- Photoreactive nanomatrix structure formed by graft-copolymerization of 1,9-nonandiol dimethacrylate onto natural rubber
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Formation of photoreactive nanomatrix structure was investigated by graft-copolymerization of an inclusion complex of 1,9-nonandiol dimethacrylate (NDMA) with β-cyclodextrin (β-CD) onto natural rubber particle using potassium persulfate (KPS), iert-butyl hydroperoxide/tetraethylenepentamine (TBHPO/TEPA), cumene hydroperoxide/tetraethylenepentamine (CHPO/TEPA), and benzoyl peroxide (BPO) as an initiator. The graft copolymer was characterized by 1H NMR and FTlR after coagulation. The conversion of NDMA and the amount of residual methacryloyl group were found to be 58.5 w/w % and 1.81 w/w %, respectively, under the suitable condi tion of the graft-copolymerization. The morphology of the film specimen, prepared from the graft copolymer, was observed by transmission electron microscopy (TEM) after staining the film with OsO4. Natural rubber particle of about 1.0 μm in diameter was dispersed in poly(NDMA) matrix of about 10 nm in thickness.
- Yamamoto, Yoshimasa,Suksawad, Patjaree,Pukkate, Nanthaporn,Horimai, Tatsuya,Wakisaka, Osamu,Kawahara, Sciichi
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- Effect of the reaction temperature on the transglycosylation reactions catalyzed by the cyclodextrin glucanotransferase from Bacillus macerans for the synthesis of large-ring cyclodextrins
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The synthesis of cyclodextrins with from 6 to more than 50 glucose units by cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) from Bacillus macerans was investigated. Analysis of the synthesized cyclic α-1,4-glucan products showed that a higher yield of large-ring cyclodextrins were obtained with a reaction temperature of 60°C compared to 40°C. The yield of large-ring cyclodextrins obtained at 60°C represented about 50% of the total glucans employed in the reaction. Analysis of the cyclodextrin-forming cyclization reaction and of the coupling reaction of the CGTase resulting in the degradation of mainly the larger cyclic α-1,4-glucans indicated higher rates of the cyclization reaction at 60°C compared to 40°C while the opposite was found for the coupling reaction.
- Qi, Qingsheng,She, Xiaoyan,Endo, Tomohiro,Zimmermann, Wolfgang
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- Water-soluble inclusion complexes of trans-polydatin by cyclodextrin complexation: Preparation, characterization and bioactivity evaluation
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The inclusion complexes of trans-polydatin (PD) with β-CD and γ-CD were prepared. The inclusion complexation behavior, characterization and interactions of PD with CDs were investigated in both the solution and the solid state by means of UV-vis, ESI-MS, NMR, FT-IR, XRD, SEM, TG and DSC. All of the characterization information demonstrated the formation of PD/CDs inclusion complex, and the PD/CDs inclusion complexes exhibited different spectroscopic features and properties from PD. The 1:1 stoichiometry of the complexes was visually proven with the ESI-MS experiment and Job's method. Meanwhile, it was the phenyl group (a and b rings) of the PD molecule that were included in the CDs cavity from the wide side. Moreover, the water solubility of PD/CDs was significantly improved from 0.161 mg/mL to 7.21 mg/mL (PD/β-CD) and 12.02 mg/mL (PD/γ-CD). Consequently, the bioavailability of PD/CDs inclusion complexes were effectively improved over free PD in vitro. The present study provides useful information for the potential application of complexation with PD, a naturally occurring hydrophobic polyphenolic compounds herbal medicine.
- Zhang, Jian-Qiang,Jiang, Kun-Ming,Xie, Xiao-Guang,Jin, Yi,Lin, Jun
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- Photochromism of dithienylethenes included in cyclodextrins
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The effect of inclusion of diarylethenes in cyclodextrin cavities on cyclization quantum yields and on circular dichroism (CD) spectral changes by photoirradiation was studied. The addition of β-and γ-cyclodextrins to an aqueous solution of the open-ring form of 2,2'-dimethyl-3,3'-(perfluoro- cyclopentene-1,2-diyl)bis(benzo[b]thiophene-6-sulfonate) (1a) increased the ratio of the antiparallel conformation. The enrichment of antiparallel conformation caused an increase in the photocyclization quantum yield of 1a. The CD spectral intensity of the mixtures of 1a or 2,2'4,4'-tetramethyl- 3,3'-(perfluorocyclopentene-1,2-dyl)bis(thiophen-5-yl-(phenyl-4-sulfonate)) (2a) and cyclodextrins in aqueous solution increased with the increasing concentration of cyclodextrins. The induced CD spectrum of 1 in β- cyclodextrin reversibly changed from negative to positive by UV irradiation. The spectral change was attributed to the change in the direction of transition moment of 1 in the cavity.
- Takeshita, Michinori,Kato, Nobuo,Kawauchi, Susumu,Imase, Tatsuya,Watanabe, Junji,Irie, Masahiro
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- A general method for the synthesis of cyclodextrinyl aldehydes and carboxylic acids
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The selective synthesis of the primary-side monoaldehyde of β-cyclodextrin, 6-deoxy-6-formyl-β-cyclodextrin, was accomplished by oxidation of the corresponding tosylate utilizing the Nace reaction (DMSO/collidine). This monoaldehyde was then used as the starting material in several reactions including reduction, addition of NaHSO3, addition of the α-nucleophiles hydroxylamine and hydrazine, and reductive amination. Of particular interest is the conversion of the monoaldehyde to the primary side carboxylic acid, 6-deoxy-6-carboxy-β-cyclodextrin, via bromine oxidation. This general method sequence can be applied to any tosyl derivative of cyclodextrin as demonstrated in the synthesis of β-cyclodextrin-A,D-dialdehyde and β-cyclodextrin-A,D-diacid.
