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1
Labes, Antje, e Peter Schönheit. "Unusual Starch Degradation Pathway via Cyclodextrins in the Hyperthermophilic Sulfate-Reducing Archaeon Archaeoglobus fulgidus Strain 7324". Journal of Bacteriology 189, n. 24 (5 ottobre 2007): 8901–13. http://dx.doi.org/10.1128/jb.01136-07.
Testo completoAbstract (sommario):
ABSTRACT The hyperthermophilic archaeon Archaeoglobus fulgidus strain 7324 has been shown to grow on starch and sulfate and thus represents the first sulfate reducer able to degrade polymeric sugars. The enzymes involved in starch degradation to glucose 6-phosphate were studied. In extracts of starch-grown cells the activities of the classical starch degradation enzymes, α-amylase and amylopullulanase, could not be detected. Instead, evidence is presented here that A. fulgidus utilizes an unusual pathway of starch degradation involving cyclodextrins as intermediates. The pathway comprises the combined action of an extracellular cyclodextrin glucanotransferase (CGTase) converting starch to cyclodextrins and the intracellular conversion of cyclodextrins to glucose 6-phosphate via cyclodextrinase (CDase), maltodextrin phosphorylase (Mal-P), and phosphoglucomutase (PGM). These enzymes, which are all induced after growth on starch, were characterized. CGTase catalyzed the conversion of starch to mainly β-cyclodextrin. The gene encoding CGTase was cloned and sequenced and showed highest similarity to a glucanotransferase from Thermococcus litoralis. After transport of the cyclodextrins into the cell by a transport system to be defined, these molecules are linearized via a CDase, catalyzing exclusively the ring opening of the cyclodextrins to the respective maltooligodextrins. These are degraded by a Mal-P to glucose 1-phosphate. Finally, PGM catalyzes the conversion of glucose 1-phosphate to glucose 6-phosphate, which is further degraded to pyruvate via the modified Embden-Meyerhof pathway.
2
Bansal, Paramjit S., Craig L. Francis, Noel K. Hart, Scott A. Henderson, David Oakenfull, Alan D. Robertson e Gregory W. Simpson. "Regioselective Alkylation of β-Cyclodextrin". Australian Journal of Chemistry 51, n. 10 (1998): 915. http://dx.doi.org/10.1071/c98064.
Testo completoAbstract (sommario):
Methodology for preparation of heptakis(2,6-di-O-alkyl)-β-cyclodextrins, heptakis(2-O-alkyl)-β- cyclodextrins, and heptakis(6-O-alkyl)-β-cyclodextrins in substantially purified form has been developed. Treatment of β-cyclodextrin (1) with sodium or barium hydroxide and various alkyl halides in dimethyl sulfoxide or a mixture of dimethyl sulfoxide and N,N-dimethylformamide provided the corresponding heptakis(2,6-di-O-alkyl)-β-cyclodextrins. Treatment of heptakis(6-O-t-butyldimethylsilyl)-β-cyclodextrin (5) with sodium hydroxide and several haloalkanes in dimethyl sulfoxide followed by desilylation provided heptakis(2-O-alkyl)-β-cyclodextrins. Protection of the secondary hydroxy groups of the t-butyldimethylsilyl-β-cyclodextrin (5) as benzyl ethers, followed by desilylation, alkylation, and debenzylation afforded several heptakis(6-O-alkyl)-β-cyclodextrins. Analytical methodology has been developed to characterize all of these compounds, with the homogeneity of the pattern of substitution verified by h.p.l.c. analysis, f.a.b.–mass spectrometry and n.m.r. spectroscopy.
3
Wang, Runmiao, Hui Zhou, Shirley W. I. Siu, Yong Gan, Yitao Wang e Defang Ouyang. "Comparison of Three Molecular Simulation Approaches for Cyclodextrin-Ibuprofen Complexation". Journal of Nanomaterials 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/193049.
