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PubMed1990

Structure of di-O-alpha-maltosyl cyclodextrins produced from alpha-maltosylfluoride and cyclodextrins.

The structures of di-O-alpha-maltosyl beta-cyclodextrins ((G2)2-beta-CDs), which were produced from alpha-maltosylfluoride (alpha-G2F) and cyclodextrin (CD) by the transfer action of debranching enzymes, were examined by the enzymic method using Bacillus subtilis saccharifying alpha-amylase (BSA). (G2)2-beta-CD was converted to (G1)2-beta-CD by treatment with glucoamylase before the examination. BSA completely hydrolyzed (G1)2-beta-CD to produce glucose, 6(3)-O-alpha-glucosylmaltotriose, and 6(3),6(5)-di-O-alpha-glucosyl maltopentaose. (G2)2-beta-CD was the mixture of 6A,6C-di-O-alpha-maltosyl beta-CD and 6A,6D-di-O-alpha-maltosyl beta-CD. The ratio of A,C/A,D in (G2)2-beta-CD synthesized with Pseudomonas isoamylase and Aerobacter pullulanase were 40:60-45:55 and 30:70, respectively. The content of 6A,6C-di-O-alpha-maltosyl gamma-CD in (G2)2-gamma-CD synthesized by isoamylase was about 35%.

Bacillus subtilis↗
PubMed1998

Conversion of cyclodextrin into high-amylose starch of low molecular mass by means of cyclodextrin glucanotransferase.

alpha-Cyclodextrin (CD) was converted by Bacillus macerans cyclodextrin glucanotransferase into highly insoluble high-amylose starch with a low average degree of polymerization (56-73), in yields as high as 78% over a wide range of temperatures (25-70 degreesC). Ability to undergo this conversion was highly concentration-dependent. gamma-CD was also convertible in good yield; however, beta-CD was relatively resistant to conversion. Degrees of polymerization and the percentages of amylose in the high-amylose products were estimated from spectrophotometric measurements on their iodine complexes. A plausible mechanism for conversion of CD into starch is proposed.

Amylose↗
PubMed2001

Complexation and (templated) synthesis of rhenium complexes with cyclodextrins and cyclodextrin dimers in water.

Several small, lipophilic rhenium complexes form inclusion complexes with native beta-cyclodextrin (beta-CD) and beta-CD dimers. Association constants larger than 10(9)M(-1) were obtained using dimers. The use of beta-CD also enabled the synthesis of these rhenium complexes in water, in excellent yields, through complexation of the otherwise insoluble corresponding ligands. The influence of the reaction time and temperature on the configuration of the reaction products has been investigated in depth for one of these complexes. Using a beta-CD dimer, it proved possible to specifically template the formation of one configuration. The strength of the complexes of the rhenium complexes in cyclodextrin dimers may allow radiolabeling of biomolecules.

Carbohydrate Conformation↗
PubMed2004

New chiral selectors: design and synthesis of 6-TBDMS-2,3-methyl beta-cyclodextrin 2-2' thioureido dimer and 6-TBDMS-2,3-methyl (or 2-methyl-3-acetyl) beta-cyclodextrin bearing an (R) Mosher acid moiety.

Cyclodextrin (CD) derivatives are important selectors for analytical chiral recognition. Their enantioselectivities and chemical properties depend on ring size and on nature, number and location of substituents. This paper describes the synthesis of 6-O-TBDMS-2,3-O-methyl beta-cyclodextrins bearing in position 2 either a single (R)-Mosher acid moiety or a second CD unit, in view of their possible application as chiral selectors. Most synthetic steps were successfully carried out under high-intensity ultrasound using a new sonochemical reactor developed in the authors' laboratory. 6-O-TBDMS-2-O-methyl-3-[(S)-2-methylbutyl]-beta-CD was also synthesized and tested with gas chromatography; the enantiorecognition power of the other CD derivatives is also being tested. A computational study of model structures to design these CD derivatives.

Alkylation↗
PubMed2004

Single-isomer sulfated alpha-cyclodextrins for capillary electrophoresis: hexakis(2,3-di-O-methyl-6-O-sulfo)-alpha-cyclodextrin, synthesis, analytical characterization, and initial screening tests.

