Ronge Xing

Antioxidant activity of different molecular weight sulfated polysaccharides from Ulva pertusa Kjellm (Chlorophyta)

Polysaccharides extracted from Ulva pertusa Kjellm (Chlorophyta) are a group of sulfated heteropolysaccharides, the ulvans. In this study, different molecular weight ulvans were prepared by H2O2 degradation and their antioxidant activities investigated including superoxide and hydroxyl radical scavenging activity, reducing power and metal chelating ability. The molecular weights of natural and degraded ulvans were 151.7, 64.5, 58.0, and 28.2 kDa, respectively, as determined by high performance gel permeation chromatography. Among the four samples, U3 (the lowest molecular weight sample) showed significant inhibitory effects on superoxide and hydroxyl radicals with IC50 values of 22.1 μ g mL−1 and 2.8 mg mL−1; its reducing power and metal chelating ability were also the strongest among the four samples. All the other samples also demonstrated strong activity against superoxide radicals. The results indicated that molecular weight had a significant effect on the antioxidant activity of ulvan with low molecular weight ulvan having stronger antioxidant activity.

Facile Template-Free Fabrication of Hollow Nestlike α-Fe2O3 Nanostructures for Water Treatment

Hollow nestlike α-Fe(2)O(3) spheres were successfully synthesized via a facile template-free, glycerol-mediated hydrothermal process employing microwave heating. The product was characterized using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption measurements. The as-prepared product was found to consist of hierarchically nanostructured spheres assembled of nanorod subunits. The effect of the relative amount of glycerol in the reaction system on the composition and morphology of the products was systematically studied, and a possible formation mechanism of the hollow nestlike spheres was proposed. Because of their large surface area and unique mesoporous structure, we investigated the potential application of the hollow α-Fe(2)O(3) spheres in water treatment. With maximum removal capacities of 75.3, 58.5, and 160 mg g(-1) for As(V), Cr(VI), and Congo red, respectively, these novel nanostructures have the potential to be used as low-cost and efficient adsorbent materials for the removal of toxic metal ions and organic pollutants from water.

Recovery of silver (I) using a thiourea-modified chitosan resin

This work describes the preparation of a chelating resin from chemically modified chitosan. The resin was synthesized by using O-carboxymethylated chitosan to cross-link a polymeric Schiffs base of thiourea/glutaraldehyde and characterized by IR. Batch method was applied for testing the resins adsorption behavior. Adsorption experiments showed the resin had good adsorption capacity and high selectivity for Ag(I) in aqueous solution. The maximum uptake of Ag(I) exhibited was 3.77 mmol/g, at pH 4.0. The results also indicated that the adsorption process was exothermic and fit well with the pseudo-second-order kinetic model. Ag(I) desorption could reach 99.23% using 0.5 M thiourea-2.0 M HCl solution.

Degradation of sulfated polysaccharides from Enteromorpha prolifera and their antioxidant activities.

The effects of degradation on molecular weights (Mws) of polysaccharides from Enteromorpha prolifera were investigated. Microwave-assistance could highly accelerate reaction rate. Six representative sulfated polysaccharides (Mw 446.5, 247.0, 76.1, 19.0, 5.0 and 3.1 KDa) were prepared by a microwave-assistance acid hydrolysis method. Chemical analysis and FT-IR spectrum showed only glycosidic linkages were cleft without breaking significant structural units. Antioxidant activities of representative polysaccharides revealed that all samples showed great inhibitory effects on superoxide radical at a low concentration compared to Vitamin C and samples with high Mws exhibited higher inhibitory effects. On the contrary, samples with low Mws possessed stronger inhibitory effects on hydroxyl radical, IC(50) of Mw 3.1 KDa was 0.39 mg/mL. The chelating effect of Mw 3.1 KDa was 77.3% at 5mg/mL, which was twice more than initial polysaccharide. The study indicated Mw was the most significant factor to influence antioxidant activities of polysaccharides from E. prolifera.

