Inclusion Complex of Carprofen with Hydroxypropyl-β-cyclodextrin

The aim of this study was to investigate the characteristics ofhydroxypropyl--cyclodextrin (HPCD) on the solubility,photostability and dissolution of carprofen (CP). It was found that the solubility of carprofen increased 52-fold when16% HPCD was added to H₂O (w/v). The phase-solubility diagram revealed the formation of a 1 : 1 inclusion complex of CP-HPCD with a stability constant (k_s) of 487 M^-1. Formation of the inclusion complex of CP-HPCD was analyzed using differential scanning calorimetry (DSC). Changes in chemical shifts of the ¹H-nuclear magnetic resonance spectra of CP-HPCD demonstrated that the inclusion site of CP by HPCD was carbazolyl aromatic ring skeleton rather thanthe side chain of propanoic acid. The photostability study revealed that theCP-HPCD complex could not significantly decrease the rate of photodegradation of CP, implying that the rate-determining step of CP mainly occurredat the side chain. The dissolution rates of CP were significantly enhanced as the proportions of HPCD increasedin the prepared discs. The dissolution of the physical mixture (in a 1 : 3 molarratio) increased by about 6-fold in comparison with the parent drug. The improvement of wettability and solubility of CP by complexing to HPCD was reflected in theenhanced dissolution rate.     

Inclusion Complex of Paclitaxel in Hydroxypropyl-β-cyclodextrin

Introduction Paclitaxel （as Taxol） is a kind of diterpenoid natural product extracted from Chinese yew. It has been reported to have high anti-tumor effects, such as the activity against oophorama, mammary cancer, encephaloma, cervical carcinoma, and non- small-cell lung carcinoma. One of the major problems of paclitaxel applied to therapy is its extremely low solubility in water. In addition, paclitaxel is administered as a slow infusion in a vehicle consisting of Cremophor EL （ polyoxyethylated castor oil ）. However, Cremophor has been observed to cause severe, occasionally fatal hypersensitivity reactions in animals and humans. Therefore, paclitaxel therapy includes a prophylactic regimen of antihistamines and corticosteroids , along with a prolonged infusion time to reduce the severity and incidence of hypersensitivity reactions. Because of the reasons mentioned above, currently its preparation needs to be improved further.     

Inclusion Complex of Paclitaxel in Hydroxypropyl-β-cyclodextrin

Introduction Paclitaxel (as Taxol) is a kind of diterpenoid natural product[1] extracted from Chinese yew. It has been reported to have high anti-tumor effects, such as the activity against oophorama, mammary cancer, encephaloma, cervical carcinoma, and non- small-cell lung carcinoma[2-5]. One of the major problems of paclitaxel applied to therapy is its extremely low solubility in water[6]. In addition, paclitaxel is administered as a slow infusion in a vehicle consisting of Cremophor EL (polyoxyethylated castor oil ). However, Cremophor has been observed to cause severe, occasionally fatal hypersensitivity reactions in animals and humans[7].Therefore, paclitaxel therapy includes a prophylactic regimen of antihistamines and corticosteroids[8] , along with a prolonged infusion time to reduce the severity and incidence of hypersensitivity reactions. Because of the reasons mentioned above, currently its preparation needs to be improved further[9].     

Inclusion Complex of β-cyclodextrin with CTAB in Aqueous Solution

Cetyltrimethylammonium bromide (CTAB)/potassium bromide (KBr) micellar system has been used as a viscosity probe to study the inclusion complexation between β-cyclodextrin (β-CD) and CTAB. Viscosity measurements show that the inclusion complexation between β-CD and CTAB may cause the breakdown of CTAB/KBr wormlike micelles, resulting in the decrease of the solution viscosity. The viscosity minimum at C_β-CD/C_CTAB=2 indicate the molecular ratio of host molecule to guest molecule is 2:1 in the β-CD/CTAB inclusion complex.     

