D-mannuronic Acid Research Articles

Discovery of a class of glycosaminoglycan lyases with ultrabroad substrate spectrum and their substrate structure preferences

Glycosaminoglycan (GAG) lyases are often strictly substrate specific, and it is especially difficult to simultaneously degrade GAGs with different types of glycosidic bonds. Herein, we found a new class of GAG lyases (GAGases) from different bacteria. These GAGases belong to polysaccharide lyase 35 family and share quite low homology with the identified GAG lyases. The most surprising thing is that GAGases can not only degrade three types of GAGs: HA, CS and HS, but even one of them can also degrade alginate. Further investigation of structural preferences revealed that GAGases selectively act on GAG domains composed of non/6-O-/N-sulfated hexosamines and d-glucoronic acids, as well as on alginate domains composed of d-mannuronic acids. Additionally, GAG lyases were once speculated to have evolved from alginate lyases, but no transitional enzymes have been found. The discovery of GAGases not only broadens the category of GAG lyases, provides new enzymatic tools for the structural and functional studies of GAGs with specific structures, but also provides candidates for the evolution of GAG lyases.

Proton- versus Cation-Selective Transport of Saccharide Rim-Appended Pillar[5]arene Artificial Water Channels.

Transport of water across cell membranes is a fundamental process for important biological functions. Herein, we focused our research on a new type of symmetrical saccharide rim-functionalized pillar[5]arene (PA-S) artificial water channels with variable pore structures. To point out the versatility of PA-S channels, we systematically varied the nature of anchoring/gate keepers d-mannoside, d-mannuronic acid, or sialic acid H-bonding groups on lateral pillar[5]arene (PA) arms, known as good membrane adhesives, to best describe the influence of the chemical structure on their transport activity. The control of hydrophobic membrane binding-hydrophilic water binding balance is an important feature influencing the channels' structuration and efficiency for a proper insertion into bilayer membranes. The glycosylated PA channels' transport performances were assessed in lipid bilayer membranes, and the channels were able to transport water at high rates (∼106-107 waters/s/channel within 1 order of magnitude as for aquaporins), serving as selective proton railways with total Na+ and K+ rejection. Molecular simulation substantiates the idea that the PAs can generate supramolecular pores, featuring hydrophilic carbohydrate gate-keepers that serve as water-sponge relays at the channel entrance, effectively absorbing and redirecting water within the channel. The present channels may be regarded as a rare biomimetic example of artificial channels presenting proton vs cation transport selectivity performances.

Cascading One-Pot Synthesis of Biodegradable Uronic Acid-Based Surfactants from Oligoalginates, Semi-Refined Alginates, and Crude Brown Seaweeds.

The present article describes a one-pot and cascade mode process using biocompatible/biodegradable reagents, for simply obtaining surfactant compositions comprising mixtures of d-mannuronic acid and l-guluronic acid directly from oligoalginates or semi-refined alginates (mixtures of alginate, cellulose, hemicellulose, laminaran, and fucan). Simple treatments of partial purification of the reaction crudes (elimination of the salts and/or the residual fatty alcohols) or isolation of the surfactant compositions result in sugar-based compounds having performance levels appropriate to applications in detergency. In addition, the challenging extension of this cascading one-pot synthesis technology to crude milled brown seaweeds was successfully carried out to provide promising surface-active compositions made up of alkyl uronate and alkyl glycoside monosaccharides.

Multi-step Strategies Toward Regioselectively Sulfated M-Rich Alginates.

Sulfated alginates (ASs), as well as several artificially sulfated polysaccharides, show interesting bioactivities. The key factors for structure-activity relationships studies are the degree of sulfation and the distribution of the sulfate groups along the polysaccharide backbone (sulfation pattern). The former parameter can often be controlled through stoichiometry, while the latter requires the development of suitable chemical or enzymatic, regioselective methods and is still missing for ASs. In this work, a study on the regioselective installation of several different protecting groups on a d-mannuronic acid enriched (M-rich) alginate is reported in order to develop a semi-synthetic access to regioselectively sulfated AS derivatives. A detailed structural characterization of the obtained ASs revealed that the regioselective sulfation could be achieved complementarily at the O-2 or O-3 positions of M units through multi-step sequences relying upon a silylating or benzoylating reagent for the regioselective protection of M-rich alginic acid, followed by sulfation and deprotection.

