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At least 865 records · Page 48Linked to original sources
PubMed1995

Interaction of 6-p-toluidinylnaphthalene-2-sulfonate with beta-cyclodextrin.

The interaction of 6-p-toluidinylnaphthalene-2-sulfonate (TNS) with beta-cyclodextrin was investigated in 0.1 M phosphate buffer at pH 7.4 by fluorescence spectroscopy. Using the fluorescence enhancement of TNS in the presence of beta-cyclodextrin, the thermodynamic parameters for the formation of two kinds of the inclusion complex (molar ratio of beta-cyclodextrin to TNS = 1:1 and 2:1) were determined as follows: delta G degree 1 (1:1 complex) = -20.0 kJ mol-1 at 25 degrees C, delta H degree 1 = -19.6 kJ mol-1, delta S degree 1 = -1.7 J mol-1 K-1, delta G degree 2 (2:1 complex) at 25 degrees C = -6.14 kJ mol-1, delta H degree 2 = -2.80 kJ mol-1, delta S degree 2 = 16.7 J mol-1 K-1. From the thermodynamic parameters, the main driving force for the 1:1 inclusion complex formation was considered to be the van der Waals-London dispersion force, while the contribution of the hydrophobic interaction was small. Also, the hydrogen bonding was suggested to contribute to the inclusion complex formation. The main driving force for the 2:1 inclusion complex formation was the hydrophobic interaction. Also, from the measurements of proton nuclear magnetic resonance spectra and studies with Corey-Pauling-Koltun atomic models, the probable structure was determined and discussed in connection with the thermodynamic parameters.

Cyclodextrins↗
PubMed2002

Liquid chromatography/mass spectrometric bioanalysis of a modified gamma-cyclodextrin (Org 25969) and Rocuronium bromide (Org 9426) in guinea pig plasma and urine: its application to determine the plasma pharmacokinetics of Org 25969.

A sensitive and specific liquid chromatography/mass spectrometry (LC/MS) method has been developed and validated for the quantification of the modified gamma-cyclodextrin Org 25969 and Rocuronium bromide (Roc or Org 9426) in the plasma and urine of guinea pigs. The assay was linear and reproducible over the range 25-10000 ng/mL for both compounds. The lowest limit of quantification (LLOQ) for both compounds in urine was 25 ng/mL. In plasma, the LLOQ was 25 ng/mL for Org 9426 and 50 ng/mL for Org 25969. The inter- and intra-day variation was lower than 20%. The physicochemical properties of both compounds imposed different modes of extraction from plasma. The modified gamma-cyclodextrin was extracted by trifluoroacetic acid (TFA) precipitation while Rocuronium was extracted by acetonitrile precipitation. Both compounds were quantified in urine by direct injection onto the column. The LC/MS analyses of Org 25969 and Org 9426 were performed using two different assay conditions. It was not possible to quantify the complex of cyclodextrin and Roc as it dissociated on the LC column. The use of LC/MS conferred great advantage to the quantification of both Org 25969 and Org 9426, as they were not chromogenic enough to afford the sensitivity and specificity required for the assay.

Androstanols↗
PubMed1998

Methyl-beta-cyclodextrins and liposomes as water-soluble carriers for cholesterol incorporation into membranes and its evaluation by a microenzymatic fluorescence assay and membrane fluidity-sensitive dyes.

A variety of methods to incorporate cholesterol into lipid membrane systems have been applied with varying success. We tested an incorporation method based on cholesterol-loaded methyl-beta-cyclodextrins and compared it to a method that uses cholesterol-loaded liposomes. With methyl-beta-cyclodextrin, we increased the cholesterol content in microsomal membranes to almost the fourfold of the original content. With cholesterol-loaded liposomes instead, we achieved an elevation of 140%. Short incubation times and well-defined carrier properties favor the beta-cyclodextrin method. For direct detection of membrane cholesterol, we slightly modified a microenzymatic fluorescence assay originally developed for precise cholesterol detection in serum. Without the need to perform lipid extraction, this assay was reliable for cholesterol detection in liposomes and in microsomes. Additionally, we compared the sensitivity of the fluidity-sensitive fluorescent dyes pyrene, pyrene-methanol, bis-pyrene, 1-6-phenyl-1,3,5,-hexatrien, and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5,-hexatrien in order to detect cholesterol indirectly by the dynamically relevant changes exerted on lipid matrices. These dyes differ not only in their membrane location but also in their dynamical behavior. We calibrated the dyes in liposomes of defined cholesterol content and used the most suited ones to follow and quantify the cholesterol incorporation into liposomal and microsomal membranes.

