Spectroscopic Determination of Binding Constants of Modified β-cyclodextrins with Brooker’s Merocyanine

Host-guest complexation occurs when a guest molecule is held inside a host molecule through weak molecular forces. β-cyclodextrin, a host molecule, has a variety of uses and is often applied in pharmaceuticals. Binding constants of host-guest complexes of Brooker’s merocyanine and various modified β-cyclodextrins (2-hydroxypropyl-β-cyclodextrin, sulfated β-cyclodextrin, and methyl-β-cyclodextrin) were studied using fluorescence and UV-Vis spectrometry to determine the strength of interaction between the host molecule and the guest molecule. By modifying the β-cyclodextrin, the effect of ionic forces, hydrogen bonding, and steric hindrance were compared. It was determined via fluorescence spectrometry that sulfated β-cyclodextrin had a binding constant of 38.3 M-1, which was significantly lower than the determined binding constants 430 M-1 for β-cyclodextrin, 359.1 M-1 for 2-hydroxypropyl-β-cyclodextrin, and 194.6 M-1 for methyl-β-cyclodextrin. These results were confirmed via UV-Vis spectrometry, where the binding constants were 335.2 M-1 for 2-hydroxypropyl-β-cyclodextrin and 178.4 M-1 for methyl-β-cyclodextrin. These results were in agreement with fluorescence data. The much lower binding constant of sulfated β-cyclodextrin could be caused by a combination of ionic forces and steric hindrance. A comparison of these results to the theoretical models will lead to verification of the effect of these forces on binding. About the author: Carly Hanson is a junior Chemistry major and German minor

Adsorption behaviour of molecularly imprinted-beta-cyclodextrin polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization for selective recognition of benzylparaben

Molecularly imprinted polymers (MIPs) are kinds of powerful materials with promising selective molecule recognition abilities. However, the conventional MIPs have relatively low binding capacity. In order to improve this characteristic of MIPs, the modification monomer based on β-cyclodextrin (β-CD) and the essential of reversible addition�fragmentation chain transfer (RAFT) polymerization process were studied to generate potential MIPs. The study focuses on the characterization and adsorption behaviour of MIPs for selective recognition of benzylparaben (BzP) analyte. The potential of β-CD in MIP was investigated by synthesizing a reversible addition-fragmentation chain transfer molecularly imprinted methacrylic acid functionalized β-cyclodextrin polymer; RAFT�MIP(MAA-β-CD) based on methacrylic acid functionalized β-cyclodextrin (MAA-β-CD) monomer, which was then compared to a reversible addition-fragmentation chain transfer molecularly imprinted methacrylic acid polymer; RAFT-MIP(MAA) synthesized without β-CD. Both MIPs were prepared by the RAFT polymerization process in bulk polymerization method. The resulting MIPs were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Field Scanning Electron Microscope (FESEM) and Brunauer-Emmett-Teller (BET) analysis. The batch adsorption study that includes studying of the pH, kinetic, isotherm and thermodynamic was conducted. The essential of RAFT polymerization on MIP was studied by comparing RAFT-MIP(MAA-β-CD) with the molecularly imprinted methacrylic acid functionalized β-cyclodextrin polymer; MIP(MAA-β-CD) was synthesized without RAFT agent, and characterized by using FTIR, elemental analysis, FESEM and BET. The binding experiments demonstrated that the RAFT-MIP(MAA-β-CD) has a higher binding capacity and higher accessibility compared to RAFT-MIP(MAA) and MIP(MAA-β-CD) for selective of BzP, respectively. The β-CD and RAFT polymerization process improved the MIP’s physical properties and iv enhanced its recognition capacity, thus affecting the adsorption behaviour of RAFT�MIP(MAA-β-CD). The effects of RAFT polymerization process were also investigated by a reversible addition-fragmentation transfer molecularly imprinted hydroxylethyl methacrylate functionalized β-cyclodextrin polymer; RAFT-MIP(HEMA-β-CD). The RAFT-MIP(HEMA-β-CD) was synthesized based on the hydroxylethyl-methacrylate functionalized β-cyclodextrin (HEMA-β-CD) monomer and was prepared by the RAFT polymerization process in bulk polymerization method. The molecularly imprinted hydroxylethyl-methacrylate functionalized β-cyclodextrin polymer; MIP(HEMA-β-CD) without a RAFT agent was synthesized as comparison. A similar study to RAFT�MIP(MAA-β-CD) had also been carried out for RAFT-MIP(HEMA-β-CD).The effects of RAFT polymerization on RAFT-MIP(HEMA-β-CD) were contrasted with RAFT�MIP(MAA-β-CD). The compact and non-porous morphology of RAFT-MIP(HEMA-β�CD) reduces its binding capacity performance compared to MIP(HEMA-β-CD). Thus, this directly affected the RAFT-MIP(HEMA-β-CD) adsorption behaviour towards BzP. It was resulted that the RAFT polymerization had not improved the synthesis of RAFT�MIP(HEMA-β-CD). Careful choice of RAFT agent and monomer is essential in realizing good control over the RAFT-MIP polymerization process, and generating potential MIP