- Yoon,Hong,Martin,Czarnik
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- Characterization of cyclodextrin glycosyltransferase immobilized on silica microspheres via aminopropyltrimethoxysilane as a spacer arm
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In this work, the enzymatic properties of immobilized cyclodextrin glycosyltransferase (CGTase) of Thermoanaerobacter sp. were investigated and compared with the soluble form of the enzyme. CGTase was immobilized on mesoporous silica microspheres synthesized using polyethylene glycol 400 as swelling agent, silanized with 3-aminopropyltrimethoxysilane (APTMS), and activated with glutaraldehyde prior to immobilization. This innovative approach for support preparation produced high yields of immobilization (83%) and activity recoveries (73%), which are the highest so far reported for CGTase. The soluble enzyme (CGTase) and its immobilized form (ImCGTase) showed similar values for the optimal pH activity, while optimal reaction temperatures were found to be 100 °C and 80 °C, respectively. The immobilized enzyme showed similar values for Km and thermal stabilities with the soluble form, while its Vmax was lower. The immobilized enzyme was tested in repeated batches in order to simulate recovery and reuse, keeping about 60% of the initial catalytic activity after 15 cycles, showing its good chemical and mechanical resistance.
- Matte, Carla Roberta,Nunes, Michael Ramos,Benvenutti, Edilson Valmir,Schoeffer, Jessie Da Natividade,Ayub, Marco Antonio Zachia,Hertz, Plinho Francisco
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- Host - Guest interactions of 4-carboxyphenoxy phthalocyanines and β-cyclodextrins in aqueous media
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β-Cyclodextrin and its permethylated derivatives form 2:1 inclusion complexes with tetrakis- and octakis(4-carboxyphenoxy)phthalocyanines 1-4, reducing their aggregation tendency and promoting their sensitization of singlet oxygen formation in aqueous media.
- Leng, Xuebing,Choi, Chi-Fung,Luo, Hai-Bin,Cheng, Yuen-Kit,Ng, Dennis K. P.
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- Preservation of Bacillus firmus strain 37 and optimization of cyclodextrin biosynthesis by cells immobilized on loofa sponge
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The preservation of Bacillus firmus strain 37 cells by lyophilization was evaluated and response surface methodology (RSM) was used to optimize the β-cyclodextrin (β-CD) production by cells immobilized on loofa sponge. Interactions were studied with the variables temperature, pH and dextrin concentration using a central composite design (CCD). Immobilization time influence on β-CD production was also investigated. B. firmus strain 37 cells remained viable after one year of storage, showing that the lyophilization is a suitable method for preservation of the microorganism. From the three-dimensional diagrams and contour plots, the best conditions for β-CD production were determined: temperature 60 °C, pH 8, and 18% dextrin. Considering that the amount of dextrin was high, a new assay was carried out, in which dextrin concentrations of 10, 15, and 18% were tested and the temperature of 60 °C and pH 8 were maintained. The results achieved showed very small differences and therefore, for economic reasons, the use of 10% dextrin is suggested. Increasing the immobilization time of cells immobilized on synthetic sponge the β-CD production decreased and did not change for cells immobilized on loofa sponge. The results of this research are important for microorganism preservation and essential in the optimization of the biosynthesis of CD.
- Pazzetto, Rubia,De Souza Ferreira, Sabrina Barbosa,Santos, Elder James Silva,Moriwaki, Cristiane,Guedes, Teresinha Aparecida,Matioli, Graciette
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- An NMR study of cyclodextrin complexes of the steroidal neuromuscular blocker drug Rocuronium Bromide
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The interaction of Rocuronium Bromide, anda model steroid Org 7402, with three cyclodextrins (β-cyclodextrin, γ-cyclodextrin and Org 25969) was studied by solution state NMR experiments. Stoichiometries and binding constants were determined from 1/s
- Cameron, Kenneth S.,Fletcher, Dan,Fielding, Lee
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- Chiral recognition for the complexation dynamics of β-cyclodextrin with the enantiomers of 2-naphthyl-1-ethanol
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The focus of this study is to understand the origin of the chiral recognition for a host-guest system containing complexes with different stoichiometries. Each enantiomer of 2-naphthyl-1-ethanol forms two different 1:1 complexes with β-cyclodextrin, leading to the formation of three different 2:2 complexes. One of these 2:2 complexes leads to excimer emission of the guest. Fluorescence studies were employed to determine the binding isotherms for the 1:1 and 2:2 complexes. No chiral discrimination was directly observed for the formation of the 1:1 complexes, while higher equilibrium constants (29% from binding isotherms and 40% from kinetic studies) were observed for the formation of the 2:2 complexes with (R)-2-naphthyl-1-ethanol when compared to the formation of the 2:2 complexes formed from (S)-2-naphthyl-1-ethanol. The relaxation kinetics was studied using stopped-flow experiments. The formation of the 2:2 complexes was followed by detecting the excimer emission from one of the 2:2 complexes. The relaxation kinetics was faster for (S)-2-naphthyl-1- ethanol, where a higher dissociation rate constant, by 47%, was observed, suggesting that the chiral discrimination occurs because the interaction between two cyclodextrins is more favorable for the complexes containing (R)-2-naphthyl-1-ethanol when compared to (S)-2-naphthyl-1-ethanol. The same overall equilibrium constants were observed for the 1:1 complexes with both enantiomers showing that at a given cyclodextrin concentration the sum of the two types of 1:1 complexes is the same for both enantiomers. However, analysis of the binding isotherms indicates that the ratio between the two different 1:1 complexes for each enantiomer was different for (R)- and (S)-2-naphthyl-1- ethanol. The Royal Society of Chemistry and Owner Societies.
- Tang, Hao,Sutherland, Andria S. M.,Osusky, Lana M.,Li, Yan,Holzwarth, Josef F.,Bohne, Cornelia
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- Photoreversible [2] Catenane via the Host-Guest Interactions between a Palladium Metallacycle and β-Cyclodextrin
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We report the efficient preparation of an A2D2 (A = acceptor and D = donor) metallacycle 2 = [(en)2Pd2(1)2](NO3)4, using the coordination driven self-assembly of trans-azobenzene based bispyridyl ligand 1 and (en)Pd(NO3)2 (en = ethylenediamine). In the metallacycle, the trans-azobenzene units serve both as a structural element and as sites for subsequent host-guest chemistry with β-cyclodextrin, leading to the formation of a [2] catenane 3. This catenation process is reversible and can be switched off and on in a photocontrollable manner via the trans-cis isomerization of the azobenzene units.
- Zhang, Dengqing,Nie, Yong,Saha, Manik Lal,He, Zuoli,Jiang, Long,Zhou, Zhixuan,Stang, Peter J.