Animals↗
PubMed1998

Artificial imitation of glutathione peroxidase with 6-selenium-bridged beta-cyclodextrin.

On the basis of cyclodextrin, 6-selenium bridged beta-cyclodextrin (6-beta-CD-Se-Se-beta-CD, known as 6-SeCD) was synthesized by the selective tosylation of beta-cyclodextrin and nucleophilic displacement by sodium hydroselenide to imitate glutathione peroxidase (GPX). The GPX activity of diselenide 6-SeCD is 4.3 times that of PZ51. The structure of the mimic 6-SeCD was characterized by means of laser mass spectroscopy, elemental analysis, IR and 1H NMR. The selenium content and its valence in 6-SeCD were determined by means of X-ray photoelectron spectra. Kinetics of the mimic showed that its enzymatic behavior was similar to that of native GPX.

Bridged-Ring Compounds↗
PubMed1993

Steroid hydroxylation with free and immobilized cells of Penicillium raistrickii in the presence of beta-cyclodextrin.

Free and Ca-alginate-immobilized cells of Penicillium raistrickii i 477 were used for 15 alpha-hydroxylation of 13-ethyl-gon-4-en-3,17-dione. The product formation of both free and immobilized cells was increased in the presence of beta-cyclodextrin, in comparison with reactions carried out in the presence of methanol. Application of beta-cyclodextrin led to increasing solubility of the steroid substrate. The fungus was able to utilize beta-cyclodextrin as a carbon source.

Alginates↗
PubMed1993

beta-cyclodextrin tetradecasulfate/tetrahydrocortisol +/- minocycline as modulators of cancer therapies in vitro and in vivo against primary and metastatic Lewis lung carcinoma.

Tetrahydrocortisol, beta-cyclodextrin tetradecasulfate, and minocycline used alone or in combination are not very cytotoxic toward EMT-6 mouse mammary tumor cells growing in monolayer. Tetrahydrocortisol (100 microM, 24 h) and beta-cyclodextrin tetradecasulfate (100 microM, 24 h) protected EMT-6 cells from the cytotoxicity of CDDP, melphalan, 4-hydroperoxycyclophosphamide, BCNU, and X-rays under various conditions of oxygenation and pH. Minocycline (100 microM, 24 h) either had no effect upon or was additive with the antitumor alkylating agents or X-rays in cytotoxic activity toward the EMT-6 cells in culture. The combination of the three modulators either had no effect upon or was to a small degree protective against the cytotoxicity of the antitumor alkylating agents or X-rays. The Lewis lung carcinoma was chosen for primary tumor growth-delay studies and tumor lung-metastases studied. Tetrahydrocortisol and beta-cyclodextrin tetradecasulfate were given in a 1:1 molar ratio by continuous infusion over 14 days, and minocycline was given i.p. over 14 days, from day 4 to day 18 post tumor implantation. The combination of tetrahydrocortisol/beta-cyclodextrin tetradecasulfate diminished the tumor growth delay induced by CDDP and melphalan and produced modest increases in the tumor growth delay produced by cyclophosphamide and radiation. Minocycline co-treatment increased the tumor growth delay produced by CDDP, melphalan, radiation, bleomycin, and, especially cyclophosphamide, where 4 of 12 animals receiving minocycline (14 x 5 mg/kg, days 4-18) and cyclophosphamide (3 x 150 mg/kg, days 7, 9, 11) were long-term survivors. The 3 modulators given in combination produced further increases in tumor growth delay with all of the cytotoxic therapies, and 5 of 12 of the animals treated with the 3-modulator combination and cyclophosphamide were long-term survivors. Although neither tetrahydrocortisol/beta-cyclodextrin tetradecasulfate, minocycline, nor the three modulator combination impacted the number of lung metastases, there was a decrease in the number of large lung metastases. Treatment with the cytotoxic therapies alone reduced the number of lung metastases. Addition of the modulators to treatment with the cytotoxic therapies resulted in a further reduction in the number of lung metastases. These results indicate that agents that inhibit the breakdown of the extracellular matrix can be useful additions to the treatment of solid tumors.

