Carbohydrate Chemistry

This research was funded by, and implemented within, a UK national research organisation, while the author was the KE and Impact Evaluation Manager responsible for assessing impact on a £15m UK government-funded research programme.

This work was also submitted as the authors MBA dissertation which was accepted and awarded in 2009.

ABSTRACT: A methodology and methods ‘toolbox’ is proposed for conducting impact research and assessment from within research programmes. The emphasis is upon how to clarify and assess the wider impacts from the early stages onwards.

The approach explicitly acknowledges, and attempts to address, the known issues and challenges of impact assessment while drawing upon the resources and opportunities available to research managers and researchers within such programmes.

The study has two triangulating foundations. Firstly, it examines the academic literature to help identify and design the pilot methodology and methods. Secondly it trials these in a real programme to both test and improve them.

The study was conducted over one year within one leading UK research organisation, where two research programmes (and around 60 research projects of £15m total value) were being assessed for their impacts. The study draws upon actual impact management experience and reflection, prospective (ex ante) and retrospective (ex post) assessments, participatory contributions from leading researchers undergoing assessment, and consultation with external users. The findings of this study outline the pilot and its first iteration. Recommendations are made for improvement to the methodology and methods.

A subsequent follow-on bid to UK government incorporating the impacts identified from implementing this methodology, successfully led to a further £15m of government funding.

It is expected the pilot methodology and methods will be applicable to other organisations, conducting and funding such research programmes, required to research and assess the wider research impacts.

Although primary focus of implemetation trials was upon research in physical sciences, technology, high-tech engineering, computing/IT, and environment, the wider literature study, the methodology design and justification, the methods proposed and used, and the resulting general recommendations and lessons are expected to apply more broadly to many other research areas, where the impact is to be found more widely in the society, economy, government or public sector or within organizations, policies, professions or the public.

Interest in this work is expected from research programme managers, impact managers and assessors, management consultants advising in this area, and government funding managers, all seeking to embed a developing approach to understand, capture, and enhance wider impact.

BAB I PENDAHULUAN Di Indonesia kita mengenal berbagai macam makanan, pokok yaitu nasi (berasal dari beras), dan singkong. Nasi seakan menjadi sebuah hal yang tak dapat dipisahkan dari kehidupan Gliseraldehida, suatu aldosa Dihidriksiaseton, suatu ketosa Karbohidrat juga berasal dari kata "sakarida" dari bahasa Yunani yang berarti gula. Nama karbohidrat beral dari senyawa karbo dan "hidrat" dengan perbandingan rumus empiris karbon, hidrogen dan oksigen. Sebagai contoh rumus kimia glukosa adalah C6H12O6 yang juga dapat ditulis sebagai (CH2O)6 atau C6(H2O)6, dapat dirumuskan secara umum (CH2O)n. Karbohidrat digolongkan menjadi tiga, yaitu Monosakarida, Disakarida dan Polisakarida. BAB II STRUKTUR KARBOHIDRAT I. Jenis-jenis Karbohidrat 1. MONOSAKARIDA Monosakarida merupakan monomer dari polisakarida yang terdiri satu unit gula. Monosakarida tidak berwarna, merupakan kristal padat yang bebas larut di dalam air

Life is an inordinately complex unsolved puzzle. Despite significant theoretical progress, experimental anomalies, paradoxes, and enigmas have revealed paradigmatic limitations. Thus, the advancement of scientific understanding requires new models that resolve fundamental problems. Here, I present a theoretical framework that economically fits evidence accumulated from examinations of life. This theory is based upon a straightforward and non-mathematical core model and proposes unique yet empirically consistent explanations for major phenomena including, but not limited to, quantum gravity, phase transitions of water, why living systems are predominantly CHNOPS (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur), homochirality of sugars and amino acids, homeoviscous adaptation, triplet code, and DNA mutations. The theoretical framework unifies the macrocosmic and microcosmic realms, validates predicted laws of nature, and solves the puzzle of the origin and evolution of cellular life in the universe. Life 2012, 2 2

La homoquiralidad presente en el planeta tierra está fundamentada en varias teorías, sin embargo, no sé conoce a ciencia cierta cual fue su inicio. A continuación se muestran conceptos básicos que encierran el tema de la quiralidad, asimismo se presentan algunas de las teorías más relevantes que han tratado de dar una explicación. Al final, se presentan unas aplicaciones de la quiralidad a nivel científico.

