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1.
Cyclodextrins as Enhancers of the Aqueous Solubility of the Anthelmintic Drug Mebendazole: Thermodynamic Considerations 总被引:3,自引:0,他引:3
Ibrahim Shehatta 《Monatshefte für Chemie / Chemical Monthly》2002,133(9):1239-1247
Summary. Inclusion complexes of mebendazole with α-, β-, and γ-cyclodextrins, hydroxylpropyl-β-cyclodextrin (HP-β-CD), and methyl-β-cyclodextrin (Me-β-CD) were investigated employing the Higuchi and Connors solubility method. The solubility of mebendazole increased as a function of cyclodextrin concentration showing an AL phase diagram indicating the formation of soluble complexes with 1:1 stoichiometry. The Gibbs free energies of transfer of the drug from aqueous solution to the cavity of cyclodextrin are negative and increase negatively
with increasing cyclodextrin concentration. The solubility of mebendazole as well as the stability constant of its complex
with Me-β-CD are found to be affected by the pH of the medium. The Me-β-CD cavity was found to have a greater affinity for the unionized mebendazole rather than the protonated one. Effects of methanol
and temperature on these interactions were also investigated to gain further knowledge on the mechanism of the inclusion process.
It was found that the interaction between the drug and the cyclodextrin is weakened as the medium becomes more apolar and
the temperature increases. Moreover, the thermodynamic parameters for the binding were derived from the dependence of the
stability constants on the temperature (van’t Hoff analysis). The formation of the inclusion complexes between the drug and β-CD or its derivatives was found to be enthalpy controlled, with |ΔH °| > T|ΔS °|. This suggests that hydrophobic and van der Waals interactions as well as solvent reorganization are the main driving forces. Furthermore, the size of the cavity of cyclodextrins
plays an important role in the association process.
Permanent address: Chemistry Department, Faculty of Science, Mansoura University, Mansoura, Egypt. E-mail: i.shehatta@uaeu.ac.ae
Received November 30, 2001. Accepted (revised) December 27, 2001 相似文献
2.
Thermal analysis of cyclodextrins and their inclusion compounds 总被引:4,自引:0,他引:4
This review examines the literature concerning the thermal properties of natural and semisynthetic cyclodextrins and their inclusion compounds. Particular emphasis is given to recent results of investigations by thermal methods of the hydrated forms of cyclodextrins. The limitations and advantages of the applications of thermal analyses concerning water- and drug-cyclodextrin interactions are also discussed. 相似文献
3.
4.
Ali H. Al-Marzouqi Ayser Solieman Ihsan Shehadi Abdu Adem 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(1-2):85-93
Econazole (C18H15Cl3N2O) is one of the common antifungal agents whose poor aqueous solubility restricts its use for the treatment of oropharyngeal
candidiasis, which is the first symptom of HIV infection. Therefore, the aim of the current study was to investigate the effect
of different preparation methods (i.e. kneading, coevaporation, sealed-heating, and supercritical carbon dioxide (SC CO2)) for obtaining solid inclusion complexes between β-cyclodextrin and econazole. The physico-chemical properties of the different products were characterized by differential
scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffractometry (PXRD). For the
complexes prepared by the SC CO2 method, the effects of temperature and pressure have also been investigated and related to the solubility of econazole in
SC CO2. Results suggested the validity of the SC CO2 method for preparing solid complexes between cyclodextrins and econazole, avoiding the use of organic solvents and problems
of their complete removal. Moreover, temperature played a major role in promoting drug-carrier interactions, whereas pressure
had limited effects. 相似文献
5.
Summary - and -cyclodextrin (CD) separated by liquid chromatography have been indirectly detected by depression of the background absorbance at a visible wavelength by means of inclusion complexation with phenolphthalein. The background signal was generated by phenolphthalein in an alkaline medium. Octadecyl-bonded poly(vinylalcohol) packings were employed as the stationary phase, which allowed the use of alkaline mobile phases, and eliminated post column mixing of reagents. The detection limits for - and -CD were 0.1–0.5 M at a signal to noise ratio of 3. -CD could not be measured by the present detection principle. 相似文献
6.