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- DIBAL-H mediated triple and quadruple debenzylations of perbenzylated cyclodextrins
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Diisobutylaluminium hydride (DIBAL-H) mediated reductive removal of benzyl groups was investigated for perbenzylated α-, β- and γ-cyclodextrins using DIBAL-H in hexane as the reagent. It was found that under the new conditions, the debenzylation can be better controlled to provide sequentially tri- and tetra-debenzylated products in moderate yields and in a regioselective manner. In the case of α-cyclodextrin, the removal of the third and fourth benzyl groups took a different path involving the secondary rim, compared to β- and γ-cyclodextrins which both gave only 6-O-debenzylated products. The Royal Society of Chemistry 2010.
- Rawal, Girish K.,Rani, Shikha,Ward, Sandra,Ling, Chang-Chun
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- Study of electron transfer reactions associated with benzyl viologen-β-cyclodextrin complexation in buffer solution of pH 7: Equilibrium and kinetic aspects
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In this study, complex formation of benzyl viologen dication (BzV2+) with β-cyclodextrin (β-CD), in its different oxidation states, had been studied in buffer solution of pH 7, through cyclic voltammetry. In buffer solution of pH 7, extensive d
- Perveen, Shazia,Naqvi, Iftikhar Imam,Masood, Summyia
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p. 1981 - 1985
(2020/09/02)
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- Preparation of α-hydroxyphenylacetic acid with cyclodextrins as an effective phase-transfer catalyst and its reaction mechanism
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An effective procedure for the synthesis of α-hydroxyphenylacetic acid with cyclodextrin (CD) catalysts was developed. The phase-transfer catalyst types, catalyst loadings, reaction times, reaction temperatures, and substrate molar ratios were investigated to optimize the reaction conditions. In addition, the factors that affect the reaction were studied, and the relationship between benzaldehyde and β-cyclodextrin (β-CD) was analyzed through 2D-ROESY. The equilibrium constant when β-CD was used as the catalyst was calculated. The results indicated that β-CD is the optimal catalyst for the reported reaction (yield: 69.08%). Furthermore, the mechanism underlying the reported reaction was proposed.
- Tian, Bing Ren,Zhang, Rui Xia,Chu, Hui Min,Huang, Qing,Wang, Zhi Zhong
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p. 359 - 368
(2019/05/16)
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- Enzyme-mediated dynamic combinatorial chemistry allows out-of-equilibrium template-directed synthesis of macrocyclic oligosaccharides
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We show that the outcome of enzymatic reactions can be manipulated and controlled by using artificial template molecules to direct the self-assembly of specific products in an enzyme-mediated dynamic system. Specifically, we utilize a glycosyltransferase to generate a complex dynamic mixture of interconverting linear and macrocyclic α-1,4-d-glucans (cyclodextrins). We find that the native cyclodextrins (α, β and γ) are formed out-of-equilibrium as part of a kinetically trapped subsystem, that surprisingly operates transiently like a Dynamic Combinatorial Library (DCL) under thermodynamic control. By addition of different templates, we can promote the synthesis of each of the native cyclodextrins with 89-99% selectivity, or alternatively, we can amplify the synthesis of unusual large-ring cyclodextrins (δ and ?) with 9 and 10 glucose units per macrocycle. In the absence of templates, the transient DCL lasts less than a day, and cyclodextrins convert rapidly to short maltooligosaccharides. Templates stabilize the kinetically trapped subsystem enabling robust selective synthesis of cyclodextrins, as demonstrated by the high-yielding sequential interconversion of cyclodextrins in a single reaction vessel. Our results show that given the right balance between thermodynamic and kinetic control, templates can direct out-of-equilibrium self-assembly, and be used to manipulate enzymatic transformations to favor specific and/or alternative products to those selected in Nature.
- Larsen, Dennis,Beeren, Sophie R.
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p. 9981 - 9987
(2019/11/14)
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- Direct regioselective esterification at O-2 of β- Cyclodextrin and hydrolysis by neighboring-group participation
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A simple and efficient strategy for direct regioselective esterification at O-2 of β-cyclodextrin was developed by using the combination of N,N?-carbonyldiimidazole and carbonate buffer in 1,4-dioxane, which does not require large amounts of polar organic solvents such as DMF, toxic solvents such as CH3CN, or flammable bases such as NaH. Moreover, their hydrolyses by neighboring-group participation were observed. Mono-2-tosyl- β-cyclodextrin was liable to epoxidation, while mono-2-(p-methylbenzoyl)- β- cyclodextrin liable to isomerization. They had different mechanisms of hydrolysis.
- Wang, Zhi-Zhong,Ma, Xuan-Ping,Wei, Xiao-Gang
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scheme or table
p. 1562 - 1568
(2012/05/21)
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- A novel cyclodextrin glucanotransferase from alkaliphilic Bacillus pseudalcaliphilus 20RF: Purification and properties
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A new cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) from the obligated alkaliphile Bacillus pseudalcaliphilus 20RF, isolated from Bulgarian soils, was purified up to 18-fold by ultrafiltration and starch adsorption with a recovery of 63% activity. The enzyme was a monomer with a molecular weight 70 kDa estimated by SDS-PAGE. The CGTase exhibited two pH optima at pH 6.0 and 9.0 and was optimally active at 60 °C. The enzyme could be effectively used for conversion of raw starch into cyclodextrins (CDs) in a wide pH range, from 5.0 to 10.0 and temperatures 60-70 °C. The enzyme was more heat resistant after its pretreatment in alkaline pH 9.0 at high temperatures 65-70 °C, than at pH 6.0 under the same reaction conditions. The CGTase showed a significant stability in the presence of 15 mM various metal ions and reagents after 30 min incubation at 25 °C. The purified CGTase could be used for an efficient cyclodextrin production without any additives which is of an industrial interest. The achieved high conversion of an insoluble raw commercial corn starch into cyclodextrins (47%) with production of only two types of cyclodextrins, β- and γ-CD (80%:20%) in alkaline pH 9.0, makes B. pseudalcaliphilus 20RF CGTase industrially desired for cyclodextrin manufacture.