Animals↗
PubMed2001

Effects of randomly methylated-beta-cyclodextrins (RAMEB) on the bioavailability and aerobic biodegradation of polychlorinated biphenyls in three pristine soils spiked with a transformer oil.

The low bioavailability of polychlorinated biphenyls (PCBs) in soils often results in their slow and partial aerobic biodegradation. The process can be enhanced by supplementing soils with cyclodextrins. However, pure cyclodextrins are expensive and we have therefore explored the use of a less costly technical grade mixture of randomly methylated-beta-cyclodextrins (RAMEB). RAMEB was tested at 0, 1, 3 and 5% (w/w) in the aerobic bioremediation and detoxification of a loamy-, a humic- and a sandy-soil, each artificially contaminated with a PCB-containing transformer oil (added PCBs: about 450 or 700 mg/kg), inoculated with an exogenous aerobic PCB-biodegrading bacterial co-culture and treated in slurry- and solid-phase laboratory conditions. Significant depletions of the spiked PCBs were observed in all microcosms of the three soils after 90 days of treatment; however, interesting yields of PCB dechlorination and detectable decreases of the original soil ecotoxicity were observed in the slurry-phase microcosms. RAMEB generally enhanced PCB-metabolism with effects which were dependent on the concentration at which it was applied, the physical-chemical nature of the amended soil, and the soil treatment conditions employed. RAMEB, which was slowly metabolized by soil microorganisms, enhanced the presence of PCBs and PCB-cometabolizing bacteria in the soil-water phase, suggesting that RAMEB enhances aerobic biodegradation of PCBs by increasing pollutant bioavailability in soil microcosms.

Aerobiosis↗
PubMed2001

Inhibition of Cryptosporidium infection in mice treated with a cyclodextrin inclusion complex with diloxanide furoate.

The efficacies of diloxanide furoate, beta-cyclodextrin and a cyclodextrin inclusion complex against Cryptosporidium parvum were evaluated in a suckling murine model. Efficacy was established by numbers of oocysts recovered from the intestinal tract of mice on day 7 postinfection. The level of infection in treated mice was significantly lower than in control mice and, surprisingly, the most efficacious treatment was beta-cyclodextrin, an excipient used in pharmaceutical technology.

Amebicides↗
PubMed2006

Dense gas processing of micron-sized drug formulations incorporating hydroxypropylated and methylated beta-cyclodextrin.

PURPOSE: Because of their importance in pharmaceutical applications, hydroxypropyl-beta-cyclodextrin and methyl-beta-cyclodextrin have been selected to study the formation of micronized complexes incorporating active pharmaceutical ingredients (APIs) and cyclodextrins (CDs) by dense gas (DG) processing. METHODS: A single-step DG technique was used as an alternative to conventional methods for the manufacturing of API/CD complexes. The DG technology is highly attractive in the pharmaceutical industry because of its potential to generate micronized particles with controlled particle size distributions at moderate operating conditions. The effect of the aerosol solvent extraction system (ASES) processing on the dissolution performance of naproxen (NPX) was examined. RESULTS: The CDs were produced as microspheres smaller than 3 microm. The coprecipitation of each CD with NPX resulted in the production of microparticles with enhanced dissolution rates. CONCLUSIONS: The ASES was operated under mild conditions and generated micron-sized spherical particles that could be of particular interest in formulations for pulmonary delivery. Particular advantages of the technique are that (1) nontoxic solvents are used, and (2) it is suitable for the processing of thermally labile compounds. The proposed process can create opportunities to improve current administration routes and exploit novel delivery systems for drug formulations incorporating CDs.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1990