Celik SE Ozyürek M Tufan AN Güçlü K Apak R 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(5):1615-1624
Measurement of total antioxidant activity/capacity of polyphenols in various solvent media necessitates the use of cyclodextrins to solubilize lipophilic antioxidants of poor aqueous solubility. The inclusion complexes of the slightly water soluble antioxidant, rosmarinic acid (RA), with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), 2-hydroxyethyl-β-cyclodextrin (HE-β-CD), and methyl-β-cyclodextrin (M-β-CD) were investigated for the first time. The effect of cyclodextrins (CDs) on the spectral features of RA was measured in aqueous medium using UV-vis and steady-state fluorescence techniques by varying the concentrations of CDs. The molar stoichiometry of RA-CD inclusion complexes was verified as 1:1, and the formation constants of the complexes were determined from Benesi-Hildebrand equation using fluorescence spectroscopic data. Among the CDs, maximum inclusion ability was measured in the case of M-β-CD followed by HP-β-CD, HE-β-CD, β-CD and α-CD. Solid inclusion complexes were prepared by freeze drying, and their functional groups were analyzed by IR spectroscopy. Antioxidant capacity of CD-complexed rosmarinic acid was measured to be higher than that of the lone hydroxycinnamic acid by the CUPric Reducing Antioxidant Capacity (CUPRAC) method. The mechanism of the TAC increase was interpreted as the stabilization of the 1-e oxidized o-catechol moiety of RA by enhanced intramolecular H-bonding in a hydrophobic environment provided by CDs, mostly by M-β-CD. 相似文献
7.
8.
Ana Figueiras Laura Ribeiro J. J. Torres-Labandeira Francisco J. B. Veiga 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):531-535
Interactions between a benzimidazolic derivative, omeprazole (OME), beta-cyclodextrin (βCD) and a chemically modified βCD,
methyl-beta-cyclodextrin (MβCD) were investigated in aqueous solution by UV-VIS spectroscopy and in solid state by differential
scanning calorimetry (DSC). Phase solubility studies were used to evaluate the complexation in aqueous solution. The two solubility
diagrams obtained were AL type, indicating the formation of a drug-cyclodextrin complex with 1:1 stoichiometry. The complex of OME with MβCD showed
a higher stability constant (K
S) than those with βCD. Some evidences of inclusion complexation in solid state were obtained from DSC. Only in thermal curves
of OME-βCD lyophilized product and in OME-MβCD spray-dried and lyophilized systems the melting point of the drug disappeared
completely suggesting the possible formation of an inclusion complex. 相似文献
9.
《Arabian Journal of Chemistry》2022,15(7):103931
Propolis is a natural resin substance produced by honeybees by collecting from parts of plants, buds, and exudates that are used for several biological activities such as antimicrobial, and fungicide functions. This study aimed to analyze the phytochemical, physicochemical, and antimicrobial activity of propolis collected from Boji Dirmaji and Fincha’a districts of western Ethiopia. The physicochemical characteristics, phytochemical screening, and antimicrobial activity of Ethiopian propolis against Aspergillus niger, Escherichia coli, and Staphylococcus aureus were evaluated using the disk diffusion method from its essential oils and crude ethanol extract were evaluated based on standard procedures. The results indicated that propolis was rich in saponins, tannins, flavonoids, steroids, triterpenes, and glycosides. Physicochemically, n-hexane extractable substances ranged between 8.6 and 33.9%, resins soluble 14.8–16.8%, insoluble residues 70.8–85.5%, moisture 1.7–4.6%, and ash content 2.8–9.7%, and 4.8 pH. The antimicrobial activities of essential oils propolis were active against Escherichia coli with an average inhibition zone of 18.3 ± 0.52 mm and 18.9 ± 0.06 mm at concentrations of 10 and 20 μl in Dirmaji districts. Moreover, the crude ethanol extracted propolis had nearly the same effect of inhibition to Escherichia coli. However, both crude extract and its essential oils didn’t show any activity on Staphylococcus aureus and Aspergillus niger. The analyzed propolis is promising antimicrobial activity from Gram-negative which is very notorious for people of the world. 相似文献
10.
Ivan Petkov Asya Petinova Stanimir S. Stoyanov Stefan Metsov Stefan I. Stoyanov 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(3-4):329-338
The effect of native and randomly methylated β-CDs on the absorption and steady-state fluorescence spectra of 2-(4-dimethylaminostyryl)-3-(2-hydroxyethyl)-benzothiazolium
chloride (DHB) in aqueous buffer solutions with various pH values was studied. The inclusion with both CDs at pH 7.2 barely
changed the UV spectra, whereas significant variations were produced in the emission spectra in all buffer solutions. In all
cases the CDs increase guest fluorescence. The 1:1 stoichiometry of the inclusion complexes of the dye with both CDs was established
according to the modified Benesi-Hildebrand method. Binding constant values were calculated using the iterative nonlinear
least-squares regression approach. The pH of the solution and the type of the CD affected complex stability. The results indicate
that native β-CD possesses better complexing ability towards DHB than randomly substituted β-CD and that the most stable inclusion
complexes are formed in basic medium because of the structural changes in the guest molecule. In basic medium an attempt is
made to interpret the proposed mechanism in terms of molecular rearrangement which take place as the dye penetrates the CD
cavity. 相似文献
11.