Study of Chlorambucil and Chlorambucil–Trimethyl-β-cyclodextrin Inclusion Complex by CE

The results of CE studies of solid inclusion complexes of chlorambucil (CHL) and trimethyl-β-cyclodextrin (TM-β-CD) are presented. Chlorambucil has low stability in aqueous solution, so the formation of complexes with β-CD is a good way to improve its stability and dissolution. The experimental results confirm the existence of inclusion complexes. CE can differentiate free CHL from CHL–TM-β-CD complexes due to their different electrophoretic mobilities.     

Inclusion of acaricides by complexation withβ-cyclodextrin

Many synthetic pesticides (herbicides, insecticides, fungicides etc.) can be complexed with cyclodextrins. The inclusion complexes of acaricides such as Fenson, Chlorfenson and Genite were prepared. The formation of inclusion complexes was established by UV and X-ray diffraction techniques. The host-to-guest ratio was determined by UV spectral and GLC methods.This paper is dedicated to Professor A.B. Kulkarni on his 75th birthday.     

Calorimetry to Evaluate Inclusion Mechanism in the Complexation Between 2-hydroxypropyl-β-cyclodextrin and Barbiturates in Aqueous Solution

Two different types (structures) of inclusion complexes with a 1:1 stoichiometry between barbiturates and 2-hydroxypropyl-β-cyclodextrin (HPCyD) were realized in aqueous solution using isothermal titration calorimetry and molecular dynamics simulation. The first type of complex with a higher association constant was entropy driven and the substituent R ₂ was inserted into the HPCyD cavity by hydrophobic interaction. The barbituric acid ring contributed to the second type of complex, which was characterized by large negative values of ΔH and small positive ΔS reflecting van der Waals interaction and/or hydrogen bonding formation between the hetero atoms in the barbituric acid ring and the secondary hydroxyl groups of HPCyD. This revised version was published online in July 2006 with corrections to the Cover Date.     

Enhanced water-solubility of albendazole by hydroxypropyl-β-cyclodextrin complexation

The inclusion complexation of methyl (5-(propylthio)-1H-benzimidazol-2-yl) carbamate, albendazole (ABZ) with 2-hydroxypropyl--cyclodextrin (HPCD) in water was investigated with a view to improving the low aqueous solubility of the drug. The combination of albendazole and HPCD in a molar ratio of 1/10 resulted in a significant increase in the aqeous solublity of the drug, up to 3500 times. Albendazole/HPCD complexes could be recommended as a parenterally administered formulation because of its good solubility properties and the safety of the cyclodextrin used.     

Study on the Interaction of Pentachlorophenol with Urease in Aqueous Solution by Multiple Spectroscopic Techniques

The interactions between pentachlorophenol (PCP) and jack bean urease were studied using UV/vis absorption, CD, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectroscopic techniques. The fluorescence data showed that the fluorescence quenching of urease by PCP the results of the formation of a PCP–urease complex involving a hydrophobic interaction. The distance r between the donor (urease) and acceptor (PCP) was obtained from the fluorescence resonance energy transfer. The effect of PCP on the conformation of urease was analyzed using UV/vis absorption, synchronous fluorescence and three-dimensional fluorescence spectroscopic techniques. The result showed that PCP can enter into the hydrophobic pocket at the interface of urease and that the micro environments around the tyrosine and tryptophan residues were changed.     