- Atanasova, Nikolina,Kitayska, Tsvetina,Bojadjieva, Ivanka,Yankov, Dragomir,Tonkova, Alexandra
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experimental part
p. 116 - 122
(2011/08/09)
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- Investigation on the inclusion behaviour of baicalein with β-cyclodextrin and derivatives and their antioxidant ability study
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The formation of the complexes of baicalein (Ba) with β-cyclodextrin (β-CD) and β-CD derivatives (HP-β-CD and Me-β- CD) was studied by UV-vis absorption spectroscopy, fluorescence method, nuclear magnetic resonance spectroscopy and phase-solubility measurement. The solid-inclusion complexes of Ba with CDs were synthesised by the co-precipitation method. The characterisations of the solid-inclusion complexes have been proved by infrared spectra and differential scanning calorimetry. Experimental conditions including the concentration of various CDs and media acidity were investigated in detail. The results suggested that the inclusion ratio of HP-β-CD with Ba was the highest among the three kinds of CDs. The binding constants (Ks) of the inclusion complexes were determined by fluorescence method and phasesolubility measurement. Kinetic studies of DPPHz with Ba and CDs complexes were also done. The results indicated that the Ba/HP-β-CD complex was the most reactive form.
- Chao, Jianbin,Su, Jian,Li, Jinxia,Zhao, Wei,Huang, Shuping,Du, Rui
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experimental part
p. 644 - 653
(2012/03/27)
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- INCLUSION COMPLEX OF SIBUTRAMINE AND BETA-CYCLODEXTRIN
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The present invention relates to a sibutramine-containing inclusion complex having superior storage stability, and particularly to a pharmaceutically stable inclusion complex suitable for the drug formulation, which prepared by reacting a sibutramine (N,N-dimethyl-1-[1-(4-chlorophenyl)-cyclobutyl]-3-methylbutylamine) of Formula 1 and beta-cyclodextrin in a predetermined ratio, its preparation method and a pharmaceutical composition comprising the same.
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- Supramolecular chemistry of pyronines B and Y, β-cyclodextrin and linked β-cyclodextrin dimers
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The complexation of cationic pyronine B(PB+) and pyronine Y(PY+) by β-cyclodextrin (CD) and two linked βCD dimers, N,N′-bis((2AS,3AS)-3A-deoxy-β- cyclodextrin-3A-yl)succinamide, 33βCD2
- Ngo, Huy T.,Clements, Philip,Easton, Christopher J.,Pham, Duc-Truc,Lincoln, Stephen F.
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experimental part
p. 687 - 692
(2010/08/22)
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- Fluorimetric and prototropic studies on the inclusion complexation of 3,3′-diaminodiphenylsulphone with β-cyclodextrin and its unusual behavior
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The photophysical and photoprototropic properties of 3,3′- diaminodiphenylsulphone (3DADPS) in aqueous β-cyclodextrin (β-CDx) solution have been investigated using absorption and fluorescence spectral techniques. β-CDx forms 1:1 inclusion complex with 3DA
- Enoch, Muthu Vijayan,Rajamohan, Rajaram,Swaminathan, Meenakshisundaram
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body text
p. 473 - 477
(2010/12/19)
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- Electrochemical investigations into host-guest interactions of a natural antioxidant compound with β-cyclodextrin
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The electrochemical behavior of mangiferin (MGN), a natural antioxidant compound, is examined using cyclic and differential pulse voltammetry in a protic medium on a glassy carbon electrode. The voltammograms exhibit a single irreversible pH-dependent anodic wave with current controlled by adsorption. Complexes of MGN with β-cyclodextrin (β-CD) were prepared and their formation was confirmed by UV-vis spectroscopy and electrochemical experiments, using a self-assembled monolayer of cyclodextrin on a gold electrode. The association constant of MGN:β-CD complexes was estimated by the Benesi-Hildebrand method, based on the spectrophotometric quantification of free β-CD and by the direct method using cyclic voltammetry and the Langmuir isotherm. PM IRRAS experiments corroborated the inclusion process based on the observation of the corresponding peaks in the spectra of the samples. MGN was quantified using a simple electrochemical method based on a β-CD incorporated carbon nanotube (CNT)-modified electrode (β-CDCNT). The presence of β-CD led to a 10-fold lower detection limit than that obtained with a CNT-modified electrode.
- Ferreira, Fabricia Da Rocha,Da Silva, Emanuella Gomes,De Leo, Lucila P. Méndez,Calvo, Ernesto J.,Bento, Edson De Souza,Goulart, Marília Oliveira Fonseca,De Abreu, Fabiane Caxico
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experimental part
p. 797 - 803
(2011/03/19)
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- Azonium-ammonium tautomerism and inclusion complexation of 4-amino-2', 3-dimethylazobenzene
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The spectral characteristics of 4-amino-2',3-dimethylazobenzene (GBC), 4-aminoazobenzene (AAB) and azobenzene (AB) have been studied in various solvents, varying hydrogen ion concentrations and in β-cyclodextrin (β-CD). The inclusion complexes of GBC, AAB and AB with β-CD have been analysed by UV-visible, fiuorometry, FT-IR,1H NMR, SEM and Cache-DFT methods. The solvent study shows that the azo form is present only in GBC and AAB molecules. No significant spectral difference is observed in GBC indicating that the presence of two methyl groups does not effectively change the spectral behaviour as compared to that of AAB. In acid solutions, unusual red shift is observed in the monocation suggesting that the azonium-ammonium tautomer is present in both molecules. The absorption maximum at ～500 nm, is due to the azonium cation while that at ～320 nm originates from the ammonium cation. In β-CD solutions, the increase in the fluorescence intensity and large bathochromic shift in S1 state indicates that both GBC and AAB form 2:2 inclusion complex, whereas AB forms 1:1 inclusion complex. Also, head-to-head dimer is formed in both the aminoazobenzene compounds.
