To Macrogels

Crosslinkers such as epichlorohydrin, sodium trimetaphosphate (STMP) and glutaraldehyde are widely used to prepare polysaccharide-based macroscopic hydrogels. Lack and co-workers 211 obtained crosslinked hydrogels by treating pullulan with STMP in alkaline aqueous medium. The crosslinking rate increased with an increase in the concentration of any of the reagents (pullulan, STMP, NaOH). A stronger gel was obtained with increasing polymer concentration whereas increasing STMP concentration led...

Structure and Enzymatic Degradation

The pullulan structure consists of a chain of d-glucopyranosyl units that alternate regularly between one a,1 6 and two a,1 4 linkages (Figure 4.1). Catley and co-workers 40 reported the presence of chain fragments resistant to the action of enzymes and such resistance was attributed to the presence of maltotetraose residues distributed randomly along the pullulan chain. These structural abnormalities may be present in the pullulan chain to a maximum extent of 7 and they do not affect the...

Fungal 5Glucans

A small number of fungi including Botryosphaeria rhodina 82 and Guignardia citricarpa 5 have been reported to synthesise pustulan-like exocellular glucans under certain cultural conditions. These were first characterised in the lichen Umbilicaria pustulata, and were shown to consist entirely of unbranched (1,6)-P-linked glucopyranosyl residues. They are similar to the glucans widely found in fungal cell walls and may derive from them 8 . However, most fungal exocellular P-glucans consist of a...

Applications of Polysaccharide Nano Microparticles in Diabetes Therapy

Diabetes is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin or because cells do not respond to the insulin that is produced. One of the most important difficulties that are met in diabetes treatment is represented by the poor gastrointestinal uptake of poorly absorbable drugs such as insulin. Polysaccharides (like those that are contained in black tea) may benefit people with diabetes because they help retard...

Pullulan Based Hydrogels as New Biomedical Materials

In the last 30 years, polysaccharide-based hydrogels have demonstrated tremendous potential applications in the medical and pharmaceutical fields as drug carriers, in the development of biomimetics, biosensors, artificial muscles and environmentally responsive or smart materials and in chemical separations 30 . As pullulan is by nature not a gelling polysaccharide, an appropriate chemical modification of its backbone is necessary to get macromolecular systems capable of forming hydrogels....

Antitumour Effects of Botanical Polysaccharides

Acemannan Macrophage Activation Pictures

Botanical polysaccharides have been shown to exhibit a range of antitumour properties utilising various mechanisms (Figure 6.5). Most antitumour activities of botanical polysaccharides are thought to be mediated via activation of host defence mechanisms, rather than direct cytotoxicity to tumour cells 301 . Note, however, that this paradigm is not absolute, and several mushroom polysaccharides have also been shown to exhibit direct inhibitory effects on cancer cell growth by modulating...

Applications of Polysaccharide Nano Microparticles in Diagnostics

In the last decade, nanotechnology has been found to be a successful alternative for solving major problems in diagnostics and imaging. Multifunctional nanoparticles, which incorporate diagnostic properties (such as quantum dots (QD), magnetic, metallic, polymeric and silica nanoparticles) and or therapeutic properties (such as magnetic and metallic nanoparticles), have already been developed. Nanoparticles due to their small size can be tailored to have specific or multiple functions and can...

Role of Intestinal Immune System in Modulating the Activity of Botanical Polysaccharides

Botanical polysaccharides are acquired orally. However, because of their high molecular weights, polysaccharides are not easily absorbed. Thus, these polysaccharides are first encountered by immune system components at mucosal surfaces, and it is clear that the enteric mucosal immune response plays an important role in the immunomodulatory effects of various botanical polysaccharides. The intestinal mucosal immune system includes Peyer's patches and other specialised lymphoid tissues (GALT) 262...

Immunomodulatory Activity of Plantderived Polysaccharides

Most polysaccharides derived from higher plants are relatively nontoxic and do not cause significant side effects, unlike immunomodulatory bacterial- and fungal-derived polysaccharides. Thus, plant polysaccharides are ideal candidates for therapeutics with immunomodulatory, antitumour and wound-healing action. In studies investigating the effects of plant polysaccharides on macrophage responses, the predominant finding is that polysaccharides derived from higher plants activate macrophages...

Applications of Hemicelluloses

The beneficial health effects of hemicelluloses include improving lipid metabolism and mineral balance 35 , improving colon function 36 , protection against colon cancer 37 , reducing the risk of heart disease and generally improving body health 38 . Hemicelluloses from various sources have potential health benefits as immunity enhancers 39, 40 . The chemical structure of hemicelluloses is the most important factor that influences their properties. This explains why polysaccharides present...

Synthesis of Dendrimers Convergent and Divergent Approaches

Convergent Synthesis

There are two major strategies of dendrimer synthesis (Figure 10.1) 6, 9, 11, 39, 63, 74 . In a 'divergent method', the growth of a dendron originates from a core site (Figure 10.1 1). Monomeric modules are built in a radial, branch-upon-branch motif in accord with certain dendritic rules and principles. In contrast, a 'convergent method' starts from blocks that will create the dendrimer shell (Figure 10.1 5) inwards to a reactive focal point, forming a single reactive dendron (7). A reaction...

