Y-Cyclo dextrin

EPMEs based on carbon paste impregnated with a-, />- and y-cyclo-dextrins are proposed for the assay of L-proline [31]. Response characteristics showed that the proposed electrodes could be reliably used in the assay of L-proline, with the best enantioselectivity and time-stability exhibited by a-cyclodextrin based EPME. The EPMEs based on the proposed unsubstituted cyclodextrins showed lower detection limits (10 10 magnitude order) than the one previously studied, based on /J-cyclodextrin derivative [30]. The widest linear concentration range is recorded for the y-cyclodextrin based EPME (10 8-10-3mol/L). The recovery tests performed for the assay of L-proline in the presence of d-proline (recoveries higher than 99.65%) proved that the proposed... 

Isomers of soman were separated by GC on a Chirasil-L-Val column but lacked baseline separation (Benschop et al, 1981, 1985 Li et al., 2003). In contrast, (+)-sarin and (—)-sarin could be completely separated by the same column (Benschop and de Jong, 2001). A recent study presented a modified method using a Chiraldex y-cyclo-dextrin trifluoroacetyl GC-column coupled to an electron impact (EI)-MS which enabled sufficient baseline separation of all four stereoisomers of soman (Smith and Schlager, 1996 Yeung et al, 2008). 

Fig. 3-114. Separation of a-, / -, and y-cyclodextrin. -Separator column CarboPac PA-1 eluent (A) 0.1 mol/L NaOH, (B) 0.1 mol/L NaOH + 0.5 mol/L NaOAc gradient linear, 100% A to 100% B in 20 min flow rate 1 vaU min detection and injection volume see Fig. 3-105 solute concentrations 500 ppm each of a- (1), ft- (2), and y-cyclo-dextrin (3).

Uekama, K., Otagiri, M., Sakai, A., et al. "(1985) Improvement in the percutaneous absorption of beclomethasone dipropionate by y-cyclo-dextrin complexation. J. Pharm. Pharmacol. 37 532-535. 

Boudad H, Legrand P, Lebas G, Cheron M, Duchene D, Ponchel G, Combined hydroxypropyl-y -cyclo-dextrin and poly(alkylcyanoacrylate)-nanoparticles intended for oral administration of saquinavir, Int. J. Pharm. 2001 218 113-124. 

Ueno, A. Moriwaki, F. Osa. T. Hamada. F. Murai, K. Association photodimerization, and induced-fit types of host-guest complexation of anthracene-appended y-cyclo-dextrin derivatives. J. Am. Chem. Soc. 1988. 110 (13), 4323-4328. 

Figure 6 Enantiomer separation of lactones by gas chromatography on octakis 3-0-butanoyl-2,6-di-0-n-pentyl)-y-cyclo-dextrin (18) (undiluted) at 150 °C and 1 bar (gage) hydrogen. Column 50 m x 0.25mm (i.d.) glass capillary. (From Konig WA, Krebber R, and Mischnick P (1989) Cyclodextrins as chiral stationary phases in capillary gas chromatography. Journal of High Resolution Chromatography 12 732-738.)...

Inoue et al, reported the intramolecular [4 + 4] photocycloaddition of 6A,6C-bis(2-anthracenecarboxylate) ester of a-cyclodextrin (a-CD) in water, which gave the antz-head-to-head cycloadduct (after base hydrolysis) in highly regio- and enantioselective manner in the presence of y-cyclo-dextrin (y-CD). " Diastereoselective photocyclodimers of ester of (249) tethered to cellulose were obtained. Saigo et al., found the diastereo- and enantio-selective photocyclodimerization of (249) and (250) by use of enantiopure amphiphilic amino alcohols as a matrix. The enantioselective photoreaction of (249) was also reported by Shinkai et al. (25Ia,b). 