Preparation and solid state properties of cyclodextrin complexes of selected drug molecules

Includes bibliographical references.A large number of pharmaceutically important drugs are poorly soluble in water. This study focuses on the 'smart' molecule that can enhance the solubility and hence increase the bioavailability of these drugs. This molecule is a cyclodextrin and is known to form inclusion compounds with various drug molecules. The preparation of β-cyclodextrin CP-CD), y-cyclodextrin (y-CD), heptakis(2,6-di-OJ, methyl)-β-cyclodextrin (Dimeb) and heptakis(2,3,6·tri-0-methyl)- β-cyclodextrin (Trimeb) 3, complexes with clofibric acid as well as the heptakis(2,3,6j·tri-O-methyl)- β-cyclodextrin (Trimeb) complex with clofibrate is reported. The complexes were characterised by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), ultraviolet spectrophotometry (UV), infrared spectroscopy (IR), X-ray powder diffraction (XRD) and single crystal X-ray analysis

Insight into inclusion complexation of indomethacin nicotinamide cocrystals

The objective of this research was to investigate the feasibility of the interaction between indomethacin-nicotinamide cocrystals with β-cyclodextrin and hydroxypropyl-β-cyclodextrin in the solid-state. The study has emphasized on the possibility of inclusion complex formation and its effect on the dissolution performance of the cocrystals. The solid systems in the molar ratio of 1:1 of the host and guest molecules were prepared by co-grinding and co-evaporation methods and compared with their physical mixtures. Furthermore, the molecular behaviors of the cocrystals in all prepared samples were thoroughly characterized by powder X-ray diffraction, differential scanning calorimetry, Fourier-transform infrared spectroscopy, scanning electron microscopy and in-vitro dissolution performance. The results of these studies indicated that complexes prepared by the co-evaporation method with hydroxypropyl-β-cyclodextrin have shown complete inclusion of the cocrystals into the cyclodextrin cavity and a partial inclusion with β-cyclodextrin. Moreover, a significant (p < 0.05; ANOVA/Tukey) higher in-vitro dissolution was achieved in co-evaporate complex prepared with hydroxypropyl-β-cyclodextrin compared to that prepared with β-cyclodextrin, indomethacin-nicotinamide cocrystals and indomethacin itself

Sol-gel Synthesis of β-Cyclodextrin-containing Silicas with 3-(chloropropyl)triethoxysilane as Precursor

The sol-gel synthesis of β-cyclodextrin-containing silica materials is reported. Organosilicas were pre-pared in tetraethylorthosilicate–3-(chloropropyl)triethoxysilane–β-cyclodextrin–ethanol–water system. These materials were characterized by IR spectroscopy and thermogravimetric analysis. Porosity of orga-nosilicas was characterized on nitrogen adsorption/desorption isotherms. The porosity analysis demon-strates that cyclodextrin-silica based materials are an isotherm Type I substance. The surface areas of the organosilicas with incorporated β-cyclodextrin are in the range 430–580 m2 g1; materials containing up to 0.005 mmol g1of β-cyclodextrin moieties have been successfully prepared. Synthesized organosilicas are stable in aqueous medium and could be used in processes of pollutants removal. The present study demon-strates a simple time-saving method of cyclodextrin-containing silicas obtaining via one-pot synthesis in mild condition without using toxic solvents, costly templates or cyclodextrin derivatives. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3523

Synthesis and in vitro evaluation of cyclodextrin hyaluronic acid conjugates as a new candidate for intestinal drug carrier for steroid hormones

Steroid hormones became increasingly interesting as active pharmaceutical ingredients for the treatment of endocrine disorders. However, medical applications of many steroidal drugs are inhibited by their very low aqueous solubilities giving rise to low bioavailabilities. Therefore, the prioritized oral administration of steroidal drugs remains problematic. Cyclodextrins are promising candidates for the development of drug delivery systems for oral route applications, since they solubilize hydrophobic steroids and increase their rate of transport in aqueous environments. In this study, the synthesis and characterization of polymeric β-cyclodextrin derivates is described, which result from the attachment of a hydrophilic β-CD-thioether to hyaluronic acid. Host-guest complexes of the synthesized β-cyclodextrin hyaluronic acid conjugates were formed with two poorly soluble model steroids (β-estradiol, dexamethasone) and compared to monomeric β-cyclodextrin derivates regarding solubilization and complexation efficiency. The β-cyclodextrin-drug (host-guest) complexes were evaluated in vitro for their suitability (cytotoxicity and transport rate) as intestinal drug carriers for steroid hormones. In case of β-estradiol, higher solubilities could be achieved by complexation with both synthesized β-cyclodextrin derivates, leading to significantly higher intestinal transport rates in vitro. However, this success could not be shown for dexamethasone, which namely solubilized better, but could not enhance the transport rate significantly. Thus, this study demonstrates the biocompatibility of the synthesized and characterized β-cyclodextrin derivates and shows their potential as new candidate for intestinal drug carrier for steroid hormones like β-estradiol

