Polysaccharide applications

The Jordi polyamine column is a polar column for simple sugar and polysaccharide applications. The amine groups are bonded to the DVB backbone and are stable in aqueous mobile phases. This material does not self-hydrolyze as do many silica-based amino packings (Fig. 13.14). 

Fischer S, Leipner H, Brendler E, Voigt W, Fischer K (2000) In El-Nokaly MA, Soini HA (eds) Polysaccharide Applications, Cosmetics and Pharmaceuticals. ACS Symposium Series, Washington, DC p 143... 

Among many available modified polysaccharides, application of only few of them is legal in view of the food law of particular countries. Some restrictions are put on the method of their manufacture and the purity of such products. 

S. Fischer, H. Leipner, E. Brendler, W. Voigt, and K. Fiseher, Molten inorganie salt hydrates as eellulose solvents, in M. A. El-Nokaly and H. A. Soini (Eds.), Polysaccharide Applications, Cosmetics and Pharmaceuticals, Ameriean Chemical Society, Washington DC, 1999, pp. 143-150. 

Lit. ACS Symp.. Ser. 737 (Polysaccharide Applications 1999) ApSimon 8, 245 -310 (synthesis) Aspinall, The Polysac charides, vols. 1,2, 3, Orlando Academic Press 1982,1983 1985 Atta-ur Rahman 19E, 689 - 746 (1997) "Creszenzi et al. Biomedical and Biotechnological Advances in Industrial Poly saccharides, New York Gordon and Breach 1989 Food Sci Technol. (N Y.) 87, 15-36 (1998) lUPAC/lUBMB, Bio chemical Nomenclature, 2nd ed., p. 127-179, London Portland Press 1992 Polysaccharides 1998,57-100 (supramolec-ular structures) Ullmann A25, 1 -55. 

Sakairi, N., Nishi, N. and Tokura, S. (1999) Cyclodextrin-linked chitosan synthesis and inclusion complexation ability, in Polysaccharide Applications Cosmetics and Pharmaceuticals (eds M.A. El-Nokaly and H.A. Soini), American Chemical Society, Washington, pp. 68-84. 

R. Moothouse, in M. Yalpani, ed.. Industrial Polysaccharides Genetic Engineering, Structure Property delations and Applications, Elsevier Science PubHshets BV, Amsterdam, the Netherlands, 1987. 

Poly(phenylenepyrazoles), 5, 300 Polypyrazoles, 5, 300 N-substituted, 5, 300 Polypyrazolines, 5, 300 Poly(pyrazol-l-yl) borates as ligands, 5, 225, 235 Polypyrroles applications, 4, 376 Polypyrrole tetrafluoroborate conductors, 1, 355 Polysaccharides as pharmaceuticals, 1, 152 Poly-2,5-selenienylenes applications, 4, 971 Polysilacyclopentanes, 1, 609 Polysufides macrocyclic... 

Sephadex. Other carbohydrate matrices such as Sephadex (based on dextran) have more uniform particle sizes. Their advantages over the celluloses include faster and more reproducible flow rates and they can be used directly without removal of fines . Sephadex, which can also be obtained in a variety of ion-exchange forms (see Table 15) consists of beads of a cross-linked dextran gel which swells in water and aqueous salt solutions. The smaller the bead size, the higher the resolution that is possible but the slower the flow rate. Typical applications of Sephadex gels are the fractionation of mixtures of polypeptides, proteins, nucleic acids, polysaccharides and for desalting solutions. 

The type of CSPs used have to fulfil the same requirements (resistance, loadabil-ity) as do classical chiral HPLC separations at preparative level [99], although different particle size silica supports are sometimes needed [10]. Again, to date the polysaccharide-derived CSPs have been the most studied in SMB systems, and a large number of racemic compounds have been successfully resolved in this way [95-98, 100-108]. Nevertheless, some applications can also be found with CSPs derived from polyacrylamides [11], Pirkle-type chiral selectors [10] and cyclodextrin derivatives [109]. A system to evaporate the collected fractions and to recover and recycle solvent is sometimes coupled to the SMB. In this context the application of the technique to gas can be advantageous in some cases because this part of the process can be omitted [109]. 

Mourier s report was quickly followed by successful enantiomeric resolutions on stationary phases bearing other types of chiral selectors, including native and deriva-tized cyclodextrins and derivatized polysaccharides. Many chiral compounds of pharmaceutical interest have now been resolved by packed column SFC, including antimalarials, (3-blockers, and antivirals. A summary is provided in Table 12-2. Most of the applications have utilized modified CO, as the eluent. 

Commercial applications for polysaccharides include their use as food additives, medicines and industrial products. Although plant polysaccharides (such as starch, agar and alginate) have been exploited commercially for many years, microbial exopolysaccharides have only become widely used over the past few decades. The diversity of polysaccharide structure is far greater in micro-organisms compared to plants and around 20 microbial polysaccharides with market potential have been described. However, microorganisms are still considered to be a rich and as yet underexploited source of exopolysaccharides. 

For food and pharmaceutical applications, the microbial count must be reduced to less than 10,000 viable cells per g exopolysaccharide. Treatment with propylene oxide gas has been used for reducing the number of viable cells in xanthan powders. The patented process involves propylene oxide treatment for 3 h in a tumbling reactor. There is an initial evacuation step before propylene oxide exposure. After treatment, evacuation and tumbling are alternated and if necessary the reactor is flushed with sterile nitrogen gas to reduce the residual propylene oxide level below the Food and Drug Administration permitted maximum (300 mg kg 1). The treated polysaccharide is then packaged aseptically. 

Polysaccharides can also be used to immobilise cells or enzymes, permitting the re-use of the catalyst and continuous flow systems. Alginates have the advantage that gel formation occurs under mild conditions, therefore cells remain viable and enzymes are not denatured but calcium gradually leaches out and the gel dissolves. Gellan or other combinations may prove superior for this application. 

Five articles on polysaccharide helices solved prior to 1979 have appeared in the volumes published between 1967 and 1982.2-6 The first was a review on X-ray fiber diffraction and its application to cellulose, chitin, amylose, and related structures, and the rest were bibliographic accounts. Since then, X-ray structures of several new polysaccharides composed of simple to complex repeating units have been successfully determined, thanks to technological advances in fiber-diffraction techniques, the availability of fast and powerful computers, and the development of sophisticated software. Also, some old models have been either re-... 

WUliams PA, PhUlips GO (1995) In Stephen AM (ed). Food Polysaccharides and Their Applications. Marcel Dekker, New York, p. 463... 

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