- Prabhu, A. Antony Muthu,Venkatesh,Sankaranarayanan,Siva,Rajendiran
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experimental part
p. 407 - 417
(2011/01/09)
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- Altered product specificity of a cyclodextrin glycosyltransferase by molecular imprinting with cyclomaltododecaose
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Cyclodextrin glycosyltransferases (CGTases), members of glycoside hydrolase family 13, catalyze the conversion of amylose to cyclodextrins (CDs), circular α-(1,4)-linked glucopyranose oligosaccharides of different ring sizes. The CD containing 12 α-D-gluc
- Kaulpiboon, Jarunee,Pongsawasdi, Piamsook,Zimmermann, Wolfgang
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experimental part
p. 480 - 485
(2011/12/02)
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- Voltammetric and spectrophotometric study on the complexation of glibenclamide with β-cyclodextrin
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The formation of an inclusion complex of glibenclamide (GL) with β-cyclodextrin (β-CD) in an aqueous ethanolic buffer solution of pH 7.0 has been investigated by UV spectrophotometry and differential pulse voltammetry and its stability constant is determined to be 855 and 354.15 M-1, respectively. The phase solubility profile, based on the spectrophotometric absorbance's variations, was classified as AL-type, indicating the formation of 1:1 stoichiometric inclusion complex of glibenclamide with β-CD with a stability constant value, KS, of 846 M-1.
- Radi, Abd-Elgawad,Eissa, Shimaa
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experimental part
p. 417 - 421
(2012/01/02)
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- Preparation and characterization of the inclusion complex of Baicalin (BG) with β-CD and HP-β-CD in solution: An antioxidant ability study
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The formation of the complexes of BG with β-CD and HP-β-CD was studied by UV-vis absorption spectroscopy, fluorescence spectra, Phase-solubility measurements and nuclear magnetic resonance spectroscopy (NMR) in solution. The formation constants (K) of com
- Li, Jinxia,Zhang, Min,Chao, Jianbin,Shuang, Shaomin
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scheme or table
p. 752 - 756
(2009/09/26)
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- Cyclodextrin-Containing Polymers and Uses Thereof
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The invention provides a cyclodextrin-containing polymer comprising one or more cyclodextrin residues. The polymer is selected from a peptide, a polypeptide, an oligonucleotide or a polynucleotide or a mixture thereof. The peptide or polypeptide has at least one amino acid residue containing a functional side group and at least one of the cyclodextrin residues is covalently linked to the functional side group of the amino acid residue of said peptide or polypeptide or to the sugar moiety of a nucleotide residue of the oligonucleotide or polynucleotide.
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Page/Page column 11
(2008/12/08)
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- Cyclodextrins functionalised with etodolac as specific site release agents
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β-Cyclodextrin was functionalized with (+/-) etodolac through an ester bond, and the two diastereomers were isolated and characterized as molecules with anti-infiammatory or antitumoral activity. The presence of cyclodextrin ensures the specific delivery to the intestine.
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Page/Page column 4-5
(2008/06/13)
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- Effects of ionic surfactants and cyclodextrins on hydride-transfer reaction of l-Benzyl-l,4-dihydronicotinamide with methylene blue
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The kinetics of the hydride-transfer reaction between methylene blue (MB+) and 1 -benzyl-1,4-dihydronictinamide (BNAH) were studied in media containing cyclodextrins (β- and γ-CD) and surfactants (sodium dodecyl sulfate (SDS), dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and hexadecyltrimethylammonium bromide). Cationic surfactants decreased the apparent first-order rate constant (k obsd) above the cmc, while SDS increased kobsd just above the cmc and then decreased kobsd with increasing surfactant concentration. This behavior for cationic surfactants was typical of micellar effects due to a separation of the reactants by the micelles. BNAH associated with micelles, whereas MB+ ions were repelled from the cationic interface of the micelles. Binding of BNAH and MB to the same SDS micelle enhanced the reaction, but dilution of reagents within the micellar interface with the increase in [SDS] caused a decrease in Kobsd. In β-CD-cationic surfactant mixtures, the results were interpreted in terms of the model which takes into account the formation of CD-BNAH, CD-MB+, and CD-surfactant complexes and the association of BNAH with micelles. The decrease in Kobsd with increasing surfactant concentration observed in γ-CD-cationic surfactant mixtures can be explained by the decrease in the concentration of free γ-CD by the formation of 1:1 and 2:1 complexes of surfactant monomer with β-CD.
- Matsumoto, Takeshi,Liu, Yingjin,Sueishi, Yoshimi,Yamamoto, Shunzo
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experimental part
p. 1383 - 1390
(2009/06/19)
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- Optimized synthesis of specific sizes of maltodextrin glycosides by the coupling reactions of Bacillus macerans cyclomaltodextrin glucanyltransferase
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Bacillus macerans cyclomaltodextrin glucanyltransferase (CGTase, EC 2.4.1.19), in reaction with cyclomaltohexaose and methyl α-d- glucopyranoside, methyl β-d-glucopyranoside, phenyl α-d- glucopyranoside, and phenyl β-d-glucopyranoside gave four kinds of maltodextrin glycosides. The reactions were optimized by using different ratios of the individual d-glucopyranosides to cyclomaltohexaose, from 0.5 to 5.0, to obtain the maximum molar percent yields of products, which were from 68.3% to 78.6%, depending on the particular d-glucopyranoside, and also to obtain different maltodextrin chain lengths. The lower ratios of 0.5-1.0 gave a wide range of sizes from d.p. 2-17 and higher. As the molar ratio was increased from 1.0 to 3.0, the larger sizes, d.p. 9-17, decreased, and the small and intermediate sizes, d.p. 2-8, increased; as the molar ratios were increased further from 3.0 to 5.0, the large sizes completely disappeared, the intermediate sizes, d.p. 4-8, decreased, and the small sizes, d.p. 2 and 3 became predominant. A comparison is made with the synthesis of maltodextrins by the reaction of CGTase with different molar ratios of d-glucose to cyclomaltohexaose.
- Yoon, Seung-Heon,Robyt, John F.