In this review, a comprehensive and illustrative survey is made of the regioselective synthesis of esters of sugars and related compounds using lipases. The main emphasis has been given to the screening and use of commercially available lipases for the enzymatic esterification of neutral monosaccharides, disaccharides, sugar alcohols and their selected ether and ester derivatives. The effect of solvents and solubilizing agents in improving the yields of the resultant sugar fatty acid esters has been incorporated. Further, solvent-free esterification with molten fatty acids, use of ionic liquids and microwave radiations for improvement in the methodology have also been discussed.

The proximate composition of Bryophyllum pinnatum leaves was evaluated in both dry and fresh samples to determine the ash, carbohydrate, fat, fibre, protein, moisture and mineral contents using the method of Association of Analytical Chemist (A OAC) and Atomic Absorption Spectrophotometer (AAS).The result shows that Bryophyllum pinnatum contain (1.21 ± 0.07 and 0.8 ± 0.03%) ash, (72.92 ± 1.08 and 4.46 ± 0.52%) carbohydrate, (1.38 ± 0.06 and 1. 15 ± 0.05%) fat, (6.02 ± 1. 06 and 0.95 ± 0.06%) fibre, (5. 38 ± 0.10 and 1.61 ± 0.02%) protein, and (13.01 ± 1.03 and 91.03± 0.55%) moisture in dry and fresh samples respectively. The result of the mineral content revealed that Bryophyllum pinnatum is good sources of minerals such as ‘Fe, Zn, Cu, Mg, Na, K, Ca, Ni, Cd and Pd. This shows that Bryophyllum pinnatum leaf is a good source of human nutrition and should be included as dietary supplement.

Cellular metabolism is represented by a large number of metabolic reactions that are involved in the conversion of the carbon source into building blocks needed for macromolecular biosynthesis. Furthermore, there are specific reactions that ensure the constant supply of Gibbs free energy via ATP and redox equivalents(generally in the form of the cofactor NADPH) needed for biosynthesis of macromolecules. This large number of metabolic reactions forms a so-called metabolic network inside the cells. Therefore, metabolic fluxes represent integrative information; i.e., the metabolic fluxes are a function of gene expression, translation, posttranslational protein modifications, and protein-metabolite  interactions. In this review an attempt has been made to depict the role of metabolic fluxes with respect to carbohydrate and lipid metabolism in health and disease.( Glycogen storage disease, Type I and Diabetes Mellitus.

Phaeophyceae, Ochrophyta) are analyzed by spectroscopic techniques. The nature of the polysaccharides (with extraction and without any type of extraction) present in these seaweeds was determined with FTIR-ATR and FT-Raman analysis of extracted phycocolloids and ground dry seaweed.

The antibacterial performance of sol-gel-derived inorganic-organic hybrid polymers filled with ZnO nanoparticles-chitosan against a gram-negative bacterium Escherichia coli and a gram-positive Micrococcus luteus has been investigated. Three different molecular weights (MW) of chitosan (CTS) 1.36 · 10 5 , 2.2 · 10 5 , and 3.0 · 10 5 Da with equal degree of deacetylation (DD, 85%) (coded as S 85-60, He 85-250, and He 85-500) with equal degree of deacetylation (DD, 85%) were examined. ZnO was prepared by the base hydrolysis of zinc acetate in isopropanol using lithium hydroxide (LiOH · H 2 O) to hydrolyze the precursor. Sol-gel-based inorganic-organic hybrid polymers were modified with these oxides and were applied to cellulosic cotton (100%) and cotton/polyester (65/35%) fabrics. Inorganic-organic hybrids polymers were based on 3-glycidyloxypropyltrimethoxysilane (GPTMS). Bacteriological tests were performed in nutrient agar media on solid agar plates and in liquid broth systems using ZnO nanoparticles with average particle size of (40 nm). Our study showed the enhanced antibacterial activity of ZnO nanoparticles chitosan (different MW) of against a gram-negative bacterium Escherichia coli DSMZ 498 and a gram-positive Micrococcus luteus ATCC 9341 in repeated experiments. The antibacterial activity of textile treated with ZnO nanoparticles chitosan increases with decreasing the molecular weight of chitosan.