Inclusion complexes of sulfanilamide with β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin

Sulfanilamide belongs to the group of drugs that have a bacteriostatic effect on different pathogenic microorganisms. This activity originates from the competitive antagonism with p-aminobenzoic acid, which is an integral part of folic acid. The safe use of sulfanilamide is limited due to poor solubility in the aqueous medium. Therefore, the aim of this paper is the synthesis of sulfanilamide, as well as preparing and structural characterization of its inclusion complexes with cyclodextrins. The crude sulfanilamide was obtained in the synthesis between acetanilide and chlorosulfonic acid according to the standard procedure. The synthesized sulfanilamide was recrystallized from water in order to obtain the satisfactory purity of the substance. Sufanilamide was complexed with β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin by the co-precipitation method. A molecular encapsulation of sulfanilamide was confirmed by using FTIR, ¹H-NMR, XRD and DSC methods. Phase-solubility techniques were used to assess the formation of the inclusion complex between sulfanilamide and cyclodextrins. The photostability of sulfanilamide and its inclusion complexes was estimated by UVB irradiation in a photochemical reactor by applying the UV–Vis method. Based on the UV–Vis analysis, sulfanilamide:2-hydroxypropyl-β-cyclodextrin complex was presented as more photostable than sulfanilamide:β-cyclodextrin complex and sulfanilamide. The obtained results enable the potential use of these inclusion complexes for the preparation of oral formulations due to the enhanced solubility of sulfanilamide.     

Using PVP/SDS Complex as a Probe to Study the Inclusion Complex of β-cyclodextrin with SDS in Aqueous Solution

PVP/SDS complex was applied as a probe to study the interaction between β-cyclodextrin （β-CD） and sodium dodecyl sulfate （SDS） in aqueous solution. It has been found that a critical concentration, namely cs, exists in the relative viscosity of solution containing PVP/SDS complex versus β-CD concentration plot. As the β-CD concentration is less than cs, the relative viscosity of solution decreases sharply by adding β-CD into solution successively. On the other hand, as the β-CD concentration is greater than cs, the relative viscosity of solution increases gradually by adding β-CD into solution. The decrease of the relative viscosity of solution containing PVP/SDS in the presence of β-CD is just due to the inclusion complex of β-CD with the guest molecule SDS. And, this inclusion interaction takes down SDS from the PVP chains in solution. The ratio of the host molecule β-CD to the guest molecule SDS can be calculated from Cs. In our experiment the inclusion ratio of β-CD to SDS is 1/1. The further experimental results indicate that cs is associated with SDS but free from PVP in PVP/SDS complex. However, the inclusion ratio of β-CD to SDS has proved to be independent of either SDS or PVP in PVP/SDS complex.     

Study of complex formation between ��-cyclodextrin and benzene

In this work study of complex formation of ??-cyclodextrin with benzene was performed both experimentally and theoretically. Interaction of benzene with ??-cyclodextrin in aqueous solutions was investigated by means of UV spectroscopy at temperatures in the range 291?C303 K. The stoichiometric composition, stability constant, and thermodynamic parameters of ????-cyclodextrin-benzene?? supramolecular structures formation were calculated from spectroscopic data. It was proved that 1:1 inclusion complex is mainly formed in aqueous solutions. The calculations of a spatial structure, formation energy, and vibration spectra in IR range for the complex of ??-cyclodextrin with benzene were performed by Hartree?CFock?CRoothaan method within PM3 semiempirical approximation with quantum chemistry package GAMESS (version 6.4). The calculated energy parameters for ????-cyclodextrin-benzene?? inclusion complex are in agreement with experimental data.     

Interaction of Polyelectrolyte with Fluorocarbon Surfactant in Aqueous Solution

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Inclusion Modes of Berberine with β-Cyclodextrin in Aqueous Solution

The possible inclusion modes of berberine(Berb)with β-cyclodextrin(BCD)in aqueous solution were predicted by molecular docking,molecular dynamics(MD)simulation and binding free energy calculations.Firs...     