Affinity of fibroblast growth factors for beta-cyclodextrin tetradecasulfate.

beta-Cyclodextrin tetradecasulfate was found to have a very strong affinity for fibroblast growth factor (FGF) and could substitute for heparin in FGF purification. Basic FGF was purified about 200,000-fold from a rat chondrosarcoma using a method of biaffinity chromatography in which the beta-cyclodextrin tetradecasulfate polymer was mixed with copper-Sepharose. This method takes advantage of the strong affinity of FGF for both beta-cyclodextrin tetradecasulfate and copper.

Animals↗
PubMed1996

Crystal structure of anhydrous hexakis-(2,3,6-tri-O-methyl)-cyclomaltohexaose (permethyl-alpha-cyclodextrin) grown from hot water and from cold NaCl solutions.

An X-ray diffraction study was carried out on anhydrous permethyl-alpha-cyclodextrin crystallized from aq solution at 40 degrees C, space group P2(1)2(1)2(1) with a = 15.424(9), b = 18.167(7), c = 23.128(8) A, vol = 6481(5) A3. The molecule is boat-shaped with the narrow end of the cyclodextrin cavity closed by two diametrically opposing glucose residues. These are strongly tilted towards the molecular axis, so that their primary methoxy groups form van der Waals contacts across the molecular opening. The remaining cavity volume is occupied by the methoxy group of a neighboring molecule (self-inclusion). From solutions containing 1 M NaCl, anhydrous permethyl-alpha-cyclodextrin crystallizes isomorphously at room temperature.

Carbohydrate Conformation↗
PubMed1996

Cyclodextrins as templates for the presentation of protease inhibitors.

Mono(6-succinylamido-6-deoxy)-beta-cyclodextrin was synthesized by classical carbohydrate chemistry and used as a template mono-functionalized with the linear, fully flexible 4C-spacer carboxylate for covalent linkage of the calpain inhibitor leucyl-leucyl-norleucinal. Spectroscopic analyses of the conjugate do not support a self-inclusion of part of the hydrophobic peptide tail, but confirm its intra- or intermolecular interaction with the template moiety that leads to full water solubility. The inhibitory potency of the beta-cyclodextrin/peptide aldehyde construct was compared with that of the parent Ac-Leu-Leu-Nle-H against cathepsin B and calpain. Despite the large size of the template the inhibition of cathepsin B was only slightly reduced in full agreement with the X-ray structure of this enzyme which shows full accessibility of the S-subsites. For this enzyme the 4C-spacer is apparently sufficient to guarantee optimal interaction of the peptide tail with the binding cleft. Conversely, for mu-calpain a significantly decreased inhibitory potency was obtained with the conjugate suggesting steric interference of the template in the binding process. These results show that the beneficial properties of the cyclodextrin template can be retained in conjugates with bioactive peptides if attention is paid to optimize in each case the size and nature of the spacer for optimal recognition of the grafted biomolecule.

Calpain↗
PubMed1990

Cyclodextrin-facilitated bioconversion of 17 beta-estradiol by a phenoloxidase from Mucuna pruriens cell cultures.

After complexation with beta-cyclodextrin, the phenolic steroid 17 beta-estradiol could be ortho-hydroxylated into a catechol, mainly 4-hydroxyestradiol, by a phenoloxidase from in vitro grown cells of Mucuna pruriens. By complexation with beta-cyclodextrin the solubility of the steroid increased from almost insoluble to 660 microM. The bioconversion efficiency after 72 hr increased in the following order: freely suspended cells (0%), immobilized cells (1%), cell homogenate (6%), phenoloxidase preparation (40%). Mushroom tyrosinase converted 17 beta-estradiol, as a complex with beta-cyclodextrin, solely into 2-hydroxyestradiol, with a maximal yield of 30% after 6-8 hr. Uncomplexed 17 beta-estradiol was not converted at all in any of these systems.