The third, concluding member of the family of single-isomer, fully sulfated alpha-cyclodextrins, the sodium salt of hexakis(2,3-di-O-methyl-6-O-sulfo)-alpha-cyclodextrin (HxDMS), has been synthesized on the kilogram scale, completing the nine-member array of the single-isomer, 6-O-sulfo CDs now available. HxDMS was tested for the capillary electrophoretic (CE) resolution of the enantiomers of nonelectrolyte, weak acid and weak base analytes contained in our CD screening kit. HxDMS complexed differently with many of the analytes tested than either its larger-ring analogs, heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-CD (HDMS) and octakis(2,3-di-O-methyl-6-O-sulfo)-gamma-CD (ODMS) or its same-ring, but differently substituted analogs, hexakis(6-O-sulfo)-alpha-CD (HxS) and hexakis(2,3-di-O-acetyl-6-O-sulfo)-alpha-CD (HxDAS). For all analytes, the effective mobilities and separation selectivities as a function of the background electrolyte concentration of HxDMS followed the trends that were found for the other single-isomer, 6-O-sulfo CDs.

Electrolytes↗
PubMed2005

A family of single-isomer positively charged cyclodextrins as chiral selectors for capillary electrophoresis: mono-6A-butylammonium-6A-deoxy-beta-cyclodextrin tosylate.

A novel single-isomer positively charged beta-cyclodextrin (beta-CD), mono-6(A)-butylammonium-6(A)-deoxy-beta-cyclodextrin tosylate (BuAM-beta-CD), has been synthesized, characterized, and used for the enantioseparations of alpha-hydroxy acids, carboxylic acids, and ampholytic analytes by capillary electrophoresis in acidic aqueous background electrolytes. The effective mobilities of all studied analytes decreased with increasing concentration of CD. Satisfactory resolutions were obtained for alpha-hydroxy acids over a wide range of chiral selector concentration. The optimum CD concentration was lower than 5 mM for the carboxylic acids, while higher than 20 mM for alpha-hydroxy acids. Inclusion complexation in combination with ion pair interaction seemed to account for the chiral discrimination process. The hydrogen bonding may provide secondary contribution for the chiral resolution of alpha-hydroxy acids. In addition, BuAM-beta-CD was further proved to be an effective chiral selector for anionic analytes by the baseline enantioseparation of a six-acid mixture within 20 min.

Buffers↗
PubMed2005

2,3-di-O-methoxymethyl-6-O-tert-butyldimethylsilyl-gamma-cyclodextrin: a new class of cyclodextrin derivatives for gas chromatographic separation of enantiomers.

Octakis(2,3-di-O-methoxymethyl-6-O-tert-butyldimethylsilyl)-gamma-cyclodextrin (2,3-MOM-6-TBDMS-gamma-CD) was employed as stationary phase for capillary gas chromatographic separation of enantiomers. Selective introduction of the acetal function at positions 2 and 3 of the glucose units was achieved by reaction of 6-O-TBDMS-gamma-cyclodextrin with methoxymethyl chloride. 2,3-MOM-6-TBDMS-gamma-CD was shown to be a chiral stationary phase suitable for enantiodifferentiation of a broad spectrum of chiral volatiles from various chemical classes. A total of 125 pairs of enantiomers could be separated. Structural influences of the analytes on the enantioseparation were demonstrated. High alpha values up to 1.8 were observed for the hydroxyketone acetoin and some methyl branched ketones. Pronounced enantioseparations were also determined for cyclic pentenolone and furanone derivatives.

Chromatography, Gas↗
PubMed2005

Enantioseparation of acidic enantiomers in capillary electrophoresis using a novel single-isomer of positively charged beta-cyclodextrin: Mono-6A-N-pentylammonium-6A-deoxy- beta-cyclodextrin chloride.

The new single-isomer of positively charged beta-cyclodextrin, mono-6A-N-pentylammonium-6A-deoxy-beta-cyclodextrin chloride (PeAM-beta-CD), was employed for the first time for the enantioseparation of anionic and ampholytic analytes by capillary electrophoresis (CE). The synthesis and characterization of PeAM-beta-CD were reported. The effect of background electrolyte (BGE) pH and selector concentration on the enantioseparation was investigated. Good separation was obtained at low BGE pH (ca. 5.0-6.0). The effective mobilities of all analytes were found to decrease with increasing CD concentration. PeAM-beta-CD proved to be an effective chiral selector for most studied anionic analytes.

Electrophoresis, Capillary↗
PubMed2002

Non-covalent associations of cyclomaltooligosaccharides (cyclodextrins) with carotenoids in water. A study on the alpha- and beta-cyclodextrin/psi,psi-carotene (lycopene) systems by light scattering, ionspray ionization and tandem mass spectrometry.

Water-soluble complexes of the dietary carotenoid psi,psi-carotene (lycopene 1) with cyclomaltohexaose (alpha-cyclodextrin, alphaCD) and cyclomaltoheptaose (beta-cyclodextrin, betaCD) have been prepared and characterized via multiangle light scattering (MALS), ionspray/electrospray ionization (IS/ESI) mass spectrometry (MS) and tandem MS. MALS experiments point out that large aggregates of particles, on the nanometer-size scale, are present in water, with meaningful differences in the shape of the alphaCD/1 aggregates with respect to betaCD/1 analogues. The true 1:1 alphaCD/1 inclusion complex has been observed by IS/ESIMS and confirmed by tandem MS. The structure of CD/1 aggregations in water is proposed which are consistent with the combined MALS and MS experimental results.