Marine ecosystems cover 70% or more of the earth's surface and are home to a great diversity of marine organisms that play vital role in the ecological balance of marine environments. Various anthropogenic activities continue to pose harm to the coastal waters thus the need to conduct more studies. The goal of this research is to determine the proximate biochemical composition and the cytotoxicity of crude extracts of selected sea stars collected from the coastal waters of Carmen, Agusan del Norte, Philippines. Proximate biochemical analysis of sea stars were only limited to the ash, lipid, carbohydrate and protein contents. Cytotoxicity was evaluated in terms of brine shrimp lethality assay. The findings showed significant differences in the ash, carbohydrates, lipid, and protein contents in the three sea stars. Brine shrimp lethality assay showed that only A. planci had cytotoxic activity while the rest of the sea stars were categorized as non-toxic. Based on this study, the collected non-toxic sea stars could be used as an alternative source of proteins in the development of feeds and other food materials. Furthermore, the presence of cytotoxic activity of A. planci indicates the advanced studies required in discovering and isolating bioactive components that can be used a lead component in antibacterial and antitumor drugs.

Recently, much attention has been given to pulmonary drug delivery by means of nanosized systems to treat both local and systemic diseases. Among the different materials used for the production of nanocarriers, chitosan enjoys high popularity due to its inherent characteristics such as biocompatibility, biodegradability, and mucoadhesion, among others. Through the modification of chitosan chemical structure, either by the addition of new chemical groups or by the functionalization with ligands, it is possible to obtain derivatives with advantageous and specific characteristics for pulmonary administration. In this paper, we discuss the advantages of using chitosan for nanotechnology-based pulmonary delivery of drugs and summarize the most recent and promising modifications performed to the chitosan molecule in order to improve its characteristics.

Phaeophyceae, Ochrophyta) are analyzed by spectroscopic techniques. The nature of the polysaccharides (with extraction and without any type of extraction) present in these seaweeds was determined with FTIR-ATR and FT-Raman analysis of extracted phycocolloids and ground dry seaweed.

Mucins are high molecular weight glycoproteins characterized by highly O-glycosylated tandem repeat domains. Mucin-type O-glycans exhibit a variety of terminal sequences including histo-blood group antigens that serve as counter receptors and participate in the adhesion and clearance of numerous bacteria including pathogens. In parallel, the pathological changes of mucin glycosylation modulate bacterial adhesion, often enhancing the adhesion of pathogenic bacteria. This review summarizes the current knowledge on the structure and biosynthesis of epithelial mucin O-glycans chains, the physio-pathological glycosylation repertoire of mucins and the role of mucin glycosylation in bacterial adhesion, focusing on the gastrointestinal tract and airway mucins.

My long journey in search of education and research in the realms of the chemistry of carbohydrates, such as sucrose and hyaluronic acid, took me through many parts of the world such as Bangladesh,. A brief description of the same is furnished hereunder. The two principal objectives of our research on carbohydrates were: (a) to understand the mechanism towards various chemical and enzymatic reactions and (b) to explore the commercial potential of the resulting carbohydrate derivatives. In this review, emphasis will mainly be placed on the second objective; and the inventions that followed as a result of the basic chemical and biochemical research on carbohydrates leading to the products of commercial significance, such as Sucralose ® (Splenda ®), a high-intensity sweetener.

Synthetic neamine mimetics have been evaluated for binding to the HIV-1 Rev response element. Modified neamine derivatives, obtained from reductive amination of neamine, led to identification of new 6-amino modified neamine-type ligands with HIV-1 RRE binding affinity up to 20× that of neamine and up to 6× that of the more complex neomycin itself. This provides a noteworthy structure-activity increase and a useful lead to simplified, chemically accessible mimetics.

A method is presented for the detailed and accurate quantitative determination of the monomeric composition of polysaccharides. The method is a modification of the well-known Saeman hydrolysis in combination with 600 MHz 1 H NMR quantification. Experimental conditions for this two-step hydrolysis have been optimized for cellulose and hemicelluloses, and the method has been applied to several other polysaccharides as well. It is shown that even very resistant polysaccharides are hydrolyzed completely, while at the same time degradation of monosaccharides is kept at a minimum. The degradation of monosacharides is corrected for by subjecting a standard mixture represented in the polymer to the same conditions. This correction results in a very accurate and reproducible method with relative deviations down to 1%. It is shown that the duration of hydrolysis and the concentration of sulfuric acid in the second hydrolysis step are the most important factors to determine the reliability of the results.

