Glucosyl-CD

The so-called first-generation cyclodextrin (CD), i.e. the native a-CD, -CD and y-CD, each has its limitations in application. -CD exhibits poor solubility a-CD owns a small cavity which restricts the size of the guest molecules y-CD has a larger cavity but expensive. Thus, to expand the application area, native CDs are usually modified to improve their physiochemical properties [ 1 ]. Until now, various branched-CDs, such as methyl-CD, hydroxypropyl-CD, glucosyl-CD (Gl-CD) and maltosyl-CD (Mal-CD) have already been commercialized. 

In a very interesting application, a-, / -, y-cyclodextrin (CD), 6-0-glucosyl-) -CD, and 6-0-/I-maltosyl-CD were resolved on a Cjg column (A = 355 nm) using a 94/6 water (0.025% I2 with 0.05% KI) mobile phase [139]. Elution was complete in 20 min. Plots of the effects of percent methanol and iodine concentration on retention were presented. Linear ranges of 0.05-0.25 mM were reported along with detection limits of 5-70 pM (analyte dependent). 

Addition of an aqueous solution of PEG to a saturated aqueous solution of a-CD at room temperature did not lead to complex formation unless the average molecular weight of PEG exceeded 200 [46]. Moreover, carbohydrate polymers such as dextran and pullulan failed to precipitate complexes with PEG, and the same was true for amylose, glucose, methyl glucose, maltose, maltotriose, cyclodextrin derivatives, such as glucosyl-a-CD and maltosyl-a-CD, and water-soluble polymers of a-CD crosslinked by epichlorohydrin. These facts suggested to Harada et al. the direction for further research. 

Many CDs have been successfully used to solubilize insoluble drugs, here are a partial list of CD derivatives reported in the literature fflFCD, SBE-ft-CDs, randomly methylated-P-cyclodextrin (RM-p-CD), 2,3,6-partially methylat flcyclodextrin (PM-ft-CD), glucosyl-ft-CD (G1-P-CD), maltosyl-p-cyclodextrin (G2- -CD), hydroxyethyl-p-cyclodextrin (He-p-CD), diethyl-P-cyclodextrin (DE-p-CD)P-carboxymethyl-Qethyl- -cyclodextrin (CME-p-CD), and (2,6-oG>-methyl)-p-cyclodextrin (DOM-p-CD). 

Valeur et al. have modified every glucosyl subunit of the primary rim of P-CD with naphthoate donor groups [374], At pH > 8, the emission spectrum of 36 is composed of naphthoate monomer and excimer fluorescence, the ratio of which readily allows surfactant concentrations to be ascertained. Ionic strength and competition binding experiments strongly point toward a micelle complex rather than a 1 1 inclusion complex. Aggregates between 36 and cationic sur-... 

Branched CDs (mono- or di-glucosyl, maltosyl and glucopyranosyl a- and p-CDs) are more resistant to a-amylase than natural CDs. Natural P-CD and mono-glucosyl-P-CD are stable in rat blood because they have no linear glycosidic bond. Branched CDs exert a lower hemolytic activity on human erythrocytes and are... 

The synthesis and properties of a malaria candidate glucosyl phosphatidyl inositol (GPI) prototype (47), and one variant, i.e., (48), of the candidate structure has been reported. The approach elaborated addresses the crucially important (vide infra) 0-2 acylation of the inositol moiety, an unusual feature which also occurs in other heavily lipidated GPIs such as CD 52 and AchE (Figure 9). ... 

The main derivatives under development as excipients are all derivatives of p-CD 1) a randomly methylated derivative with an average MS of 14 (M14-p-CD) 2) two different 2-hydroxypropyl derivatives, one with an average MS of approximately 3 ((2HP)3-p-CD) and the other with an average MS of 7 ((2HP)7-p-CD) and 3) a sulfobutyl ether derivative with an average MS of 7 (SBE7-p-CD). Glucosyl and maltosyl CDs which contain a mono- (Gi-p-CD) or disaccharide (G2-P-CD) substituent, have also been reported and show promise for the future. 

TABLE 5 Quantum Yields and Lifetimes t of Phosphorescence aud Oxygen Quenching Rate Constants of 1-Bromonaphthalene-Glucosyl-p-CD-alcohol Complexes in Water ... 

Freudenberg and co-workers correctly proposed a cyclic structure for the CDs. However, the numbers of D-glucosyl moieties which they assigned to the a- and p-dextrin rings (five and six, respectively) were incorrect. The correct values of six and seven were determined... 

Modification of the CDs either with glucosyl, maltosyl, hydroxypropyl, hydrox-yethyl, methyl or sulfate groups increases their aqueous solubihty. Modification of CDs with low aqueous solubility or those that are insoluble in water can be achieved by adding aliphatic groups or short nonpolar groups to the cyclodextrin or by cross-linking CDs with a suitable cross-linker, such as epichlorohydrin, to form spherical beads of polymers. These modified CDs have the same functional properties as the immodified CDs such as stabilization of guests, etc. [3]. 

Enzymatic process is the main method to produce cyclodextrins (CDs), and so far, chemical methods have been reported. CD is industrially produced from starch, glucogen, malto-oligosaccharides, and other dextrins through catalysis by cyclodextrin glucosyl transferase (CGTase). More and more researchers focus on the essential CGTase to prepare CD due to its wide applications in food, medicine, cosmetics, environmental protection, and analytical chemistry. 

CDs also can be used as stabihzersfor color indicators to increase the stability of indicators used for the spectrophotometric determination of hydrogen peroxide in body fluids. In addition, CDs and their derivatives also have applications in enzyme assays and enzyme activity measurement. For example, glucosyl- or maltosyl-a-CD have been used to increase the accuracy and sensitivity of the assay of amylase. 

To try to determine the number of subsites of the acceptor part of the active site we incubated 1,6-anhydro-maltose 13 and maltotriose 14 with CGTase in the presence of a-CD. Only compound 14 gave coupling products at a reasonable rate. It is suggested that two glucosyl residues are recognized on a coupling reaction so only two subsites constitute the acceptor part of the active site. 

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