Effects of inclusion of cetirizine hydrochloride in β-cyclodextrin

Following the preparation of inclusion complex of cetirizine (CTZ) and β-cyclodextrin (β-CD), the compound was investigated to assess the possibility of modifying the physicochemical properties (solubility, release, stability, permeability) of CTZ after complexation that are vital for subsequent formulation studies involving the said complex. Changes in FT-IR/Raman spectra, DSC thermograms and XRD diffractograms confirmed the formation of a CTZ–β-CD system. Hydrophilic interaction chromatography with a DAD detector was employed to determine alterations of the CTZ concentration during studies following complexation. An analysis of a phase-solubility diagram of c_CTZ?=?fc_β-CD indicated a linear rise in the solubility of CTZ as the concentration of β-CD increased. The inclusion of CTZ in a system with β-CD significantly reduced the instability of CTZ in the presence of oxidizing factors. It was also found that regardless of the pH of the acceptor fluids used in the release studies an increase was observed in the concentration of CTZ in CD system compared to its free form. The ability to permeate artificial biological membranes manifested by CTZ after complexation was enhanced as well. In summary, CD has significant potential to mask the bitter taste of CTZ and to counter the instability induced by oxidizing factors.     

Study on β-cyclodextrin inclusion of Zn(II) aromatic complex and its analytical application

A new β-cyclodextrin (β-CD) inclusion compound Zn(2H1NA)₂·2β-CD (2H1NA = 2-hydroxy-1-naphthoic acid) was prepared. The structure was characterized by ¹H NMR, IR, the fluorescence spectra, thermogravimetric analysis (TG–DTA) and elementary analysis. Meanwhile, the mechanism of the formation of the supramolecular system (2H1NA:Zn(II):β-CD) was studied and discussed by spectrofluorimetry. The results showed that the naphthalene rings of the Zn(II) aromatic complex Zn(2H1NA)₂ were encapsulated within the β-CD's cavity to form a 2:1 stoichiometry host–guest compound. The inclusion constant calculated was 1.27 × 10⁴ (L/mol)². A spectrofluorimetric method for the determination of 2H1NA in bulk aqueous solution in the presence of β-CD was developed based on the great enhancement of the fluorescence intensity of 2H1NA. The linear relationship was obtained in the range of 9.00 × 10^?7 to 2.50 × 10^?5 mol/L and the detection limit was 8.00 × 10^?7 mol/L. The proposed method was successfully applied to determine 2H1NA in waste water with recoveries of 97–104%.     

Disposition of copper(II) inβ-cyclodextrin

Distances of glucose protons in-cyclodextrin (BCD) from copper(II) in copper(II)--cyclodextrin have been determined from¹H NMR spin-lattice relaxation time (T ₁) measurements for the first time. Very lowT _1p /T _2p values indicated the dipolar mechanism to be the most dominant one in determining the paramagnetic contribution to relaxation. The distances of copper(II) from BCD glucose protons indicated copper(II) to be present almost in the centre, inside the cavity in the same plane as H-1 and H-4. An average distance of about 5.0–5.9 Å was obtained for copper(II) from the H-2, H-3, H-1, H-4 and H-6 a and b protons in BCD.     

The adsorption of mercury(II) on the surface of silica modified with β-cyclodextrin

Multistage chemical modification of the surface of silica with β-cyclodextrin was performed. IR spectroscopy and quantitative analysis of surface compounds were used to prove the structure of modified silica. The adsorption of Hg(II) from dilute solutions was studied. The adsorption affinity of silica for mercury ions increased because of the formation of supramolecular structures with chemically immobilized β-cyclodextrin.     

The structural analysis of the inclusion complex of β-cyclodextrin with m-nitrophenoxyacetic acid

The inclusion complex of β-cyclodextrin with m-nitrophenoxyacetic acid was studied by single crystal X-ray diffraction,2D NMR spectroscopy and semi-empirical methods AMI.The crystallographic study shows that two β-cyclodextrins are held together by hydrogen bonds to form head-to-head dimers.The disordered guest molecule adjusts itself to attain the most stable accommodation into the cavity in which the nitro group is located at the dimer interface while the carboxyl group is buried in the primary hydroxyl groups of β-cyclodextrin.The guest inside the cavity is disordered over two sites and exhibits mobility.Moreover,2D NMR spectroscopy and theoretical study show the same inclusion behavior.In comparison to the inclusion complex of β-cyclodextrin with p-nitrophenoxyacetic acid,the host-guest stoichiometries are different,i.e.,2:1 for m-nitrophenoxyacetic acid and 1:1 for p-nitrophenoxyacetic acid,while the inclusion orientation and the packing pattern of the host are similar in both complexes.     

