alpha-cyclodextrin and gamma-cyclodextrin
alpha-cyclodextrin has been researched along with gamma-cyclodextrin* in 58 studies
Other Studies
58 other study(ies) available for alpha-cyclodextrin and gamma-cyclodextrin
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Encapsulation of menthol into cyclodextrin metal-organic frameworks: Preparation, structure characterization and evaluation of complexing capacity.
Cyclodextrin (CD)-metal-organic frameworks (MOFs) are developed as a new type of food-acceptable multi-porous material, which shows a great potential for controlled volatile compound release. This study aimed to synthesize CD-MOFs from potassium nitrate, crystallized with α-cyclodextrin (α-CD), β-CD or γ-CD, and their complex capacities were further evaluated using menthol encapsulation. Compared with CD, all the CD-MOFs had highly ordered crystal structures and more regular shapes. β-CD-MOF showed better thermal stability, with an initial thermal degradation temperature of 253 °C, higher than the other two CD-MOFs. The CD-MOFs were used for menthol encapsulation and the resulting menthol concentration within the inclusion complexes (ICs) was determined. The menthol concentration in ICs followed the order: β-CD-MOF > β-CD > γ-CD-MOF > γ-CD > α-CD ≥ α-CD-MOF. The menthol content and encapsulation efficiency of β-CD-MOF were 21.76% (w/w) and 22.54% (w/w) respectively, significantly higher than those of other reported solid materials, such as amylose, CD and V-type starch. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Crystallography, X-Ray; Cyclodextrins; gamma-Cyclodextrins; Menthol; Metal-Organic Frameworks; Porosity; Spectroscopy, Fourier Transform Infrared; Temperature; Thermogravimetry | 2021 |
Antifungal activity of econazole nitrate/cyclodextrin complex: Effect of pH and formation of complex aggregates.
Econazole nitrate (ECN) is a weakly basic drug with very low aqueous solubility that hampers its permeation through biological membranes and results in low ECN bioavailability. Formation of drug/cyclodextrin (drug/CD) inclusion complexes is a formulation technology that can be applied to enhance drug solubility in aqueous media. The aim of this study was to determine the effect of CD complexation and pH adjustments on the ECN solubility. The ECN pH-solubility and ECN/CD phase-solubility profiles were determined. The solubility of ECN in aqueous acidic solutions containing α-cyclodextrin (αCD) was relatively high and much higher than in aqueous γ-cyclodextrin (γCD) solutions under same conditions. The complexation efficiency of the ECN/CD complex was relatively low for the unionized drug. Formation of ECN/CD inclusion complex was verified by proton nuclear magnetic resonance spectroscopy. Formation of ECN/CD complexes enhanced the drug stability during autoclaving. γCD complexes self-assembled to form nano- and microparticles whereas αCD complexes had negligible tendency to self-assemble. Formation of CD complex nano- and microparticles was investigated by dynamic light scattering and by drug permeation through semipermeable membranes of different molecular weight cut-off. The largest aggregate fraction was observed for the unionized ECN in aqueous pH 7.5 solution containing high CD concentration, that is 10% (w/v) CD. It was shown that in acidic solutions ECN/αCD can enhance the antifungal activity to filamentous fungi. This was associated with the increased ECN solubility and increase of readily available ECN molecules in aqueous αCD solutions. Topics: alpha-Cyclodextrins; Antifungal Agents; Chemistry, Pharmaceutical; Drug Delivery Systems; Drug Stability; Dynamic Light Scattering; Econazole; gamma-Cyclodextrins; Hydrogen-Ion Concentration; Nanoparticles; Solubility | 2020 |
The binding mechanism between cyclodextrins and pullulanase: A molecular docking, isothermal titration calorimetry, circular dichroism and fluorescence study.
This work investigated the interaction between cyclodextrins and pullulanase to provide insight into the production and application of cyclodextrins. Enzyme activity and kinetic assays showed that α-cyclodextrin (α-CD), β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) inhibited pullulanase in a competitive manner. Circular dichroism spectra and fluorescence spectroscopy suggested the formation of cyclodextrin and pullulanase complexes. According to ITC assays and molecular docking results, compared with α-CD and γ-CD, β-CD had the strongest affinity for pullulanase because of its appropriate cavity geometric dimensions. In addition, cyclodextrins interacted with pullulanase through hydrogen bonds, van der Waals force and hydrophobic interactions, the latter of which were verified as the major driving force. Phenylalanine 476 was the key amino acid residue in pullulanase for cyclodextrin recognition and binding. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Calorimetry; Circular Dichroism; Cyclodextrins; gamma-Cyclodextrins; Glycoside Hydrolases; Hydrogen Bonding; Molecular Docking Simulation; Phenylalanine; Protein Structure, Secondary; Spectrometry, Fluorescence | 2020 |
Unsaturation of the phospholipid side-chain influences its interaction with cyclodextrins: A spectroscopic exploration using a phenazinium dye.
The interaction of a cationic photosensitizer Safranin-O with liposome membranes having similar surface charge (negative) but differing in the presence of saturation on the lipid side-chain has been studied. To this end, dimyristoyl-l-R-phosphatidylglycerol (DMPG) and 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DOPG) phospholipids were employed to prepare small unilamellar vesicles. The dye is found to bind in the headgroup region of both the liposome membranes with significantly higher affinity to DOPG lipid containing unsaturated side chain. The effects of various cyclodextrins (CDs) on the stability of the probe-bound liposome membranes have also been investigated using steady-state and picosecond-resolved fluorescence as well as dynamic light scattering techniques. The modulations of the fluorescence properties of the lipid-bound dye were exploited to rationalize the membrane destabilization following interaction with the cyclodextrins. Experimental results reveal the selective interaction of DMPG membrane with CDs leading to rupture of the integrated structure of the liposome units accompanying release of the bound probe to the bulk aqueous phase. On the contrary, no discernible interaction of the CDs was observed with DOPG liposome membrane. Our results also show the differential extents of interaction of various CDs (α-CD, β-CD, methyl-β-CD, and γ-CD) with DMPG leading to varying degrees of release of the bound-dye molecule. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Drug Liberation; gamma-Cyclodextrins; Kinetics; Phenazines; Phosphatidylglycerols; Photosensitizing Agents; Solutions; Spectrometry, Fluorescence; Static Electricity; Unilamellar Liposomes | 2019 |
Removal of off-flavour-causing precursors in soy protein by concurrent treatment with phospholipase A
Topics: Aldehydes; alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Food Storage; gamma-Cyclodextrins; Hydrogen-Ion Concentration; Phospholipases A2; Phospholipids; Solubility; Soybean Proteins; Taste; Temperature | 2018 |
The self-assemble of natural cyclodextrins in aqueous solutions: Application of miniature permeation studies for critical aggregation concentration (cac) determinations.
Permeation techniques can be applied to determine the critical aggregation concentration (cac) of natural cyclodextrins (CDs) in aqueous solutions although the method is both laborious and time consuming. In the present study, the permeation technique was modified and the influence of osmotic pressure, sampling time, CD concentration and molecular weight-cut off (MWCO) of the membrane were investigated in two different permeation units, that is Franz diffusion cells and Slide-A-Lyzer™ MINI Dialysis. While both the osmotic pressure and CD concentration affect the steady state flux in both permeation units, effects of sampling time and the MWCO of the mounted membrane were only observed in the Franz diffusion cells. The osmotic effect was negligible in the Slide-A-Lyzer™ MINI Dialysis units. The modified permeation technique using Slide-A-Lyzer™ MINI Dialysis units was then used to determine the cac of natural CDs in water. The cac of αCD, βCD and γCD was 1.19±0.17, 0.69±0.05 and 0.93±0.04% (w/v), respectively. The results indicated that the cac values depended on their intrinsic solubility. Moreover, the cac value of γCD in aqueous hydrocortisone/γCD inclusion complex solution was identical to the γCD cac value determined in pure water. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Chemistry, Pharmaceutical; Excipients; gamma-Cyclodextrins; Hydrocortisone; Molecular Weight; Osmotic Pressure; Permeability; Solubility | 2016 |
In vitro fermentation characteristics, in vivo ileal and total tract nutrient digestibilities, and fecal microbiota responses of dogs to α-cyclodextrin.
The objectives were to examine in vitro fermentation characteristics, in vivo nutrient digestibility, fecal microbiota, and serum lipid profiles as affected by α-cyclodextrin (ACD) supplementation. Short-chain fatty acid (SCFA) production was measured after in vitro fermentation for 3, 6, 9, and 12 h of ACD, β-cyclodextrin, and γ-cyclodextrin. Five mixed-breed hounds were used in a Latin square design. Each experimental period comprised 14 d, including 10 d for diet adaptation and 4 d for fecal collection. Dogs were fed, twice a day, an extruded diet made with poultry byproduct meal and brewer's rice as the main ingredients. Dogs were supplemented with 0, 1, 2, 3, or 4 g of ACD diluted in 15 mL of water twice daily for a total of 0, 2, 4, 6, and 8 g ACD/d. Maximal in vitro production of total SCFA was lowest for ACD. However, the greatest maximal production of propionate was noted for ACD treatment. Total tract nutrient digestibility and fecal DM concentration linearly decreased ( < 0.05) for treatment groups receiving ACD; no changes were observed for ileal digestibility. Serum cholesterol and triglyceride concentrations were within normal ranges for dogs and were not different among treatments. Similarly, no changes in fecal microbiota were observed. Overall, ACD supplementation appears to have no effect on nutrient absorption in the small intestine but may alter fermentation in the large bowel, which could lead to a higher proportion of propionate production as observed in the in vitro experiment. Topics: alpha-Cyclodextrins; Animal Feed; Animal Nutritional Physiological Phenomena; Animals; beta-Cyclodextrins; Diet; Dietary Supplements; Digestion; Dogs; Dose-Response Relationship, Drug; Fatty Acids, Volatile; Feces; Fermentation; gamma-Cyclodextrins; Gastrointestinal Tract; Microbiota | 2016 |
Complexation of estragole as pure compound and as main component of basil and tarragon essential oils with cyclodextrins.