Synthesis of Hydroxypropyl-β-cyclodextrin Bonded Silica-gel and its Application to Resolution

Many chiral separation methods have been set up for efficient, precise and dependable determination of optical purity and/or separation of optical isomers in preparative scale. However, most of the methods could only be used to analyze chiral substances, …     

Theoretical Studies on the Conformation of mono-6-O-p-nitrobenzoyl-β-cyclodextrin in Aqueous Solution

It is well known that a substituted cyclodextrin (CD) can often form a self-included complex, in which the substituent group is incarcerated into the CD cavity1. The phenomenon is interesting, as the self-inclusion is a nice model of protein folding2 and it has also been successfully used in the construction of various molecular devices3. Studies have showed that van der Waals force, hydrophobic effect, and electrostatic interaction are the major driving forces leading to the self-inclusion4…     

Competition between the Hydrated Fluoride Anion and Hexanoic Acid for Inclusion in β-Cyclodextrin: An 1H-NMR Study in Aqueous Solution

β-cyclodextrin (βCD) and two guests (hexanoic acid and the hydrated fluoride ion) are considered as a system in the NMR chemical shift fast exchange regime. The measured chemical shift variations for the βCD H5 protons are expressed as functions of the mole fractions for the free and complexed states, and their slopes, , are evaluated. When the NaF concentration is varied ([NaF]₀/mM = {50,100, 150, 200, 250}) for a defined value of the hexanoic acid concentration ([Hex]₀/mM = {5, 7.5, 10, 12.5, 15}), the chemical shift variations of the βCD H5 protons for 2.5 mM βCD solutions in D₂O present a second order polynomial variation with a minimum, suggesting two opposing trends. The first trend corresponding to the decrease of Δδ values (relative shielding) is traced to increasingly negative values of . Corresponding to the increase of Δδ values (relative deshielding), the second trend is mainly associated with the increase of the mole fraction for the inclusion complex βCD·F(H₂O)₆⁻, as the concentration of NaF increases. The kosmotropic, stabilizing features of the fluoride ion are consistent with the results of HF/6–31G* single point energy calculations showing that βCD·F(H₂O)₆⁻ is energetically favourable, in contrast with βCD·Cl(H₂O)₆⁻ and βCD·Br(H₂O)₈⁻. Due to its smaller size, F(H₂O)₆⁻ is not appreciably distorted inside the βCD cavity as compared with Cl(H₂O)₆⁻ and Br(H₂O)₈⁻.     

Thermochemical Study of the Reactions of Acid–Base Interaction in an Aqueous Solution of β-Aminobutyric Acid

Russian Journal of Physical Chemistry A - The enthalpies of interaction between β-aminobutyric acid and HNO3 and KОН solutions are measured calometrically in different pH ranges, a...     

Inclusion complexes of α- andβ-cyclodextrin with α-lipoic acid

A UV spectroscopic study has been performed in neutral aqueous solution to give the complex stability constants. Data analyses assuming 1:1 stoichiometry were successfully applied to both of the host-guest combinations employed, where 1:1 host-guest complex formations were observed at lower concentration of cyclodextrins (CDs). X-ray powder diffraction and IR spectroscopy measurements also demonstrated that inclusion complexes were formed in the solid state. Furthermore, thermogravimetry and DTA were used to investigated the thermal properties of these complexes. The differential thermal analysis, as well as temperature variation experiments below 100°C, indicated that after complexing the 1,2-thiolane moiety of -lipoic acid (LP) penetrated into the cavity of the CD and the S-S linkage was protected against heat.     

Interaction of some antibiotics with hydroxypropyl-β-cyclodextrin

The interaction between 19 antibiotics and hydroxypropyl--cyclodextrin (HPCD) was studied by reversed-phase thin-layer chromatography. HPCD formed inclusion complexes with 16 compounds, the complex always being more hydrophilic than the uncomplexed drug. The intensity of interaction significantly increased with increasing specific hydrophobic surface area of the guest molecule proving the preponderant role of hydrophobic interactions in inclusion complex formation. The intensity of the HPCD-drug interaction significantly decreased with increasing concentration of methanol in the environment indicating that methanol can also enter the cyclodextrin cavity and inhibits competitively the inclusion complex formation or the free energy of transfer from water to the HPCD cavity should be less negative at higher concentration of methanol in the aqueous medium.Dedicated to Professor József Szejtli.