. Source


Yana J.-K.,Physical Processing of Agricultural Products Key Laboratory of Jiangsu Province | Cai P.-F.,Jiangsu University | Cao X.-Q.,Jiangsu University | Maa H.-L.,Physical Processing of Agricultural Products Key Laboratory of Jiangsu Province | And 3 more authors.
Carbohydrate Polymers | Year: 2013

A facile, simple, and eco-friendly method using 4-acetamido-2,2,6,6- tetramethypiperidine-1-oxyl radical-oxidized curdlan (Oc) as both reducing and stabilizing agents was developed for the fabrication of silver nanoparticles (AgNPs) from silver nitrate (AgNO3). The structure, morphology, and particle size of the as-prepared AgNPs were investigated by ultraviolet-visible spectroscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and dynamic laser light scattering. The well-dispersed AgNPs were sphere like with a mean diameter of 15 nm. Their formation was dependent on reaction duration, reaction temperature, Oc concentration, and AgNO3 concentration. Fourier transform-infrared and Raman spectra demonstrated that the as-prepared AgNPs can readily bind covalently with the carboxylate groups of Oc through the strong monodentate interaction in the reaction medium. © 2013 Elsevier Ltd. All rights reserved. Source


Yan J.-K.,Jiangsu University | Yan J.-K.,Physical Processing of Agricultural Products Key Laboratory of Jiangsu Province | Wang Y.-Y.,Jiangsu University | Ma H.-L.,Jiangsu University | And 3 more authors.
Ultrasonics Sonochemistry | Year: 2016

In this study, a high-molecular-weight polysaccharide PL-N isolated from the alkaline extract of Phellinus linteus mycelia was degraded by ultrasound. Results showed that ultrasound treatment at different ultrasonic intensities decreased the intrinsic viscosity and molecular weight of PL-N, as well as narrowed the molecular weight distribution. A larger reduction in intrinsic viscosity and molecular weight was caused by a higher ultrasonic intensity. The degradation kinetics model was fitted to (1/Mt - 1/M0) = k·t, and the reaction rate constant (k) increased with increasing ultrasonic intensity. Ultrasound degradation did not change the primary structure of PL-N, and scanning electron microscopy analysis indicated that the morphology of the original PL-N was different from that of degraded PL-N fractions. Antioxidant activity assays in vitro indicated that the degraded PL-N fraction with low molecular weight had stronger hydroxyl radical scavenging capacity and higher TEAC and FRAP values. © 2015 Elsevier B.V. All rights reserved. Source

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