Carotenoids↗
PubMed1988

Use of cyclodextrins in isotachophoresis. VI. Cyclodextrins as leading electrolyte additives for the separation of bile acids.

Cyclodextrins (CDs) and some of their methyl derivatives have been used for the optimization of the isotachophoretic separation of bile acids in aqueous electrolyte systems. The addition of heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin to the leading electrolyte proved useful for both the solubilization and the structural differentiation of the solutes studied and led to the successful separation of their mixtures. Other CDs tested, even if they gave a satisfactory solubilization effect, did not support the resolution of bile acid mixtures.

Bile Acids and Salts↗
PubMed1989

Displacement chromatography on cyclodextrin-silicas. II. Separation of cis-trans isomers in the reversed-phase mode on alpha-cyclodextrin-silica.

The feasibility of preparative separations of cis-trans isomers by displacement chromatography on analytical-scale alpha-cyclodextrin-silica columns operated in the reversed-phase mode is demonstrated by using the isomers of 3-hexen-1-ol as model substrates and n-alkanols as displacers. The importance of matching the size of the cyclodextrin cavity and the solutes is shown. The crucial role of the displacer (both type and concentration) in the success of the displacement chromatographic separation is demonstrated.

Chromatography, Liquid↗
PubMed1996

HPLC of structural isomers with cyclodextrin-poly(vinylamine)-coated silica columns, Part I: Synthesis and characterization of cyclodextrin-bonded stationary phases by NMR solid state.

Different supports for high-performance liquid chromatography are prepared by using the coating technology. These supports are based on silica beads coated with a beta-cyclodextrin-containing poly(vinylamine). Surface area, pore size distribution, and solid-state nuclear magnetic resonance are used for the characterization of these supports. The two different methods of preparation used lead to different arrangements of the polymer layers; hence, the supports have different mobility, rigidity, and accessibility of the cyclodextrin ring.

Carbon Isotopes↗
PubMed2006

Site-directed mutations in Alanine 223 and Glycine 255 in the acceptor site of gamma-Cyclodextrin glucanotransferase from Alkalophilic Bacillus clarkii 7364 affect cyclodextrin production.

A cyclodextrin glucanotransferase (CGTase) from Bacillus clarkii 7364 converts starch into gamma-cyclodextrin (gamma-CD) with high specificity. Comparison of the deduced amino acid sequence of this CGTase with those of other typical CGTases revealed that several amino acids are deleted or substituted with others at several subsites. Of these amino acids, Ala223 at subsite +2 and Gly255 at subsite +3 in the acceptor site of the enzyme were replaced by several amino acids through site-directed mutagenesis. The replacement of Ala223 by lysine, arginine and histidine strongly enhanced the gamma-CD-forming activity in the neutral pH range. On the other hand, all mutants obtained on replacing Gly255 with the above amino acids showed significant decreases in the gamma-CD-forming activity. Taking into account both the kinetic parameters and pKa values of the side chains of the three basic amino acids, the protonation state of the amino groups in their side chains at subsite +2 seems to enhance the hydrogen bonding interaction between these basic amino acids and the glucose residues of linear oligosaccharides. The enhancement of the interaction may play an important role by helping the substrate reach subsite +1, hence increasing the gamma-CD-forming activity and kcat value.

Amino Acid Sequence↗
PubMed1995

Cyclodextrin formation by the thermostable alpha-amylase of Thermoanaerobacterium thermosulfurigenes EM1 and reclassification of the enzyme as a cyclodextrin glycosyltransferase.

Extensive characterization of the thermostable alpha-amylase of Clostridium thermosulfurogenes EM1, recently reclassified as Thermoanaerobacterium thermosulfurigenes, clearly demonstrated that the enzyme is a cyclodextrin glycosyltransferase (CGTase). Product analysis after incubation of the enzyme with starch revealed formation of alpha-, beta-, and gamma-cyclodextrins, as well as linear sugars. The specific activity for cyclization of this CGTase was similar to those of other CGTases, whereas the specific activity for hydrolysis was relatively high in comparison with other CGTases. Alignment of the amino acid sequence of the T. thermosulfurigenes enzyme with sequences from known bacterial CGTases showed high homology. The four consensus regions of carbohydrate-converting enzymes, as well as a C-terminal raw-starch binding motif, could be identified in the sequence.

Amino Acid Sequence↗
PubMed2005

Colon-specific drug delivery systems based on cyclodextrin prodrugs: in vivo evaluation of 5-aminosalicylic acid from its cyclodextrin conjugates.