Jellyfish venomics and venom gland transcriptomics analysis of Stomolophus meleagris to reveal the toxins associated with sting

UNLABELLED Jellyfish Stomolophus meleagris is a very dangerous animal because of its strong toxicity. However, the composition of the venom is still unclear. Both proteomics and transcriptomics approaches were applied in present study to investigate the major components and their possible relationships to the sting. The proteomics of the venom from S. meleagris was conducted by tryptic digestion of the crude venom followed by RP-HPLC separation and MS/MS analysis of the tryptic peptides. The venom gland transcriptome was analyzed using a high-throughput Illumina sequencing platform HiSeq 2000 with de novo assembly. A total of 218 toxins were identified including C-type lectin, phospholipase A₂ (PLA₂), potassium channel inhibitor, protease inhibitor, metalloprotease, hemolysin and other toxins, most of which should be responsible for the sting. Among them, serine protease inhibitor, PLA₂, potassium channel inhibitor and metalloprotease are predominant, representing 28.44%, 21.56%, 16.06% and 15.14% of the identified venom proteins, respectively. Overall, our combined proteomics and transcriptomics approach provides a systematic overview of the toxins in the venom of jellyfish S. meleagris and it will be significant to understand the mechanism of the sting. BIOLOGICAL SIGNIFICANCE Jellyfish Stomolophus meleagris is a very dangerous animal because of its strong toxicity. It often bloomed in the coast of China in recent years and caused thousands of people stung and even deaths every year. However, the components which caused sting are still unknown yet. In addition, no study about the venomics of jellyfish S. meleagris has been reported. In the present study, both proteomics and transcriptomics approaches were applied to investigate the major components related to the sting. The result showed that major component included C-type lectin, phospholipase A₂, potassium channel inhibitor, protease inhibitor, metalloprotease, hemolysin and other toxins, which should be responsible for the effect of sting. This is the first research about the venomics of jellyfish S. meleagris. It will be significant to understand the mechanism of the biological effects and helpful to develop ways to deal with the sting.

Microwave-assisted degradation of chitosan for a possible use in inhibiting crop pathogenic fungi.

Degradation of chitosan by H(2)O(2) under microwave irradiation was investigated. The oxidative degradation of chitosan was highly accelerated by microwave irradiation under the condition of low temperature and low concentration of H(2)O(2). The degraded chitosans with low molecular weight (M(w)) were characterized by gel permeation chromatography, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction and elemental analysis. The decrease of M(w) led to transformation of crystal structure and increase of water solubility, whereas no significant chemical structure change in the backbone of chitosan was observed. Antifungal activities of chitosans with different M(w) against crop pathogenic fungi Phomopsis asparagi, Fusarium oxysoporum f. sp. Vasinfectum and Stemphylium solani were investigated at the concentrations of 100, 200 and 400 mg/L. All degraded chitosans with low M(w) exhibited enhanced antifungal activity compared with original chitosan and the chitosan of 41.2 kDa showed the highest activity. At 400 mg/L, the chitosan of 41.2 kDa inhibited growth of P. asparagi at 89.3%, stronger than polyoxin and triadimefon, the inhibitory effects of which were found to be 55.5% and 68.5%. All the results indicated that oxidative degradation under microwave irradiation was a promising technique for large-scale production of low M(w) chitosan for use in crop protection.

Antimicrobial activity of hydroxylbenzenesulfonailides derivatives of chitosan, chitosan sulfates and carboxymethyl chitosan

Chitosan, carboxymethyl chitosan (CMCS) and chitosan sulfates (CSS) with different molecular weight were modified by reacting with 4-hydroxyl-5-chloride-1,3-benzene-disulfo-chloride or 2-hydroxyl-5-chloride-1,3-benzene-disulfo-chloride to give 12 kinds of new hydroxylbenzenesulfonailides derivatives of them. The preparation conditions of the derivatives were discussed in this paper, and their structures were characterized by FT-IR and 13C NMR spectroscopy. The solubility of the derivatives was measured in the experiment. In addition, their antimicrobial activities against four bacteria and five crop-threatening pathogenic fungi were tested in the experiment. Besides, the rule and mechanism of their antibacterial activities were discussed in this paper.