Total Synthesis of Trisaccharide Repeating Unit of Staphylococcus aureus Type 8 (CP8) Capsular Polysaccharide.

Herein, we report a highly efficient total synthesis of Staphylococcus aureus type 8 trisaccharide repeating unit in a lesser number of steps and high stereoselectivity. The complex trisaccharide contains rare amino sugars, viz., d-fucosamine, l-fucosamine, and 2-acetamido d-mannuronic acid. The installation of consecutive sterically hindered 1,2-cis glycosidic linkages, especially β-mannosylation, is the key challenge in this synthesis. The total synthesis of target molecule was completed via a longest linear sequence of 18 steps in 7.1% overall yield.

The production of pH indicator Ca and Cu alginate ((1,4)- β -d-mannuronic acid and α -l-guluronic acid) cryogels containing anthocyanin obtained via red cabbage extraction for monitoring chicken fillet freshness

In recent days, intelligent food packaging has gained attention due to consumers' needs and monitoring of the freshness of food. Biopolymers are used to produce matrix parts and dye chemicals, because of their unique properties, such as biodegradability and biocompatibility. In this study, alginate molecules and anthocyanins were used to produce to monitor chicken fillet freshness via pH response characteristics. Anthocyanins' color and UV characteristics at different pHs were investigated. The obtained anthocyanin solution showed visible color response at different pH level. In the red cabbage extract, the anthocyanin concentration was as 0.65 ± 0.03 mg/g. Alginate and extracted anthocyanins from red cabbage were mixed at the solution phase, then metal alginate hydrogels were synthesized via crosslinking Ca2+ and Cu2+ with alginate molecules. Due to the porous structure of the cryogels, hydrogels were freeze dried at −80 °C for 24 h at vacuum atmosphere. The obtained cryogel indicated significant color changes from pH 4 to pH 10, and at a basic environment, the color change was observed with the naked eye. The porosity amounts and sizes of the produced cryogels were examined, the average pore amount of cryogels was found to be 85.46 ± 4.36 %, and the average pore size 97.98 ± 26.20 μm. Furthermore, it was seen that the color change was not directly related to the porosity, but the interaction of anthocyanin and metal alginate matrix effected color changes degree of cryogels. Due to the electronegativity of Cu2+ ions, and the use of a low amount of anthocyanin was found to be more suitable for color change. The color was changed to blue-purple while total volatile basic nitrogen content increased to 46.67 mg/100 g from 14.00 mg/100 g. As a result, prepared cryogels should be a better candidates for use as a freshness indicator and intelligent packaging.

Soluble dietary fiber and cellulose from Saccharina japonica by-product ameliorate Loperamide-induced constipation via modulating enteric neurotransmitters, short-chain fatty acids and gut microbiota

The effects of soluble dietary fiber (SDF) and cellulose (IDF) from Saccharina japonica by-product and their differences in improving constipation were further clarified in the present study. We demonstrated that SDF was mainly made up of d-mannuronic acid and d-mannose while IDF consisted of d-glucose , which is different from other reported dietary fibers of terrestrial plants. In this research, both SDF and IDF improved fecal-related indicators, gastrointestinal transit rate and histological morphology in Lop-induced mice. Moreover, they could increase the level of antioxidant enzymes (SOD and GSH-Px), restore the expression of enteric neurotransmitters, and maintain the function of ZO-1, JAM-1 as well as Occludin. Interestingly, SDF and IDF had a significant up-regulated effect on the proportion of Muribaculacea, Prevotellaceaen and Lachnospiraceae, which are critical to preserving intestinal immune homeostasis. Besides, they promoted the biosynthesis of short-chain fatty acids (SCFAs). The overall index showed that SDF is more effective for constipation due to its better water retention capacity. Thus, they can be used as a safe dietary supplement for the treatment of chronic or occasional constipation in humans.

Alginate as a Promising Biopolymer in Drug Delivery and Wound Healing: A Review of the State-of-the-Art.