Testo completoAbstract (sommario):
Cyclodextrins are widely used for the solubilisation of poorly soluble drugs in the formulations. However, current cyclodextrin formulation development strongly depends on trial-and-error in the laboratory, which is time-consuming and high cost. The aim of this research was to compare three modeling approaches (Docking, molecular dynamics (MD), and quantum mechanics (QM)) for cyclodextrin/drug complexation. Ibuprofen was used as a model drug. Binding free energy from three simulation methods was calculated as an important parameter to compare with the experimental results. Docking results from AutoDock Vina program showed that the scoring of complexation capability between ibuprofen and cyclodextrins is alpha (α), gamma (γ), beta (β), and HP-beta-cyclodextrins, which indicated similar ranking with the results from phase, solubility diagram experiments. MD simulation indicated that ibuprofen could form the stable complexes withβ-,γ-, and HP-β-cyclodextrins, but not for alpha cyclodextrin. Binding free energies from the MD simulation forβ-,γ-, and HP-β-cyclodextrins were −3.67, −0.67, and −3.87 kcal/mol, individually. The enthalpies of QM simulation forβ-,γ-, and HP-β-cyclodextrins were −17.22, −14.75, and −20.28 kcal/mol, respectively. Results from all three modeling approaches showed similar ranking between ibuprofen and four cyclodextrin molecules as the experimental data. However, MD simulation with entropy calculation had the closest value to experimental data forβand HP-beta-cyclodextrins. Thus, MD simulation with MM-PBSA method may be fit toin silicoscreen for cyclodextrin formulations.
4
Lavandier, CD, MP Pelletier e VC Reinsborough. "Surfactant Inclusions by Modified β-Cyclodextrins". Australian Journal of Chemistry 44, n. 3 (1991): 457. http://dx.doi.org/10.1071/ch9910457.
Testo completoAbstract (sommario):
Binding constants for the inclusion of sodium alkane-1-sulfonates (C5-C10, C12) by four modified β- cyclodextrins (2,6-O-dimethyl-β-cyclodextrin, 2,3,6-O-trimethyl-β-cyclodextrin, hydroxypropyl-β-cyclodextrin and maltosyl-β-cyclodextrin ) were determined conductimetrically at 25°C. Binding increased with increasing length of the alkyl chain. Generally, the substituted β- cyclodextrins were no more effective as encapsulating agents than ordinary β- cyclodextrin with the persubstituted 2,3,6-O-trimethyl-β-cyclodextrin being the weakest.
5
Easton, Christopher J., Steven J. van Eyk, Stephen F. Lincoln, Bruce L. May, John Papageorgiou e Michael L. Williams. "A Versatile Synthesis of Linked Cyclodextrins". Australian Journal of Chemistry 50, n. 1 (1997): 9. http://dx.doi.org/10.1071/c96168.
Testo completoAbstract (sommario):
Reactions of amino-substituted cyclodextrins with bis(3-nitrophenyl) oxalate, malonate, succinate and glutarate, and with diphenyl carbonate, afford a range of linked cyclodextrins. These include α- and β-cyclodextrin dimers, joined by substitution at either C6 or C3, and asymmetric species with a β-cyclodextrin bonded to an a-cyclodextrin and a C3-substituted cyclodextrin attached to a C6-substituted moiety.
6
Castillo Cruz, Betzaida, Sandra Chinapen Barletta, Bryan G. Ortiz Muñoz, Adriana S. Benitez-Reyes, Omar A. Amalbert Perez, Alexander C. Cardona Amador, Pablo E. Vivas-Mejia e Gabriel L. Barletta. "Effect of Cyclodextrins Formulated in Liposomes and Gold and Selenium Nanoparticles on siRNA Stability in Cell Culture Medium". Pharmaceuticals 17, n. 10 (8 ottobre 2024): 1344. http://dx.doi.org/10.3390/ph17101344.
Testo completoAbstract (sommario):
Background: Encapsulation of siRNA fragments inside liposome vesicles has emerged as an effective method for delivering siRNAs in vitro and in vivo. However, the liposome’s fluid-phospholipid bilayer of liposomes allows siRNA fragments to diffuse out of the liposome, decreasing the dose concentration and therefore the effectiveness of the carrier. We have previously reported that β-cyclodextrins formulated in liposomes help increase the stability of siRNAs in cell culture medium. Here, we continued that study to include α, γ, methyl-β-cyclodextrins and β-cyclodextrin-modified gold and selenium nanoparticles. Methods: We used Isothermal Titration Calorimetry to study the binding thermodynamics of siRNAs to the cyclodextrin-modified nanoparticles and to screen for the best adamantane derivative to modify the siRNA fragments, and we used gel electrophoresis to study the stabilization effect of siRNA by cyclodextrins and the nanoparticles. Results: We found that only β- and methyl-β-cyclodextrins increased siRNA serum stability. Cyclodextrin-modified selenium nanoparticles also stabilize siRNA fragments in serum, and siRNAs chemically modified with an adamantane moiety (which forms inclusion complexes with the cyclodextrin-modified-nanoparticles) show a strong stabilization effect. Conclusions: β-cyclodextrins are good additives to stabilize siRNA in cell culture medium, and the thermodynamic data we generated of the interaction between cyclodextrins and adamantane analogs (widely used in drug delivery studies), should serve as a guide for future studies where cyclodextrins are sought for the delivery and solvation of small organic molecules.