Abstract Pseudo-C-nucleosides have potential biological
activity, and an efficient synthesis of new pseudo-C-nucleosides
has been developed via the reaction of a b-formyl-a,bunsaturated
ester bearing a b-sugar moiety with hydrazines in
neutral and acidic conditions. The preparation of the b-formyl-
a,b-unsaturated ester was accomplished by oxidation of
the secondary hydroxyl group of 3-O-benzyl-1,2-O-isopropylidene-
a-D-glucofuranose, followed by elongation of its
carbon chain with (ethoxycarbonylmethylene)triphenylphosphorane
and oxidation of the hydroxymethyl group.

Keywords Carbohydrates Heterocycles
Pseudo-C-nucleosides  Pyridazinone  Wittig reaction

Cassava is a very important food to the low income group of people in Uganda. A study was therefore carried out in four districts of Uganda to study how cassavabased foods are traditionally prepared. The report includes the production level of cassava and the population that depends on it. The traditional methods of processing cassava were found to be boiling, baking, frying, sundrying, and either hand grinding or milling. Cassava was also found to be prepared mixed with broad beans, peas and sometimes with meat. Composite flour was also found to be produced; this usually consisted of cassava flour mixed with either millet, sorghum or maize (corn). Cyanide and nutrient values of the cassava products were determined. Cyanide ranged from 20.1 to 94.5 mglkg, crude protein from 1 .O4 to 4.38 g/100 g, and soluble carbohydrates from 0.4 to 2.68 g/lOO g. The main method of processing cassava is boiling. However, composite flour consumption is also significant and is the major method of cassava preservation. Les teneurs en composés cyanés et en nutriments des produits derives du manioc ont et6 d6termindes. Les teneurs en compos6es cyanes varient entre 20,l et 94,s b mgkg, celles en proteines entre 1 ,O4 et 438 g/lOO g et celles en sucres solubles entre 0,4 et 2,68 g/l 00 g.

Glycosidation of fully acetylated glucopyranosyl iodide with methanol under the influence of iodine gave a-glucoside selectively. Use of less reactive acceptors led to the formation of a/b-mixtures. Glycosylations with fully benzoylated glucosyl iodide yielded b-glucosides only. In contrast, iodine-promoted glycosylation of serine and threonine with 2-azido-2-deoxy-glycosyl iodides, easily obtained in three steps, proceeded smoothly, resulting in only a-linked products in high yield in most cases.

Isotopic and biochemical features of suspended particulate organic matter (POM) in the water column and of sedimentary organic matter (SOM) were investigated seasonally in the Bay of Marseilles. Biochemical compounds (carbohydrates, lipids and proteins) were consistently more concentrated in POM than in SOM, with SOM mainly composed of insoluble carbohydrates. POM displayed lower d 13 C and higher d 15 N values than SOM. Phytoplanktonic production represented the major contributor of POM year-round with spatial and seasonal variations. Climatic parameters and wind-induced currents created differences in POM contributions, with more important inputs of terrestrial OM at one sampling site. Spatial and seasonal variations were lower for SOM. The composition of this pool appeared to be linked with the permanent inputs of phytoplankton and Posidonia oceanica detritus. The combined use of biochemical and isotopic analyses was a useful tool to characterize OM pools and would help understanding the trophic functioning of this coastal environment.

Carbohydrates play an immense role in different aspects of life. NMR spectroscopy is the most powerful tool for investigation of these compounds. Nowadays, progress in computational procedures has opened up novel opportunities giving an impulse to the development of new instruments intended to make the research simpler and more efficient. In this paper, we present a new approach for simulating 13 C NMR chemical shifts of carbohydrates. The approach is suitable for any atomic observables, which could be stored in a database. The method is based on sequential generalization of the chemical surroundings of the atom under prediction and heuristic averaging of database data. Unlike existing applications, the generalization scheme is tuned for carbohydrates, including those containing phosphates, amino acids, alditols, and other non-carbohydrate constituents. It was implemented in the Glycan-Optimized Dual Empirical Spectrum Simulation (GODESS) software, which is freely available on the Internet. In the field of carbohydrates, our approach was shown to outperform all other existing methods of NMR spectrum prediction (including quantum-mechanical calculations) in accuracy. Only this approach supports NMR spectrum simulation for a number of structural features in polymeric structures.