Biopolymeric nanoparticulate systems hold favorable carrier properties for active delivery. The enhancement in the research interest in alginate formulations in biomedical and pharmaceutical research, owing to its biodegradable, biocompatible, and bioadhesive characteristics, reiterates its future use as an efficient drug delivery matrix. Alginates, obtained from natural sources, are the colloidal polysaccharide group, which are water-soluble, non-toxic, and non-irritant. These are linear copolymeric blocks of α-(1→4)-linked l-guluronic acid (G) and β-(1→4)-linked d-mannuronic acid (M) residues. Owing to the monosaccharide sequencing and the enzymatically governed reactions, alginates are well-known as an essential bio-polymer group for multifarious biomedical implementations. Additionally, alginate’s bio-adhesive property makes it significant in the pharmaceutical industry. Alginate has shown immense potential in wound healing and drug delivery applications to date because its gel-forming ability maintains the structural resemblance to the extracellular matrices in tissues and can be altered to perform numerous crucial functions. The initial section of this review will deliver a perception of the extraction source and alginate’s remarkable properties. Furthermore, we have aspired to discuss the current literature on alginate utilization as a biopolymeric carrier for drug delivery through numerous administration routes. Finally, the latest investigations on alginate composite utilization in wound healing are addressed.

Structures, Properties and Applications of Alginates.

Alginate is a hydrocolloid from algae, specifically brown algae, which is a group that includes many of the seaweeds, like kelps and an extracellular polymer of some bacteria. Sodium alginate is one of the best-known members of the hydrogel group. The hydrogel is a water-swollen and cross-linked polymeric network produced by the simple reaction of one or more monomers. It has a linear (unbranched) structure based on d-mannuronic and l-guluronic acids. The placement of these monomers depending on the source of its production is alternating, sequential and random. The same arrangement of monomers can affect the physical and chemical properties of this polysaccharide. This polyuronide has a wide range of applications in various industries including the food industry, medicine, tissue engineering, wastewater treatment, the pharmaceutical industry and fuel. It is generally recognized as safe when used in accordance with good manufacturing or feeding practice. This review discusses its application in addition to its structural, physical, and chemical properties.

Structure and dynamics of sodium alginate as elucidated by chemical shift anisotropy and site-specific spin-lattice relaxation time measurements.

The biocompatible, biodegradable, linear copolymer sodium alginate is fabricated from [Formula: see text] linked [Formula: see text]-D-mannuronic acid (M block) and [Formula: see text]-L-guluronic acid (G-block). It has wide applications in drug delivery, cell encapsulation, and commercial application in the textile, cosmetics, paper, food, biomedical, and pharmaceutical industries. The structure and dynamics of sodium alginate were here investigated by measuring chemical shift anisotropy (CSA) parameters, spin-lattice relaxation time, and molecular correlation time. The principal components of the CSA tensor were determined by two-dimensional phase-adjusted spinning sideband (2DPASS) cross-polarization magic angle spinning (CP-MAS) SSNMR. The alternating M and G blocks of both equatorial and axial links are associated with greater overall flexibility. The molecular correlation time of the carboxyl carbon of both G and M blocks is faster than for the anomeric carbon and pyranose carbon. This is further experimental evidence of the coexistence of two different dynamics within the polysaccharide chains of sodium alginate, which was previously established by 1H-13C dipolar profile analysis. The relaxation time of the para-crystalline region of sodium alginate is comparable with that of chitosan, but it is much shorter than that of cellulose and chitin. The order of the molecular correlation time of sodium alginate and chitosan is also the same. Hence, it can be concluded that sodium alginate exhibits greater flexibility than cellulose and chitin. These types of investigation into the local electronic configuration and nuclear spin dynamics at various carbon nuclei sites of the biopolymer at atomic-scale resolution will help in the design of biomimetic materials.