If Y-cyclodextrin is crystallized as "empty" molecule from water, it arranges in a fishbone type cage structure similar as observed for a- and (5-cyclodextrins (17). If, however, a small guest like n-propa-nol is added, a channel type structure is formed in which the Y-cyclo-dextrin molecules with eightfold symmetry are stacked along a fourfold symmetry axis and therefore exactly linear channels are produced (18), Fig. 3. 

Since the drugs to be complexed have molecular weights between 100-400, and cyclodextrins have rather large molecular weight (972, 1132, and 1297 or or-, (5- and y-cyclo-dextrins) 100 mg complex contains only about 5-25 mg active ingredient, (23)-... 

Distribution of Maltooligomers at the Hydrolysis of y-cyclo-dextrin by Aspergillus oryzae a-amylase at pjj 5.2 and 31 C... 

Capillary gas chromatography (GC) using modified cyclodextrins as chiral stationary phases is the preferred method for the separation of volatile enantiomers. Fused-silica capillary columns coated with several alkyl or aryl a-cyclo-dextrin, -cyclodextrin and y-cyclodextrin derivatives are suitable to separate most of the volatile chiral compounds. Multidimensional GC (MDGC)-mass spectrometry (MS) allows the separation of essential oil components on an achiral normal phase column and through heart-cutting techniques, the separated components are led to a chiral column for enantiomeric separation. The mass detector ensures the correct identification of the separated components [73]. Preparative chiral GC is suitable for the isolation of enantiomers [5, 73]. 

A real breakthrough in this field occurred when enantio-cGC became more and more available. In particular, since 1988 selectively modified cyclodextrins have been synthesised, serving as chiral stationary phases in enantio-cGC, reported by Schurig and Novotny [I], Konig et al. [2, 3], Armstrong et al. [4], Dietrich et al. [5,6 ], Saturin et al. [7], and Bicchi et al. [8]. 6-O-silylated modified /I-cyclo dextrin and y-cyclodextrin derivatives of well-defined structure and purity were synthesised and have proved to be chiral stationary phases of unique selectivity and versatility and, therefore, are successfully used in simultaneous enantio-cGC analysis [5,6]. Further derivatives were recently reported by Taka-hisa and Engel [9, 10], dealing with 2,3-di-0-methoxymethyl-6-0-tert-butyldi-methylsilyl modified cyclodextrins as chiral stationary phases in enantio-cGG. 

Four EPMEs based on cyclodextrins (a-, //-, y- and 2-hydroxy-3-trim-ethylammoniopropyl-/)-cyclodextrin (as chlorine salt) (//-derivative-cyclo-dextrins)) have been designed for the enantioanalysis of L-vesamicol [34], The linear concentration ranges for the proposed EPMEs based on cyclodextrins were from 10 9 to 10 7 mol/L for the electrodes based on a-, //- and //-derivative-cyclodextrins with detection limits of 5.7 x 10 10, 2.42 x 10 10 and 4.77 x 10 10 mol/L, respectively, while y-cyclodextrin based electrode is characterized by linear concentration range between 10-5 and 10-2 mol/L with detection limit of 7.86 x 10 6 mol/L. The electrodes displayed near-Nemstian slopes of 52-59 mV per decade of... 

Monflier E, Tilloy S, Castanet Y, Martreux A. Chemically modified [3-cyclo-dextrins—efficient supramolecular carriers for the biphasic hydrogenation of water-insoluble aldehydes. Tetrahedron Lett 1998 39 2959-2960. 

Solubilisation by surface-active agents is discussed in Chapter 6. Alternatives to micellar solubilisation (or solubilisation in vesicles) include the use of the cyclodextrin family. When the first edition of this book was published in 1981 (and a diagram of a cyclo-dextrin-dmg complex was used to adorn the cover), the use of cyclodextrins was in its infancy. Attention was then focused around a-, P- and yavailable commercially for pharmaceutical use. Ten per cent of this cyclodextrin can enhance the solubility of betamethasone 118 times, of diazepam 21 times and of ibuprofen 55 times. 