Two free-radical cyclization reactions with the radical at the chiral C4 of the pentose sugar and the intramolecularly C1-tethered olefin (on radical precursors 8 and 17) gave a new diastereospecific C4−C8 bond in dimethylbicyclo[2.2.1]heptane 9, whereas the new C4−C7 bond in 7-methyl-2-oxabicyclo[2.2.1]heptanes 18a/18b gave trans and cis diastereomers, in which the chirality of the C4 center is fully retained as that of the starting material. It has been shown how the chemical nature of the fused carbapentofuranose scaffolds, dimethylbicyclo[2.2.1]heptane 9 vis-avis 7-methyl-2-oxabicyclo[2.2.1]heptanes 18a/18b (C7-Me in the former versus 2-O-in the latter), dictates the stereochemical outcome both at the Grignard reaction step as well as in the free-radical ring-closure reaction. The formation of pure 1,8-trans-bicyclo[2.2.1]heptane 9 from 8 suggests that the boat-like transition state is favored due to the absence of steric clash of the bulky 1(S)-O-p-methoxybenzyl (PMB) and 7(R)-Me substituents (both in the α-face) with that of the 8(R)-CH 2

A convergent strategy has been developed for the synthesis of the tetrasaccharide repeating unit of the O-antigen from Edwardsiella tarda PCM 1156. Sequential glycosylations of a series of rationally protected monosaccharide intermediates were achieved either by the activation of thioglycosides using N-iodosuc-cinimide (NIS) in conjunction with H 2 SO 4 –silica or by activation of trichloroacetimidate by H 2 SO 4 –silica only. All glycosylation reactions resulted in the formation of the desired linkage with absolute stereose-lectivity and yielded the required derivatives in good to excellent yields. Both azido and phthalimido groups have been used as the precursor of the desired acetamido group depending on the requirement of 1,2-cis-or 1,2-trans-glycosidic linkage.

Galectins form a family of carbohydrate-binding proteins defined by their affinity for -galactosides containing glycoconjugates. The carbohydrate recognition domain (CRD) is responsible for the specificity of galectins for saccharides. This binding may result in modulated cell proliferation, cell death and cell migration, three processes that are intimately involved in cancer initiation and progression. Galectins can also display protein-protein types of interactions with their binding partners. Certain galectins directly involved in cancer progression seem to be promising targets for the development of novel therapeutic strategies to combat cancer. Indeed, migrating cancer cells resistant to apoptosis still constitute the principal target for the cytotoxic drugs used to treat cancer patients. Reducing the levels of migration in apoptosis-resistant cancer cells can restore certain levels of sensitivity to apoptosis (and so to pro-apoptotic drugs) in restrictedmigration cancer cells. Anti-galectin agents can restrict the levels of migration of several types of cancer cell and should therefore be used in association with cytotoxic drugs to combat metastatic cancer. We provide experimental proof in support of this concept. While the present review focuses on various experimental strategies to impair cancer progression by targeting certain types of galectins, it pays particular attention to glioblastomas, which constitute the ultimate level of malignancy in primary brain tumors. Glioblastomas form the most common type of malignant brain tumor in children and adults, and no glioblastoma patient has been cured to date.