Functional Exploration of Desmarestia ligulate and Anti-inflammatory Activity of Functional Substance D-mannuronic acid

This study was conducted to investigate the anti-inflammatory activity of Desmarestia ligulate (D. ligulate) leaf. The effects on cell viability and anti-inflammatory activities of D. ligulata leaf extract, as well as those of D-mannuronic acid (DMA), on RAW 264.7 cells (macrophages) and peripheral blood mononuclear cells (PBMCs) during inflammation-induced stress were analyzed by determining the levels of NO, IL-17, IL-4, and TNF-α using ELISA and evaluating the expression of iNOS and MPO genes. D. ligulata leaf extract and DMA exhibited low toxicity in RAW 264.7 cells and PBMCs, which secreted lower levels of TNF-α and IL-4. The anti-inflammatory effect of DMA was higher than that of D. ligulata leaf extract as indicated by the levels of the inflammatory cytokine IL-17. Furthermore, treatment with D. ligulata leaf extract and DMA decreased the expression of iNOS and MPO genes after stress induction. These findings suggested that D. ligulata leaf extract and DMA exert anti-inflammatory effects as well as regulate cytokine release activities and inflammatory gene expression. Therefore, D. ligulata leaf extract and DMA may be used as cosmetic materials to control skin inflammation. Keywords: Anti-inflammatory; Desmarestia ligulate; D-mannuronic acid; IL-17; IL-6

Solution-state behaviour of algal mono-uronates evaluated by pure shift and compressive sampling NMR techniques

Sodium salts of the algal uronic-acids, d-mannuronic acid (HManA) and l-guluronic acid (HGulA) have been isolated and characterised in solution by nuclear magnetic resonance (NMR) spectroscopy. A suite of recently-described NMR experiments (including pure shift and compressive sampling techniques) were used to provide confident assignments of the pyranose forms of the two uronic acids at various pD values (from 7.5 to 1.4). The resulting high resolution spectra were used to determine several previously unknown parameters for the two acids, including their pKa values, the position of their isomeric equilibria, and their propensity to form furanurono-6,3-lactones. For each of the three parameters, comparisons are drawn with the behaviour of the related D-glucuronic (HGlcA) and D-galacturonic acids (HGalA), which have been previously studied extensively. This paper demonstrates how these new NMR spectroscopic techniques can be applied to better understand the properties of polyuronides and uronide-rich macroalgal biomass.

Karakteristik Bubuk Alginat dari Alga Coklat Sargassum sp. pada Perlakuan Waktu dan Suhu Maserasi

Sargassum sp. is an example of a brown algae plant that produces alginates in the form of an organic polysaccharide polymer composed of two units of L-guluronic acid and D-mannuronic acid monomers. The polymer is hydrophilic, that is, alginate is a linear molecule with a high molecular weight, so it is easy to absorb water causing alginate compounds can be used as emulsifiers. This research aims to know the effect of maceration time and temperature on the characteristics of alginate powder from brown algae Sargassum sp. and determine the best maceration time and temperature to produce alginate powder from brown algae Sargassum sp. This research used a Factorial Randomized Block Design. The first factor is time (A) which consists of 3 levels, namely 1 hour, 2 hours and 3 hours. The second factor is temperature (B) which consists of 3 levels namely 50°C,60°C,70°C. Each treatment were grouped into 2 based on the time of implementation so that 18 units of the experiment were obtained. The variables observed were the yield, water content, ash content, and viscosity. The data obtained were then analyzed by variance analysis and continued using the HRD method (Honest Real Difference). The results showed that the treatment of maceration time and temperature had a very significant effect on the observed variables namely yield, moisture content, ash content, and viscosity. The results showed that the treatment of 3 hours with a temperature of 70±1°C was the best treatment to produce alginate powder from brown algae Sargassum sp. with yield characteristics 39.44±0.06 %, water content 9.86±0.04 %, ash content 31.75±0.02 %, and viscosity value 19.00±1.41 cPs.
 Keywords: maseration, time, temperature, alginate, Sargassum sp.