Inclusion complexes of estragole (ES) as pure compound and as main component of basil and tarragon essential oils (EOs) with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), randomly methylated-β-cyclodextrin (RAMEB), a low methylated-β-cyclodextrin (CRYSMEB) and γ-cyclodextrin (γ-CD) were characterized. Formation constants (Kf) of the complexes were determined in aqueous solution by nonlinear regression analysis using static headspace gas chromatography (SH-GC) and UV-visible spectroscopy. Solid inclusion complexes were prepared by the freeze-drying method for different CD:ES molar ratios and were characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). Inclusion complexes formation allowed the controlled release of ES. Moreover, increased DPPH radical scavenging activity and photostability of ES and ES containing EOs (ESEOs) were observed in the presence of CDs. These findings suggest that encapsulation with CDs could be an efficient tool to improve the use of ES and ESEOs in aromatherapy, cosmetic and food fields. Topics: Allylbenzene Derivatives; alpha-Cyclodextrins; Anisoles; Artemisia; beta-Cyclodextrins; Calorimetry, Differential Scanning; Cyclodextrins; gamma-Cyclodextrins; Ocimum basilicum; Oils, Volatile; Spectroscopy, Fourier Transform Infrared | 2015 |
Cyclodextrin-Based Solid-Gas Clathrates.
"Cyclodextrin-gas" clathrates were obtained by crystallization from water solution of α-, β-, and γ-cyclodextrins (CDs) under pressure of the gas to be entrapped into the CD molecules. When the pressure is released, these clathrates are stable at ambient conditions and dissociate at elevated temperature, which makes them interesting for various applications as foam boosters in food and other industries. It was found that under these conditions α-CD forms clathrates with all of the gases used in this study (N2, N2O, CO2, Ar), whereas β- and γ-CDs can form clathrates only with N2. The concentration of the cyclodextrin and the temperature and pressure of the gas were varied for achieving higher clathrate yield and larger amount of embedded gas. Highest values of about 2 wt % were found for α-CD-N2O, as it releases in the temperature range of 40-60 °C. Topics: alpha-Cyclodextrins; Argon; beta-Cyclodextrins; Carbon Dioxide; Crystallization; Cyclodextrins; Drug Stability; gamma-Cyclodextrins; Gases; Nitrogen; Nitrous Oxide; Pressure; Temperature | 2015 |
Molecular dynamic analysis of mutant Y195I α-cyclodextrin glycosyltransferase with switched product specificity from α-cyclodextrin to γ-cyclodextrin.
Alpha-cyclodextrin (α-CD) glycosyltransferase (α-CGTase) can convert starch into α-CD blended with various proportions of β-cyclodextrin (β-CD) and/or γ-cyclodextrin (γ-CD). In this study, we verified the catalytic characteristics of purified Y195I α-CGTase and elucidated the mechanism of action with molecular dynamic (MD) simulations. We found that purified Y195I α-CGTase produced less α-CD, slightly more β-CD, and significantly more γ-CD than wild-type α-CGTase. Correspondingly, α-CD-based K m values increased, and β-CD- and γ-CD-based K m values decreased. MD simulation studies revealed that the dynamic trajectories of the substrate oligosaccharide chain in the mutant CGTase binding site were significantly different from those in the wild-type enzyme, with reduced hydrophobic interaction, finally resulting in different product specificity and more γ-CD formation. Topics: alpha-Cyclodextrins; Bacterial Proteins; gamma-Cyclodextrins; Glucosyltransferases; Molecular Dynamics Simulation; Mutation, Missense; Substrate Specificity; Thermoanaerobacterium | 2015 |
Surface modification of electrospun polyester nanofibers with cyclodextrin polymer for the removal of phenanthrene from aqueous solution.
Surface modified electrospun polyester (PET) nanofibers with cyclodextrin polymer (CDP) were produced (PET/CDP). CDP formation onto electrospun PET nanofibers was achieved by polymerization between citric acid (CTR, crosslinking agent) and cyclodextrin (CD). Three different types of native CD (α-CD, β-CD and γ-CD) were used to form CDP. Water-insoluble crosslinked CDP coating was permanently adhered onto the PET nanofibers. SEM imaging indicated that the nanofibrous structure of PET mats was preserved after CDP surface modification process. PET/CDP nanofibers have shown rougher/irregular surface and larger fiber diameter when compared to untreated PET nanofibers. The surface analyses of PET/CDP nanofibers by XPS elucidated that CDP was present on the fiber surface. DMA analyses revealed the enhanced mechanical properties for PET/CDP where PET/CDP nanofibers have shown higher storage modulus and higher glass transition temperature compared to untreated PET nanofibers. The surface area of the PET/CDP nanofibers investigated by BET measurements showed slight decrease due to the presence of CDP coating compared to pristine PET nanofibers. Yet, it was observed that PET/CDP nanofibers were more efficient for the removal of phenanthrene as a model polycyclic aromatic hydrocarbon (PAH) from aqueous solution when compared to pristine PET nanofibers. Our findings suggested that PET/CDP nanofibers can be a very good candidate as a filter material for water purification and waste treatment owing to their very large surface area as well as inclusion complexation capability of surface associated CDP. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cellulose; Cyclodextrins; gamma-Cyclodextrins; Nanofibers; Phenanthrenes; Polyesters; Surface Properties; Water Pollutants, Chemical; Water Purification | 2013 |
Sulfadiazine-selective determination in aquaculture environment: selective potentiometric transduction by neutral or charged ionophores.
Solid-contact sensors for the selective screening of sulfadiazine (SDZ) in aquaculture waters are reported. Sensor surfaces were made from PVC membranes doped with tetraphenylporphyrin-manganese(III) chloride, α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin ionophores that were dispersed in plasticizer. Some membranes also presented a positive or a negatively charged additive. Phorphyrin-based sensors relied on a charged carrier mechanism. They exhibited a near-Nernstian response with slopes of 52 mV decade(-1) and detection limits of 3.91×10(-5) mol L(-1). The addition of cationic lipophilic compounds to the membrane originated Nernstian behaviours, with slopes ranging 59.7-62.0 mV decade(-1) and wider linear ranges. Cyclodextrin-based sensors acted as neutral carriers. In general, sensors with positively charged additives showed an improved potentiometric performance when compared to those without additive. Some SDZ selective membranes displayed higher slopes and extended linear concentration ranges with an increasing amount of additive (always <100% ionophore). The sensors were independent from the pH of test solutions within 2-7. The sensors displayed fast response, always <15s. In general, a good discriminating ability was found in real sample environment. The sensors were successfully applied to the fast screening of SDZ in real waters samples from aquaculture fish farms. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in locus measurements of sulfadiazine or parent-drugs. Topics: alpha-Cyclodextrins; Animals; Aquaculture; beta-Cyclodextrins; Biosensing Techniques; Fishes; gamma-Cyclodextrins; Hydrogen-Ion Concentration; Ionophores; Membranes, Artificial; Metalloporphyrins; Molecular Structure; Potentiometry; Quaternary Ammonium Compounds; Reproducibility of Results; Sulfadiazine; Water Pollutants, Chemical | 2011 |
Similarities and differences between cyclodextrin-sodium dodecyl sulfate host-guest complexes of different stoichiometries: molecular dynamics simulations at several temperatures.
An extensive dynamic and structural characterization of the supramolecular complexes that can be formed by mixing α-, β-, and γ-cyclodextrin (CD) with sodium dodecyl sulfate (SDS) in water at 283, 298, and 323 K was performed by means of computational molecular dynamics simulations. For each CD at the three temperatures, seven different initial conformations were used, generating a total of 63 trajectories. The observed stoichiometries, intermolecular distances, and relative orientation of the individual molecules in the complexes, as well as the most important interactions which contribute to their stability and the role of the solvent water molecules were studied in detail, revealing clear differences and similarities between the three CDs. Earlier reported findings in the inclusion complexes field are also discussed in the context of the present results. For any of the three native cyclodextrins, the CD(2)SDS(1) species in the head-to-head conformation appears to be a promising building block for nanotubular aggregates both in the bulk and at the solution/air interface, as earlier suggested for the case of α-CD. Moreover, the observed noninclusion arrangements involving β-CD are proposed as the seed for the premicellar (β-CD)-induced aggregation of SDS described in the literature. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; gamma-Cyclodextrins; Molecular Dynamics Simulation; Sodium; Sodium Dodecyl Sulfate; Temperature; Time Factors | 2010 |
Dissolution studies of physical mixtures of indomethacin with alpha- and gamma-cyclodextrins.
Oral administration of indomethacin has been limited by its poor water solubility. Cyclodextrins have been recognized as potential candidates to overcome the poor solubility of indomethacin through the formation of inclusion complexes. The aim of our study was to compare the dissolution profiles of pure indomethacin and its mixtures with α- and γ-cyclodextrins The inclusion complexes of indomethacin with α- and γ-cyclodextrins were prepared by direct mixing in dissolution vessel. Fixed volumes of the dissolution medium were withdrawn at 0,5; 1 and 4 hours. Dissolution tests were performed on the USP Apparatus 2, rotating speed 100 rpm at 37±0.5 ° C, 500 ml, distilled water and 0,1 M HCl solution). Quantification of dissolved indomethacin was performed by UV/VIS spectrophotometric method at the absorption maximum around 320 nm. The results were expressed as relative dissolution rate (ratio between indomethacin dissolved from its physical mixtures with α- and γ-cyclodextrins and that dissolved the pure drug). Relative dissolution rates of indomethacin in combination with α- and γ-cyclodextrins at the end of testing were in the range of 91,66 to 337,14 % (for α- cyclodextrin) and in the range of 128,57 to 301,92 % (for γ-cyclodextrin). The complexation of indomethacin with α- and γ-cyclodextrins resulted in the enhancement of dissolution rate. Topics: alpha-Cyclodextrins; Anti-Inflammatory Agents, Non-Steroidal; Excipients; gamma-Cyclodextrins; Indicators and Reagents; Indomethacin; Kinetics; Solubility; Spectrophotometry, Ultraviolet | 2010 |
Nanosponge formulations as oxygen delivery systems.
