Polysaccharides antibiotic derivatives

Little work has, however, been done on the preparation of insolubilized antibiotics, but, in view of the success of initial trials, the field may be expected to develop quite rapidly. Many of the polysaccharide derivatives discussed in the present article may have antibiotic characteristics, although few have been tested for such. Furthermore, many of the polysaccharide derivatives used for insolubilization of other molecules (see Sections VIII-X, pp. 361-387) are suitable for insolubilization of antibiotics, the choice of derivative depending upon the functional groups available in the particular antibiotic substance under consideration. 

At present CSPs based on polysaccharide derivatives, chiral ion exchangers, and macrocycUc antibiotics are most commonly used for CEC enantioseparations, but CyD-based CSPs played an important role in establishing of this technique in both open tubular [64, 65] and packed capillary format [65]. 

D-Giucosamine and o-gaiactosamine, usually as A-acetyl derivatives, are part of the structures of several natural polysaccharides, whilst other uncommon aminosugars are components of the aminoglycoside antibiotics. We have also noted the occurrence of A-glycosides, where the nitrogen substitution is at the anomeric centre (see Box 12.3). 

Amino sugars are components of antibiotic substances109 and bacterial polysaccharides,1,0 and are therefore of interest. The nucleoside antibiotics amicetin, bamicetin, and plicacetin contain, as the sugar residue, a monoaminopentadeoxy disaccharide that is closely related to maltose. In view of the reported antibiotic and antitumor properties of these pyrimidine nucleosides,111,112 the synthesis of aminodeoxy derivatives of maltose would be of interest. 

Temperature is also an important parameter for controlling the resolution of enantiomers in HPLC. The enthalpy and entropy control of chiral resolution on antibiotic CSPs is similar to the case of polysaccharide-based CSPs (Chapter 2). Armstrong et al. [1] have studied the effect of temperature on the resolution behavior of proglumide, 5-methyl-5-phenylhydantoin and A-carbamyl-D-pheny-lalanine on the vancomycin column. The experiments were carried out from 0°C to 45°C. These results are given in Table 6 for three chiral compounds. It has been observed that the values of k, a, and Rs for the three studied molecules have decreased with the increase in temperature, indicating the enhancement of chiral resolution at low temperature. In another work, the same workers [22] have also studied the effect of temperature on the resolution of certain amino acid derivatives on the teicoplanin chiral stationary phase. They further observed poor resolution at ambient temperature, whereas the resolution increased at low... 

CMD and mixed derivatives based on CMD may be used for the fixation of antibiotics and enzymes on a polysaccharide matrix. A procedure was developed for amidation of CMD and its ethyl ester (CMDEE) with various aromatic amines in dioxane (100 °C), ethanol (78 °C), n-propanol (97 °C) and 2-propanol (82 °C) in the presence of a small amount of water [301]. CMDEE reacts with aliphatic and aromatic amines but in the case of amino acids the degree of amidation depends on the position of the amino moieties in the acids [302,303]. The DS decreases from S-, y-, /3, to a-amino acids. For the reaction with a-amino acids, carboxymethyl and carboxyethyl dextran azides are used [304],... 

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