β-D-Mannuronic Acid (M2000) as a Landmark in Pharmacology

The goal of this article is to retrace the studies of β-D-Mannuronic Acid (M2000) as a new immunosuppressive drug with non-steroidal anti-inflammatory drugs (NSAIDs) property in miscellaneous aspects including in vitro, in vivo examinations, clinical trials and related to clinical trials studies. Our goal is to compare the effect of this drug with other similar drugs through varied researches and to follow tolerability, biocompatibility, potency, safety, and efficacy of this medication in different studies, as well as to evaluate its therapeutic effectiveness in various diseases. Different methods were applied in the studies of β-D-Mannuronic Acid under in vitro, in vivo examinations, and clinical trials phase I, II and III and related investigations to these clinical trials using different techniques showing the efficacy of this medication in the treatment of various diseases. The administration of β -D-Mannuronic Acid showed the greatest tolerability and biocompatibility compared to diclofenac, piroxicam, and dexamethasone without or very low side effects. The drug has shown a punchy effect on many molecules which participate either in physiologic or in pathogenic activities in animal models and human. This new drug not only revealed the anti-inflammatory and immunosuppressive properties but also based on the results of various investigations, β-D-Mannuronic Acid showed the antidiabetic, cardioprotective and anti-tumoral effects. β-D-Mannuronic Acid (M2000) as a novel immunosuppressive drug with NSAID properties along with antidiabetic, cardioprotective and anti-tumoral efficacy showed great tolerability and safety profile. In addition, it has no or mild adverse events compared with many other medicines, therefore this medicament could be considered as a landmark in pharmacology and represent turn point in the treatment of different diseases based on the experimental and in vitro studies explained and clinical and related studies proved.

Advances in Application of Alginate Lyase And Its Enzymatic Hydrolysate

Alginate is a linear, water-soluble acidic seaweed polysaccharide composed of L-guluronic acid and its C5 epimer D-mannuronic acid, a general term for hydrophilic derivatives of alginic acid. It is widely found in various brown algae. Alginate lyase and its enzymatic hydrolysate have a variety of biological activities and become a new research hotspot. This paper reviews the source, classification, enzymatic mechanism and enzymatic properties of alginate lyase, and summarizes the function and application of alginate lyase and its enzymatic hydrolysate brown algal oligosaccharide, in order to provide a base for the development and application of alginate lyase and its products.

Structural and Rheological Characteristics of Alginate from Sargassum cristaefolium Extracted by Twin Screw Extruder

ABSTRACTThis study aimed to investigate the effects of process extrusion on the characteristics of Sargassum cristaefolium sodium alginate (SCSA) extracted using twin-screw extruder. Box-Behnken Design (BBD) from response surface methodology (RSM) was established to understand the effects of temperature, screw speed, and pH on the multiple-responses of alginate characteristics including intrinsic viscosity, yield, and molecular weight. The results revealed that temperature, screw speed, and pH significantly affected (P < .05) all responses. The optimum extraction condition was found at temperature of 58.18°C, screw speed of 77.99 rpm, and pH 10.11. At this condition, the response of residence time distribution was 7.07 ± 0.029 min, yield of 34.01 ± 0.12%, intrinsic viscosity of 460.13 ± 14.75 mL/g, and molecular weight of 217.94 ± 7.14 × 103 g/mol. This alginate had mannuronic acid to guluronic acid (M/G) ratio of 0.28, and the L-guluronic acid block was 0.78, which was higher than the D-mannuronic acid block. Rheological characterization of SCSA in aqueous solution was shear-thinning pseudoplastic, and alginate gel in 1 M CaCl2 was more elastic than liquid.

On Ionic and Covalent Cross-Linking of Alginic Acid Derived Binders for High Capacity Silicon Anodes