AIM: To investigate the release of cyclodextrin-5-aminosalicylic acid (CyD-5-ASA) in cecum and colon. METHODS: An anti-inflammatory drug 5-ASA was conjugated onto the hydroxyl groups of alpha-, beta- and gamma-cyclodextrins (CyDs) through an ester linkage, and the in vivo drug release behavior of these prodrugs in rat's gastrointestinal tract after the oral administration was investigated. RESULTS: The 5-ASA concentration in the rat's stomach and small intestine after the oral administration of CyD-5-ASA conjugate was much lower than that after the oral administration of 5-ASA alone. The lower concentration was attributable to the passage of the conjugate through the stomach and small intestine without significant degradation or absorption, followed by the degradation of the conjugate site-specific in the cecum and colon. The oral administration of CyD-5-ASA resulted in lower plasma and urine concentration of 5-ASA than that of 5-ASA alone. CONCLUSION: CyD-5-ASA conjugates may be used as prodrugs for colon-specific drug delivery system.

Animals↗
PubMedDate not supplied

[Characteristics of cyclodextrin production using cyclodextrin glucanotransferases of various groups of microorganisms].

Cyclodextrin glucanotransferases (CGTases; EC 2.4.1.19) from newly isolated mesophilic, thermophilic, alkalophilic, and halophilic bacilli, as well as from thermoactinomycetes, have been purified to homogeneity, and some of their physicochemical and biochemical characteristics (cyclizing, disproportionating, and hydrolytic activities) have been studied. Cyclodextrin (CD) production in the presence and absence of compounds favoring formation of complexes had certain specific features. We were able to demonstrate that CG-Tases of mesophilic and thermophilic strains form mixtures of alpha-, beta-, and gamma-CDs, whereas the enzymes from halophilic and alkalophilic microorganisms preferentially catalyze the formation of beta-CDs.

Bacillaceae↗
PubMed2002

High-performance liquid chromatographic determination of 2-hydroxypropyl-gamma-cyclodextrin in different biological fluids based on cyclodextrin enhanced fluorescence.

A high-performance size exclusion chromatographic method with analyte enhanced fluorescence detection is described for the analysis of 2-hydroxypropyl-gamma-cyclodextrin (HPGCD) in different biological fluids. The principle of detection was the in situ complexation of 8-anilinonaphthalene-1-sulfonic acid (ANS) by HPGCD. When HPGCD eluted from the column the increased fluorescence was measured at excitation and emission wavelengths of 270 and 512 nm, respectively. Solid-phase extraction cleanup and concentration of samples resulted in higher than 78% recovery of HPGCD for each of the studied biological fluids. Some important details of the method development as well as the validation of the method for rabbit plasma, rabbit aqueous humour, monkey plasma and monkey urine are given. The limits of quantification varied between 1 and 10 nmol/ml (correspond to 1.5-15 microg/ml) depending on the biological matrix used. The method was successfully adapted in another laboratory proving that HPGCD had not absorbed into aqueous humour and plasma after topical application of HPGCD containing eye drop in rabbits.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1991

Effect of hydrotropic substances on the complexation of sparingly soluble drugs with cyclodextrin derivatives and the influence of cyclodextrin complexation on the pharmacokinetics of the drugs.

The influence of hydrotropic compounds on complex formation by 2-hydroxypropyl-beta-cyclodextrin (2-HP-beta-CD) was investigated with methyltestosterone (MeT). Various representatives of the lyotropic series were used for this purpose. Additive hydrotropic effects were observed for nicotinamide and urea, which disrupt the water structure, while structure formers such as sorbitol exerted negative effects. The effects of hydrotropic substances on the phase solubility relationship of MeT showed that inclusion complex formation with 2-HP-beta-CD depends on the degree of ordering of the solvent and is apparently subject to entropy effects. Combined systems comprising 2-HP-beta-CD and auxiliary substances with various underlying solubilizing principles were also investigated. Combination of 2-HP-beta-CD with conventional solubilizers, such as 1,2-propylene glycol or sodium deoxycholate, reduced the solubilization capacity of 2-HP-beta-CD. Competitive displacement of the inclusion molecule from its 2-HP-beta-CD complex by sodium deoxycholate suggested that cholesterol participates in the release mechanism of the inclusion molecule under in vivo conditions. The spontaneous release of complexed drug molecules could indirectly be shown on the basis of the spontaneous action of a complexed dihydropyridine derivative after iv administration in rats. The bioavailability of an investigational drug in cynomolgus monkeys could be enhanced sevenfold by inclusion complexation with 2-HP-beta-CD.

2-Hydroxypropyl-beta-cyclodextrin↗