Encapsulation of Satureja montana essential oil in β-cyclodextrin

Inclusion complexes between the Satureja montana essential oil and β-cyclodextrin were prepared by co-precipitation method with the four oil to β-cyclodextrin ratios of 5:95, 10:90, 15:85 and 20:80 (w/w) in order to determine the effect of the ratio on the inclusion efficiency of β-cyclodextrin for encapsulating oil volatiles. The characterization of the complex involved the analysis of the initial essential oil, the surface and the total extracted oils. The retention of essential oil volatiles reached a maximum of 93.15 % at the oil to β-cyclodextrin ratio of 15:85. Though, the maximum inclusion efficiency of β-cyclodextrin was achieved at the ratio of 20:80. The qualitative and quantitative composition of the volatiles in the total oil extracts was similar to the starting oil which is confirmed the high inhibition zone as antifungal and high antioxidant properties after encapsulation to β-cyclodextrin. This justifies the use of β-cyclodextrin as complexion agent for S. montana essential oil in the food and pharmaceutical industries.     

Encapsulation of quercetin in β-cyclodextrin and (2-hydroxypropyl)-β-cyclodextrin cavity: In-vitro cytotoxic evaluation

The formation of host-guest inclusion complex of Quercetin (QRC) with β-Cyclodextrin (β-CD) and (2-Hydroxypropyl)-β-Cyclodextrin (HP-β-CD) is prepared by various methods such as physical method (PM), kneading method (KM) and co-precipitation method (CP). The solid inclusion complex is characterized by UV, Fluorescence, FT-IR, SEM, powder XRD and TG/DTA analysis. The cytotoxic activity of the solid complex is performed against breast cancer cell line and it is noticed that there is better activity than the QRC alone. Hence, the solid complex showed an improvement in the anticancer activity against MDA MB 231 cell line.     

Complexes of copper(II) with the β-blocker atenolol

Mono- and binuclear copper(II) complexes with atenolol (HAt) can be obtained, depending on the reaction conditions. The mononuclear violet complex cation has the general formula Cu(HAt)₄ ²⁺ with an elongated octahedral geometry. The two ligands in the equatorial plane are bound in a bidentate fashion through the hydroxyl oxygen and amino nitrogen, while the other two atenolol molecules in axial position are coordinated in a monodentate way. The binuclear green complex Cu₂At₂Cl₂, is neutral, where atenolol acts as a bidentate (O^–, NH) bridging ligand. The bridge between the two Cu atoms is realized by the deprotonated oxygen of the alcohol group.     

Complexes of β-cyclodextrin with chloronitrobenzenes and with solvents in water + organic solvent mixtures

Inclusion complexes of chloronitrobenzenes with -cyclodextrin in aqueous 0.1 M phosphate buffer solutions containing various concentrations of ethanol, dimethylsulfoxide, dimethylformamide, acetone and acetonitrile have been studied by a polarographic method. The diffusion coefficients and the stability constants of the corresponding complexes have been determined. Using an equation derived by us which takes account of the change in the cyclodextrin concentration due to the simultaneous complexation of the solvent, both stability constants have been calculated. The influence of solvent on the stability constant of chloronitrobenzenes is discussed     

Synthesis and Thermal Rearrangement of Tetramethyldisilane-bridged Bis(cyclopentadienyl) Diiron Complexes with Bis(phosphine)Substitution

Photolysis of [Me2SiSiMe2)[C5H4Fe(CO2)]2with a series of bis(phosphine)ligands Ph2P(CH2)n PPh2(n=1-4) leads to the formation of the corresponding diiron complexes with intramolecular and intermolecular bis(phosphine) substitution.When these complexes were heated in refluxing xylene.only in the complexes with intermolecular bis(phosphine )substitution the thermal rearrangement reaction occurred.     

Complexation of ebastine with β-cyclodextrin derivatives

Complexation of ebastine (EB) with hydroxypropyl and methyl-β-cyclodextrin (HP-β-CD and Me-β-CD) was studied in aqueous solutions and in the solid state. The formation of inclusion complexes in aqueous solutions was analysed by the solubility method. The assays were designed using low CD concentrations compared with the solubility of these derivatives in order to avoid non-inclusion phenomena and to obtain a linear increase in EB solubility as a function of CD concentration. The values of complexation efficiency for HP-β-CD and Me-β-CD were 1.9 × 10^?2 and 2.1 × 10^?2, respectively. It seems that the non polar character of the methyl moiety slightly favoured complexation. In relation to solid state complexation, 1:1 EB:CD systems were prepared by kneading, and by heating a drug-CD mixture at 90 ºC. They were analysed using X ray diffraction analysis by comparison with their respective physical mixtures. A complex with a characteristic diffraction pattern similar to that of the channel structure of β-CD was formed with Me-β-CD in 1:1 melted and 1:2 EB:CD kneaded systems. Complexation with HP-β-CD was not clearly evidenced because only a slight reduction of drug crystallinity was detected. Finally, the loading of EB in two β-CD polymers cross-linked with epichlorohydrin yielded 7.3 and 7.7 mg of EB/g polymer respectively.     