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p. 210 - 217
(2007/10/03)
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- Formation of linear polymers with pendant vinyl groups via inclusion complex mediated polymerization of divinyl monomers
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Ethylene glycol dimethacrylate (EGDMA) and ethylene glycol methacrylate 4-vinyl benzoate (EGMAVB) were shown to form 1:1 inclusion complexes with cyclodextrin and were characterized by instrumental techniques. Computational analysis showed that the bent conformation of the included divinyl monomer was more stable than its linear conformation. Complexation of the divinyl monomer with the first CD molecule offered substantial stabilization than with the second CD molecule. The vinyl group included in the CD cavity did not participate in polymerization. As a result, solvent soluble, linear polymers with pendant vinyl unsaturation per repeat unit were obtained. This was unequivocally established by the polymerization of a complex comprising CD and EGMAVB. The unreacted vinyl group can be polymerized in the subsequent step to yield cross-linked products. Copyright
- Satav, Sunita S.,Karmalkar, Rohini N.,Kulkarni, Mohan G.,Mulpuri, Nagaraju,Sastry, G. Narahari
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p. 7752 - 7753
(2007/10/03)
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- A spectroscopic study of the inclusion of azulene by β- And γ-cyclodextrins
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The inclusion of azulene (AZ) inside the cavities of β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) was studied using absorption, fluorescence and induced-circular dichroism spectroscopy. The inclusion of AZ into the cavity of β-CD has a stoichiometry of 1:1, whereas that of AZ/γ-CD complex is 1:2. The equilibrium constants for the formation of the two complexes were calculated to be 780 ± 150 M-1 for AZ:β-CD and (4.5 ± 0.86) × 105 M-2 for AZ:(γ-CD)2. The latter is due to a stepwise equilibrium mechanism in which a 1:1 complex is formed with a binding constant of 775 M -1, followed by the formation of a 1:2 complex with a binding constant of 580 M-1. The difference between the two binding constant values is slight, indicating an almost equal contribution from each of the γ-CD molecules to the overall binding in AZ:(γ-CD)2. From the induced-circular dichroism spectra, the inclusion of AZ was found to be axial in AZ:β-CD and nearly axial in AZ:(γ-CD)2.
- Abou-Zied, Osama K.
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p. 245 - 251
(2007/10/03)
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- Ultrasonic relaxation due to complexation reaction between β-cyclodextrin and alkylammonium ions
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Ultrasonic absorption coefficients in an aqueous solution of propylammonium chloride (PACL) and butylammonium chloride (BACL) (pH ≈ 7.2) were measured in the presence and absence of β-cyclodextrin (β-CD) at 25 °C in the frequency range 0.8-220 MHz. There was no relaxation in the solution of individual alkylammonium chloride or β-CD. Also, in the solution with PACL and β-CD, the relaxation was not observed. However, a single relaxational absorption was found in the solution of BACL when β-CD coexisted. The cause of the relaxation was attributed to a perturbation of a chemical equilibrium associated with an interaction between β-CD and the butylammonium ion from the concentration dependence of the relaxation frequency and the maximum absorption per wavelength. The rate and thermodynamic constants were determined for the association and dissociation reactions of the complex in the system of BACL with β-CD. The results obtained were compared with those for other similar systems, e.g., propionate ion or propionic acid and alcohols with β-CD. It was ascertained that the stability of the complex formed between BACL and β-CD is relatively lower than those between other guests and β-CD.
- Nishikawa, Sadakatsu,Yamaguchi, Kyohei,Fukahori, Takanori
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p. 6415 - 6418
(2007/10/03)
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- Isolation of Paenibacillus illinoisensis that produces cyclodextrin glucanotransferase resistant to organic solvents.
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A bacterium that secreted cyclodextrin glucanotransferase (CGTase) in a medium overlaid with n-hexane was isolated and identified as Paenibacillus illinoisensis strain ST-12 K. The CGTase of the strain was purified from the culture supernatant. The molecular mass was 70 kDa. The enzyme was stable at pH 6 to 10 and active at pH 5.0 to 8.0. The optimum temperature at pH 7.0 was 65 degrees C in the presence of 5 mM CaCl2. The enzyme produced mainly beta-cyclodextrin. The total yield of alpha-, beta-, and gamma- cyclodextrins was increased 1.4-fold by the addition of ethanol. In particular, the yield of beta-cyclodextrins in the presence of 10% (vol/vol) ethanol was 1.6-fold that without ethanol. The CGTase was stable and active in the presence of large amounts of various organic solvents.
- Doukyu, Noriyuki,Kuwahara, Hirokazu,Aono, Rikizo
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p. 334 - 340
(2007/10/03)
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- Thermodynamic study on the effects of β-cyclodextrin inclusion with berberine
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The fluorescence enhancement of berberine (Berb) as a result of complex with β-cyclodextrin (β-CD) is investigated. The association constants of α-CD and β-CD with Berb are 60 and 137 M-1 at 20°C in pH 7.20 aqueous solution. Effects of temperature on the forming inclusion complexes of β-CD with Berb have been examined through using fluorescence titration. Enthalpy and entropy values calculated from fluorescence data are -33.7 kJ·mol-1 and 74.3 J·mol-1·K-1, respectively. It was found that the dielectric constant of β-CD cavity is about 24 in a rough analogy with absolute alcohol. These results suggest that the extrusion of 'high energy water' molecules from the cavity of β-CD and hydrophobic interaction upon the inclusion complex formation are the main forces of the inclusion reaction. Effect of pH on the association of β-CD with Berb was also studied. Mechanism of the inclusion of β-CD with Berb is further studied by absorption and NMR measurements. Results show that β-CD forms a 1:1 inclusion complex with Berb.
- Yu,Wei,Gao,Zhao
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p. 249 - 256
(2007/10/03)
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- Influence of cyclodextrins on the fluorescence of some short and long chain linked flexible bisbenzenes in aqueous solution
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The UV absorption, induced circular dichroism (icd) spectra, steady state and time resolved fluorescence emission of the flexible bisbenzenes 1-4 were obtained in aqueous solution and in presence of α-, β-, and γ-cyclodextrin (CD). Bisbenzenes 1 and 2 in an aqueous environment exhibit a dual emission which is differently affected by the CDs. The long-wavelength emission is quenched by α- and β-CD and enhanced by γ-CD. This is due to the formation of inclusion complexes between the CDs and 1 (2) in the ground state, in agreement with the modifications of the UV spectrum and the appearance of icd signals. On the basis of these effects and of the influence of the CDs on the 1 and 2 lifetimes, the dual emission of these bisbenzenes is attributed to a set of different ground-state conformations.