Three types of cyclodextrin nanosponges were synthetized cross-linking α, β or γ cyclodextrin with carbonyldiimidazole as cross-linker. Nanosponges are solid nanoparticles previously used as drug carriers. In this studies cyclodextrin nanosponges were developed as oxygen delivery system. For this purpose the three types of nanosponges suspended in water were saturated with oxygen and in vitro characterized. The nanosponge safety was tested on Vero cells. Their ability to release oxygen in the presence and in the absence of ultrasound (US) was determined over time. Oxygen permeation through a silicone membrane was obtained using a β-cyclodextrin nanosponge/hydrogel combination system. Nanosponge formulations might be potential gas delivery systems showing the ability to store and to release oxygen slowly over time. Topics: alpha-Cyclodextrins; Animals; beta-Cyclodextrins; Chlorocebus aethiops; Cross-Linking Reagents; Drug Carriers; gamma-Cyclodextrins; Imidazoles; Nanoparticles; Oxygen; Permeability; Time Factors; Ultrasonography; Vero Cells | 2010 |
Preparation and characterization of n-alkane/water emulsion stabilized by cyclodextrin.
Emulsions consisting of n-alkane/water using alpha, beta, and gamma-cyclodextrin (alpha, beta, and gamma-CD) as an emulsifier were prepared and characterized by means of several physicochemical techniques. A phase diagram of the n-alkane/CD/water system showed that an oil in water (O/W) emulsion can be prepared from a mixture of the appropriate composition. The dissolved n-alkane/CD complexes formed at low CD concentrations showed surface-activity, but emulsions could not be prepared from these complexes. On the other hand, the precipitated complexes formed at high CD concentrations when adsorbed to the oil/water interface, and served as an emulsifier for formation of emulsions. These results showed that the emulsions formed were of the Pickering emulsion. In addition emulsion formation was governed by the wettability and the surface free energy of the precipitated complexes. Topics: Adsorption; Alkanes; alpha-Cyclodextrins; beta-Cyclodextrins; Chemistry; Emulsions; gamma-Cyclodextrins; Hydrogen-Ion Concentration; Oils; Plant Oils; Salts; Surface Properties; Temperature; Water | 2009 |
Photoinduced DNA cleavage by alpha-, beta-, and gamma-cyclodextrin-bicapped C60 supramolecular complexes.
Water-soluble supramolecular inclusion complexes of alpha-, beta-, and gamma-cyclodextrin-bicapped C60 (CD/C60) have been investigated for their photoinduced DNA cleavage activities, with the aim to assess the potential health risks of this class of compounds and to understand the effect of host cyclodextrins having different cavity dimensions. Factors such as incubation temperature, irradiation time, and concentration of NADH or CDs/ C60 supramolecular inclusion complexes have been examined. The results show that alpha-, beta-, and gamma-CDs/C60 are all able to cleave double-stranded DNA under visible light irradiation in the presence of NADH. However, a difference in the photoinduced DNA cleavage efficiency is observed, where the cleavage efficiency increases in the order of alpha-, beta-, and gamma-CD/C60. The difference is attributed to the different aggregation behavior of the inclusion complexes in aqueous solution, which is correlated to the cavity dimension of the host cyclodextrin molecules. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; DNA; DNA Damage; Environmental Exposure; Environmental Monitoring; Fullerenes; gamma-Cyclodextrins; Humans; Light; Macromolecular Substances; NAD; Risk; Temperature | 2009 |
Interaction of native alpha-cyclodextrin, beta-cyclodextrin and gamma-cyclodextrin and their hydroxypropyl derivatives with selected organic low molecular mass compounds at elevated and subambient temperature under RP-HPLC conditions.
The main focus of this study was to explore the capability of native alpha-cyclodextrin, beta-cyclodextrin and gamma-cyclodextrin and their hydroxypropyl derivatives for host-guest interaction with 7,8-dimethoxyflavone, selected steroids (estetrol, estriol, estradiol, estrone, testosterone, cortisone, hydrocortisone, progesterone and 17alpha-hydroxyprogesterone) and polycyclic aromatic hydrocarbons (toluene, naphthalene, 1,8-dimethylnaphthalene, 1-acenaphthenol, acenaphthylene and acenaphthene) under reversed-phase liquid-chromatography conditions. The study revealed that native cyclodextrins interact more efficiently with the analytes investigated than do their hydroxypropyl counterparts. In the low-temperature region, enormously high ratios were observed for polycyclic aromatic hydrocarbons, particularly 1,8-dimethylnaphthalene, acenaphthene and acenaphthylene chromatographed on a beta-cyclodextrin-modified mobile phase. In such a case, the retention times of the polycyclic aromatic hydrocarbons were strongly reduced (e.g. from 127 to 1.2 min for 1,8-dimethylnaphthalene) and were close to the hold-up time of the high-performance liquid chromatography (HPLC) system (0.7 min). Moreover, chiral separation of 1-acenaphthenol optical isomers was observed and the elution order of the enantiomers was determined. Within the steroids group, strong interaction was observed for estradiol and testosterone. The results of cluster analysis indicate that beta-cyclodextrin as well as gamma-cyclodextrin and its hydroxypropyl derivative can be most effective mobile-phase additives under reversed-phase HPLC conditions for 3D-shape-recognition-driven separation, performed at subambient and elevated temperatures, respectively. Topics: 2-Hydroxypropyl-beta-cyclodextrin; alpha-Cyclodextrins; beta-Cyclodextrins; Chromatography, High Pressure Liquid; Circular Dichroism; gamma-Cyclodextrins; Models, Molecular; Molecular Structure; Molecular Weight; Oligosaccharides; Organic Chemicals; Polycyclic Aromatic Hydrocarbons; Steroids; Temperature | 2008 |
Complexation behavior of alpha-, beta-, and gamma-cyclodextrin in modulating and constructing polymer networks.
A systematic study of the host-guest complexation by alpha-, beta-, and gamma-cyclodextrin (CD) in either the free state or as substituents of poly(acrylic acid) (PAA) with the hydrophobic n-octadecyl groups, C18, substituted onto PAA (HMPAA) and its effect on polymer aggregation and network formation is reported. Free alpha-CD, beta-CD, and gamma-CD mask hydrophobic associations between the C18 substituent of HMPAA in aqueous solution and form host-guest complexes with a 1:1 or CD:C18 substituent stoichiometry at 0.5 wt % polymer concentration. For alpha-CD this host-guest stoichiometry changes to 2:1 or 2alpha-CD:C18 at > or =1 wt % polymer concentrations but not for beta-CD and gamma-CD. Shear-thickening occurs when gamma-CD complexes C18 HMPAA substituents. Upon addition of sodium dodecyl sulfate, SDS (SDS:CD = 1:1), the hydrophobic associations between C18 diminished by alpha-CD masking were fully restored, were only partly restored in the case of beta-CD, and not restored for gamma-CD. When alpha- and beta-CD substituted PAA (alpha-CDPAA and beta-CDPAA) were mixed with HMPAA polymer, networks formed. As for free beta-CD, the beta-CD substituents of beta-CDPAA also formed 1:1 or beta-CD:C18 stoichiometry host-guest complexes with the C18 substituents of HMPAA. The alpha-CD substituents of alpha-CDPAA also formed 1:1 or alpha-CD:C18 stoichiometry host-guest complexes with some indication of the formation of 2:1 or 2alpha-CD:C18 stoichiometry host-guest complexes at polymer concentrations > or =1 wt %. The polymer networks formed by beta-CDPAA with HMPAA are less viscous than those formed by alpha-CDPAA, for which shear-thickening occurs at polymer concentrations > or =2 wt %. It is evident that the difference in CD annular size and its match with the C18 of HMPAA control the diversity of the interactions of alpha-CD, beta-CD, gamma-CD, alpha-CDPAA, and beta-CDPAA with HMPAA. Topics: Acrylic Resins; alpha-Cyclodextrins; beta-Cyclodextrins; gamma-Cyclodextrins; Molecular Structure; Viscosity | 2008 |
Formulation and characterisation of beads prepared from natural cyclodextrins and vegetable, mineral or synthetic oils.
A continuous external shaking for 2.5 days of a mixture composed of alpha-cyclodextrin (6%), soybean oil (19.6%) and water (74.4%) resulted in a calibrated lipid carrier namely bead with a high fabrication yield. The purpose of this work was to explore the possibility to substitute alpha-cyclodextrin by other natural cyclodextrins, i.e. beta- and gamma-cyclodextrin and then soybean oil by mineral (Primol) 352 and Marcol 82) or synthetic (Silicon 200) fluid 10, 50 or 100cSt) oils. Beads can be successfully prepared using Marcol 82 with alpha-cyclodextrin and Silicon 50 or 100cSt with gamma-cyclodextrin. The area inside oil/cyclodextrin/water ternary diagram corresponding to bead occurrence was superior for the Marcol 82/alpha-cyclodextrin couple compared to that observed with soybean oil/alpha-cyclodextrin couple. Only a few ratios of Silicon 50 and 100cSt/gamma-cyclodextrin/water led to beads. The combinations which did not induce bead occurrence gave either emulsions, two non-miscible liquids or a solid mixture. Whatever the materials used, beads exhibited similarities: presence of a crystalline organisation and viscoelastic properties. Manufacturing process of paraffin- and silicon-based beads need further optimisation to increase fabrication yield and later on, to take advantages from the high stability of both oils for the formulation of drugs with beads. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Chemistry, Pharmaceutical; Crystallization; Dosage Forms; Drug Carriers; Drug Stability; Elasticity; Emulsions; gamma-Cyclodextrins; Oils; Particle Size; Phase Transition; Rheology; Viscosity | 2008 |
Biochemical and structural features of a novel cyclodextrinase from cow rumen metagenome.