Preparation And Characterization Of Atenolol-Β-Cyclodextrin Orally Disintegrating Tablets

Atenolol is a hypertension drug that has a low solubility characteristic in water and gastric fluid. The rate of absorption of the drug with poor solubility characteristics is determined by the dissolution process. In this study, an attempt has been conducted to increase the dissolution of atenolol by increasing its solubility. The solubility of atenolol has been enhanced by the inclusion complex using β-cyclodextrin made by several methods (physical mixing, kneading, and solvent evaporation). Evaluation and characterization of atenolol-β-cyclodextrin inclusion complex consist of drug content, dissolution test, Fourier Transformed Infrared analysis (FT-IR), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). The results of the drug content analysis, dissolution test, and characterization showed that atenolol- β-cyclodextrin inclusion complex, which has been made by the solvent evaporation method was the best approach. Therefore, a solvent evaporation method was chosen to formulate orally disintegrating tablets of atenolol-β-cyclodextrin using direct compression technique. Orally disintegrating tablets of atenolol-β-cyclodextrin were prepared using crospovidone as disintegrant. The results of pre-compression test and the post-compression test revealed that orally disintegrating tablets of atenolol-β-cyclodextrin inclusion complex disintegrate within 8.17 ± 0.41 sec. In-vitro dispersion time in simulated saliva was found to be 45.33 ± 0.58 sec and the percentage of atenolol dissolved from this formula was 92.22% in 30 min. Hence, this formula shows good physicochemical characteristics and fulfill pharmaceutical quality requirements of orally disintegrating tablet

Analysis of monoterpenoids in inclusion complexes with β-cyclodextrin and study on ratio effect in these microcapsules.

In recent studies, the insecticide activity against some stored products pests of monoterpenoids, such as linalool, S-carvone, camphor, geraniol, γ-terpinene and fenchone, and phenylpropanoids, like E-anethole and estragole, has been proved. Currently, applications of these volatile compounds are complicated due to their chemical and physical properties. This is one of the major problems for their use as insecticides; therefore, microencapsulation could be the solution to problems of stability, evaporation and release. Microencapsulation of these chemicals was carried out with β-cyclodextrin using a chemical precipitation method at four different ratios (β-cyclodextrin: monoterpenoids), 1.33:1, 3.33:1, 4.66:1 and 6.66:1 (w/w) in order to determine the ratio effect. This study establishes that encapsulation at the ratio of 3.33:1 to linalool and γ-terpinene was higher, whereas S-carvone, camphor, E-anethole, geraniol, estragole and fenchone showed the greatest encapsulation when the ratio was 6.66:1. Furthermore, the efficiency of encapsulation was estimated by measuring the content of the compounds in the powder by gas chromatography. The maximum inclusion efficiency of β-cyclodextrin was reached by camphor (52%) followed by geraniol (34%) using 10 g of β-cyclodextrin and linalool (31%) using 5 g of this matrix. The present study indicates that natural products such as monoterpenoids or phenylpropanoids could be microencapsulated in an efficient way using an appropriate amount of β-cyclodextrin. Keywords: Microencapsulation, β-cyclodextrin, Camphor, Geraniol and Linaloo

Influence of feeding regimens on rat gut fluids and colonic metabolism of diclofenac-β-cyclodextrin

Feeding states may affect the performance of colonic prodrugs. The aim is to investigate the influence of feeding regimen in Wistar rats on: (i) distribution and pH contents along the gut and (ii) metabolism of two colonic prodrugs, diclofenac-β-cyclodextrin and a commercially available control, sulfasalazine, within the caecal and colonic contents. Male Wistar rats were subject to four different feeding regimens, the gut contents characterized (mass and pH) and the metabolism of prodrugs investigated. The feeding regimen affects gut contents (mass and pH), more specifically in the stomach and lower intestine, and affects the rate of metabolism of diclofenac-β-cyclodextrin, but not that of sulfasalazine. The latter's degradation is much faster than that of diclofenac-β-cyclodextrin while the metabolism of both prodrugs is faster in colonic (versus caecal) contents. Fasting results in most rapid degradation of diclofenac-β-cyclodextrin, possibly due to lack of competition (absence of food) for microbial enzymatic activity