Dissolution enhancement of artemisinin with β-cyclodextrin

The main objective of this research is to improve the dissolution rate of artemisinin (ART) by fabrication with β-cyclodextrin (β-CD) as a hydrophilic carrier. Artemisinin nanoparticles and ART/β-CD complexes were successfully fabricated by means of evaporative precipitation of nanosuspension. Characterization of the samples was done by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and dissolution tester. Percent dissolution efficiency, mean dissolution time, relative dissolution and similarity factor were calculated for the statistical analysis of dissolution data. FT-IR showed some interaction between ART and β-CD, which can be due to the formation of some ART/β-CD complexes. XRD study indicated the presence of two polymorphs of ART, i.e. orthorhombic and triclinic form. Original ART particles and ART nanoparticles fabricated were orthorhombic whereas the free ART in the ART/β-CD complexes (not forming complex with β-CD) was of triclinic form. The crystallinity of ART reduced and more and more ART/β-CD complexes were formed with increasing concentration of β-CD as indicated by the DSC, XRD and FT-IR studies. Artemisinin nanoparticles and ART/β-CD complexes showed significantly faster dissolution than the pure drug due to smaller size (larger surface area), formation of the inclusion complex with β-CD, formation of the triclinic form for remaining free ART (not forming complex with β-CD), and amorphous state formation. Evaporative precipitation of nanosuspension was able to successfully fabricate artemisinin in the nanoparticles and complex forms with significantly faster dissolution rates than that of the original artemisinin. The two polymorphic forms of ART were also fabricated and studied.     

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.     

Reactions of Chalcogenide β-Diiminate Nickel Complexes with Samarium Bis(pentamethylcyclopentadienide)

The reactions of [(L^iPrNi)₂(μ-η²:η²-S₄)] (I) and [(L^iPrNi)₂(μ-η²:η²-Se₂)] (II) (L^iPr = CH[C(Me)N(2,6- ⁱ Pr₂C₆H₃)]₂) with decamethylsamarocene [Sm(Cp*)₂(Тhf)₂] (Cp* = η⁵-C₅Me₅) are studied. It is assumed that the reactions afford hetero-d/f-metal complexes. However, these complexes are not observed but the transfer of chalcogens from Ni to Sm and the formation of [(Sm(Cp*)₂(Тhf))₂(μ-S)] (III) and [(Sm(Cp*)₂(Тhf))₂(μ-Se)] (IV) occur. The second reaction products are [(L^iPrNi)₂(μ-η²:η²-S₂)] (V) in the case of sulfur and [(L^iPrNi^I)₂(μ-η⁶:η⁶-C₇H₈)₂] (VI) in the case of selenium. All reaction products have been described previously, but compounds III and V are isolated as new crystalline phase, the structures of which are determined by X-ray diffraction analysis (CIF files CCDC nos. 1559045 (V) and 1559046 (III)).     

pH-dependent complex formation of amino acids with β-cyclodextrin and quaternary ammonium β-cyclodextrin

Stability constants for the complexes of anionic, neutral (zwitterionic) and protonated forms of l- and d-enantiomers of eight amino acids with β-cyclodextrin and the positively charged quaternary ammonium β-cyclodextrin (QA-β-CD, DS?=?3.6?±?0.3) have been determined by spectrophotometric and pH-potentiometric methods. The highest stability constants have been obtained for the aromatic amino acids phenylalanine, tyrosine and tryptophan. Except the dianion of tyrosine and QA-β-CD, values for the anions in the range of 80–120 have been found, the stability constants for the zwitterionic forms are much smaller and complex formation is negligible with the protonated species. In the case of the other amino acids the differences are less pronounced. The results are interpreted in terms of hydrogen bonding, steric effects and electrostatic interactions between the amino acid moiety and the rims of the cyclodextrins, in addition to the inclusion of the side chain, and are supported by ¹H and ¹³C NMR investigations on the systems containing l-phenylalanine and l-tyrosine. The differences between the complex formation constants of the l- and d-enantiomers do not exceed the limits of experimental error in most cases.     

Freeze-Dried Complexes of Furosemide with β-Cyclodextrin Derivatives

A freeze-drying method was used to prepare complexes of furosemide (guest) with three derivatives of -cyclodextrin (hosts) in different molecular ratios in order to increase the aqueous solubility and rate of dissolution of the drug, and also to study the influence of this method on different parameters of the guest and the host, such as the diffusion rate constant and the partition coefficient, and additionally the surface tension activity of the host (if any). The hosts were found to have significant, increasing effects on the solubility and the rate of dissolution of furosemide. X-ray diffraction confirmed the host–guest interaction, in support of the earlier results. The freeze-drying method increased the diffusion rate of the drug in complex form, while the partition coefficient varied with the type of -cyclodextrin in the product. It is well known that CD derivatives are highly surface active which gives rise to their hemolytic action. Our observations showed that their presence with furosemide in complex form might decrease (if not diminish) the hemolytic action.     