7
Fenyvesi, Ferenc. "Biological Studies on Cyclodextrins". Proceedings 78, n. 1 (1 dicembre 2020): 60. http://dx.doi.org/10.3390/iecp2020-08692.
Testo completoAbstract (sommario):
In recent years, our knowledge of the biological effects of cyclodextrins has grown significantly. Cellular actions of cyclodextrins originate in their ability to form complexes with lipophilic biomolecules. Cyclodextrins can target different types of molecules according to their size, for instance, alpha-cyclodextrins form complexes with phospholipids, while beta-cyclodextrins can bind cholesterol or prostaglandin E2. Due to their interactions with the main membrane constituents, cyclodextrins can affect the barrier function of biological barriers or influence the function of membrane proteins. Nevertheless, cyclodextrins can enter the cells by endocytosis and affect the intracellular cholesterol storage. Based on these findings, 2-hydroxypropyl-beta cyclodextrin (HPBCD) received the orphan designation for the treatment of Niemann–Pick disease type C. The endocytosis of cyclodextrins works in different cell types and can be applied in the delivery of drugs into the cells. The tissue distribution and pharmacokinetics of cyclodextrins could be further characterized by imaging techniques. Radiolabeled HPBCD and randomly methylated beta-cyclodextrin (RAMEB) were recently used to study their in vivo behavior by positron emission tomography. Interestingly, RAMEB accumulation was detected in prostaglandin E2 (PGE2)-positive tumors. These findings can promote further research and the application of cyclodextrins in inflammation and tumor diagnosis or targeting. The presentation aims to give an overview of the main biological effects of cyclodextrins and the recent results of this research field.
8
Yhaya, Firdaus, Andrew M. Gregory e Martina H. Stenzel. "Polymers with Sugar Buckets - The Attachment of Cyclodextrins onto Polymer Chains". Australian Journal of Chemistry 63, n. 2 (2010): 195. http://dx.doi.org/10.1071/ch09516.
Testo completoAbstract (sommario):
This Review summarizes the structures obtained when marrying synthetic polymers of varying architectures with cyclodextrins. Polymers with cyclodextrin pendant groups were obtained by directly polymerizing cyclodextrin-based monomers or by postmodification of reactive polymers with cyclodextrins. Star polymers with cyclodextrin as the core with up to 21 arms were usually obtained by using modified cyclodextrins as initiator or controlling agent. Limited reports are available on the synthesis of star polymers by arm-first techniques, which all employed azide-functionalized cyclodextrin and ‘click’ chemistry to attach seven polymer arms to the cyclodextrin core. Polymer chains with one or two cyclodextrin terminal units were reported as well as star polymers carrying a cyclodextrin molecule at the end of each arm. Cyclodextrin polymers were obtained using different polymerization techniques ranging from atom transfer radical polymerization, reversible addition–fragmentation chain transfer polymerization, nitroxide-mediated polymerization, free radical polymerization to (ionic) ring-opening polymerization, and polycondensation. Cyclodextrin polymers touch all areas of polymer science from gene delivery, self-assembled structures, drug carriers, molecular sensors, hydrogels, and liquid crystalline polymers. This Review attempts to focus on the range of work conducted with polymers and cyclodextrins and highlights some of the key areas where these macromolecules have been applied.
9
S. Panwar, Vikas, Lokesh Adhikari, Mona Semalty e Ajay Semalty. "DRUG-CYCLODEXTRIN COMPLEXES: CURRENT STATUS AND RECENT ADVANCEMENTS". INDIAN DRUGS 60, n. 10 (28 ottobre 2023): 7–18. http://dx.doi.org/10.53879/id.60.10.12952.