- Bortolus, Pietro,Monti, Sandra,Smoluch, Miroslawa,Bouas-Laurent, Henri,Desvergne, Jean-Pierre
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p. 1165 - 1171
(2007/10/03)
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- Suitability and limitations of methods for characterisation of activity of malto-oligosaccharide-forming amylases
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The suitability and limitations of essential methods and reference substrates used for characterisation of activity of amylolytic enzymes is investigated. Saccharogenic, chromogenic and chromatographic methods are included. The results are discussed in relation to the measurement of reaction rates, determination of action mode and product specificity and the impact on identification and nomenclature of malto-oligosaccharide-forming amylases. An accurate determination of reaction rates using the saccharogenic methods strongly depends on the degree of polymerisation (DP) of the standards used and the hydrolysis products formed by the amylase. Particularly the use of glucose as standard can lead to overestimates due to the differences in the reducing potential of glucose and malto-oligosaccharides. The reliability of the chromogenic methods for determination of action mode depends on the DP of the substrate and the specificity of the amylase. For a characterisation of the starch hydrolysis products and the variation in the DP during hydrolysis, high performance anion-exchange chromatography with pulsed amperometric detection provided a fast and reliable method. A literature survey revealed varying and inconsistent use of nomenclature of malto-oligosaccharide forming amylases. Therefore a systematic approach identifying three main classes of activity is suggested using not only the mode of action and the DP of the major product but also the stage of hydrolysis at which this product is formed. (C) 2000 Elsevier Science Ltd.
- Duedahl-Olesen, Lene,Haastrup Pedersen, Lars,Lambertsen Larsen, Kim
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p. 109 - 119
(2007/10/03)
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- Quantitative estimation of the bitter taste intensity of oxyphenonium bromide reduced by cyclodextrins from electromotive force measurements
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The bitter taste of oxyphenonium bromide, an antiacetylcholine drug, is suppressed by cyclodextrins. The extent of the suppression can be predicted from the electromotive force measurements with an oxyphenonium bromide- selective electrode. The relationship between the bitter taste intensity and the electromotive force holds true, regardless of the kind and concentration of natural and modified cyclodextrins. This result is explicable on the basis of the observation that both the bitter taste and the electric potential are determined by the concentration of free oxyphenonium bromide. Some implications and limitations of the present approach are discussed.
- Funasaki, Noriaki,Kawaguchi, Ryusaku,Ishikawa, Seiji,Hada, Sakae,Neya, Saburo,Katsu, Takashi
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p. 1733 - 1736
(2007/10/03)
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- Induced circular dichroism and UV-VIS absorption spectroscopy of cyclodextrin inclusion complexes: Structural elucidation of supramolecular azi-adamantane
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The first induced circular dichroism (ICD) analyses of diazirineγyciodextrin inclusion complexes are reported. The stoichiometries and association constants of the guestηost complexes with α-, β-, and γ- cyclodextrin were determined. In addition, with the α-cyclodextrin complex, UV-vis spectroscopy of water-ethanol solutions showed remarkable fine structure, probably indicating that the diazirine experiences a nonpolar microenvironment. These analytical methods provide details about the architecture and nature of these supramolecular carbene precursors.
- Krois, Daniel,Brinker, Udo H.
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p. 11627 - 11632
(2007/10/03)
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- Retardation of acetal hydrolysis by cyclodextrins and its use in probing cyclodextrin-guest binding
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Hydrolysis of benzaldehyde dimethyl acetal 1 in aqueous acid is slowed down greatly by cyclodextrins (SDs): α-CD, β-CD, hp-β-CD (hydroxypropyl-β-cyclodextrin) and γ-CD. The variations of the observed first-order rate constants (Kobs) with [CD] exhibit saturation behaviour consistent with 1:1 binding between 1 and the CDs. In the case of β-CD and hp-β-CD, the binding is relatively strong and the CD-bound acetal is unreactive. In contrast, binding of the acetal by α-CD and γ-CD is much weaker, but only with α-CD does the CD-bound form show significant reactivity. The four CD-mediated reaction, have been evaluated as probe reactions for determining dissociation constants of {CD-'guest'} complexes. In this approach, added guests attenuate the retarding effect of CD-substrate binding and cause an increase in the rate of acetal hydrolysis. The method works well for alipharic alcohols and ketones binding to β-CD and hp-β-CD, but it is less successful with α-CD because of the shallow dependence of kobs on [α-CD] in the probe action. With γ-CD, the approach is not applicable at all, because added guests cause a further reduction in the rate of acetal hydrolysis, not an increase. Various implications of these findings are discussed.
- Tee, Oswald S.,Fedortchenko, Alexei A.,Soo, Patrick Lim
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p. 123 - 128
(2007/10/03)
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- Thermodynamic and nuclear magnetic resonance study of the reactions of α- and β-cyclodextrin with acids, aliphatic amines, and cyclic alcohols
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Titration calorimetry was used to determine equilibrium constants and standard molar enthalpy, Gibbs energy, and entropy changes for the reactions of a series of acids, amines, and cyclic alcohols with α- and β-cyclodextrin. The results have been examined in terms of structural features in the ligands such as the number of alkyl groups, the charge number, the presence of a double bond, branching, and the presence of methyl and methoxy groups. The values of thermodynamic quantities, in particular the standard molar Gibbs energy, correlate well with the structural features in the ligands. These structural correlations can be used for the estimation of thermodynamic quantities for related reactions. Enthalpy-entropy compensation is evident when the individual classes of substances studied herein are considered, but does not hold when these various classes of ligands are considered collectively. The NMR results indicate that the mode of accommodation of the acids and amines in the α-cyclodextrin cavity is very similar, but that the 1-methyl groups in 1-methylhexylamine and in 1-methylheptylamine and the N-methyl group in N-methylhexylamine lie outside the α-cyclodextrin cavity. This latter finding is consistent with the calorimetric results. Many of the thermodynamic and NMR results can be qualitatively understood in terms of van der Waals forces and hydrophobic effects.
- Rekharsky, Mikhail V.,Mayhew, Martin P.,Goldberg, Robert N.,Ross, Philip D.,Yamashoji, Yuko,Inoue, Yoshihisa
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- Dynamics of H/D and D/H exchanges in β-cyclodextrin dodecahydrate observed in real time: effects from zero-point vibrational energy
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Cyclic H/D and D/H exchange processes in crystalline β-cyclodextrin dodecahydrate exposed to D2O (or H2O) vapour, monitored in real time by the integrated intensity of the O-H Raman stretching band, exhibit different rate constants and activation energies ascribed to different zero-point vibrational energies of OH and OD.