The preparation and antioxidant activity of 2-[phenylhydrazine (or hydrazine)-thiosemicarbazone]-chitosan

Chitosan (CS) with two different molecular weight were modified by reacting with methyl hydrazine-dithiocarboxylate and methyl phenylhydrazine-dithiocarboxylate to give 2-(hydrazine-thiosemicarbazone)-chitosan (2-HTCHCS, 2-HTCLCS) and 2-(phenylhydrazine-thiosemicarbazone)-chitosan (2-PHTCHCS, 2-PHTCLCS). The structure of the derivatives was characterized by FT-IR spectroscopy and elemental analysis. The antioxidant activities of the derivatives were investigated employing various established systems, such as hydroxyl radical (OH)/superoxide anion (O(2)(.-)) scavenging/reducing power and chelating activity. All of the derivatives showed strong scavenging activity on hydroxyl radical than chitosan and ascorbic acid (Vc), and IC(50) of 2-HTCHCS, 2-HTCLCS, 2-PHTCHCS and 2-PHTCLCS was 0.362, 0.263, 0.531 and 0.336mg/mL respectively. The inhibitory activities of the derivatives toward superoxide radical by the PMS-NADH system were strong. The results showed that the superoxide radical scavenging effect of 2-[phenylhydrazine (or hydrazine)-thiosemicarbazone]-chitosan were higher than that of chitosan. The derivatives had obviously reducing power and chelating activity. The data obtained from vitro models clearly establish the antioxidant potency of 2-[phenylhydrazine (or hydrazine)-thiosemicarbazone]-chitosan.

Isolation and characterization of lethal proteins in nematocyst venom of the jellyfish Cyanea nozakii Kishinouye

Cyanea nozakii Kishinouye, a jellyfish widely distributed in coastal areas of China, has garnered attention because of its stinging capacity and the resulting public health hazard. We used a recently developed technique to extract jellyfish venom from nematocysts; the present study investigates the lethality of C. nozakii venom. The nematocyst contents were extremely toxic to the grass carp, Ctenopharyngodon idellus, producing typical neurotoxin toxicity. The ID(50) was about 0.6microg protein/g fish. Toxin samples were stable when kept at -80( degrees )C, but after 48h, an 80% decline in lethality occurred at -20( degrees )C. Poor stability of the venom was observed within the range of 65-80( degrees )C and at pH 3.5. The venom was hydrolyzed by a proteolytic enzyme, trypsin. Fractionation of the venom yielded two protein bands with molecular weights of 60kDa and 50kDa. Our results provide the first evidence that C. nozakii produces lethal toxins. These characteristics highlight the need for the isolation and molecular characterization of new active toxins in C. nozakii.

Synthesis and evaluation of a thiourea-modified chitosan derivative applied for adsorption of Hg(II) from synthetic wastewater

In this work, a thiourea-modified chitosan derivative (TMCD) was synthesized through two steps, O-carboxymethylated first and then modified by a polymeric Schiffs base of thiourea/glutaraldehyde. The adsorption behavior of mercury (II) ions onto TMCD was investigated through batch method. The maximum adsorption capacity for Hg(II) was found to be 6.29 mmol/g at pH 5.0 and both kinetic and thermodynamic parameters of the adsorption process were obtained. The results indicated that adsorption process was spontaneous exothermic reaction and kinetically followed pseudo-second-order model. The adsorption experiments also demonstrated TMCD had high adsorption selectivity towards Hg(II) ions when coexisted with Cu(II), Zn(II), Cd(II) and Ca(II) in solution and it could be easily regenerated and efficiently reused.