Testo completoAbstract (sommario):
Cyclodextrins are water-soluble oligosaccharides formed by the action of cyclodextrin glucosyl transferase enzyme (CGTase) on the medium containing starch. Cyclodextrins are proven to be a cost-effective breakthrough in the pharmaceutical industry by formulating them with polymers and drugs to improve the safety, bioavailability, and solubility of APIs. This review describes the current status and advancement of cyclodextrin research in drug delivery. The use of cyclodextrins to improve the solubility and dissolution properties of poor water-soluble products has been reviewed exhaustively with a specific focus on their physicochemical property, practical methods, toxicity, the drug-cyclodextrin compatibility and its applications.
10
Sivakumar, Ponnurengam M., Shohreh Peimanfard, Ali Zarrabi, Arezoo Khosravi e Matin Islami. "Cyclodextrin-Based Nanosystems as Drug Carriers for Cancer Therapy". Anti-Cancer Agents in Medicinal Chemistry 20, n. 11 (8 luglio 2020): 1327–39. http://dx.doi.org/10.2174/1871520619666190906160359.
Testo completoAbstract (sommario):
Background and Objective: Cyclodextrins have been of great interest as excellent candidates for fabricating versatile nano-drug delivery systems due to their commercial availability, easy functionalization, low immunogenicity, biocompatibility and safety. The possibility of reversible inclusion complex formation between cyclodextrins and various guest molecules in association with versatile exclusive properties of cyclodextrins offer a route towards the fabrication of highly sophisticated nanostructures with enormous potential for cancer treatment. Methods and Results: The current review discusses important recent advances in the fabrication and development of cyclodextrin-based nanostructures for cancer therapy. Firstly, the formation of inclusion complexes between cyclodextrin derivatives and anticancer compounds, as well as their application, are summarized. Secondly, the cyclodextrins -based nanosystems including cyclodextrin-containing polymers, cyclodextrin-based supramolecular necklaces, which consist of polyrotaxanes and polypseudorotaxanes and cyclodextrin based hydrogels accompanied by their applications in cancer treatment are highlighted. In the end, the future perspective of this field is discussed. Conclusion: Numerous investigations in this area pave the way for the flourishing of the next generation of nano-therapeutics towards enhanced cancer therapy.
11
Masoumi, Saeideh, Sahar Amiri e Seyed Hajir Bahrami. "PCL-based nanofibers containing ibuprofen/cyclodextrins nanocontainers: A potential candidate for drug delivery application". Journal of Industrial Textiles 48, n. 9 (21 marzo 2018): 1420–38. http://dx.doi.org/10.1177/1528083718764910.
Testo completoAbstract (sommario):
Poor solubility and low dissolution rate of ibuprofen (IBU) in the aqueous gastro-intestinal fluids restrict its application, absorption, distribution, target organ delivery, and bioavailability. For improvement of aqueous solubility of IBU, supramolecular nanocontainers of IBU/cyclodextrin were prepared via formation of inclusion complex between ibuprofen and cyclodextrins (α-cyclodextrin and β-cyclodextrin) at various conditions (at room temperature at 25℃ and under sonic energy). The formation of inclusion complex between IBU and cyclodextrins can be confirmed by hydrogen nuclear magnetic resonance, differential scanning calorimetry, fourier transform Infrared spectroscopy (FTIR), X-ray diffraction, and scanning electron microscopy study. FTIR of pure IBU and cyclodextrins is similar to the obtained complex, which indicated intactness of drug in the complex. The encapsulation of IBU in cyclodextrins cavity improved its solubility, phase solubility, and in vitro dissolution and also controlled its release which ensures the long-term delivery. Electro-spun nanofibers of poly-ɛ-caprolactone containing IBU/cyclodextrins is a promising method for controlled drug delivery electro-spun which is bead-free without any aggregation on the surface.
12
Ji, Xin-Yu, Yi-Xuan Zou, Han-Fang Lei, Yong Bi, Rui Yang, Ji-Hui Tang e Qing-Ri Jin. "Advances in Cyclodextrins and Their Derivatives in Nano-Delivery Systems". Pharmaceutics 16, n. 8 (9 agosto 2024): 1054. http://dx.doi.org/10.3390/pharmaceutics16081054.