Conformation of permethylated cyclodextrins and the host-guest geometry of their inclusion complexes
Kazuaki Harata Kaneto Uekama Masaki Otagiri Fumitoshi Hirayama 《Journal of inclusion phenomena and macrocyclic chemistry》1984,1(3):279-293
Macrocylic conformation of permethylated cyclodextrins and the geometry of their inclusion complexes were examined on the basis of the X-ray data of three permethylated -cyclodextrin complexes and two permethylated -cyclodextrin complexes. The host macrocyclic ring is remarkably distorted owing to steric hindrance involving the methyl groups and the inability to form intramolecular hydrogen bonds. The guest molecules are included within the host cavity, but their position and orientation are quite different from those found in the corresponding cyclodextrin complexes. 相似文献
12.
13.
Ana Figueiras Laura Ribeiro M. Teresa Vieira Francisco Veiga 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):173-177
In this work, we illustrate the usefulness of cyclodextrins, namely, methyl-β-cyclodextrin (MβCD), an amorphous, methylated
derivative of the natural β-cyclodextrin (βCD), as a tool to form an inclusion complex with omeprazole (OME), a poorly water
soluble drug. Solid binary systems between OME and MβCD were prepared experimentally in a stoichiometry 1:1 by different techniques
(physical mixing, kneading, spray-drying and freeze-drying). Afterward these products were characterized by Fourier transformation-infrared
spectroscopy (FTIR); X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results obtained suggest that
spray-drying and freeze-drying methods yield a higher degree of amorphous entities suggesting the formation of inclusion complexes
between OME and MβCD. 相似文献
14.
The effect of β-CD and α-CD on the electrochemical behaviour of H2A and HA− on platinum is studied. The adsorption of β-CD on this electrode is demonstrated and proved to be dependent on the base electrolyte composition. The maximum adsorption coverage was reached in phosphate solution at pH 6.95. The homogeneous H2A---β-CD complex formation produced a decrease in the oxidation current and a positive shift in the oxidation peak potential. These effects are predominant in acid solutions. In neutral solutions the opposite behaviour is observed, i.e. an increase in the oxidation current at lower oxidation potentials. The presence of a parallel oxidation route for the vitamin involving strongly adsorbed CO residues is considered, and evidence for a decrease in COad in the presence of β-CD was given by variations in hydrogen adsorption charges. This fact, more important in neutral solutions, must be responsible for the catalytic effect observed. α-CD was not adsorbed, neither did it modify the electro-oxidation behaviour of H2A and HA−. 相似文献
15.
Joana Marques Maria P.M. Marques Filipe A. Almeida Paz 《Journal of organometallic chemistry》2008,693(18):3021-3028
The complex [Ru([9]aneS3)(bpy)Cl]Cl (bpy = 2,2′-bipyridine) was immobilised in plain β-cyclodextrin (β-CD) and permethylated β-CD (TRIMEB) to yield two adducts with a 1:1 host:guest stoichiometry. The adducts were studied by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), 13C{1H} CP/MAS NMR and vibrational spectroscopy (FT-IR and Raman). Results support the formation of stable supramolecular adducts with a proposed geometry in which the coordinated bypiridine fragment of the guest is partially included in the host cavities, and the bulky [9]aneS3 fragment protrudes out to the interstitial spaces. A packing mode is proposed for [Ru([9]aneS3)(bpy)Cl]Cl · TRIMEB, obtained by Monte Carlo optimisation of the XRD data. TRIMEB molecules are stacked in tilted channels, with the voluminous part of the guest molecules in the inter-channel space. The behaviour of [Ru([9]aneS3])(bpy)Cl]Cl upon CD encapsulation and the chloride ligand hydrolysis process in solution for all compounds were studied in detail by Raman spectroscopy. 相似文献
16.
