Cyclodextrins enzymatic degradation

One of the most attractive ways to bind organic molecules to a substrate on a temporary basis is to use hydrophobic binding. Some synthetic hydrophobic cavities have been developed. However, the most generally useful and available materials have been the cyclodextrins, enzymatic degradation products of starch [20]. These simple molecules have glucose units in a ring, and form a hydrophobic cavity into... 

A. Fetzner, L. Pfeuffer, and R. Schubert, Enzymatic degradation studies of (5-cyclodextrin with regard to the development of colonic specific release formulations, Proceed. Intern. Symp. Control. Rel. Bioact. Mater. 24 801-802 (1997). 

Cyclodextrins are manufactured by the enzymatic degradation of starch using specialized bacteria. For example, P-cyclodextrin is produced by the action of the enzyme cyclodextrin glucosyltransferase upon starch or a starch hydrolysate. An organic solvent is used to direct the reaction that produces P-cyclodextrin, and to prevent the growth of microorganisms... 

Antenucci, R., Palmer, J. K. Enzymatic degradation of a-and (3-cyclodextrins by bacteroides of the human colon. J. Agric. Food Chem. 1984, 32, 1316-1321. 

They are prepared by enzymatic degradation of starch. The enzyme cyclodextrin glucanosyltransferase (CGT) from Bacillus macerans, Bacillus megaterium or other bacterial strains cut the starch helix and join both ends of such destruct forming a cyclic compound. Because enzymes are not very specific, the obtained mixture contains cyclodextrins from 6 to 12 glucose units. The main fractions are a-, (3- and y-cyclodextrins which correspond to 6, 7 and 8 glucose units. 

Cyclodextrins are prepared on a commercial scale by the enzymatic degradation of starch. The corresponding cylodextrin transferases are nonspecific with respect to ring size. Pure a-5 cyclodextrins are precipitated selectively, and the transferases then establish a new equilibrium of all four cyclodextrins. a-Cy-clodextrin can be obtained in 40% yield in one step by precipitation with 1-de-canol, P-cyclodextrin in 60% yield by precipitation with toluene, and y-cyclodextrin in 50% yield with cyclohexadec-8-en-one. 

Cyclodextrins are natural polymers obtained by the enzymatic degradation of starch they have a unique torus-shaped structure and are pseudo-amphiphilic. They are classified as a-, p- or y-cyclodextrin according to the number of glucopyranose units. a-Cyclodextrin has six, p-cyclodextrin has seven and y-cyclodextrin has eight glucopyranose units. As a consequence of their unique structure, cyclodextrins are able to form inclusion complexes with therapeutics and increase the solubility, stability and compatibility of the molecules they carry under physiological conditions and within dosage forms. These inclusion complexes also help to mask the side effects, unwanted taste and odor of therapeutics. ... 

Closely related to the helical amyloses are the cycloamyloses which are produced by enzymatic degradation of amylose by glucosyl transferase enzymes. Cycloamyloses, better known as cyclodex-trins (Table 10.5), have been characterised with 6,7,8 and 9 glucose units (a,p,Y,8, varieties). The p form (10.28a) is the most studied and most used to date. Like the helical amyloses, the toroidalshaped cyclodextrins can form inclusion complexes with various molecules. These are usually formed by adding guest molecules to saturated solutions of the latter. 

ENZYMATIC DEGRADATION OF CYCLODEXTRINS PREPARATION AND APPLICATION OF THEIR FRAGMENTS... 

Cyclodextrins (CDs) have never ceased to fascinate scientists around the world due to their structures and properties [1], These inexpensive natural cyclic oligosaccharides could be obtained from the enzymatic degradation of a renewable material, namely starch. This family of water-soluble macrocycles are built up from D-(+)-glucopyranosyl units linked by a-l,4-glycosidicbonds (Fig. 2.1). In the enzymatically produced CD family, three derivatives are mainly known a-, (3-, and y-CD, constituted of six, seven, and eight glucose units, respectively (Fig. 2.1). 

Cyclodextrin One of a family of cyclic oligosaccharides produced by the enzymatic degradation of starch. 

Cyclodextrins are cyclic oligosaccharides formed by the enzymatic degradation of starch. In the process, one portion of the starch helix is hydrolyzed off, and the ends are joined together. The most common results are molecules made up of six, seven, or eight glucose units a-, or y-cyclodextrins, respectively. A schematic view of these structures is shown in Fig. 18. 

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