A novel enzyme, RA.04, belonging to the alpha-amylase family was obtained after expression of metagenomic DNA from rumen fluid (Ferrer et al.: Environ. Microbiol. 2005, 7, 1996-2010). The purified RA.04 has a tetrameric structure (280 kDa) and exhibited maximum activity (5000 U/mg protein) at 70 degrees C and was active within an unusually broad pH range from 5.5 to 9.0. It maintained 80% activity at pH 5.0 and 9.5 and 75 degrees C. The enzyme hydrolyzed alpha-D-(1,4) bonds 13-fold faster than alpha-D-(1,6) bonds to yield maltose and glucose as the main products, and it exhibited transglycosylation activity. Its preferred substrates, in the descending order, were maltooligosaccharides (C3-C7), cyclomaltoheptaose (beta-CD), cyclomaltohexaose (alpha-CD), cyclomaltooctaose (gamma-CD), soluble starch, amylose, pullulan and amylopectin. The biochemical properties and amino acid sequence alignments suggested that this enzyme is a cyclomaltodextrinase. However, despite the similarity in the catalytic module (with Glu359 and Asp331 being the catalytic nucleophile and substrate-binding residues, respectively), the enzyme bears a shorter N-terminal domain that may keep the active site more accessible for both starch and pullulan, compared to the other known CDases. Moreover, RA.04 lacks the well-conserved N-terminal Trp responsible for the substrate preference typical of CDases/MAases/PNases, suggesting a new residue is implicated in the preference for cyclic maltooligosaccharides. This study has demonstrated the usefulness of a metagenomic approach to gain novel debranching enzymes, important for the bread/food industries, from microbial environments with a high rate of plant polymer turnover, exemplified by the cow rumen. Topics: alpha-Cyclodextrins; Amylopectin; Amylose; Animals; Bacterial Proteins; beta-Cyclodextrins; Binding Sites; Catalysis; Cattle; Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; gamma-Cyclodextrins; Glucans; Glycoside Hydrolases; Hydrogen-Ion Concentration; Maltose; Oligosaccharides; Rumen; Starch; Substrate Specificity; Temperature | 2007 |
Theoretical studies on hydrogen bonding, NMR chemical shifts and electron density topography in alpha, beta and gamma-cyclodextrin conformers.
Hydrogen-bonded interactions in alpha-, beta-, and gamma-CD conformers are investigated from the molecular electron density topography and chemical shift in the nuclear magnetic resonance (NMR) spectra calculated by using the Gauge Invariant Atomic Orbital (GIAO) method within the framework of density functional theory. For the lowest-energy CD conformers in the gas phase, the O3-H...O2' hydrogen-bonding interactions are present. Calculated 1H NMR chemical shifts (delta H) correlate well with the hydrogen-bond distance as well as electron density at the bond critical point in the molecular electron density (MED) topography. The conformers of beta- and gamma-CD comprised of relatively strong secondary hydroxyl interactions are stabilized by solvation from polar solvents. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Carbohydrate Conformation; Computer Simulation; gamma-Cyclodextrins; Glucose; Hydrogen Bonding; Magnetic Resonance Spectroscopy; Models, Molecular; Protons; Solvents; Static Electricity; Thermodynamics | 2007 |
Encapsulation of shiitake (Lenthinus edodes) flavors by spray drying.
Powdery encapsulation of shiitake flavors, extracted from dried shiitake, was investigated by spray drying. Flavor retention increased with an increase in drying air temperature and solid content, and decreased with an increase in dextrose equivalents of maltodextrin. A heat-treatment of the extract liquid made the lenthionine concentration increase, but did not influence the concentrations of the other flavors. The formation of lenthionine with heat-treatment could be described by the consecutive unimolecular-type first order reaction. Lenthionine content in a spray-dried powder prepared with the heated extracted liquid significantly increased. alpha-Cyclodextrin was the most suitable encapsulant of alpha-, beta-, and gamma-cyclodextrins to prepare the spray-dried powder, including lenthionine. The flavor retentions were markedly increased by using of alpha-cyclodextrin and maltodextrin in combination as an encapsulant. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Capsules; Cyclodextrins; Food Technology; gamma-Cyclodextrins; Hot Temperature; Polysaccharides; Powders; Shiitake Mushrooms; Taste; Temperature; Thiepins | 2004 |
Effect of camphor/cyclodextrin complexation on the stability of O/W/O multiple emulsions.
Camphor (CA) encapsulation in oil/water/oil multiple emulsions prepared with cyclodextrin disturbs the emulsifier potential of alpha- and beta-natural cyclodextrins (CD). It was suggested that the size and geometrical fit between the CD cavity and CA could induce CD/CA complex formation in place of emulsifier formation leading to perturbation of emulsion stability. The complexation between CA and alpha-, beta- or gamma-CD in solution in the presence of oil phase are confirmed by phase-solubility diagrams, circular dichroism and 1H NMR. Furthermore, in order to mimic the emulsion system, CD/CA/soybean oil ternary dispersions were prepared to observe the complexation behavior of alpha-, beta- or gamma-CD/CA by circular dichroism. X-ray diffraction on emulsion samples prepared with alpha- and beta-CD confirms that the precipitates observed in emulsions are probably composed of crystals of CD/CA complexes. A preliminary study of the interaction between drug and CD before the formulation seems indispensable to prevent the risk of incompatibility. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Camphor; Chemistry, Pharmaceutical; Circular Dichroism; Crystallization; Cyclodextrins; Drug Stability; Emulsions; gamma-Cyclodextrins; Magnetic Resonance Spectroscopy; Molecular Weight; Solubility; Soybean Oil; Surface-Active Agents; Water; X-Ray Diffraction | 2003 |
The binding of beta- and gamma-cyclodextrins to glycogen phosphorylase b: kinetic and crystallographic studies.
A number of regulatory binding sites of glycogen phosphorylase (GP), such as the catalytic, the inhibitor, and the new allosteric sites are currently under investigation as targets for inhibition of hepatic glycogenolysis under high glucose concentrations; in some cases specific inhibitors are under evaluation in human clinical trials for therapeutic intervention in type 2 diabetes. In an attempt to investigate whether the storage site can be exploited as target for modulating hepatic glucose production, alpha-, beta-, and gamma-cyclodextrins were identified as moderate mixed-type competitive inhibitors of GPb (with respect to glycogen) with K(i) values of 47.1, 14.1, and 7.4 mM, respectively. To elucidate the structural basis of inhibition, we determined the structure of GPb complexed with beta- and gamma-cyclodextrins at 1.94 A and 2.3 A resolution, respectively. The structures of the two complexes reveal that the inhibitors can be accommodated in the glycogen storage site of T-state GPb with very little change of the tertiary structure and provide a basis for understanding their potency and subsite specificity. Structural comparisons of the two complexes with GPb in complex with either maltopentaose (G5) or maltoheptaose (G7) show that beta- and gamma-cyclodextrins bind in a mode analogous to the G5 and G7 binding with only some differences imposed by their cyclic conformations. It appears that the binding energy for stabilization of enzyme complexes derives from hydrogen bonding and van der Waals contacts to protein residues. The binding of alpha-cyclodextrin and octakis (2,3,6-tri-O-methyl)-gamma-cyclodextrin was also investigated, but none of them was bound in the crystal; moreover, the latter did not inhibit the phosphorylase reaction. Topics: alpha-Cyclodextrins; Animals; beta-Cyclodextrins; Binding Sites; Circular Dichroism; Crystallography, X-Ray; Cyclodextrins; gamma-Cyclodextrins; Glucans; Glucose; Glycogen; Glycogen Phosphorylase, Muscle Form; Hydrogen Bonding; Kinetics; Models, Chemical; Oligosaccharides; Phosphorylation; Protein Binding; Protein Structure, Tertiary; Rabbits | 2003 |
Inclusion complexation of artemisinin with alpha-, beta-, and gamma-cyclodextrins.
The present study was conducted to investigate the inclusion complexation of artemisinin (ART) with natural cyclodextrins (CyD), namely alpha-, beta-, and gamma-CyDs with the aim of improving its solubility and dissolution rate. Complex formation in aqueous solution and solid state was studied by solubility analysis, dissolution, and thermal analysis. Solubility diagrams indicated that the complexation of ART and the three CyDs occurred at a molar ratio of 1:1, and showed a remarkable increase in ART solubility. Moreover, the thermodynamic parameters calculated by using the van't Hoff equation revealed that the complexation process was associated with negative enthalpy of formation and occurred spontaneously. The complexation capability of CyDs with ART increased in the order of alpha- < gamma- < beta-CyDs and could be ascribed to the structural compatibility between the molecular size of ART and the diameter of the CyD cavities. Dissolution profiles of the three complexes demonstrated an increased rate and extent of dissolution compared with those of their respective physical mixtures and a commercial preparation. In solid-state analysis, using differential scanning calorimetry, the gamma-CyD was capable of complexing the highest percentage of ART, followed by beta- and alpha-CyDs. The respective estimated percentage of ART complexed by the CyDs were 85%, 40%, and 12%. Topics: alpha-Cyclodextrins; Artemisinins; beta-Cyclodextrins; Cyclodextrins; Dose-Response Relationship, Drug; gamma-Cyclodextrins; Sesquiterpenes; Solubility | 2003 |
Enhancement of solubility and bioavailability of beta-lapachone using cyclodextrin inclusion complexes.
To explore the use of cyclodextrins (CD) to form inclusion complexes with beta-lapachone (beta-lap) to overcome solubility and bioavailability problems previously noted with this drug.. Inclusion complexes between beta-lap and four cyclodextrins (alpha-, beta-, gamma-, and HPbeta-CD) in aqueous solution were investigated by phase solubility studies, fluorescence, and 1H-NMR spectroscopy. Biologic activity and bioavailability of beta-lap inclusion complexes were investigated by in vitro cytotoxicity studies with MCF-7 cells and by in vivo lethality studies with C57Blk/6 mice (18-20 g).. Phase solubility studies showed that beta-lap solubility increased in a linear fashion as a function of alpha-, beta-, or HPbeta-CD concentrations but not gamma-CD. Maximum solubility of beta-lap was achieved at 16.0 mg/ml or 66.0 mM with HPbeta-CD. Fluorescence and 1H-NMR spectroscopy proved the formation of 1:1 inclusion complexes between beta-CD and HPbeta-CD with beta-lap. Cytotoxicity assays with MCF-7 cells showed similar biologic activities of beta-lap in beta-CD or HPbeta-CD inclusion complexes (TD50 = 2.1 microM). Animal studies in mice showed that the LD50 value of beta-lap in an HPbeta-CD inclusion complex is between 50 and 60 mg/kg.. Complexation of beta-lap with HPbeta-CD offers a major improvement in drug solubility and bioavailability. Topics: 2-Hydroxypropyl-beta-cyclodextrin; Adjuvants, Pharmaceutic; alpha-Cyclodextrins; Animals; beta-Cyclodextrins; Biological Availability; Cyclodextrins; gamma-Cyclodextrins; Humans; Injections, Intraperitoneal; Lethal Dose 50; Mice; Mice, Inbred C57BL; Naphthoquinones; Solubility; Tumor Cells, Cultured | 2003 |
The trapping of a spontaneously "flipped-out" base from double helical nucleic acids by host-guest complexation with beta-cyclodextrin: the intrinsic base-flipping rate constant for DNA and RNA.