Cellulose Whiskers

The intense hydrolysis of microcrystalline cellulose results in pure cellulose crystallites. By subsequent treatment with ultrasound, the cellulose crystallites assemble into rigid rod-like cellulose particles called cellulose whiskers 105 . The preparation is also possible by mechanical treatments whereby the amorphous parts are cleaved by mechanical disintegration of a cellulose suspension. This high energy consuming process could be optimised by an enzymatically produced precursor resulting...

References

Villiers, Comptes Rendus de l' Acad mie des Sciences, 1891, 112, 536. 2. F. Schardinger, Zeitschrift f r Lebensmittel-Untersuchung und - Forschung A, 1903, 6, 865. 3. L. Szente and J. Szejtli, Trends in Food Science & Technology, 2004, 15, 137. 4. J. Szejtli, Starch, 1982, 34, 379 . 5. H.J. Buschmann and E. Schollmeyer, Journal of Cosmetic Science, 2002, 53, 185. 6. A. Bochot and D. Duch ne in Actifs et Additifs en Cosm tologie, Eds., C. Martini and M. Seiller, Tec et Doc Lavoisier,...

Sulfation

Pullulan was sulfated with the aim of developing new alternatives to heparin, which suffers from its heterogeneous and variable structure, the animal origin and multiple in vivo effects. In 2001, two independent studies were published about the sulfation process on pullulan as compared to dextran, and optimised conditions to reach DS in sulfate groups up to 2.00 were established 123, 159 . The final characteristics of the sulfated pullulans (PS) depend to a great extent on the temperature, the...

Toxicity

The toxicity of natural CD and their water-soluble derivatives has been much studied. There are excellent reviews that provide detailed information on this topic, and the interested reader is referred to these 40-42 . When used by the oral route, CD can be hydrolysed by amylases from the digestive tract, in a manner similar to starch 43 . The hydrolysis of a-CD, with a small diameter, is more difficult than that of P-CD, and much more difficult than that of Y-CD. For this reason, there is not...

Bbreviations

acid) ADAMTS A disintegrin-like and metalloproteinase with AEPS Polysaccharides from Actinidia eriantha AOSMC Aortic smooth muscle cells APS-1 Polysaccharides from Aloe vera APTT Activated partial thromboplastin time ASGPR Asialoglycoprotein receptor ATCC American Type Culture Collection BAD Bcl-associated death protein BASYC Bacterial synthesised cellulose Bcl-xL B-cell lymphoma leukaemia-x BDNF Brain-derived neurotrophic factor bFGF Basic fibroblast growth factor CCI...

Rheology of Pullulan Solutions and Films

Pullulan fermentation broths may generally be considered as non-Newtonian fluids, which may be modelled by a power law 65 . Consequently, pullulan viscosity itself is a key parameter during pullulan production. Because of viscosity changes, oxygen and mass transfer modifications that occur during fermentation may influence the properties of the final product 66, 67 . By combining the techniques of confocal microscopy and optical tweezers, an image of the viscosity distribution around a...

Bacteria

Due to enhanced resistance of bacteria towards common antimicrobial agents, the search for new effective drugs is a challenge for scientists today. The resistant microorganisms cause several diseases that have a dramatic impact on mortality, disability and economics. A set of infectious diseases is initiated by the adhesion of bacterial lectins to host cells glycoconjugates. Escherichia coli and several other enterobacteria use Type 1 fimbriae - 30 kDa lectin-like subunit FimH - for...

Edicated to the memory of Severian Dumitriu

The idea of bringing out this book was that of one of my best, Severian Dumitriu, of the University of Sherbrooke, Canada, who unfortunately passed away 1 year ago. Keeping in mind his previous contributions to a number of books in the field of polysaccharides in the capacity of scientist as well as editor, we decided together with Daniela, his beloved daughter, and Helene Chavaroche, project coordinator, to continue with and finalise this book, and dedicate it to his memory. Severian Dumitriu...

Cyclodextrins in Nanoparticulate Drug Delivery Systems

Recently, nanoparticles, after liposomes and microparticles, have become the necessary carriers of fragile drug molecules such as anticancer products, proteins, genes and so on. The main reasons are that nanoparticles are more stable than liposomes, and, because of their small size, they have a larger surface area than microparticles, leading to higher bioavailability due to better contact with biological membranes. In this new type of formulation, CD revealed their ability to be more than...

Rh hr0 0 rh

Figure 2.2 Structure proposed for galactoglucomannan of Cassia laevigata seeds Arabinogalactans are a class of polysaccharides found in a wide range of plants however, they are most abundant in plants of the genus Larix 6 . Arabinogalactan represents 5-40 by mass of Larix wood. Larch arabinogalactan is composed of galactose and arabinose units in a 6 1 ratio, with a trace amount of uronic acid. The molecular mass of the major fractions of arabinogalactan in larch is 16,000 and 100,000. Glycosyl...