Self-assembly behavior of inclusion complex formed by β-cyclodextrin withα-aminopyridine

~~Self-assembly behavior of inclusion complex formed by β-cyclodextrin withα-aminopyridine~~     

Spectral characteristics of desipramine in β-cyclodextrin cavity through inclusion complex

The inclusion complexation behavior and its characterization of Desipramine (DP) with β-Cyclodextrin (β-CD) in solution phase are analyzed by UV and fluorescence spectroscopy. The solid inclusion complex is characterized by FT-IR, SEM, Powder XRD and TG/DTA. The stoichiometric ratio of the complexation is found to be 1:1. The orientation and structure of the complex are proposed based on the analysis of Patch-Dock server. The formation of inclusion complex has been confirmed on the base of the changes of spectroscopic properties will be encapsulated in partly either by any aromatic ring or by the aliphatic side chain. But our results showed that the aliphatic group of DP is in the cavity of β-CD.β-CD encapsulation and enhances the in-vitro cytotoxicityeffect of DP compound by forming inclusion complex in the solid state.     

Preparation and evaluation of inclusion complexes of diacerein with β-cyclodextrin and hydroxypropyl β-cyclodextrin

The objective of this research was to improve the aqueous solubility, dissolution rate and, consequently, bioavailability of diacerein, along with avoiding its side effect of diarrhea, by complexation with β-cyclodextrin (β-CD) and HP-β-cyclodextrin (HP-β-CD). Phase solubility curve was classified as an A_N type for both the CDs, which indicated formation of complex of diacerein with β-CD and HP-β-CD in 1:1 stoichiometry and demonstrating that both CDs are proportionally less effective at higher concentrations. The complexes were prepared by kneading method and were evaluated to study the effect of complexation on aqueous solubility and rate of dissolution in phosphate buffer (pH 6.8). Based on the dissolution profile HP-β-CD was selected for preparing fast disintegrating tablet of diacerein which was compared with marketed formulation (MF-J). The HP-β-CD complex was probed for Fourier transform infrared spectroscopy, differential scanning calorimetry, and powder X-ray diffraction studies which evidenced stable complex formation and increase in amorphousness of diacerein in complex. In brief, the characterization studies confirmed the inclusion of diacerein within the non-polar cavity of HP-β-CD. HP-β-CD complex showed improved in vitro drug release profile compared to pure drug and similar to that of marketed formulation respectively.     

The role of β-cyclodextrin in mediating regioselective dimethylaminomethylation of phenol

Regioselective reactions with supramolecular control are of great interest. Herein, the para-regioselectivity in the Mannich reaction of phenol with formaldehyde and dimethylamine was achieved with the use of β-cyclodextrin (β-CD), giving 4-(N,N-dimethylaminomethyl)phenol (p-AP) as major product. ¹H NMR and ITC measurements of the binding of β-CD with the reactants and the products o- and p-AP revealed a new mechanism, in which β-CD includes p-AP instead of phenol to control the reaction regioselectivity. This product-inclusion mechanism is remarkably different to the known reactant-inclusion process.     

Study on inclusion behaviour of forsythiaside A with β-cyclodextrin

Inclusion behaviour of forsythiaside A with β-cyclodextrin (β-CD) was investigated by fluorescence spectrum, nuclear magnetic resonance (NMR) and molecular modelling. A ratio of 1:1 stoichiometry has been proposed for the inclusion complex of forsythiaside A with β-CD in aqueous media according to the continuous variation Job’s method based on the fluorescence spectroscopy data. The stability constant (K) of the inclusion complex was 669 M^?1. The pH, ionic strength and temperature of solution showed great effect on the formation of inclusion complex. The spatial configuration of complex demonstrated that the B ring of forsythiaside A might be embedded inside the lipophilic cavity of β-CD and the A ring of the forsythiaside A might be exposed outside the cavity of β-CD according to NMR spectra and molecular modelling.     

Study on the inclusion compound of β-cyclodextrin with (η5-cyclopentadienyl)tricarbonylmanganese(0)

The supramolecular inclusion compound of β-cyclodextrin (β-CD, host) with (η5-cyclopentadienyl)tricarbonylmanganese [MnCp(CO)3, guest] was obtained in a crystalline state. The host-guest compound is thermally stable and do not liberate the guest on heating at 100$ in vacuum. It was characteried by elemental analysis,1H NMR, differential scanning thermal (DSC) analysis and TLC. Continueous variation plot by NMR method shows that β-CD formed 1:1 inclusion compound with MnCp(CO)3. On the basis of 1H NMR spectra and the model building with Corey Pauling Koltum (CPK) models, the most probable inclusion mode is proposed.     