Testo completoAbstract (sommario):
The diversity of cyclodextrins and their derivatives is increasing with continuous research. In addition to monomolecular cyclodextrins with different branched chains, cyclodextrin-based polymers have emerged. The aim of this review is to summarize these innovations, with a special focus on the study of applications of cyclodextrins and their derivatives in nano-delivery systems. The areas covered include nanospheres, nano-sponges, nanogels, cyclodextrin metal–organic frameworks, liposomes, and emulsions, providing a comprehensive and in-depth understanding of the design and development of nano-delivery systems.
13
Prior, Marguerite, Sylvain Lehmann, Man-Sun Sy, Brendan Molloy e Hilary E. M. McMahon. "Cyclodextrins Inhibit Replication of Scrapie Prion Protein in Cell Culture". Journal of Virology 81, n. 20 (15 agosto 2007): 11195–207. http://dx.doi.org/10.1128/jvi.02559-06.
Testo completoAbstract (sommario):
ABSTRACT Prion diseases are fatal neurodegenerative disorders that are caused by the conversion of a normal host-encoded protein, PrPC, to an abnormal, disease-causing form, PrPSc. This paper reports that cyclodextrins have the ability to reduce the pathogenic isoform of the prion protein PrPSc to undetectable levels in scrapie-infected neuroblastoma cells. Beta-cyclodextrin removed PrPSc from the cells at a concentration of 500 μM following 2 weeks of treatment. Structure activity studies revealed that antiprion activity was dependent on the size of the cyclodextrin. The half-maximal inhibitory concentration (IC50) for beta-cyclodextrin was 75 μM, whereas α-cyclodextrin, which possessed less antiprion activity, had an IC50 of 750 μM. This report presents cyclodextrins as a new class of antiprion compound. For decades, the pharmaceutical industry has successfully used cyclodextrins for their complex-forming ability; this ability is due to the structural orientation of the glucopyranose units, which generate a hydrophobic cavity that can facilitate the encapsulation of hydrophobic moieties. Consequently, cyclodextrins could be ideal candidates for the treatment of prion diseases.
14
Gatiatulin, Askar K., Ivan A. Grishin, Aleksey V. Buzyurov, Timur A. Mukhametzyanov, Marat A. Ziganshin e Valery V. Gorbatchuk. "Determination of Melting Parameters of Cyclodextrins Using Fast Scanning Calorimetry". International Journal of Molecular Sciences 23, n. 21 (28 ottobre 2022): 13120. http://dx.doi.org/10.3390/ijms232113120.
Testo completoAbstract (sommario):
The first evidence of native cyclodextrins fusion was registered using fast scanning calorimetry (FSC) with heating rates up to 40,000 K s−1. The endothermal effects, detected at low heating rates, correspond to the decomposition processes. Upon the increase of the heating rate the onset of these effects shifts to higher temperatures, reaching a limiting value at high heating rates. The limiting temperatures were identified as the melting points of α-, β- and γ-cyclodextrins, as the decomposition processes are suppressed at high heating rates. For γ-cyclodextrin the fusion enthalpy was measured. The activation energies of thermal decomposition of cyclodextrins were determined by dependence of the observed thermal effects on heating rates from 4 K min−1 in conventional differential scanning calorimetry to 40,000 K s−1 in FSC. The lower thermal stability and activation energy of decomposition of β-cyclodextrin than for the other two cyclodextrins were found, which may be explained by preliminary phase transition and chemical reaction without mass loss. The obtained values of fusion parameters of cyclodextrins are needed in theoretical models widely used for prediction of solubility and solution rates and in preparation of cyclodextrin inclusion compounds involving heating.
15
Braga, Susana Santos. "Cyclodextrins as Multi-Functional Ingredients in Dentistry". Pharmaceutics 15, n. 9 (31 agosto 2023): 2251. http://dx.doi.org/10.3390/pharmaceutics15092251.
Testo completoAbstract (sommario):
Cyclodextrins are present in a variety of oral hygiene compositions. The present work describes the role of cyclodextrins in several toothpastes and mouthwashes that are already available in the market, as well as their prospective use in other applications as investigated in studies in the literature. Moreover, cyclodextrins are under study for the development of materials used in various techniques of dental repair, such as fillings, cements and binders therein. Their role in each of the innovative materials is presented. Finally, the prospect of the use of cyclodextrin-based delivery systems for the oral cavity is introduced, with a focus on new cyclodextrin molecules with dual action as bone-targeting agents and osteogenic drugs, and on new cross-linked cyclodextrin particles with a high drug loading and sustained drug delivery profile for the treatment of diseases that require prolonged action, such as periodontitis. In conclusion, cyclodextrins are herein demonstrated to act as versatile and multi-action ingredients with a broad range of applications in dentistry.
