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Nuclear factor kappa B (NF-κB) is the critical transcriptional factor in the pathogenesis of acute lung injury (ALI). NF-κB regulates the expression changes of inflammatory factors such as tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β) and interleukin 6 (IL-6). In a previous study we showed that decompression sickness (DCS) caused by simulated unsafe fast buoyancy ascent escape (FBAE) could result in ALI, which was characterized by expression changes of inflammatory factors in rat lung tissue. The purpose of the present work was to study the roles of NF-κB and TNF-α in the process of DCS-induced rat lung injury caused by simulated unsafe FBAE. The research methods aimed to detect the rat lung tissue messenger ribonucleic acid (mRNA) and protein level variations of NF-κB, inhibitory ×B (I×B), TNF-α, IL-1β, IL-6, IL-10 and IL-13 by using pretreatment of the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) and TNF-α antibody (Ab). Our experimental results demonstrated that PDTC could improve the survival rate of the rats with DCS caused by unsafe FBAE more effectively than TNF-α Ab. However, the inhibition of TNF-α Ab on the nuclear translocated protein expression of NF-κB was more effective than PDTC. Both PDTC and TNF-α Ab can abrogate the increment of the rat lung tissue mRNA levels of TNF-α, IL-1β, IL-6 and protein levels of NF-κB, TNF-α, IL-1β effectively and increase the rat lung tissue content of I×B significantly. In conclusion, TNF-α-mediated NF-κB signaling may be one of the critical signaling pathways in the pathogenesis of DCS-induced rat lung injury caused by simulated unsafe FBAE. PDTC may ameliorate this type of injury partly through inhibiting the NF-κB pathway., Competing Interests: The authors of this paper declare no conflicts of interest exist with this submission., (Copyright© Undersea and Hyperbaric Medical Society.)

Regioselective modification is an effective approach to synthesize polysaccharides with different structure features and improved properties. In this study, regioselective sulfation of Artemisia sphaerocephala polysaccharide (SRSASP) was prepared by using triphenylchloromethane (TrCl) as protecting precursor. The decrease in fractal dimension (df) values (1.56-2.04) of SRSASP was observed in size-exclusion chromatography combined with multi angle laser light scattering (SEC-MALLS) analysis. Compared to sample substituted at C-6, SRSASP showed a more expanded conformation of random coil, which was attributed to the breakup of hydrogen bonds and elastic contributions. Circular dichroism (CD), methylene blue (MB) and congo red (CR) spectrophotometric method and atomic force microscopy (AFM) results confirmed the conformational transition and stiffness of the chains after sulfation. SRSASP exhibited enhanced antioxidant activities in the DPPH, superoxide and hydroxyl radical scavenging assay. Sulfation at C-2 or C-3 was favorable for the chelation which might prevent the generation of hydroxyl radicals. It concluded that the degree of substitution and substitution position were the factors influencing biological activities of sulfated polysaccharides., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Phosphorylated derivatives of galactomannan from guar gum (GG) with the degree of substitution (DS) of 0.35-0.52 were synthesized using POCl3/pyridine. FT-IR, (13)C NMR and XPS results revealed that phosphorylation had occurred and C-6 substitution was predominant in phosphorylated guar gum (PGG). PGG showed an increase in Mw and more broad molar mass distribution in size exclusion chromatography (SEC) analysis. Higher reaction temperature (above 60 °C) resulted in a higher MW value in PGG. It might be due to the cross-linking of polysaccharide chains by POCl3 via di-ester which was also supported by monosaccharide composition result. Results of M(W) - (S(2))(z)(1/2) showed a decrease in fractal dimension (df) values. DS had greater influence on its conformation in aqueous solution. The introduction of -PO3H2 groups improved significantly the stiffness of the chains due to the electrostatic effect. Furthermore, antioxidant experiments revealed that high DS could enhance the scavenging activities of radicals of PGG in vitro., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