Synthesis and characterization of inclusion complexes of aliphatic-aromatic poly(Schiff base)s with β-cyclodextrin (highlight)

This paper describes the formation of polymer inclusion complexes(polymer-CD-ICs) between β-cyclodextrin(β-CD) and aliphatic-aromatic poly(Schiff base)s. Fourier transform infrared(FTIR) spectroscopy, ¹H nuclear magnetic resonance spectroscopy(¹H-NMR), thermogravimetric analysis(TGA) and X-ray diffraction(XRD) have been used to observe the formation of polymer-CD-ICs. In FTIR spectra, the characteristic peaks of β-CD at 3391 cm⁻¹ shifted to 3418 cm⁻¹ and the intense peak at 1602 cm⁻¹ due to the –C = N– stretching vibration diminished after formation of inclusion complexes. Compared the ¹H-NMR of polymer-CD-ICs with β-CD, the chemical shift of the protons H-3, H-5 have shifted to higher field after the formation of inclusion complexes, which is perhaps due to the interaction of these protons with polymers. The TGA analysis revealed that the polymer-CD-ICs had better thermal stability than β-CD, suggesting that the polymer increased the stability of β-CD. The X-ray diffraction patterns displayed that the strong peak for both polymer-CD-ICs at approximately 20.0° (2θ) may confirm their IC formation.     

The effect of inclusion inβ-cyclodextrin on the chemistry of peroxides: Reactions of radicals withβ-cyclodextrin

Studies by electron paramagnetic resonance (EPR), differential scanning calorimetry, thermogravimetric analysis, HPLC and NMR showed that radicals produced by thermolysis and photolysis of benzoyl peroxide,t-butyl peroxide and cumene hydroperoxide included in-cyclodextrin (-CD), undergo significant reaction with the-CD. The formation of-CD radicals was observed by EPR. Products formed by addition of radicals to-CD were also observed. Such host:guest radical reactions explain the reported stabilization of peroxides, found with-CD inclusion, as being primarily due to the interruption of chain reactions by trapping of the chain carriers. A small increase in activation barrier for cleavage of the included peroxide in-CD was also observed.     

Spectroscopic studies of inclusion complex of β-cyclodextrin and benzidine diammonium dipicrate

Formation of inclusion complex between benzidine diammonium dipicrate and β-cyclodextrin with stoichiometry 1:2 (guest–host) has been established by UV, ¹H NMR, ¹³C NMR, IR spectra and powder X-ray diffractometry. ¹H NMR studies are used to confirm the inclusion and to provide information on the geometry of dipicrate inside the cavity of β-cyclodextrin.     

The crystal structure of the inclusion complex of cyclomaltoheptaose (β-cyclodextrin) with 3,5-dimethylbenzoic acid

The crystal of theCD-3,5-dimethylbenzoic acid inclusion complex is triclinicP1 witha=15.707(3),b=15.694(3),c=15.999(3) Å, =101.502(5),=101.557(5), =103.805(4)°,V=3624 ų, andZ=1. Two crystallographically independentCD molecules form a dimer by means of hydrogen bonds between secondary hydroxyl groups in which disordered guest molecules in six orientations are accommodated. In two of them the guest molecules are situated at the dimer interface, their carboxyl groups interacting with the carboxyl groups of two other guest orientations that are found on either side of the monomer cavity. In the two last orientations the guest molecules enter the monomer cavities in an opposite sense with the carboxyl groups protruding from the primary side and are stabilized by cyclodextrin hydroxyl groups. A dense water network is formed in the interdimer space consisted of 18.2 water molecules distributed over 24 sites. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82175 (61 pages).Dedicated to Professor József Szejtli.     

Difference in formation mechanism of inclusion complex between configuration isomers of gallate-type catechin and β-cyclodextrin

Journal of Thermal Analysis and Calorimetry - The formation mechanism of inclusion complex between (-)-epigallocatechin gallate (EGCg), which is the main catechin in tea leaves, or...     

Influence of different techniques on formulation and comparative characterization of inclusion complexes of ASA with β-cyclodextrin and inclusion complexes of ASA with PMDA cross-linked β-cyclodextrin nanosponges

Acetyl salicylic acid (ASA), a non-steroidal anti-inflammatory drug, was formulated into inclusion complexes by grinding and precipitation with β-cyclodextrin and freeze drying with pyromellitic dianhydride (PMDA) cross-linked β-cyclodextrin nanosponges. Particle size, zeta potential, encapsulation efficiency, accelerated stability study, in vitro and in vivo release studies were used as characterization parameters. TEM studies showed that the particle sizes of different inclusion complexes of ASA have diameters ranging from 40.12?±?8.79 to 59.53?±?15.55?nm. It also revealed the regular spherical shape and sizes of complexes that are even unaffected after drug encapsulation. Zeta potential was sufficiently high to obtain a stable colloidal formulation. The in vitro and in vivo studies indicated a slow and prolonged ASA release from PMDA cross-linked β-cyclodextrin nanosponges over a long period. XRPD, DSC and FTIR studies confirmed the interactions of ASA with nanosponges. XRPD showed the crystalline nature of ASA decreased after encapsulation. These results indicate that ASA nanosponges formulation can be used for oral delivery.