Natural products carrageenans used

In the field of natural red algal galactans, MS was used for the first time in the structural analysis of odonthalan.353 Galactose and 6-O-methylgalactose, the hydrolysis products of the polysaccharide, were separated by column chromatography and identified by MS in the form of their di-O-isopropylidene derivatives. Cyclic derivatives of this type had been shown previously to be especially suitable for mass-spectrometric characterization of the structure and (in certain instances) stereochemistry of monosaccharides.349,354 A combination of GLC and MS was also used for identification of methyl 4.6-O-0 -methoxycarbonylethylidene)-D-galactosides (as their trifluoroacetates) in the methanolysis products of Ji-carrageenan from Petrocelis middendorfii,355... 

Many PECs are prepared using chitosan as the polycationic component, therefore they will be discussed separately. Chitosan, the product of N-deacetylation of chitin, is one of the most commonly used cationic polymers of pharmaceutical interest due to its biocompatibility, nontoxicity, and mucoadhesivity. It is frequently used to form PECs, often in combination with alginate, carrageenan," hyaluronic acid, chondroitin sulfate (CS)," carboxymethyl cellulose (CMC), or poly(galacturonic acid), since these are natural anionic polysaccharides with favorable pharmaceutical properties. 

Some of the currently most successful industrial-scale biotransformations exploit such cultures (e.g. the production of L-aspartic acid from fumaric acid by cells of the bacterium Escherichia coli immobilized in K-carrageenan) (see Scheme 6.11 in Chapter 6). Interestingly, there are several reported examples, such as that shown in Figure 25 and Table 27, where the stereochemical outcome of a biotransformation can be influenced by whether the microbial biocatalyst is used as free cells or immobilized cells in addition, the nature of the immobilization method itself can be influential in this respect. 

Natural thickeners are common used in products such as toothpaste, shampoo and creams and lotions to control the rheolog) of the product. In toothpaste for example, CMC, carrageenan and xanthan are used to control the smoothness and gloss of the product. They can also improve the extrusion properties and prevent tailing when the product is squeezed from the tube. Stability is also important and natural thickeners help to maintain the ribbon on the brush and also provide stability to temperature fluctuations. 

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