We reported here a new synthesis of C-2 and C-3 sulfated guar gum (SRSGG) with low degree of substitution (DSS) of 0.58, employing triphenylchloromethane (TrCl) as a protected precursor. The yield and DSTr (calculated from the weight of triphenylmethanol) of triphenylmethylated GG (GGTr) was 165.6% and 0.71, respectively. In addition, low ratio (1:4) of chlorosulfuric acid to pyridine (1:4) was chosen in sulfation reaction since the protecting group was slightly sensitive to acid. Results of FT-IR and (13)C NMR spectroscopy indicated that C-2 and C-3 substitution was predominant but not fully sulfated in SRSGG. Size-exclusion chromatograph combined with multi-angle laser photometer (SEC-LLS) showed a decrease in molecular weight in the reaction. This might be due to the degradation in sulfation and deprotection process. Finally, we investigated the effect of structure features on the antioxidant activities in vitro. Vitro antioxidant experiments revealed that the regioselective sulfation at C-2 and C-3 and low molecular weight afforded strong antioxidant activities showing a much higher scavenging abilities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical than that by the known C-6-sulfated derivative. The antioxidant activities of sulfated polysaccharides were not a function of a single factor but a combination of molecular weight, DSS and substitution positions., (Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.)

It was essential to understand the chemical structure of polysaccharides for further research and biochemical or medical application of this natural biopolymer. In the present study, sulfated derivatives of guar gum with high degree of sulfation (DS) were synthesized using 4-dimethylaminopyridine (DMAP)/dimethylcyclohexylcarbodiimide (DCC) as catalyst in homogeneous conditions. The effects of the ratio of chlorosulfuric acid to pyridine, the content of catalyst and reaction temperature were investigated. Results of FT-IR, (1)H and (13)C NMR indicated that C-6 substitution was predominant in sulfated polysaccharide. In the sulfation reaction, a sharp decrease in M(W) was observed. The enhanced antioxidant activities of sulfated polysaccharides were not a function of a single factor but a combination of high DS and low molecule weight., (Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.)

Sulfated polysaccharides exerted potential biological property which was relative to degree of sulfation (DS), M(w), substitution position and chain conformation. In the present study, commercial guar gum was purified and its sulfated derivates with different DS and M(w) were synthesized. FT-IR and 13C NMR analysis indicated that C-6 substitution was predominant in sulfated samples compared with other positions. In the sulfation reaction, a sharp decrease in M(w) was observed. The d(f) values from 1.92 to 2.85 indicated that the -SO3H groups led to the relatively expanded conformation of sulfated polysaccharides. Antioxidant assays showed that sulfated polysaccharides had better antioxidant activities. The data obtained in in vitro models indicated that high DS and low M(w) showed the best antioxidant capacities., (Crown Copyright 2009. Published by Elsevier B.V. All rights reserved.)

The conventional extraction methods for polysaccharides were time-consuming, laborious and energy-consuming. Microwave-assisted extraction (MAE) technique was employed for the extraction of Artemisia sphaerocephala polysaccharides (ASP), which is a traditional Chinese food. The extracting parameters were optimized by Box-Behnken design. In microwave heating process, a decrease in molecular weight (M(w)) was detected in SEC-LLS measurement. A d(f) value of 2.85 indicated ASP using MAE exhibited as a sphere conformation of branched clusters in aqueous solution. Furthermore, it showed stronger antioxidant activities compared with hot water extraction. The data obtained showed that the molecular weights played a more important role in antioxidant activities.

Abstract: Potentilla anserina L. polysaccharide had been selenizingly modified by nitric acid–selenious acid method with microwave-assistant. The optimal reaction parameters on selenylation modification were time 116min, temperature 63°C, microwave power 190W and the actual value of selenium content was 2690.1±7.2μg/g. The scavenging ability of DPPH, OH and superoxide radicals, the metal chelating ability and reducing power in vitro were compared by antioxidant assay taking the non-modified PAP as a control. The results showed that selenylation modification could significantly enhance the antioxidant activity of SePAP and SePAP could be used as a potential antioxidant. [Copyright &y& Elsevier]