Carbohydrates are biomolecules that have an essential role in every form of life. The reservoir of naturally occurring glyco-structures is incredibly large and involves a tremendous number of carbohydrate-active enzymes (more than 280,000 released modules in the Carbohydrate Active enZymes database) for their synthesis and degradation. Nevertheless, natural enzymes do not necessarily present all the requested properties in terms of efficiency, specificity or stability when considering their usage for carbohydrate or glyco-derivative manufacturing. In addition, if existing, the identification of an enzyme perfectly adapted to a specific function from the natural diversity may be critical due to the lack of available biochemical data and may necessitate intensive screening efforts. To circumvent such limitations and provide optimized solutions, protein engineering has been considered. Leloir-type glycosyltransferases, for example, are mainly involved in the biosynthesis of glycoconjugates in Nature and they have been widely studied and engineered for this purpose. However, these enzymes are often found as membrane-bound proteins, what renders difficult their isolation and purification. In addition, their need of low-abundant activated sugars as glycosyl donors also impairs their usage. Alternatively, enzymes that use more abundant glycosyl donor directly issued from agro-ressources have been considered to access to new glyco-derivatives. This has promoted the use of glucansucrases (GS) that catalyze transglycosylation reactions from sucrose substrate. These enzymes are of particular interest for synthetic purpose and have found industrial interest for pharmaceutical and fine chemical applications. To diversify their applications, various approaches of engineering have been exploited to improve expression level, stability, or change substrate or product specificity of these enzymes. In particular, the range of molecules recognized and the osidic linkages formed by GS is broad but yet limited. Therefore, protein engineering methods have been applied to further increase the diversity of glycosylation reactions catalyzed by these enzymes. Sequence analysis and mutagenesis experiments have enabled the identification of key amino acid residues of glucansucrases either involved in catalysis or substrate specificity. Moreover, the determination of three-dimensional structures of glucansucrases from both families 13 and 70 of Glycoside-Hydrolases (GH) have provided powerful information for understanding the sequence-structure-function relationships and guiding structure-based rational and semi-rational engineering of these proteins. To assist these efforts, high-throughput screening and biomolecular methods have been developed for the directed evolution of these enzymes. Here are reported some of the successes in the bioengineering of glucansucrases from precursor work to latest results, as well as the methods developed for screening and developing efficient variant libraries. The major progresses and breakthroughs in the field will be highlighted and further prospects will be considered and discussed.

Nucleoside analogues have proven to be highly successful chemotherapeutic agents in the treatment of a wide variety of cancers. Several such compounds, including gemcitabine and cytarabine, are the go-to option in first-line treatments. However, these materials do have limitations and the development of next generation compounds remains a topic of significant interest and necessity. Herein, we discuss recent advances in the chemical synthesis and biological evaluation of nucleoside analogues as potential anticancer agents. Focus is paid to 4′-heteroatom substitution of the furanose oxygen, 2′-, 3′-, 4′-and 5′-position ring modifications and the development of new prodrug strategies for these materials.

Legumes, such as black beans (Phaseolus vulgaris L.) and chickpeas (Cicer arietinum L.), have a low glycemic index, and may reduce the glycemic load of meals in which they are included. Although the low glycemic response of beans consumed alone has been documented, few studies have examined the glycemic response to traditional food combinations such as black beans and rice or chickpeas and rice. This randomized cross-over study examined the glycemic and insulinemic impact of 50 grams of available carbohydrate from three test meals: plain white rice (control), black beans with rice, and chickpeas with rice among healthy adult women (n = 12, 18–65 years). Treatments were consumed on different mornings, a minimum of 7 days apart. Blood samples were collected at time 0 (fasting), and at 30, 60, 90, and 120 min postprandial, and were subsequently analyzed for glucose and insulin concentrations. Glucose response based on the incremental area under the curve showed a significant difference by treatment (p = 0.027). Changes in blood glucose concentrations were significantly different for the black bean meal and the chickpea meal in comparison to rice alone at 60 min (p = 0.026 and p = 0.024), 90 min (p = 0.001 and p = 0.012) and 120 min post prandial (p = 0.024; black bean meal). Findings indicate that combinations of black beans and chickpeas with white rice improve glycemic response, providing evidence that has promising implications for dietary guidance to reduce postprandial glucose and related health risks through traditional food patterns.

Atomic force microscopy has been used to characterise populations of extracted water-soluble wheat endosperm arabinoxylans. The adsorbed molecules are extended structures with an estimated Kuhn statistical segment length of 128 nm, suggesting that they adopt an ordered helical structure. However, estimates of the molecular weight distribution, coupled with size exclusion data, suggest that, in solution, the polysaccharides behave as semi-flexible coils, with a Kuhn length of 16 nm. These data imply that adsorption of the arabinoxylan structures onto mica promotes formation of the helical structure. Adoption of this ordered structure is fortunate because it has permitted characterisation of branching observed in a small proportion (approximately 15%) of the population of otherwise linear molecules. The degree of branching has been found to increase with the contour length of the molecules. Degradation of the polysaccharides with xylanase has been used to confirm that both the backbone and branches are based on beta-(1-->4) linked D-xylopyranosyl residues.