- Silva, Aida Moreira da,Steiner, Thomas,Saenger, Wolfram,Empis, Jose,Teixeira-Dias, Jose J. C.
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p. 465 - 466
(2007/10/03)
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- Shaving aid composite with an inclusion complex of a skin-soothing agent and a cyclodextrin
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The present invention is directed to a shaving system of the wet shave type comprising a blade member (one or more) and a structure which supports or holds the blade member and which has an external skin engaging portion in proximity to the blade member. The skin engaging portion includes an improved shaving aid composite (or lubricating strip) which contains an inclusion complex of a skin-soothing agent, such as menthol, with a cyclodextrin. Preferably the shaving aid composite comprises a matrix of a water-insoluble polymer, an effective amount of a skin lubricating water-soluble polymer dispersed within the matrix, and an inclusion complex of a skin-soothing agent with a cyclodextrin. Alternatively, the shaving aid composite may comprise a sheath of water-insoluble polymer that surrounds a core which includes a skin-lubricating water-soluble polymer and an inclusion complex of a skin-soothing agent with a cyclodextrin. The improved shaving aid composite is capable of retaining during normal storage conditions substantially all of the skin-soothing agent included during fabrication of the composite and delivering an effective amount of the skin-soothing agent during use.
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- Spectroscopic determination of pressure-induced shifts in inclusion complexation equilibria
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The effect of modest hydrostatic pressure (c ranging from clearly pressure dependent (-14%) to pressure independent over 338 bar. Additional solvation perturbations are observed in the pressure dependence of the quantum efficiency for both complexes (-7.3% and -9.4%). Thus, pressure-induced perturbation in the fluorescence properties of the complex need not be accompanied by simultaneous changes in the complexation equilibrium. Finally, these pressure-induced changes in complexation selectivity are important for all measurements conducted under variable pressure conditions, including liquid chromatography and process monitoring.
- Evans, Christine E.
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p. 2136 - 2142
(2007/10/03)
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- Capillary Electrophoresis as a Method for Determining Binding Constants: Application to the Binding of Cyclodextrins and Nitrophenolates
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For analytes involved in dynamic aquilibrium processes, capillary electrophoresis is a powerful method of determining binding constants.Equilibrium constants from capillary electrophoresis for the binding of nitrophenolates to α-cyclodextrin show good agreement with literature values obtained using calorimetric and spectroscopic methods, confirming capillary electrophoresis as a viable method.We show that it is imperative to make viscosity corrections, to study the full binding range, and to use an algorithm which calculates the concentration of free cyclodextrin rather than the total cyclodextrin concentration.Binding constants for analytes in a complex mixture can be determined simultaneously.The methods have been applied to 2-, 3-, and 4-nitrophenolates with native and derivatized α- and β-cyclodextrins, and results provide insight into the binding process.Data analysis methods for capillary electrophoresis are also successfully applied to liquid chromatography with the use of the same selector as mobile phase additive.
- Penn, Sharron G.,Bergstroem, Edmund T.,Knights, Ian,Liu, Gaoyuan,Ruddick, Andrew,Goodall, David M.
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p. 3875 - 3880
(2007/10/02)
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- Improvement of some pharmaceutical properties of drugs by cyclodextrin complexation. 2. Colchicine
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The potentiality of interaction of colchicine with β-cyclodextrin (β-CD) was investigated by spectrophotometric and vapour pressure osmometric methods. Differential UV spectrophotometry revealed marked effect of β-CD on the extinction coefficient of colchicine at different wavelengths. The continuous variation method was utilized to elucidate the stoichiometry of molecular interaction via spectrophotometric as well as vapour pressure measurements. Both types of data were in full agreement and revealed the formation of 1:1 complex between colchicine and β-CD. The stability constant of the complex was determined at different temperatures by the vapour pressure osmometric method. The complex was found to undergo partial dissociation with increasing temperature above 25°C and more or less complete dissociation at 60°C. The enthalpy and entropy of interaction were evaluated. The results indicate that the interaction is exothermic and enthalpy-controlled. The colchicine-β-CD complex was prepared; the photochemical stability of the drug, its physical mixture with β-CD and the complex were investigated. The results revealed first-order degradation kinetics. The degradation rate constant as well as the half-life time were computed and the data indicate that inclusion complexation of colchicine with β-CD leads to a marked protection of the drug against photo-degradation.
- Ammar,El-Nahhas
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p. 269 - 272
(2007/10/02)
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- Complementary Diastereoselectivity in the Synthesis and Hydrolysis of Acylated Cyclodextrins
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The diastereoselectivity of acylation of β-cyclodextrin with the acid chlorides of Ibuprofen, Flurbiprofen and 2-phenylpropanoic acid is complementary, in absolute and relative terms, to that observed in the hydrolysis of the corresponding cyclodextrin esters.
- Coates, John H.,Easton, Christopher J.,Fryer, Nicholas L.,Lincoln, Stephen F.
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p. 1153 - 1156
(2007/10/02)
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- Synthesis of a Cyclodextrin Heterodimer Having α- and β-Cyclodextrin Units and Its Cooperative and Site-Specific Binding
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A cyclodextrin heterodimer, which has α- and β-cyclodextrin units as two different receptor sites, was prepared.It showed cooperative and site-specific binding to isoamyl p-dimethylaminobenzoate with the alkyl group included in the β-cyclodextrin cavity while dimethylaminobenzene moiety partially included in the α-cyclodextrin cavity.This binding mode was substantiated by the fact that the TICT emission of this guest is greatly enhanced by the cyclodextrin heterodimer.
- Wang, Yong,Ueno, Akihiko,Toda, Fujio
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p. 167 - 170
(2007/10/02)
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- Synthesis of a new molecular carrier: N-(Leu-enkephalin)yl 6-amido-6-deoxy-cyclomaltoheptaose
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The synthesis of N-(Leu-enkephalin)yl 6-amido-6-deoxy-cyclomaltoheptaose has been performed in high yield. The final derivative has been characterized by proton NMR in terms of chemical and inclusion properties and represents a new class of target-directed transporters.
- Djedaini-Pilard, Florence,Desalos, Jacques,Perly, Bruno
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p. 2457 - 2460
(2007/10/02)
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