Oxidative stress, which involved in several inflammatory and degenerative diseases, has become interesting in most of biomedical disciplines and many types of clinical research. Antioxidants can protect biological systems from the harmful effects of oxidative stress. It can reflect the monitor effect to oxidative stress from another aspect by detecting the antioxidant capacity. Therefore, it is particularly significant to assay the antioxidant capacity of biological fluids. Herein, for the first time a fluorescence-tunable probe was developed based on polydopamine-quenched fluorescent graphitic carbon nitride (g-C 3 N 4 ) for assessing the antioxidant capacity of biological fluids. Dopamine (DA) can self-polymerize on the surface of g-C 3 N 4 to produce a polydopamine (PDA) uniform coating layer in which the fluorescence of g-C 3 N 4 is efficiently quenched by the PDA layer, showing the fluorescence “off” state. However, in the presence of antioxidants, the self-polymerized effect of DA can be effectively inhibited and leading to the fluorescence “on” state. Therefore, detecting antioxidants can be achieved by monitoring the fluorescent emission of g-C 3 N 4 . Moreover, endowed with high sensitivity and selectivity, the proposed sensing system was successfully applied to assessment antioxidant capacity in biological fluid and the results matched well with commonly used antioxidant detection method. [ABSTRACT FROM AUTHOR]

Abstract: We reported here a regioselective synthesis of non-C-6 phosphorylated guar gum (PRSGG) with a degree of substitution (DS) 0.34. Triphenylchloromethane (TrCl) was employed as a key protected precursor. Detritylation was performed by treatment with an excess of dichloroacetic acid. Phosphorylated GG was successfully characterized by FT-IR and 13C NMR spectroscopies. It was indicated that C-2 and C-3 substitution was predominant in phosphorylated polysaccharide. A decrease in weight average molar mass (M w) was observed in the reaction due to the acid environment in deprotection procedure. The results of vitro antioxidant experiments revealed that regioselective phosphorylation at C-2/C-3 and low M w afforded strong antioxidant activities. Non-C-6 phosphorylated guar gum showed a much higher scavenging abilities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical than C-6-phosphorylated derivative. [Copyright &y& Elsevier]

Abstract: Selenium (Se) is an essential trace element for human beings and many other forms of life. Organic Se from natural foods has higher bioavailability and is safer than inorganic Se species. In the present study, selenium-containing derivatives of Artemisia sphaerocephala polysaccharide with the highest Se content of 1703μg/g were synthesized using H2SeO3/HNO3 and BaCl2 as a catalyst. The effects of the ratio of HNO3 concentration and reaction temperature were investigated. Results of Raman and 13C NMR spectroscopy indicated that C-6 substitution was predominant in selenized polysaccharide. A sharp decrease in M w was observed in the selenized reaction due to the acid environment. The in vitro antioxidant results suggest that selenium-containing polysaccharide should be applied as a novel selenium source in dietary supplements, with potent antioxidant properties. [Copyright &y& Elsevier]

Abstract: Sulfated polysaccharides exerted potent biological property which was relative to degree of sulfation (DS), M w, substitution position and chain conformation. In the present study, sulfated derivatives of Artemisia sphaerocephala polysaccharide (ASP) with different DS were synthesized by chlorosulfuric acid/pyridine method. FT-IR and 13C NMR analysis indicated that C-6 substitution was predominant in sulfated ASP (SASP) compared with other positions at C-2. In the sulfation reaction, a sharp decrease in M w was observed in SASP. The d f values from 1.96 to 2.77 indicated that the –SO3H groups leading to the relatively expanded conformation of SASP. Antioxidant assays showed that SASP had better antioxidant activities. The data obtained in vitro models indicated that high DS and moderate M w showed the best antioxidant capacities. [Copyright &y& Elsevier]

Abstract: The conventional extraction methods for polysaccharides were time-consuming, laborious and energy-consuming. Microwave-assisted extraction (MAE) technique was employed for the extraction of Potentilla anserina polysaccharides (PAPMAE), which is a traditional Chinese functional food. The extracting parameters of PAPMAE were optimized by Box–Behnken design. The optimum conditions were ratio of water to raw material 14.5:1, microwave power 369W, extraction temperature 63.3°C and extraction time 76.8min with an enhanced yield of 13.33%. In microwave heating process, a sharp decrease in M w was detected in SEC-LLS measurement. A d f value of 3.03 indicated that PAPMAE exhibited a compact hard sphere conformation in an aqueous solution. Furthermore, it showed stronger antioxidant activities compared with hot water extraction by evaluating in superoxide radical (), hydroxyl radical ( OH), 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical, reducing power and metal chelating assay. The data obtained clearly showed that the molecular weights played a more important role in antioxidant activities. [Copyright &y& Elsevier]