Water extraction (at 60, 70, 80, and 90°C) was applied to Eucheuma to explore the relationship between the extraction temperature and the structure of the extracted polysaccharides. The extracts mainly comprised iota carrageenan. The extraction temperature affected the compositions and properties of the polysaccharide extract. The yield decreased as the temperature increased (30.33-24.49%). Higher temperature extraction resulted in lower molecular height (60-90°C: 0.57-0.48 nm) and layer height (60-90°C: 0.76-0.58 nm) on atomic force microscopy images, leading to a better gel-forming potential; lower temperature extraction produced more diverse polysaccharides. 60 and 80°C extracts were selected to represent low temperature extract and high temperature extract. Though the extracts had a weakness gelling ability, they cooperated with kappa carra-geenan through synergistic effect. 80°C extracts provided even higher synergistic effect than commercial IC (iota carrageenan) with stronger gel. It can be due to the amount of crosslink density variation. Possible schematic presentation was shown accordingly to illustrate the synergy.

Polysaccharide fractions isolated from L. tessellatus eggs were purified and eluted using the DEAE-sepharose fast flow column. These were collected, tested and pooled based on their sugars content: F1, F2, and F3 which contain 26.8, 23.3, and 20.2% sulfated glycans; 34.5, 38.2, and 45.0% uronic acids; and 23.5, 19.0, and 7.5% acetylhexosamines and hexosamines, respectively. Hyaluronidase inhibitory effects of the fractions are in the order F3 > F2 > F1 > Ascorbic acid, with F3 having the highest inhibition among the fractions and that of the standard, ascorbic acid. The electrospray ionization tandem mass spectrom-etry (ESI-MS/MS) confirmed the presence of uronic acids on F3, which could be a 0,2 A 2 fragment plus loss of methyl group which is very common among non-methylated, sulfated disaccharides.

a-Amylase a b s t r a c t A halotolerant bacterium, Planococcus maritimus VITP21 isolated from a saltern region in Kumta along the Arabian Sea Coast of India was found to have increased cellular levels of sugars (up to 2.3-fold) under osmotic stress when grown in minimal medium with glucose as the sole carbon and energy source supplemented with 10% w/v NaCl. The major sugar osmolyte which increased with the concentration of NaCl in the growth medium was purified and characterized using various nuclear magnetic resonance spectroscopy techniques. The sugar was found to be similar to sucrose but with the C-2 hydroxyl group of the glucose ring substituted with acetamido group, which is not previously reported for its natural synthesis by any other organism. This novel sugar, (2-acetamido-2-deoxy-a-D-glucopyranosyl)-(1?2)-b-Dfructofuranose, exhibited stabilizing effect on a model protein a-amylase by increasing the apparent midpoint transition, onset temperature of denaturation, and free energy of thermal unfolding.

Tannin/furanic rigid foams were modified by either polymeric 4,4’ diphenylmethane diisocyanate (pMDI) or a one-component polyurethane still presenting reactive isocyanate groups (PUR). Several different sequences of mixing the isocyanate and polyurethane with the chemicals used to prepare tannin-based foams were tested. Scanning electron microscopy (SEM) showed that addition of either pMDI or PUR yielded a more ordered microstructure of the foam and a larger cell size. Series of two different cell sizes were noticed: those obtained by the evaporation of the blowing agent used for classical tannin-based foams and those caused by the formation of CO2 issued by the reaction of the isocyanate groups with water. The cell size, density, thermal conductivity and mechanical property of tannin/furanic foams were controlled by changing the amount of blowing agent and weight fraction of pMDI. The cell size of pMDI modified foams was largest when the weight fraction of pMDI was 5% and kept decreasing as the pMDI percentage became higher. The density of the foams increased with the increase of the weight fraction of pMDI. The addition of pMDI increased slightly the thermal conductivity of tannin/furanic foam with the foams still presenting good thermal insulation. Moreover, the addition of pMDI in tannin/furanic foams improved markedly the foam's mechanical properties.