Cellulose and Its Use in Blood Purification

The term dialysis was coined by Thomas Graham, Professor of Chemistry at Anderson's University in Glasgow. In 1861, he demonstrated through his experiments that crystalloids were able to diffuse through vegetable parchment coated with albumin. Although Graham predicted that his findings might be applicable to medicine, he did not venture into this area. Dialysis may therefore be considered as a rate-governed membrane process in which microsolutes are driven across a semi-permeable membrane by...

Assembly of Pullulan

Little is known about how pullulan is synthesised in A. pullulans either. All the evidence suggests that pullulan is not a component of the cell walls of this fungus 4, 6, 100 . Instead it may be synthesised at the cytoplasmic membrane and then transported outside the cell by an unidentified lipid carrier 144 , although Campbell and co-workers 145 suggested that pullulan may be synthesised and initially stored intracellularly. No 'pullulan synthase' enzyme(s) has ever been detected or...

Fungal flGlucans

As Gidley and Nishinari 81 emphasise, there is still much to learn about the relationships between the chemical and physicochemical properties of these glucans. However, several of their important physicochemical behavioural properties can now be explained in structural terms. Thus, their inherent chain stiffness explains why their solutions have very high intrinsic shear rate-dependent viscosities. Furthermore, these glucans adopt a helical chain shape determined by the geometrical...

Periodate Oxidation and Smith Degradation

When periodate oxidation is combined with Smith degradation, further structural information, like glucan branching frequency, can be obtained 60 , and has been used to help elucidate, for example, 1,3 1,6 -P-glucan structure of Claviceps glucan 73 , scleroglucan 74 and the glucan from Laetisaria arvali 75 . However, this usually requires more than one round of oxidation degradation and a comparison of reaction products after each step 25 . Nonreducing ends are cleaved between C2 C3 and C3 C4,...

Botanical Polysaccharides as Adjuvants

Recently, many polysaccharides have been shown to possess adjuvant activity, as demonstrated by their ability to enhance specific cellular and humoral immune responses against antigens. Thus, botanical polysaccharides have been proposed to represent excellent candidates to replace alum as the adjuvant of choice for many vaccines 158, 288, 289 . For example, acemannan has been shown to increase lymphocyte responses to alloantigens in vitro 290 , exhibit adjuvant activity in vaccination against...

Nkjain Med Chem Topics

Roy, Advances in Carbohydrate Chemistry and Biochemistry, 2010, 63, 165. 2. D. Astruc, E. Boisselier and C. Ornelas, Chemical Reviews, 2010, 110, 4, 1857. 3. P.M.H. Heegaard, U. Boas and N.S. Sorensen, Bioconjugate Chemistry, 2010, 21, 3, 405. 4. T. Dutta, N.K. Jain, N.A.J. McMillan and N.H.S. Parekh, Nanomedicine Nanotechnology, Biology and Medicine, 2010, 6, 1, 25. 5. D.A. Tomalia, Soft Matter, 2010, 6, 3, 456. 6. G.R. Newkome and C. Shreiner, Chemical Reviews, 2010,...

Applications of Polysaccharide Nano Microparticles in Cancer Therapy

Micro nanotechnology generally is applied to cancer in two main areas the development of vectors carriers, such as micro nanoparticles, which can be loaded with drugs or imaging agents and then targeted to tumours, and nanosensor devices for detecting the biological signatures of cancer 11 . Polysaccharides have been found useful in both areas of applications in cancer therapy. They have been used as native or modified polysaccharides, as combination of two or more polysaccharides and as...

Bacterial Cellulose

Bacterial Cellulose

Bacterial cellulose, which was first described by Brown in 1886, is of particular interest in research and development 152 . There are various bacterial strains that produce cellulose extracellularly, including Acetobacter, Agrobacterium, Aerobacter, Achromobacter, Azotobacter, Rhizobium, Sarcina and Alcaligenes 153 . In particular, the bacterial strain Gluconacetobacter xylinum is used for the production of bacterial cellulose in a larger scale. The nonpathogenic bacteria produce cellulose...

Immunomodulatory Activity of Fungal Algae and Lichenderived Polysaccharides

Complement Receptor Neutrophil

Among the group of botanical polysaccharides, fungal-derived polysaccharides are the best-known and one of the most powerful immune stimulants. The reason may be that these types of polysaccharides are also constituents of cell walls of certain pathogenic microorganisms such as Pneumocystis carinii, Cryptococcus neoformans, Aspergillus fumigatus, Histoplasma capsulatum and Candida albicans. It has recently been recognised that the initial interaction between fungi and the innate immune system...

Microcrystalline Cellulose

For the production of microcrystalline cellulose, the biomass is generally treated with aqueous NaOH in order to purify the cellulose by removing other constituents 105 . The bleached material is then submitted to an acidic treatment. The natural cellulose fibrils are not uniform because they consist of crystalline and amorphous regions. The acidic hydrolysis of the cellulose substrate results in the dissolution of regions of low lateral order with the consequence that the water-insoluble,...