The anode market for automotive Li-ion batteries is still governed by carbonaceous materials with a market share of 96%.[1] The graphite electrodes used today can only deliver a moderate capacity of 300-350 mAh/g, and improvements are highly sought. Silicon, often in the form of a silicon/carbon composite, is a promising alternative material with its high theoretical capacity of about 3600 mAh/g. As an alloy former this capacity is accompanied with a huge volume change of over 300%, deeming PVDF unsuitable as binder as it cannot withstand the volume changes upon cycling. A variety of technical and biopolymers were shown to drastically increase the cyclability of silicon based anodes. Prominent examples are s poly (acrylic acid) (PAA), carboxymethyl cellulose (CMC) and alginic acid (algin) derivatives. Algin, often purified as water soluble Na alginate, is a polysaccharide found in the cell walls of brown algae. It consists of the two epimers D-mannuronic acid (M) and L-guluronic acid (G), which's content and distribution have a strong impact on the 3D structure and properties. Superior cycling of Na alginate bound Si anodes was first described by Kovalenko et al..[2] The incorporation of divalent ions such as calcium, strontium, barium or transition metals causes strong chelation of the ions resulting in a hydrogel. Several studies have described that this ionic cross-linking has a profound effect on the cyclability of Si based anodes. [3],[4],[5],[6] Divalent ions are usually chelated by two adjacent G units on two polymer chains forming a so called egg-box and high degrees of saturation cause gelling, which obstructs processing. Since chelation including G units only is much stronger than the interaction with M groups, the M to G ratio should have a strong effect on the stability of the network. Covalent cross-linking should have an even stronger effect on the stability of the binder network as it is constructed of chemical bonds rather than ionic interactions. This study concerns the effect of different saturation degree of calcium and barium cross-linking on alginates with different M to G ratio as binder for Si based anodes. Furthermore, we discuss routes to form a covalently cross-linked algin derived network that is grafted to the Si surface. [1] Schmuch R., Wagner R., Hoerpel G., Placke T., Winter M., Performance and cost of materials for lithium-based rechargeable automotive batteries, Nature Energy, 3 (2018), 267-278. [2] Kovalenko, I., et al., A Major Constituent of Brown Algae for Use in High-Capacity Li-Ion Batteries. Science, 2011. 334(6052): p. 75-79. [3] Wua Z-Y., Deng L., Li J-T., et al. Multiple hydrogel alginate binders for Si anodes of lithium-ion battery. Electrochimica Acta, 245 (2017), 371–378. [4] Gu Y., Yang S., Zhu G., et al. The effects of cross-linking cations on the electrochemical behavior of silicon anodes with alginate binder, Electrochimica Acta, 269 (2018), 405-414. [5] Zhang L., Zhang L., Peng L. C., et al. A coordinatively cross-linked polymeric network as a functional binder for high-performance silicon submicro-particle anodes in lithium-ion batteries, J. Mater. Chem. A,2 (2014), 19036–19045 [6] Yoon J., Oh D. X., Jo C. et al., Improvement of desolvation and resilience of alginate binders for Si-based anodes in a lithium ion battery by calcium-mediated cross-linking, PCCP, 16 (2014), 25628-25635. Figure 1

The Effect of Molecular Weight, M/G Ratio and pH on the Cyclability of Alginate Bound High Capacity Silicon Anodes

Classical rocking chair Li-ion batteries are dominating the market as they are currently the battery concept with the highest energy density, both per weight and volume. As the technology is rather mature, only small increases in energy density are expected without changing the electrode chemistry. Though the positive electrode currently limits the capacity of a Li-ion battery most, the state of the art graphite negative electrodes only deliver a moderate capacity of 300-350 mAh/g and improvements to this are also highly desirable. Silicon is a promising alternative negative electrode material. Under cathodic polarisation it forms a Li rich alloy, delivering a very high specific capacity of about 3600 mAh/g. Alloying, in contrast to an intercalation reaction, is associated with immense volume changes of the material. The currently used binder (PVDF) has been shown to be unsuitable for Si based electrodes as it cannot withstand the volume changes associated with cycling. Lately, a variety of biopolymers have been described as potential binders for Si based electrodes. These usually come with the advantage of being water soluble and hence makes the electrode production more environmentally benign. One class of biopolymers which have shown encouraging results are derivates of alginic acid. Most commonly applied as water soluble Na salts, alginates have shown encouraging results in accommodating the volume changes and hence can improve the cyclability of Si based electrodes. [1-3] Most published studies describe the alginates they are using rather incompletely. Alginic acid consists of the two epimers D-mannuronic acid (M) and L-guluronic acid (G). The content and distribution of the repetition units have a strong impact on the 3D structure and hence the properties. Furthermore, the chain length influences the properties of the corresponding alginates. Another crucial factor is the pH of the binder solution, which influences the degree of protonation of the carboxyl groups of the alginate. Protonated carboxyl groups ease esterification of the alginate with the native oxide layer on the Si surface which has a strong influence on the binding strength. [4] This systematic study addresses the effect of pH, Mw and M/G ratio of Na alginates as a binding agent for high capacity Si anodes using commercially available materials. The examined electrodes consisted of Si as main active material, Graphite and carbon black as conductivity enhancers and different Na alginates as binding agents. Na alginates with different Mw and M/G ratio were supplied by FMC BioPolymer AS (DuPont) and a commercially available battery grade Si (Silgrain ®, e-Si 400) was provided by ELKEM AS Technology. Kovalenko, I., et al., A Major Constituent of Brown Algae for Use in High-Capacity Li-Ion Batteries. Science, 2011. 334(6052): p. 75-79.Erk, C., et al., Toward Silicon Anodes for Next-Generation Lithium Ion Batteries: A Comparative Performance Study of Various Polymer Binders and Silicon Nanopowders. Acs Applied Materials & Interfaces, 2013. 5(15): p. 7299-7307.Zhang, L., et al., A coordinatively cross-linked polymeric network as a functional binder for high-performance silicon submicro-particle anodes in lithium-ion batteries. Journal of Materials Chemistry A, 2014. 2(44): p. 19036-19045.Mazouzi, D., et al., New insights into the silicon-based electrode's irreversibility along cycle life through simple gravimetric method. Journal of Power Sources, 2012. 220: p. 180-184.

