Maltosyl-CD

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. 

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). 

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... 

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]. 

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. 

A branched cyclodextrin, 6-0-a-maltosyl cyclodextrin (G2-CD), was produced from a-D-maltosyl fluoride and a cyclodextrin by the transglycosylation reaction catalyzed by pullulanase or isoamylase [100, 101]. 

The enzymatic reaction of maltosyl fluoride leading to the formation of native a-, p- and y-CDs was demonstrated much earlier by Hehre, Mizokami and Kitahata, thus laying the foundation to the enzymatic synthesis of CDs through the polycondenzation method. ... 

Whatman KC2F bonded silica gel developed with 0.4 M maltosyl-j8-CD and 0.6 M NaCl in acetonitrile/water (30 70) separated enantiomers of D,L-alanine-/3-naphthylamide, dansyl D,L-leucine, dansyl D,L-valine, D,L-methionine-j8-naphthylamide, and V -(2-naphthylmethyl)nornicotine, and the diastereomers... 

A p-CD in saturated aqueous solution of urea containing 3.5% NaCPacetonitrile (80 20) Acetonitrile water (30 70) containing 0.4 M maltosyl-jd-CD and 0.6 M NaCl... 

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