Ueno, M., Ijitsu, T., Horiuchi, Y. et al. Improvement of dissolution and absorption characteristics of ubidecarenone by dimethyl-p-cyclo-dextrin complexation. Acta Pharm. Nord. 1989, 2, 99-104. 

Uekama, K., Horiuchi, Y., Kikuchi, M. et al. Enhanced dissolution and oral bioavailabiUty of a-tocopheryl esters by dimethyl-(3-cyclo-dextrin complexations. J. Inclusion Phenom. 1988, 6,167-174. 

Inoue Y, Kuad P, Okumura Y, Takashima Y, Yamaguchi H, Harada A. 2007. Thermal and photochemical switching of conformation of poly(ethylene glycol) substituted cyclo dextrin with an azobenzene group at the chain end. J Am Chem Soc 129(20) 6396 6397. 

Monflier, E. Tilloy, S. Fremy, G. Castanet, Y. Mortreux, A. A further breakthrough in biphasie rhodium-catalyzed hydroformylation Use of per(2,6-di-o-methyl)-P-cyclo-dextrin as inverse phase transfer eatalyst. Tetrahedron Lett. 1995. 36. 9481-9484. 

Rekliarsky, M.V. Inoue. Y. Complexation and chiral recognition thermodynamics of 6-amino-6-deoxy-0-cyclo-dextrin with anionic, cationic, and neutral chiral guests Counterbalance between van der Waals and coulombic interactions. J. Am. Chem. Soc. 2002. 724. 813-826. 

Synonyms Alphadex Betadex Cycloamylase a-Cyclodextrin p Cyclo-dextrin y-Cyclodextrin Cycloheptaamylose Cycloheptaglucosan Cyclomaltoheptaose Cyclomaltohexaose Cyclomaltooctaose Schardinger a-dextrin... 

Phenoxy acid herbicides, sulfonyl ureas, quaternary ammonium derivatives (quats), and aryloxy propanoic acids are the main classes of compounds subjected to capillary zone electrophoresis (CZE). Triazines are also separated using nonaqueous CZE, while low pfCa characterized chlorotriazines require an ion-pair-like solubilization using cationic surfactants (tetradecylammonium bromide, dodecyltrimethyl-ammonium bromide). Chiral selectors are added in CZE for obtaining enantioselectivity. Chiral selectors used for herbicide enantiomeric discrimination are vancomycin, y-cyclodextrin, ethyl carbonate -cyclo-dextrin, cyclohexyl-alkyl-)S-D-maltoside, sulpropyl ether a-cyclodextrin, and hexakis(2,3-di-0-methyl)-a-cyclodextrin. 

Y. Lu, N. Tang, J. Qi, and W. Wu, Phase solubility behavior of hydrophilic polymer/cyclo-dextrin/lansoprazole ternary system studied at high polymer concentration and by response surface methodology, Pharm. Dev. Technol, 17 (2), 236-241,2012. 

The a-, )5-, and y-cyclodextrins are cyclic oligosaccharides consisting of six, seven, and eight glucose units respectively. Although they have found many applications [1] they have some undesirable properties. The limited application of cyclodextrins in the pharmaceutical field seems to be related to their relatively low aqueous solubility [2]. Recently, the chemically modified cyclodextrins have received considerable attention because their pharmaceutical properties and inclusion behaviors are different from those of natural cyclodextrins. For example, the methylated )8-cyclo-dextrins, such as heptakis-(2,6-di-0-methyl)-)8-cyclodextrin (DM-)8-CD) and hepta-kis-(2,3,6-tri-0-methyl)-)8-cyclodextrin (TM-yS-CD), are extremely soluble in water (more than 30 w/v % at 25 °C), and they interact with a variety of drug molecules [3]. 

Mechref, Y. El Rassi, Z. Capillary electrophoresis of herbicides 1. Pre-column derivatization of chiral and g achiral phenoxy acid herbicides with a fluorescent tag for electrophoretic separation in the presence of cyclo- 2 dextrins and micellar phases. Anal. Chem. 1996, 68, "5 1771-1777. 4... 

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