Characterization of alginates from Ghanaian brown seaweeds: Sargassum spp. and Padina spp.

Alginates of four locally harvested Ghanaian brown seaweeds from the Sargassum and Padina genus were assessed for their rheological and chemical characteristics. The seaweeds contained 16–30% by weight of alginate assessed as the sum of d-mannuronic acid (M) and l-guluronic acid (G). In comparison, alginate samples from Laminaria digitata and Macrocystis pyrifera, used commercially for alginate extraction, contained 29% and 27% by weight of the two constituent uronic acids (M + G), respectively. Alginate extraction yields of the Ghanaian seaweeds ranged from 17 to 23% by weight of dry material; the corresponding yields from L. digitata and M. pyrifera were 26–29% by weight; these yields were equivalent to ∼49–99% of the theoretical yields, but the purity of the extracted alginates varied, and were lowest for the Ghanaian seaweed alginates. 1H NMR analysis of the uronic acid block-structure in the alginates gave M/G ratios of 0.47 and 0.70 for the alginates extracted from Sargassum natans and Sargassum vulgare, while alginates from Padina gymnospora and Padina antillarum had M/G ratios of 1.75 and 1.85, respectively. The alginates from the two Ghanaian Sargassum spp. had high contents of dimeric and trimeric homoguluronate elements: FGG and FGGG values were 0.61 and 0.58 for S. natans and 0.49 and 0.44 for S. vulgare. The alginates from the two Padina spp. had gel strengths estimated as G′ surpassing those from the commercial alginates with G′ values after 4 h of rheological oscillation of 340 Pa (P. gymnospora) and 376 Pa (P. antillarum), whereas the gelling properties of the Sargassum spp. alginates were poor. The degree of polymerization of the acid tolerant alginate backbone fragments, but not M/G ratio or homoguluronate dimer and trimer element contents, appeared to correlate to the alginate gel strength. The study shows that notably Ghanaian Padina spp. hold alginate having desirable properties for high gel-strength applications.

Effects of M2000 (D-Mannuronic Acid) on Learning, Memory Retrieval, and Associated Determinants in a Rat Model of Alzheimer's Disease.

The d-mannuronic acid (M2000) is a novel nonsteroidal anti-inflammatory drug that has immunosuppressive effects together with antioxidant property. M2000 has shown a notable efficacy in experimental models of multiple sclerosis, rheumatoid arthritis, and nephrotic syndrome. In this work, the effect of M2000 on the treatment of Alzheimer's disease (AD) was performed by Morris water maze experiment, and the immunological assessments were carried out by Western blot, apoptosis (procaspase-3, Bax/Bcl2, P53), enzymatic (superoxide dismutase [SOD]), and nonenzymatic oxidative stress (malondialdehyde [MDA]) tests. We found that pretreatment of AD in the rat model by M2000 had a potent efficacy on rat behavior and also it led to a significant inhibition of amyloid plaque production. Moreover, our data showed that M2000 can reduce the amount of Bax/Bcl2, P53, MDA, and SOD, as well as it normalized the level of procaspase-3. Our results suggest M2000 is a potential therapeutic agent for the treatment of AD.