Biotransformation↗
PubMed1995

Effect of piroxicam beta-cyclodextrin complex on experimental inflammation.

1. The effectiveness of the inclusion product of piroxicam with beta-cyclodextrin was compared to that of free piroxicam on inflammatory reactions by using three experimental inflammatory models in rats. 2. The inclusion compound showed anti-inflammatory effects similar to those of simple piroxicam on granuloma tissue formation and arthritis induced by complete Freund adjuvant. 3. In carrageenin-induced pleurisy, the piroxicam beta-cyclodextrin reduced leukocyte mobilization more intensely than non-complexed piroxicam. 4. These results suggest that beta-cyclodextrin is a useful tool for improving the efficacy of piroxicam.

Animals↗
PubMed1993

Separation and determination of warfarin enantiomers in human plasma samples by capillary zone electrophoresis using a methylated beta-cyclodextrin-containing electrolyte.

A methyl beta-cyclodextrin with a degree of substitution of 1.8 proved to be an effective chiral selector, among other cyclodextrins tested, for the separation of warfarin enantiomers by capillary electrophoresis. The operating conditions were optimized with respect to electrolyte composition (buffer pH, ionic strength, cyclodextrin concentration, methanol content) and applied voltage. The influence of a high ionic strength on the resolution was clearly shown. A baseline separation can be obtained in less than 15 min with an efficiency of ca. 250,000 theoretical plates. These conditions were applied to the determination of warfarin enantiomers in the plasma of patients under warfarin therapy. The limit of detection for the whole procedure (dichloromethane extraction followed by evaporation to dryness and capillary electrophoresis) was of the order of 0.2 mg/l (6.5.10(-7) M) of each enantiomer.

Cyclodextrins↗
PubMed1992

Characterization of sulphoalkyl ether derivatives of beta-cyclodextrin by capillary electrophoresis with indirect UV detection.

A capillary electrophoresis method which characterizes the degrees of substitution of heterogeneous sulphoalkyl ether beta-cyclodextrin derivatives is described. The separation is based on the different electrophoretic mobilities observed from changes in the overall charge of the molecule as a result of substitution. Individual peaks of the electropherogram then provide a measure of each degree of substitution of the present beta-cyclodextrin. Detection of these beta-cyclodextrin derivatives is performed by indirect UV detection.

Benzoates↗
PubMed1995

Control of enantiomer migration order in capillary electrophoresis separations using sulfobutyl ether beta-cyclodextrin.

The control of enantiomer migration order in capillary electrophoresis (CE) by use of sulfobutyl ether beta-cyclodextrin (SBE-beta-CD) was investigated. At high pH, electroosmotic flow (EOF) dominated and the enantiomer most strongly associated with the anionic cyclodextrin was detected last. At low pH (and reversed polarity), EOF was minimal and SBE-beta-CD functioned as a carrier. Under such conditions, the enantiomer migration order for a neutral chiral compound was reversed. Factors involved in optimization (cyclodextrin and organic modifier concentration) were studied. The impact of migration order on quantitation of low levels (below 1%) of one enantiomer in the presence of the other was also investigated. The precision of peak area ratios (minor/major enantiomer) was evaluated for samples of both enantiomers run by each method. The migration of minor before major enantiomer yielded better quantitation precision in each case.

Borates↗
PubMed1994

Effect of cyclodextrin on improvement of enantioselectivity in the reduction of ketopantolactone with baker's yeast.

Addition of beta-cyclodextrin improves enantioselectivity dramatically in the reduction of ketopantolactone mediated by baker's yeast. It has been found that the selectivity increases with the decrease in concentration of ketopantolactone in bulk solvent, and beta-cyclodextrin controls its effective concentration. The role of beta-cyclodextrin is discussed.

4-Butyrolactone↗