Beta-cyclodextrin, which forms stable host-guest complexes with purine bases, induces the melting of RNA and DNA duplexes below their normal melting temperatures. Alpha-cyclodextrin, which does not form stable complexes, has no effect on either RNA or DNA. Gamma-cyclodextrin, which forms weaker complexes, has no effect on RNA and a smaller effect than beta-cyclodextrin on DNA. The rate of melting is kinetically first-order in duplex and, above about 20 mM beta-cyclodextrin, is independent of the beta-cyclodextrin concentration with a first-order rate constant, common to both RNA and DNA, of (3.5 +/- 0.5) x 10(-3) s(-1) at 61 degrees C (DNA) and at 50 degrees C (RNA). This is taken to be the rate constant for spontaneous "flipping out" of a base from within the duplex structure of the nucleic acids, the exposed base being rapidly trapped by beta-cyclodextrin. Like beta-cyclodextrin, nucleic acid methyltransferases bind the target base for methylation in a site that requires it to have flipped out of its normal position in the duplex. The spontaneous flip-out rate constant of around 10(-3) s(-1) is near the value of k(cat) for the methyltransferases (ca. 10(-3) to 10(-1) s(-1)). In principle, the enzymes, therefore, need effect little or no catalysis of the flipping-out reaction. Nevertheless, the flip-out rate in enzyme/DNA complexes is much faster. This observation suggests that the in vivo circumstances may differ from in vitro models or that factors other than a simple drive toward higher catalytic power have been influential in the evolution of these enzymes. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Chemical Phenomena; Chemistry, Physical; Cyclodextrins; DNA; gamma-Cyclodextrins; Kinetics; RNA; Spectrophotometry, Ultraviolet | 2002 |
Inclusion complex of conjugated linoleic acid (CLA) with cyclodextrins.
Conjugated linoleic acid (CLA) inclusion complexes with alpha-cyclodextrin (alpha-CD), beta-cyclodextrin (beta-CD), and gamma-cyclodextrin (gamma-CD) (designated CLA/CDs inclusion complexes) were prepared to determine the mole ratio of CLA complexed with CDs and the oxidative stability of CLA in the CLA/CDs inclusion complexes. When measured by GC, (1)H NMR, and T(1) value analyses, 1 mole of CLA was complexed with 5 mol of alpha-CD, 4 mol of beta-CD, and 2 mol of gamma-CD. The oxidation of CLA induced at 35 degrees C for 80 h was completely prevented by the formation of CLA/CDs inclusion complexes. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Chromatography, Gas; Cyclodextrins; Drug Stability; gamma-Cyclodextrins; Linoleic Acid; Magnetic Resonance Spectroscopy; Oxidation-Reduction | 2002 |
Mechanism of porcine pancreatic alpha-amylase. Inhibition of amylose and maltopentaose hydrolysis by alpha-, beta- and gamma-cyclodextrins.
The effects of alpha-, beta- and gamma-cyclodextrins on the amylose and maltopentaose hydrolysis catalysed by porcine pancreatic alpha-amylase (PPA) were investigated. The results of the statistical analysis performed on the kinetic data using the general initial velocity equation of a one-substrate reaction in the presence of one inhibitor indicate that the type of inhibition involved depends on the substrate used: the inhibition of amylose hydrolysis by alpha-, beta- and gamma-cyclodextrin is of the competitive type, while the inhibition of maltopentaose hydrolysis is of the mixed noncompetitive type. Consistently, the Lineweaver-Burk plots intersect on the vertical axis when amylose is used as the substrate, while in the case of maltopentaose, the intersection occurs at a point located in the second quadrant. The inhibition of the hydrolysis therefore involves only one abortive complex, PPA-cyclodextrin, when amylose is used as the substrate, while two abortive complexes, PPA-cyclodextrin and PPA-maltopentaose-cyclodextrin, are involved with maltopentaose. The mixed noncompetitive inhibition thus shows the existence of one accessory binding site. In any case, only one molecule of inhibitor binds to PPA. In line with these findings, the difference spectra of PPA produced by alpha-, beta- and gamma-cyclodextrin indicate that binding occurs at a tryptophan and a tyrosine residue. The corresponding dissociation constants and the inhibition constants obtained using the kinetic approach are in the same range (1.2-7 mM). The results obtained here on the inhibition of maltopentaose hydrolysis by cyclodextrin are similar to those previously obtained with acarbose as the inhibitor [Alkazaz, M., Desseaux, V., Marchis-Mouren, G., Prodanov, E. & Santimone, M. (1998) Eur. J. Biochem. 252, 100-107], but differ from those obtained with amylose as the substrate and acarbose as inhibitor [Alkazaz, M., Desseaux, V., Marchis-Mouren, G., Payan, F., Forest, E. & Santimone, M. (1996) Eur. J. Biochem. 241, 787-796]. It is concluded that the hydrolysis of both long and short chain substrates requires at least one secondary binding site, including a tryptophan residue. Topics: alpha-Amylases; alpha-Cyclodextrins; Amylose; Animals; beta-Cyclodextrins; Binding Sites; Binding, Competitive; Cyclodextrins; gamma-Cyclodextrins; Hydrolysis; Kinetics; Models, Chemical; Oligosaccharides; Pancreas; Spectrophotometry; Swine; Tryptophan | 2001 |
Separation of multicomponent mixtures of 2,4-dinitrophenyl labelled amino acids and their enantiomers by capillary zone electrophoresis.
The use of capillary zone electrophoresis (CZE) for the separation of a group of 33 2,4-dinitrophenyl labeled amino acids (DNP-AA), including DNP-AA racemates, DNP-L-AA enantiomers and achiral DNP-AAs, was investigated. Alpha-, beta- and gamma-cyclodextrins (CDs) and their derivatives (hydroxypropyl derivatives of alpha-, beta- and gamma-CDs, polymeric beta-CD and 6A-methylamino-beta-cyclodextrin (MA-beta-CD)) served as complexing agents and chiral selectors in this investigation. Although native alpha- and gamma-CDs and their derivatives influenced the effective mobilities of the studied DNP-AAs in different ways, they generally failed to resolve enantiomers of the individual DNP-AAs. On the other hand, beta-CD and all of its derivatives were found to be effective in this respect. Of these, the best results were achieved with a positively charged MA-beta-CD and this chiral selector resolved enantiomers of ten DNP-AA racemates available for this study. However, a complete resolution of these enantiomers in one CZE run required that the effect of the chiral selector be complemented by complexing effects of polyvinyl pyrrolidone (PVP) or gamma-CD. Complexing and chiral recognition capabilities of MA-beta-CD combined with complexing effects of gamma-CD and PVP provided separating conditions suitable for the CZE separations of multicomponent mixtures of DNP-AAs with preserved resolutions of the enantiomers. For example, a mixture consisting of 43 DNP-AA constituents was resolved using an MA-beta-CD/gamma-CD combination with three peak overlaps. Topics: alpha-Cyclodextrins; Amino Acids; beta-Cyclodextrins; Cyclodextrins; Dinitrobenzenes; Electrophoresis, Capillary; gamma-Cyclodextrins | 2001 |
Enantioseparation of chiral thiobarbiturates using cyclodextrin-modified capillary electrophoresis.
The racemates of several chiral thiobarbiturates were separated by using different cyclodextrins in capillary electrophoresis (CE). Six neutral and negatively charged cyclodextrins 1 (CDs) were employed as chiral separators whereof five led to successful separation of enantiomeric thiobarbiturate pairs. The CDs used were the native alpha-CD, beta-CD, gamma-CD, and heptakis-(2,6-di-O-methyl)-beta-cyclodextrin (HDM) as well as heptakis-(2,3-di-O-methyl-6-sulfato)-beta-cyclodextrin (HDMS) and heptakis-(2,3-di-O-acetyl-6-sulfato)-beta-CD (HDAS). Five of the six chiral thiobarbiturates studied could be resolved at a basic pH value of 9.4 and a phosphate buffer concentration of 100 mM in a fused-silica capillary. Structurally related substances showed a similar behavior in separation: 1 and 2 bearing the center of chirality in the side chain at C5 can be best separated using gamma-CD, the N-alkyl-substituted compounds 3 and 4 as well as the N/S-dialkyl-substituted compound 5 could be resolved with HDM. Using the neutral CDs, the migration times were relatively small (< 11 min). 3 and 4 could be also resolved by means of the negatively charged HDMS. In the latter case, the migration time is twice as long as with HDM. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Electrophoresis, Capillary; gamma-Cyclodextrins; Stereoisomerism; Thiobarbiturates | 2001 |
Cyclodextrin-assisted capillary electrophoretic resolution of 1,1'-bi-2-naphthol atropisomers.
Native beta- and gamma-cyclodextrin (CD), neutral beta-CD derivatives and ethylcarbonate derivatives of beta- and gamma-CD were used as stereoselective additives for CD-capillary zone electrophoresis (CZE) resolution of atropisomers of 1,1'-bi-(2-naphthol) (BN). CZE experiments at variable CD concentration allowed calculating binding constants from electrophoretic mobility data, corrected for electroosmotic flow (EOF) and running buffer viscosity variations. The CDs were chosen on the basis of geometric examination of molecular models of BN and CDs that suggested the possibility of inclusion complexes formation. Optimum concentrations, with aqueous 25 mM phosphate running buffer at pH 10.5, 36 cm x 50 microm capillary and 10 kV applied potential, were 3.6, 3.9, 2.1, 2.2, 1.9 mM for beta-CD, gamma-CD, ethylcarbonate-beta-CD, methyl-beta-CD and hydroxypropyl-beta-CD, respectively. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Electrophoresis, Capillary; gamma-Cyclodextrins; Molecular Conformation; Naphthols; Stereoisomerism | 2001 |
Nutritional effects of cyclodextrins on liver and serum lipids and cecal organic acids in rats.
