Polysaccharides type polymers

Some additives can suppress dissociation of CyD complexes. Morphine occurs naturally in the opium poppy. It is a potent narcotic analgesic, and its primary clinical use is in the suppression of moderately severe pain. In patients with vomiting, a rectal dosage form such as a suppository should be usefiil, especially a prolonged-release-type suppository. We have demonstrated that a combination of a-CyD and xanthan gum, a polysaccharide-type polymer with high swelling capacity, enhanced rectal absorption of morphine in rabbits, when administered to rabbit s rectum in the form of Witepsol H-15 [81] hollow-type suppositories. The combination of CyDs and viscous polymers may be useful for optimizing the trans-mucosal delivery of morphine [81]. 

Poly(rra j-3,4-dihydroxytetrahydropyran-6,2-diyloxymethene)[(l->6)-(4-deoxy-a-D-glucan)] (6), a new polysaccharide-type polymer containing two hydroxy-groups on its repeating unit, has been prepared from poly(5,6-dihydro-2/f-pyran-6,2-diyloxymethylene) (7) which is obtained by ring-opening polymerization of 6,8-dioxabicyclo[3.2.1]-oct-3-ene (8) (Scheme 2). The water... 

It should be added that polymers have been prepared from unsaturated dioxabicyclic monomers. These polymers may be hydroxylated to form polysaccharide-type polymers. 6,8-Dioxabicyclo[3.2.l]oct-3-ene (l8) will undergo selective ring-opening polymerization ... 

The unsaturated polymer has via epoxidation and hydrolysis been converted into a polysaccharide type polymer. ... 

As mentioned in the introduction, various reviews over the last ten years show that many plants contain bioactive polysaccharides. Most of the plants studied were chosen due to their traditional use for different kinds of illnesses where the immune system could be involved. The following section will describe the pectic type polymers from the plants most studied for their structure, and activities related to the structure where possible. 

The first paper on the bioactive polysaccharides from Glycyrrhiza uralensis roots was published in 1996 by Kiyohara et al. [57]. They isolated a pectic type polymer with anti-complementary and mitogenic activity that was an acidic pectin, possibly containing rhamnogalacturonan type I as part of the total structure. Degradation of the uronic acid part of the molecule decreased both types of bio activities. The neutral oligosaccharide chains were shown to retain some of the activities of the native polymer, but it was suggested that they should be attached to the acidic core to retain maximum activity. 

Molecular Structure. Most starches consist of a mixture of two polysaccharide types amylose, an essentially linear polymer, and amylopectin, a highly branched polymer. The relative amounts of these starch fractions in a particular starch are a major factor in determining the properties of that starch. 

Different classifications for the chiral CSPs have been described. They are based on the chemical structure of the chiral selectors and on the chiral recognition mechanism involved. In this chapter we will use a classification based mainly on the chemical structure of the selectors. The selectors are classified in three groups (i) CSPs with low-molecular-weight selectors, such as Pirkle type CSPs, ionic and ligand exchange CSPs, (ii) CSPs with macrocyclic selectors, such as CDs, crown-ethers and macrocyclic antibiotics, and (iii) CSPs with macromolecular selectors, such as polysaccharides, synthetic polymers, molecular imprinted polymers and proteins. These different types of CSPs, frequently used for the analysis of chiral pharmaceuticals, are discussed in more detail later. 

C. Rochas and M. Lahaye, Average molecular weight and molecular weight distribution of agarose and agarose-type polysaccharides, Carbohydr. Polym., 10 (1989) 289-298. 

The starch granule contains two polysaccharide types amylose, which is a linear polymer, and amylopectin, which is a branched polymer. Amylose is composed of linear chains of about 800 to 22,000 a-D-glucopyranosyl units in (a-1,4) linkage... 

A) Macromolecular SOs They can be divided (a) into those consisting of the same repeat units or monomers (homopolymer) comprising the naturally occurring polysaccharide type SOs as well as synthetic polymeric type SOs (including polymethacrylate and imprinted polymer type SOs), and (b) into those made up of different repetitive units or monomers like the proteins. 

Many ATPS systems contain a polymer which is sugar based and a second one which is of hydrocarbon ether type. Sugar-based polymers include dextran (Dx), hydroxy propyl dextran (HPDx), FicoU (Fi) (a polysaccharide), methyl cellulose (MC), or ethylhydroxyethyl cellulose (EHEC). Hydrocarbon ether-type polymers include poly (ethylene glycol) (PEG), poly (propylene glycol) (PPG), or the copolymer of PEG and PPG. De-rivatized polymers can also be useful, such as PEG-fatty acids or di-ethylaminoethyl-dextran (Dx-DEAE). 

We have seen that polysaccharides are polymers composed of a single type of monomer (carbohydrates), as are proteins (amino acids). The third type of hiopolymer is more complex. Nucleic acids use three very different types of monomers the phosphate group, one of two simple carbohydrate units (deox)tribose or ribose), and selected organic bases (Figure 28-15). A typical segment of the resulting polymer is shown in Figure 28-16. 

One of the major hmitations of coated polysaccharide-type CSPs is their incompatibility with so-called non-standard solvents. Specifically, the exposure of coated CSPs to dichloromethane, chlororform, ethyl acetate, tetrahydrofuran, dioxane, toluene and acetone, induces swelling and/or dissolution of the physically adsorbed polymer films and thus destruction of fhe columns. To address this serious drawback, a considerable amount of research has focused on the development of immobihzed versions with global solvent compatibility. In the last two decades numerous immobilization strategies have been reported [126], and the quest for solvent-stable versions capable of reproducing with fidelity the excellent separation characteristics of their coated congeners is still an active field of study [100, 127-130]. Reported immobilization approaches capitalize on (i) surface at-... 

Polysaccharides are polymers of monosaccharides. Starch, glycogen, and cellulose are examples of polysaccharides. Polysaccharides can be homogeneous in terms of its fundamental unit (monosaccharide). If more than one type of monosaccharide is present in a polysaccharide, then it is called a heteropolysaccharide. 

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