Polysaccharides carbonates, preparation

A traditional system for the preparation of table olives, involves a treatment of the fresh fruit with a solution of NaOH to hydrolised the bitter glycoside oleuropein, followed by a lactic fermentation in brine. The modifications that take place on pectic polysaccharides of olives (Manzanilla variety) during this process was smdied. Processing induced a net loss of polysaccharides soluble in sodium carbonate and a paralel accumulation of water and Imidazole/HCl soluble polysaccharides. A general decrease of the apparent molecular weight of water and carbonate soluble polysaccharides was also detected. 

Xanthan is the extracellular (exocellular) polysaccharide produced by Xanthomonas campestris. As with other microbial polysaccharides, the characteristics (polymer structure, molecular weight, solution properties) of xanthan preparations are constant and reproducible when a particular strain of the organism is grown under specified conditions, as is done commercially. The characteristics vary, however, with variations in the strain of the organism, the sources of nitrogen and carbon, degree of medium oxygenation, temperature, pH, and concentrations of various mineral elements. 

Easily prepared from the appropriate monosaccharide, a glycal is an unsatii-rated sugar with a C1-C2 double bond. To ready it for use in polysaccharide synthesis, the primary —OH group of the glycal is first protected at ts primary -OH group by formation of a silyl ether (Section 17.8) and at its two adjacent secondary —OH groups by formation of a cyclic carbonate ester. Then, the protected glycal is epoxidized. 

The formation of cyclic carbonates of polysaccharides for biopolymer insolubilization [20] has been described and has found application in the preparation of immunosorbents. Coupling of enzymes to polysaccharides, glass and nylon structures using titanium halides has been described [21]. In this case coupling is through hydroxyl groupings. 

PHARMACOLOGICAL EFFECTS The type of extract or preparation can be important since alcoholic extracts are unlikely to contain polysaccharides, whereas aqueous extracts may not contain the lipophilic alkamides. Tests have been performed with the pressed juice, alcoholic extracts and isolated pure compounds. Effects such as increased phagocytosis as measured by the carbon clearance test, macrophage activation,... 

Related to the cyclic carbonates are the cyclic imidocarbonates produced by the action of cyanogen bromide on polysaccharides. " In terms of a monosaccharide model, " the major derivative of the reaction from a (1- 4)- or (I->6)-glucan is the trans-2,3-imidocarbonate, small proportions of the 2,3-carbonate, 2- and 3-carbamate, and, possibly, triazinyl groups also being formed. Cyclic imidocarbonate derivatives of Sephadex and 0-(2-aminoethyl)- and 0-[3-(p-aminophenoxy)-2-hydroxypropyl]-Sephadex have been prepared, " and the derivatization occurs equally well... 

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