The effect of dietary cyclodextrins on liver and serum lipids and cecal organic acid production was investigated. Male Wistar rats were fed a basal diet and a diet containing 5% of alpha-, beta-, or gamma-cyclodextrin. The body weight gain in rats fed the alpha-cyclodextrin diet was not significantly different from rats fed the other three kinds of diets. The feeding of dietary alpha-cyclodextrin increased total lipid and phospholipids in the liver. Beta-cyclodextrin significantly lowered serum total cholesterol and phospholipid levels compared with the basal diet et al. A decrease in serum triacylglycerol levels was also observed in beta-cyclodextrin-fed rats. Dietary alpha-cyclodextrin significantly increased the weight of cecal tissues and contents, and an approximate fourfold increase in acetate, propionate, and total organic acids was noted, indicating the fermentibility of beta-cyclodextrin compared with the basal diet. It seems likely that the suppression of serum cholesterol levels by alpha- and beta-cyclodextrins might be due to the increasing acetate and propionate productions in the cecum. cecal organic acid, cyclodextrin, serum cholesterol, rats Topics: Acetates; alpha-Cyclodextrins; Animals; beta-Cyclodextrins; Blood Glucose; Butyrates; Cecum; Cholesterol; Cyclodextrins; Fermentation; gamma-Cyclodextrins; Lipid Metabolism; Lipids; Liver; Male; Propionates; Rats; Rats, Wistar; Succinic Acid; Triglycerides; Weight Gain | 2001 |
Simultaneous determination of alpha, beta and gamma cyclodextrins by LC.
Cyclodextrins (CDs) can be synthesized from starch by cyclodextrin glycosyltransferase (CGTase). This enzyme produces alpha-, beta- and gamma-CDs in varying proportions. In the production of cyclodextrins, purity as well as yield are important factors. A precise and reproducible method was developed and validated for the simultaneous determination of alpha-, beta-, and gamma-CDs. Optimum separation between the three CDs was achieved using a Finepak amino column with a mobile phase consisting of acetonitrile-water (70:30, v/v) at a flow rate of 1 ml/min. Detection was carried out using a differential refractive index detector. The developed method gave good chromatographic resolution of the three components with retention times of 13.16, 16.83 and 21.74 min for alpha-, beta- and gamma-CDs, respectively. The polynomial regression data for the calibration plots exhibited good linear relationship (coefficient of correlation r = 0.9987 for alpha, r = 0.9986 for beta and r = 0.9998 for gamma-CDs) over a concentration range of 2-10 mg/ml. Statistical analysis proves that the proposed LC method is precise, reproducible and accurate for the estimation of alpha-, beta- and gamma-cyclodextrins. The method can be employed for determination of percent purity as well as estimation of process yields of the cyclodextrins during the enzymatic production. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Chromatography, Liquid; Cyclodextrins; gamma-Cyclodextrins; Quality Control; Reproducibility of Results; Solvents | 2000 |
Predicting the free energies of complexation between cyclodextrins and guest molecules: linear versus nonlinear models.
In the present paper, linear and nonlinear models for complexation of alpha- beta- and gamma-cyclodextrin with guest molecules are developed, with the aim of free energy prediction and interpretation of the association process.. Linear and nonlinear regression is used to correlate experimental free energies of complexation with calculated molecular descriptors. Molecular modeling supports the interpretation of the results.. Highly predictive models are obtained, although the structural variability of the compounds used for their deduction is large, reaching from synthetic heterocycles to steroids and prostaglandins.. The scaled regression coefficients give insight to the complexation mechanisms, which appear to be different for the three types of cyclodextrins. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Energy Transfer; gamma-Cyclodextrins; Linear Models; Models, Molecular; Nonlinear Dynamics; Pharmaceutical Preparations; Protein Structure, Tertiary; Structure-Activity Relationship | 2000 |
Optimised separation of endogenous urinary components using cyclodextrin-modified micellar electrokinetic capillary chromatography.
In this study both native and chemically modified cyclodextrins (CDs) were investigated as buffer additives to improve the micellar electrokinetic capillary chromatography (MEKC) separation of endogenous bioanalytes in human urine. The following CDs were investigated: alpha, beta, gamma-CDs; hydroxypropyl-alpha-CD, hydroxypropyl-beta-CD, methylated beta-CD, sulphated beta-CD, sulphobutyl ether-beta-CD and hydroxypropyl-gamma-CD. The separations were compared to MEKC without additives. The best improvement in peak resolution and separation of urine components was observed with the sulphated beta-CD. A four-factor three-level full factorial design study was conducted on voltage, temperature, pH and sulphated beta-CD molarity. The optimum conditions were 25 mM sodium tetraborate, pH 9.5, 75 mM sodium dodecyl sulphate (SDS) and 6.25 mM sulphated beta-CD and were able to resolve 70 peaks from a urine pool in 12 min. These optimum conditions have been successfully applied to a number of clinical samples. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Chromatography, Micellar Electrokinetic Capillary; Cyclodextrins; gamma-Cyclodextrins; Humans; Urine | 2000 |
Complex permittivities of cyclomaltooligosaccharides (cyclodextrins) over microwave frequencies to 26 GHz.
Complex permittivities (epsilon*) for microwave radiation between 0.5 and 26 GHz have been determined for alpha-, beta-, and gamma-cyclodextrins in the solid state at room temperature. For the real component of epsilon*, maxima occur near 0.6 GHz, and the relation beta > alpha > gamma is evident across the full-frequency spectrum. Dielectric loss is significant only between 5 and 12 GHz for beta- and gamma-cyclodextrins with maxima near 7.5 GHz. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; gamma-Cyclodextrins; Microwaves; Structure-Activity Relationship | 2000 |
Cyclodextrin encapsulation to prevent the loss of l-menthol and its retention during drying.
The taste and flavor of spray-dried powdered products are the most important quality factors. In the present study, molecular encapsulation in cyclodextrin was applied to prevent the loss of a hydrophobic flavor compound (l-menthol) during the drying of a droplet. beta-Cyclodextrin appeared to be a better encapsulant for menthol than alpha- and gamma-cyclodextrin. The retention of menthol increased with increasing concentration of both cyclodextrin and maltodextrin. A simple mathematical model is proposed for estimating the flavor retention. The theoretical results by this model estimated well the final retention of menthol encapsulated in a blend of beta-cyclodextrin and maltodextrin. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Drug Compounding; Freeze Drying; gamma-Cyclodextrins; Menthol; Models, Chemical; Polysaccharides; Taste | 2000 |
Statistical properties of thermodynamic quantities for cyclodextrin complex formation.
Literature values of DeltaG degrees (change in Gibbs free energy), DeltaH degrees (change in enthalpy), and TDeltaS degrees (temperature times change in entropy) for 1:1 complex formation by alpha-, beta-, and gamma-cyclodextrins constitute normally distributed populations with the following statistical parameters (all energy quantities in kcal mol(-1); n is the number of data points; mu is the population mean; sigma is the standard deviation): for alpha-cyclodextrin, n = 512, micro(DeltaG) = -2.85, sigma(DeltaG) = 1.23, micro(DeltaH) = -4.77, sigma(DeltaH) = 2.98, micro(TDeltaS) = -1.96, and sigma(TDeltaS) = 2.72; for beta-cyclodextrin, n = 415, micro(DeltaG) = -3.67, sigma(DeltaG) = 1. 37, micro(DeltaH) = -4.24, sigma(DeltaH) = 2.89, micro(DeltaS) = -0. 56, and sigma(TDeltaS) = 2.63; for gamma-cyclodextrin, n = 42, micro(DeltaG) = -3.71, sigma(DeltaG) = 1.19, micro(DeltaH) = -3.10, sigma(DeltaH) = 3.39, micro(TDeltaS) = +0.69, and sigma(TDeltaS) = 3. 29. The temperature is 298.15 K. The mean DeltaG degrees values correspond to binding constants of 123, 490, and 525 M(-1) for alpha-, beta-, and gamma-cyclodextrins, respectively. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Entropy; gamma-Cyclodextrins; Thermodynamics | 2000 |
Enantioseparation of dihydropyridine derivatives by means of neutral and negatively charged beta-cyclodextrin derivatives using capillary electrophoresis.
Employing capillary electrophoresis, the racemates of 29 acidic, neutral and basic dihydropyridines (DHPs) were separated by means of neutral and negatively charged cyclodextrins (CDs). Whereas the enantiomers of the acidic DHPs could be resolved with neutral CDs, mostly alpha- and beta-CD, the enantiomers of the neutral DHPs were only baseline-separated using the sulfobutyl ether-substituted beta-CD. Working in reversed polarity mode (detector at the anode) improved the peak shape and the resolution of the enantiomers. The racemates of the DHP bearing a secondary or tertiary amine function in the side chain at position 3 could be separated by using either the neutral gamma-CD or negatively charged CDs. The poor peak shape found with anionic CDs could be improved by the addition of methanol. The combination of gamma-CD and sulfated beta-CD allowed the detection of the minor enantiomer of lercanidipine (24) at less than 1% w/w. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Dihydropyridines; Electrophoresis, Capillary; gamma-Cyclodextrins; Molecular Structure | 2000 |
Improvement of the in vitro dissolution of praziquantel by complexation with alpha-, beta- and gamma-cyclodextrins.
Although praziquantel (PZQ) is the primary drug of choice in the treatment of schistosomiasis, its poor solubility has restricted its delivery via the oral route. In spite of its poor solubility, PZQ is well absorbed across the gastrointestinal tract, but large doses are required to achieve adequate concentrations at the target sites. Improving the solubility would enable the parenteral route to be used, thereby avoiding significant first pass metabolism. The aqueous solubility of PZQ was improved by forming inclusion complexes with alpha-, beta- and gamma-cyclodextrins (CDs). These complexes were assessed and confirmed by solubility analysis, Fourier transform infrared analysis, elemental analysis, differential scanning calorimetry and mass spectrometry. Dissolution of PZQ from the alpha-, beta- and gamma-CD complexes was 2.6-, 5- and 8-fold greater, respectively, than that of the pure drug. However, only the beta-complex had a stability constant in the optimum range for pharmaceutical use, suggesting that the preferred complex for further development would be a water-soluble beta-CD derivative. Topics: alpha-Cyclodextrins; Antiplatyhelmintic Agents; beta-Cyclodextrins; Calorimetry, Differential Scanning; Circular Dichroism; Computer Simulation; Cyclodextrins; Excipients; gamma-Cyclodextrins; Magnetic Resonance Spectroscopy; Mass Spectrometry; Praziquantel; Solubility; Spectroscopy, Fourier Transform Infrared | 1999 |
A new specific enzyme immunoassay allowing an efficient pharmacokinetic evaluation of gamma-cyclodextrin after intravenous administration to rats.
