Polysaccharides cation complexes

Molecular Interactions. Various polysaccharides readily associate with other substances, including bile acids and cholesterol, proteins, small organic molecules, inorganic salts, and ions. Anionic polysaccharides form salts and chelate complexes with cations some neutral polysaccharides form complexes with inorganic salts and some interactions are stmcture specific. Starch amylose and the linear branches of amylopectin form inclusion complexes with several classes of polar molecules, including fatty acids, glycerides, alcohols, esters, ketones, and iodine/iodide. The absorbed molecule occupies the cavity of the amylose helix, which has the capacity to expand somewhat to accommodate larger molecules. The starch—Hpid complex is important in food systems. Whether similar inclusion complexes can form with any of the dietary fiber components is not known. 

We were successful earlier in achieving anioiuc/cationic complexes with glycosaminoglycans, e.g., hyaluronic acid/cationic polysaccharide compositions [44], now used in personal care applications. Those compositions are substantive, stable and user-friendly. Unfortunately, despite the highly anionic nature of hyaluronic acid (and other glycosaminoglycans), these materials do not block viral infections [39]. Furthermore, as shown by the in vivo rabbit irritation studies, such compositions displayed minimal irritation [13]. 

Other reactions may also be affected by the presence of complexing cations. Methyl furanosides that complex readily are hydrolyzed by acids at a lower rate in the presence of calcium chloride than those which do not. The first step of the hydrolysis, protonation by the acid, is impeded by the positive charge of the glycoside-cation complex. This retardation may be useful for the selective hydrolysis of polysaccharides. 

In case of polysaccharides the complexation of the pollutant by the ligand can displaced using acidic solution. The interaction between free electron doublet of nitrogen on amine groups and metal cations on chito-san derivatives by change in the pH of the solution reverses the sorption. Because the chelation mechanism is very sensible to pH. 

In the course of screening N9/cationic polymer formulations, an important observation was made. Hydrophobe modified cationic polysaccharides [33] displayed unique sperm impedance, but not spermicidal, properties. By contrast, the related non-hydrophobe modified material was devoid of that effect. It is important to state that hydrophobe incorporation into water soluble polymers, at the desired level for optimum efficacy, is complex. Chemical efficiency can be low in the derivatized polymer and solubility characteristics change dramatically. Of the various hydrophobes evaluated in these studies, the —C12H25 hydrophobe was preferred. 

The electrostatic interaction between oppositely charged protein and polysaccharide can be utilized for encapsulation and delivery of hydro-phobic nutraceuticals. As a result of this interaction, we may have either complex coacervation (and precipitation) or soluble complex formation, depending on various factors, such as the type of polysaccharide used (anionic/cationic), the solution pH, the ionic strength, and the ratio of polysaccharide to protein (see sections 2.1, 2.2 and 2.5 in chapter seven for more details) (Schmitt et al, 1998 de Kruif et al., 2004 Livney, 2008 McClements et al, 2008, 2009). The phenomenon of complex... 

Let us consider now the case of a specific ionic polysaccharide. The unique properties of complexes of the cationic chitosan with non-ionic sorbitan esters provides an interesting example. Grant and co-workers (2006) have established that mixtures of chitosan and surfactant form emulsion-like solutions and/or creams, where the surfactant component is present as droplets or micelle-like particles and the chitosan solution acts as the system s continuous phase. It was established that the length and the degree of saturation of the surfactant hydrocarbon chain have a significant impact on the development of the chitosan-surfactant complexes. Moreover, an optimal distance between the chitosan s protonated amine groups is required for effective interactions to occur between the polysaccharide and the sorbitan esters. 

In our study, formation of isoluble complexes between pectin, a heterogeneous mixture of a number of neutral and acidic polysaccharides, and lipoprotein was studied. The basic limitation with the formation of insoluble complexes is that it is difficult to quantitate the said interaction. Furthermore, the observed interaction between pectic polysaccharides and lipoprotein is at a pH which is not physiological. We, therefore, are attempting to study this interaction under physiological conditions and by use of buffer systems which are devoid of cations, in order to facilitate formation of soluble complexes. In addition, by using labelled pectic polysaccharides, studies resulting in the elucidation of kinetics, specificity and nature of the interaction between labelled pectic polysaccharides and lipoprotein will be performed. 

The action of chlorine in alkaline media is much slower than that of bromine. Lewin29 reported that the rate of oxidation of D-glucose at pH 9.8 by hypobromite is 1360 times higher than that by hypochlorite at the same pH. For cellulose, the ratio is much smaller (33 to 1). The complexity of the latter system is, however, revealed by the variability of this ratio over the pH range of 8-13 at pH 6-7, the action of hypochlorite is actually slightly faster than that of hypobromite. Maltodextrins and starch have been oxidized with alkaline sodium hypochlorite. The resulting oxidized polysaccharide formed stable complexes with calcium cations.30... 

Tonegawa et al. (2004) created a cationic polylysine with a tetrapeptide end sequence (glycine-tyrosine-glycine-lysine), which is a motif common to the consensus sequences of mussel adhesive proteins. They then cross-linked this with the anionic polysaccharide, gellan, enzymatically. The polyionic complexation between the cationic peptide and the anionic polysaccharide formed a hybrid fiber at the aqueous solution interface that, when cross-linked, mimicked the byssus gel that marine mussels use to adhere to surfaces, despite the presence of water and salt. 

Karadjova and coworkers [90] in a detailed and comprehensive investigation established a scheme for fractionation of wine components and Cu, Fe, and Zn determination in the different fractions. Like Fe, the other two metals may analogously exist in wines as free ions, as complexes with organic acids and as complexes with proteins, polyphenols and polysaccharides. The resin XAD-8 was used for the separation of wine polyphenols. Dowex ion exchange resins were used for the separation of cationic and anionic species of metals that were subsequently quantified off-line in Bulgarian and Macedonian wines by FAAS or ET-AAS (depending on their concentration levels). 

Plants contain signiFcant concentrations of polysaccharides of which the potentially negatively charged oxygen functions can bind cations electrostatically or chelate them via polyhydroxy groups [89]. Particular attention was attracted by a structurally complex pectic polysaccharide rhamnogalacturonan-II (RG-II) [90]. This ubiquitous component of primary plant cell walls forms dimers cross-linked by 1 2 borate diol esters (dRG-II) that were found to complex in vitro sped be divalent cations and the majority of Ba, Pb, Sr, and rare earth elements (REEs) in fruit and vegetables [45, 91]. 

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