Inclusion complexes of β-cyclodextrin with dihydroxyphenols of various nature

The ways for the practical preparation of stable inclusion complexes of β-cyclodextrin with dihydroxyphenols of various nature are developed. Mutual orientation of hydroxy groups and the nature of the bridge in the bisphenols are shown to affect considerably their ability to the complex formation.     

Supramolecular assemblies of Al3+ complexes with vitamin D3 (cholecalciferol) and phenothiazine. Encapsulation and complexation studies in β-cyclodextrin

Ternary assemblies of β-cyclodextrin with cholecalciferol (or vitamin D₃) or phenothiazine and Al³⁺ ions were studied. The stability constants of aluminium binary complexes with cholecalciferol or phenothiazine and of ternary assemblies (β-cyclodextrin, cholecalciferol or phenothiazine and Al³⁺) were determined using potentiometric titrations at 25 °C (I = 0.100 M). The ¹³C NMR spectra of the supramolecular structures in the solid state showed that ternary supramolecular structures associating β-cyclodextrin, cholecalciferol or phenothiazine and aluminium(III) ions were obtained. Finally, X-ray powder diffraction patterns showed that the ternary assemblies with phenothiazine are channel type inclusion complexes.     

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.     

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.     

Six-Nuclear Complexes of Platinum(II) and Palladium(II) with Mercamine and β-Mercaptoethanol

The platinum(II) and palladium(II) complexes [Pt₆(SCH₂CH₂NH₂)₈]Cl₄ and [Pd₆(SCH₂CH₂OH)₈ Cl₄· 5H₂O with mercamine and β-mercaptoethanol, respectively, were synthesized. It was found on the basis of the comparison of IR and X-ray electron spectra of the ligands and complexes, and also of the data of X-ray diffraction analysis that the bidentate coordination of ligands through sulfur and nitrogen atoms is realized in the platinum(II) complex. In the palladium(II) complex β-mercaptoethanol is coordinated in a mixed-mode type. In both complexes sulfur atoms of the ligands occupy a bridging position.     

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.     

Encapsulation of β-cyclodextrin by in situ polymerization with vinyl chloride leading to suppressing the migration of endocrine disrupting phthalate plasticizer

We performed the encapsulation of β-cyclodextrin (β-CD) in PVC by in situ polymerization with vinyl chloride monomer (VCM), and investigated the effect of CD encapsulation on the suppression of dioctyl phthalate (DOP) migration suspected as endocrine disruptor. β-CD was partially modified with 3-(methacryloxy)propyl trimethoxysilane and modified β-CD (MCD) was then encapsulated in PVC through suspension polymerization via radical reaction between double bonds MCD and VCM. Resulting MCD-encapsulated PVC (MCD_x-PVC) exhibited the similar morphology and characteristics to commercial PVC. For MCD_x-PVCs plasticized with DOP, they showed the considerably suppressed DOP migration as well as the similar optical and mechanical properties to conventionally plasticized PVC. In particular, the plasticized MCD_x-PVCs exhibited the superior suppression of DOP migration compared to the plasticized PVC where MCD and DOP were introduced by conventional melt mixing. Therefore, the encapsulation of MCD in PVC is thought to be an effective approach to producing the ecological PVC material.     

Studies on Inclusion Complexes of Felodipine with β-Cyclodextrin

The inclusion behaviour of -cyclodextrin(-CD) with felodipine (FL) as a guest moleculewas studied. Inclusion complexes were obtained by thekneading method in a binary or ternary system with anaddition of polyethylene glycol 6000. Formation ofinclusion complexes was studied by IR spectroscopy,differential scanning calorimetry (DSC), and¹³C-NMR. It has been shown that an aromaticphenyl ring was involved in the process ofcomplexation, and that in the solid clathrates thesolubility of FL increased two fold when compared tothe physical mixture, while it increased 10 fold inliquid three-component complexes. Moreover, thephotochemical stability of felodipine was studied inits crystalline form and in the inclusion complexeswith -CD. Quantitative assessment of thefelodipine photochemical decomposition was made on thebasis of the rate constants of decomposition (k) inthe first order kinetic reaction, half life time(t_0.5) and the time of decomposition of 10% of thecompound (t_0.1). It was shown that complexationof FL with -CD causes a two fold increase ofthe rate of the photodegradation process.     

Selective Activation of Ar–Cl and Ar–C Bonds with Iron(II) Complexes

The electrophilic iron–carbene chelate complexes 1 and 2 react with alkoxides RO⁻ to give the neutral chelate complex 3 and the carbene complex 4 , respectively. Depending on the nature of the chelating ortho substituent, selective activation of the Ar–Cl or Ar–C bond occurs; these processes are promoted by the chelation.