Because of its ability to form complexes with drugs, gamma-cyclodextrin is of great potential value in pharmaceutical formulations. The biological fate of y-cyclodextrin must therefore be considered in safety evaluation, using sensitive and specific methods applicable to biological fluids.. Antibodies were raised against gamma-cyclodextrin, allowing the development of a new enzyme immunoassay. The analytical characteristics of this assay were evaluated. Rats were given a single intravenous 25 mg/kg dose of gamma-cyclodextrin. Plasma and urine samples were collected and assayed.. This new enzyme immunoassay was sensitive (limit of detection close to 94 pg/mL) and suitable for quantification of gamma-cyclodextrin in urine and plasma after methanol extraction. The use of different linear and cyclic compounds demonstrated the high specificity of the assay. After i.v. administration, the concentration of gamma-cyclodextrin rapidly decreased in the plasma while the molecule was probably distributed into the tissues. Although urinary elimination predominates, only 50% of the injected gamma-cyclodextrin was recovered in urine, suggesting enzymatic degradation and/or tissular storage.. This assay may provide important information on the fate of gamma-cyclodextrin inclusion complexes dedicated to drug-delivery using various modes of administration (oral, parenteral, transmucosal or dermal). Topics: Acetylcholinesterase; alpha-Cyclodextrins; Animals; Antibodies; Body Fluids; Cross Reactions; Cyclodextrins; Drug Delivery Systems; gamma-Cyclodextrins; Immunoenzyme Techniques; Injections, Intravenous; Male; Rats; Rats, Sprague-Dawley; Sensitivity and Specificity | 1999 |
Interactions of cyclodextrins with DPPC liposomes. Differential scanning calorimetry studies.
The interaction of cyclodextrins (CDs) with dipalmitoylphosphatidylcholine (DPPC) liposomes has been studied using differential scanning calorimetry (DSC). The phase transition temperature and the enthalpy change due to the gel-to-liquid crystalline phase transition of the liposomes were measured in the presence of alpha-CD, beta-CD, gamma-CD, heptakis (2,6-di-O-methyl)-beta-CD (DOM-beta-CD), heptakis (2,3,6-tri-O-methyl)-beta-CD (TOM-beta-CD) and 2-hydroxylpropyl beta-CD, respectively. The effects on the change of enthalpy of the transition temperature were remarkable in the order of DOM-beta-CD > alpha-CD > TOM-beta-CD. The residual CDs caused scarcely detectable changes in the enthalpy changes and the transition temperatures. In order to clarify the DSC curves in the presence of the CDs mentioned above, the type of interactions which occurred between CDs and DPPC liposomes were studied. Consequently, it was found that DOM-beta-CD forms a soluble complex and alpha-CD forms an insoluble complex with DPPC liposomes, whereas only a slight amount of TOM-beta-CD was suggested to penetrate the matrix of the liposomes. Topics: 1,2-Dipalmitoylphosphatidylcholine; 2-Hydroxypropyl-beta-cyclodextrin; alpha-Cyclodextrins; beta-Cyclodextrins; Calorimetry, Differential Scanning; Cyclodextrins; gamma-Cyclodextrins; Liposomes; Thermodynamics | 1998 |
Cyclodextrins are not the major cyclic alpha-1,4-glucans produced by the initial action of cyclodextrin glucanotransferase on amylose.
The initial action of cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) from an alkalophilic Bacillus sp. A2-5a on amylose was investigated. Synthetic amylose was incubated with purified CGTase then terminated in the very early stage of the enzyme reaction. When the reaction mixture was treated with glucoamylase and the resulting glucoamylase-resistant glucans were analyzed with high performance anion exchange chromatography, cyclic alpha-1,4-glucans, with degree of polymerization ranging from 9 to more than 60, in addition to well known alpha-, beta-, and gamma-cyclodextrin (CD), were detected. The time-course analysis revealed that larger cyclic alpha-1, 4-glucans were preferentially produced in the initial stage of the cyclization reaction and were subsequently converted into smaller cyclic alpha-1,4-glucans and into the final major product, beta-CD. CGTase from Bacillus macerans also produced large cyclic alpha-1, 4-glucans except that the final major product was alpha-CD. Based on these results, a new model for the action of CGTase on amylose was proposed, which may contradict the widely held view of the cyclization reaction of CGTase. Topics: alpha-Cyclodextrins; Amylose; Bacillus; beta-Cyclodextrins; Cyclodextrins; gamma-Cyclodextrins; Glucan 1,4-alpha-Glucosidase; Glucans; Glucosyltransferases | 1997 |
Enantiomer separation of disopyramide with capillary electrophoresis using various cyclodextrins.
Enantiomers of disopyramide display different biological actions, and therefore chiral selective analysis is necessary. Fifteen different cyclodextrins (CDs) and CD derivatives were tested as capillary electrophoresis (CE) additives for the chiral separation of disopyramide. Eleven types of CDs showed chiral recognition features and four types had a baseline or close to baseline separation. The best resolution (Rs = 3.0) was with 15 mM carboxymethylated beta-CD (pH 4.9). A sharp decrease in the selectivity of gamma-phosphate (gamma-PhoCD) was observed in the pH range of 2-3, indicating a structural change of gamma-PhoCD. The enantiomers of disopyramide were separated in its ionized as well as neutral forms using acidic substituted CDs. The results show that the size of the CD cavity can not be used as a guide to estimate chiral separations, suggesting a more complex separation mechanism of these CDs towards disopyramide. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Disopyramide; Electrophoresis, Capillary; gamma-Cyclodextrins; Molecular Structure | 1997 |
Thermodynamics of the hydrolysis and cyclization reactions of alpha-, beta-, and gamma-cyclodextrin.
A thermodynamic investigation of the hydrolysis and cyclization reactions of cyclomaltohexa-, hepta-, and octa-ose (alpha-, beta-, and gamma-cyclodextrins) has been performed using microcalorimetry and high-performance liquid-chromatography. The calorimetric measurements lead to standard molar enthalpy changes delta rHm0 (T = 298.15 K, KH2PO4 buffer (m = 0.10 mol kg-1), pH = 4.58 to 5.15) for the following reactions: alpha-cyclodextrin(aq) + 6H2O(l) = 6 D-glucose(aq), beta-cyclodextrin(aq) + 7H2O(l) = 7 D-glucose(aq), gamma-cyclodextrin(aq) + 8H2O(l) = 8 D-glucose(aq). Equilibrium constants were determined for the following generalized cyclization reactions (T = 329.6 K, 0.005 mol kg-1 K2HPO4 buffer adjusted to pH = 5.55 with H3PO4) catalyzed by cyclomaltodextrin glucanotransferase: Gu(aq) = alpha-cyclodextrin(aq) + G(u-6)(aq), Gv(aq) = beta-cyclodextrin(aq) + G(v-7)(aq), Gw(aq) = gamma-cyclodextrin(aq) + G(w-8)(aq). Here, G1 is D-glucose and the Gn's (n is a positive integer) are linear maltodextrins; u, v, and w are, respectively, integers > or = 7, > or = 8, and > or = 9. Values of the equilibrium constants, standard molar Gibbs energy change delta rGm0, standard molar enthalpy change delta rHm0, standard molar entropy change delta rSm0, and standard molar heat-capacity change delta rCp,m0 are tabulated for the above reactions at T = 298.15 K. The values of delta rGm0 and delta rSm0 for the first three above-mentioned reactions rely upon an estimated value of delta rSm0 for the hydrolysis reaction of maltose to D-glucose. The thermodynamics of the disproportionation reaction Gm(aq) + Gn(aq) = Gm-1(aq) + Gn+1(aq) is also discussed. Values of the quantities delta rHm0/N, delta rGm0/N, delta rSm0/N, and delta rCp,m0/N for the three above-mentioned hydrolysis reactions where N is the number of (1-->4)-alpha-D-glucosidic bonds broken in each of these reactions, have been calculated and compared with thermodynamic quantities for the similar hydrolysis reaction of a linear oligosaccharide. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Calorimetry; Chromatography, High Pressure Liquid; Cyclization; Cyclodextrins; gamma-Cyclodextrins; Hydrolysis; Polysaccharides, Bacterial; Thermodynamics | 1997 |
Investigation of the conformational behaviour of permethylated cyclodextrins by molecular modelling.
Conformations of manually built native and permethylated alpha-, beta-, and gamma-cyclodextrins (CD) were investigated using various computer assisted molecular modelling methods. Calculations were carried by applying the MM+ and the Tripos force field. The influences of atomic charges on the macrocyclic conformations during the optimization procedure were analyzed. The permethylation of hydroxyl groups of cyclodextrins changes bond and torsion angles between the glucose monomers and of the primary substituents. A method to determine the diameters of the cyclodextrin cavity by a modelling approach is described. It is shown that due to permethylation the larger cavity opening is increased and the primary substituents are canted outwards. As a consequence, the torus shape of the molecule changes, which is an important feature for docking and fitting studies. Topics: Algorithms; alpha-Cyclodextrins; beta-Cyclodextrins; Carbohydrate Conformation; Carbohydrate Sequence; Computer Simulation; Cyclodextrins; gamma-Cyclodextrins; Glycosides; Methylation; Models, Molecular; Molecular Sequence Data | 1996 |
Capillary electrophoretic analysis of cyclodextrins and determination of formation constants for inclusion complexes.