Capillary electrophoretic analysis of cyclodextrins with dynamic fluorescence labeling and detection
The use of 8-anilinonaphthalene-1-sulfonic acid (8,1-ANS) as buffer additive in the capillary electrophoretic separation of cyclodextrins (CDs) was investigated. Better detection sensitivity was obtained for - and γ-CDs than with previously reported capillary electrophoretic methods. Increasing the concentration of 8,1-ANS improved resolution and sensitivities for -, β- and γ-CDs, while decreasing the pH of the background electrolyte can improve sensitivities. Detection limits for -, β- and γ-CDs were determined to be 60, 20 and 7 μM, respectively. The formation constants of CD–8,1-ANS complexes at pH 6 were also measured by capillary electrophoresis. Finally the specificity of amyloglucosidase to CDs was analyzed as a practical application of this method. 相似文献
17.
Ana I. Olives Emiliano E. Romero-Ale M. Antonia Martín Benito del Castillo Pilar López-Alvarado J. Carlos Menéndez 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):553-559
Carbazole-9-carbonyl chloride (C9CC) and 9-carbazolylacetic acid (9CAA) were selected as model fluorescent reagents. The effect
of different chemically modified cyclodextrins (CDs) added to the aqueous solutions of these reagents was studied in water
and in buffered aqueous solutions at pH 4.5 and 8.8. The CDs employed were 2-hydroxypropyl-β-cyclodextrin (HP-βCD), 2,3-di-O-methyl-β-cyclodextrin (DM-βCD) and 2,3,6-tri-O-methyl-β-cyclodextrin (TM-βCD). The inclusion of these reagents inside the cavities of the CDs was verified and this process
can affect the derivatization reaction because CDs can modify the reactivity of the guest molecules. The basic conditions
necessary for the derivatization reaction between C9CC and amines lead to the formation of carbazole anion through hydrolysis
followed by decarboxylation. In the presence of CDs, the hydrolysis-decarboxylation of carbazole-9-carbonyl chloride is faster
than in buffered aqueous homogeneous solutions. The behaviour observed for these reagents in aqueous solutions of CDs was
compared to the one observed in basic ethanolic solutions. These changes are particularly noticeable in the case of 2,3-di-O-methyl-β-CD and 2-hydroxypropyl-β-CD. The characteristics of the fluorescent reagents are compared to carbazole and 9-methylcarbazole
as model compounds.
This paper was presented at XIIIth International Cyclodextrin Symposium. Torino, Italy, May 14–17, 2006. 相似文献
18.
相溶解度法研究芦荟大黄素和环糊精及其衍生物的包结作用 总被引:13,自引:1,他引:13
本文用相溶解度法研究了芦荟大黄素与β-环糊精(CD)衍生物的包结作用,测定了包结物的包结常数,表明β-CD衍生物对芦蔡大黄素有较好的增溶作用,有应用价值。 相似文献
19.
Cristiano Andrade-Dias Brian J. Goodfellow Luís Cunha-Silva José J. C. Teixeira-Dias 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):151-156
The association in aqueous solutions of small amphiphilic molecules [2-phenoxyethanol, PhE1, and some α-n-alkyl-ω-hydroxyoligo(oxiethylenes], C4E1, C4E2 and C6E2) with β-cyclodextrin (βCD), heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TRIMEB) was investigated by 1H NMR spectroscopy. The upfield shifts observed for the H3 and H5 NMR signals due to anisotropic shielding confirm that the
host–guest associations are of inclusion type. The stoichiometries and the apparent inclusion constants, K
app, were determined by 1H NMR spectroscopy using the H5 and H3 signals. The relative differences in the K
app values for βCD inclusion complexes seem to reflect the hydrophobic/hydrophilic balance of the guests. The K
app values for the PhE1 inclusion complexes can be related to the degree of methylation and hydrophobicity variation within the considered hosts.
In addition, a comparative study between βCD and TRIMEB inclusion complexes using 2D ROESY (Rotating-frame Overhauser Enhancement
SpectroscopY) NMR spectra provides structural features for these complexes which are inaccessible by other experimental methods. 相似文献
20.
CE estimation of the association constants of several steroid hormones with beta-CD and gamma-CD and their hydroxypropyl derivative is presented. Estriol, 17beta-estradiol, ethynylestradiol, estrone, progesterone, mestranol and norethindrone are among the target analytes. The calculation of the cyclodextrin:analyte association constants were performed from the electrophoretic mobility values of steroids at different concentration of CDs in the run buffer. The reliability of the final data was ensured by employing three different linearisation plots (double reciprocal fit, Y-reciprocal fit and X-reciprocal fit). The highest inclusion affinity of target analytes was observed towards gamma-CD and its hydroxypropyl derivative, which is demonstrated by high association constant values and corresponding good linearity of the plots. The affinity of steroids towards a particular CD type based on physical and structural characteristics is explored. 相似文献