Capillary zone electrophoresis (CZE) methods with indirect absorbance detection for analyzing mixtures of alpha-, beta-, and gamma-cyclodextrins (CDs) and their derivatives have been developed. Benzylamine, salicylic, sorbic, or 1-naphthylacetic acid (NAA) was utilized as background electrolyte (BGE) and absorbance provider. Separation of alpha-, beta-, and gamma-CD could be achieved in less than 18 min when the CZE was run in 2 mM NAA or 5 mM sorbate solution (pH 12.2) and detected by indirect absorbance at 222 or 254 nm, respectively. Mixtures of alpha- and beta-CDs, and dimethyl- and trimethyl-derivatives of beta-CD could also be analyzed by CZE, using 50 mM salicylic acid or benzylamine solution (pH 6.0) as BGE with indirect absorbance detection at 230 and 210 nm, respectively. CZE methods for determining the inclusion complex formation constants of various CDs for salicylic acid or benzylamine with either direct or indirect absorbance detection have also been developed. The formation constants of salicylate are in the range from ca. 8 +/- 0.3 mole-1 for the complex with alpha-CD to ca. 99 +/- 2 molarity-1 for the complex with methyl-beta-CD. The detection limits (determined at a signal-to-noise ratio of 3) for the NAA and the salicylate system are ca. 0.1 mM and 1 mM, respectively. Topics: alpha-Cyclodextrins; Benzylamines; beta-Cyclodextrins; Cyclodextrins; Electrolytes; Electrophoresis, Capillary; gamma-Cyclodextrins; Naphthaleneacetic Acids; Salicylates; Salicylic Acid; Sorbic Acid | 1996 |
Post-source decay fragment spectra of cyclomalto-octaose and branched cyclomalto-hexaose by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
gamma-Cyclodextrin, maltosyl-alpha-cyclodextrin and diglucosyl-alpha-cyclodextrin were analyzed using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. All of these compounds have the same molecular weight (M.W. = 1297.15) and consist of only D-glucopyranose. From a comparison of the intensities in the post-source decay (PSD) fragment spectra of these cyclodextrin derivatives, correlation between the chemical structures and the relative intensities in the PSD fragment ions was found. The correlation is considered to be caused by the difference in the number of cleavage sites at the glycosyl binding. It was found that the intensity of the PSD ion resulting from one cleavage is higher than that resulting from two cleavages at a glycosyl bond. The results show that PSD fragment-ion spectrum method used in MALDI-TOF mass spectrometry is a very powerful technique for the structural analyses of the sugar-substituted cyclodextrins. Topics: alpha-Cyclodextrins; Carbohydrate Sequence; Cyclodextrins; gamma-Cyclodextrins; Molecular Sequence Data; Molecular Weight; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization | 1996 |
Acetolytic fission of a single glycosidic bond of fully benzoylated alpha-, beta-, and gamma-cyclodextrins. A novel approach to the preparation of maltooligosaccharide derivatives regioselectively modified at their nonreducing ends.
Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Carbohydrate Sequence; Cyclodextrins; gamma-Cyclodextrins; Glycosides; Molecular Sequence Data; Oligosaccharides | 1995 |
Structural effects on the binding of amine drugs with the diphenylmethyl functionality to cyclodextrins. II. A molecular modeling study.
Molecular modeling has been used to study the complexation between alpha, beta, or gamma-cyclodextrin (CD) and a group of amine compounds having the diphenylmethyl functionality. The computer program SYBYL 5.3 and the Tripos force field (version 5.2) were used for all the calculations. Three-dimensional structures of 13 amine compounds were built individually from their atoms, and CDs were built based on the X-ray crystallographic coordinates. The diphenylmethyl derivative-CD complexes were constructed and optimized. Based on the calculated binding energies accompanying the inclusion process, the preferred method of approach of the compounds to the cavities of the CD molecules, and the structural effects on the binding between amine compounds and three CDs were explored. The calculated binding energies exhibited a good correlation with the stability constants obtained from solution calorimetric titrations. The present study shows that for similar ligand molecules, the molecular modeling technique should enable us to visualize the structure of the inclusion complexes and will also assist us in determining the ability of a potential drug molecule to form a stable complex with CDs. Topics: alpha-Cyclodextrins; Amines; beta-Cyclodextrins; Biphenyl Compounds; Calorimetry; Chemical Phenomena; Chemistry, Physical; Cyclodextrins; gamma-Cyclodextrins; Models, Molecular; Software; X-Ray Diffraction | 1991 |
Lipoprotein-cyclodextrin interaction.
Interaction of cyclodextrins with native and isolated lipoproteins was studied by electrophoretic and spectroscopic means. Reaction between these two biomolecules resulted in the formation of soluble and insoluble complexes. Cyclodextrin-mediated precipitation of lipoproteins was strongly affected by the concentration of the oligosaccharide and the presence of guest molecules capable of being entrapped within the cyclodextrin cavity. Lipoprotein precipitation by cyclodextrins was observed under acidic, neutral as well as alkaline conditions. The ionic strength of the medium did not significantly affect this interaction. Under appropriate experimental conditions, most types of cyclodextrins were able to form complexes with the various lipoprotein classes. The ability of cyclodextrins to precipitate lipoproteins was in the order of beta-cyclodextrin greater than alpha-cyclodextrin greater than gamma-cyclodextrin and hydroxyalkylated beta-cyclodextrin. Among the lipoproteins, the order of reactivity with a given cyclodextrin was: low density lipoproteins greater than high density lipoproteins greater than very low density lipoproteins. Competitive studies using L-phenylalanine and methanol, both of which form inclusion complexes with cyclodextrins, reveal that molecular encapsulation plays an important role in the stabilization of beta-cyclodextrin-lipoprotein complexes. The present data also suggests that the binding of cyclodextrins to lipoproteins may involve the formation of exclusion complexes. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Binding, Competitive; Chemical Precipitation; Cyclodextrins; Electrophoresis, Agar Gel; gamma-Cyclodextrins; Humans; Hydrogen-Ion Concentration; Lipoproteins; Lipoproteins, HDL; Lipoproteins, LDL; Lipoproteins, VLDL; Methanol; Osmolar Concentration; Phenylalanine | 1991 |
Differential effects of alpha-, beta- and gamma-cyclodextrins on human erythrocytes.
Alpha-, beta- and gamma-cyclodextrins are cyclic hexamers, heptamers, and octamers of glucose, respectively, and thus are hydrophilic; nevertheless, they have the ability to solubilize lipids through the formation of molecular inclusion complexes. The volume of lipophilic space involved in the solubilization process increases with the number of glucose units in the cyclodextrin molecule and, consequently, cyclodextrins were found to have different effects on human erythrocytes: (a) in the induction of shape change from discocyte to spherocyte the potency was observed to be alpha greater than gamma, but with beta-cyclodextrin hemolysis occurred before the change was complete; (b) in the increase of fluorescence intensity of 1-anilinonaphthalene-8-sulfonate in cyclodextrin-pretreated membranes, the observed potency was beta much greater than gamma greater than alpha; (c) in the release of potassium and hemoglobin, the potency was beta greater than alpha greater than gamma. The potencies of cyclodextrin for solubilizing various components of erythrocytes were alpha greater than beta much greater than gamma for phospholipids, beta much greater than gamma greater than alpha for cholesterol and beta much greater than gamma greater than alpha for proteins. The solubilization potencies were derived from concentration/final-effect curves. The above processes occurred without entry of solubilizer into the membrane, since (a) beta-[14C]cyclodextrin did not bind to erythrocytes and (b) cyclodextrins did not enter the cholesterol monolayer. A study of the [3H]cholesterol in erythrocytes indicated that beta-cyclodextrin extracted this lipid from membrane into a new compartment located in the aqueous phase which could equilibrate rapidly with additional erythrocytes. Therefore, the effects of cyclodextrins differ from those of detergents which first incorporate themselves into membranes then extract membrane components into supramolecular micelles. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Dextrins; Erythrocyte Membrane; Erythrocytes; gamma-Cyclodextrins; Humans; Membrane Lipids; Membrane Proteins; Starch; Structure-Activity Relationship | 1989 |
Alkylation of cyclomalto-oligosaccharides (cyclodextrins) with dialkyl sulfate-barium hydroxide: heterogeneity of products and the marked effect of the size of the macrocycle.
The alkylation of cyclomalto-oligosaccharides (cyclodextrins, CDs) with dialkyl sulfate-barium hydroxide has been claimed to yield 2,6-di-O-alkyl derivatives. Re-investigation by plasma desorption-m.s. of the products of laboratory methylation of alpha CD, beta CD, or gamma CD and ethylation of beta CD and several commercial preparations revealed them to be mixtures with broad and roughly symmetrical distributions of the degree of substitution. Recrystallization separated the components only partially. Analysis of the product of methylation of a mixture of CDs established the order of reactivity gamma much greater than alpha greater than or equal to beta. The reactivity of gamma CD thus resembles that of amylose. Topics: Alkylation; alpha-Cyclodextrins; Barium; Barium Compounds; beta-Cyclodextrins; Cyclodextrins; Dextrins; gamma-Cyclodextrins; Mass Spectrometry; Methylation; Starch; Sulfuric Acid Esters; Sulfuric Acids | 1989 |
Inactivation of sarin and soman by cyclodextrins in vitro.
Cyclodextrins catalyzed the inactivation of sarin and soman but did not inactivate tabun and VX. Furthermore, sarin and soman showed greater affinity for beta-cyclodextrin than for alpha- or gamma-cyclodextrins. Thus beta-cyclodextrin appears to be an attractive starting material for the preparation of a catalyst able to inactivate sarin and soman more effectively. Such a catalyst might contribute to improving the therapy of poisoning caused by these two nerve agents. Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Cyclodextrins; Dextrins; gamma-Cyclodextrins; Kinetics; Organophosphates; Organophosphorus Compounds; Organothiophosphorus Compounds; Sarin; Soman; Starch | 1987 |
The binding of fluorescent 4,6,8(14)-triene-3-one steroids to cyclodextrins as a model for steroid-protein interactions.
The 4,6,8(14)-triene-3-one steroids, highly fluorescent in aqueous solutions, lose their fluorescence power when binding occurs to hydrophobic regions of other molecules, such as the hydrophobic cavity in the ring system of cyclodextrins. The fluorescence intensity decreases almost completely when beta- and gamma-cyclodextrins are present in the solution. Scatchard plots derived from fluorescence titrations show that one or two molecules of steroid bind to one cyclodextrin molecule with KD,F-values of about 10(-4)-10(-5) mol/liter. Temperature-jump experiments show a single relaxation process, with rate constants for the decay of the beta-cyclodextrin-steroid complexes of about 10(4)-10(5) per s. For alpha- and gamma-cyclodextrins such relaxation processes are not observed. Topics: 17-alpha-Hydroxyprogesterone; alpha-Cyclodextrins; Androstatrienes; beta-Cyclodextrins; Cyclodextrins; Dextrins; gamma-Cyclodextrins; Hydroxyprogesterones; Kinetics; Pregnatrienes; Protein Binding; Spectrometry, Fluorescence; Starch; Testosterone | 1987 |
Different mode of prednisolone within alpha-, beta-, and gamma-cyclodextrins in aqueous solution and in solid state.
Topics: alpha-Cyclodextrins; beta-Cyclodextrins; Chemistry, Pharmaceutical; Cyclodextrins; Dextrins; gamma-Cyclodextrins; Prednisolone; Solutions; Starch | 1985 |