16
Székely-Szentmiklósi, Blanka, e B. Tőkés. "Study of Cyclodextrin/Fluoroquinolone Inclusion Complexes by Capillary Electrophoresis". Acta Medica Marisiensis 59, n. 2 (1 aprile 2013): 107–10. http://dx.doi.org/10.2478/amma-2013-0026.
Testo completoAbstract (sommario):
AbstractIntroduction: In the present work we evaluated the complexation role of cyclodextrins toward fluoroquinolones in an attempt to assess their potential as new formulation additives for more efficient fluoroquinolone delivery and as selectors in capillary electrophoresis.Material and method: Guest-host interactions of two second generation quinolones, ciprofloxacin and norfloxacin with four cyclodextrins, beta-cyclodextrin (β-CD), gamma-cyclodextrin (γ-CD) and two beta-cyclodextrin derivatives, 2-hydroxypropyl beta-cyclodextrin (HP-β-CD) and randomly methylated beta-cyclodextrin (RAMEB), were tested by capillary electrophoresis in borate running buffer. Experimental parameters like buffer concentration, pH, organic modifier, voltage and cyclodextrin concentration have been varied for a better resolution.Results: In capillary zone electrophoresis ciprofloxacin and norfloxacin are migrating together, a difference in their migration times and thus separation occured by the addition of cyclodextrins.Conclusion: Our results suggest formation of inclusion complexes between fluoroquinolones and cyclodextrins. Differences in their affinity to host molecules resulted in separation of the two fluoroquinolones
17
Braga, Susana Santos, Karyna Lysenko, Firas El-Saleh e Filipe A. Almeida Paz. "Cyclodextrin-Efavirenz Complexes Investigated by Solid State and Solubility Studies". Proceedings 78, n. 1 (1 dicembre 2020): 15. http://dx.doi.org/10.3390/iecp2020-08690.
Testo completoAbstract (sommario):
This short paper investigates the solubilizing ability of various cyclodextrins with efavirenz as well as the formation of solid inclusion complexes of efavirenz with β-CD and γ-CD. (1) Background: Efavirenz is a non-nucleoside reverse transcriptase inhibitor used as first-line treatment for adult and pediatric human immunodeficiency virus type 1 infection (HIV-1). Belonging to class II of Biopharmaceutical Classification System (BCS), efavirenz is poorly water-soluble. Inclusion into cyclodextrins is a possible strategy for increasing its solubility. (2) Methods: Solubility modulation was investigated by the phase solubility method; inclusion of efavirenz with β- and γ-cyclodextrins was attempted by co-dissolution with co-precipitation; the precipitates were studied by DSC, FT-IR, powder X-ray diffraction and optical microscopy. (3) Results: Solid state analysis of the precipitates shows evidence of separate recrystallization of β-cyclodextrin and efavirenz, whereas in the case of γ-cyclodextrin, a single new phase was observed. (4) Conclusion: Results show that the cavity of β-cyclodextrin is too narrow to accommodate efavirenz and only γ-cyclodextrin, the largest of native cyclodextrins, is able to form a true inclusion complex with this bulky guest.
18
Wang, Lei, Xuguo Duan e Jing Wu. "Enhancing the α-Cyclodextrin Specificity of Cyclodextrin Glycosyltransferase from Paenibacillus macerans by Mutagenesis Masking Subsite −7". Applied and Environmental Microbiology 82, n. 8 (5 febbraio 2016): 2247–55. http://dx.doi.org/10.1128/aem.03535-15.
Testo completoAbstract (sommario):
ABSTRACTCyclodextrin glycosyltransferases (CGTases) (EC 2.4.1.19) catalyze the conversion of starch or starch derivates into mixtures of α-, β-, and γ-cyclodextrins. Because time-consuming and expensive purification procedures hinder the widespread application of single-ingredient cyclodextrins, enzymes with enhanced specificity are needed. In this study, we tested the hypothesis that the α-cyclodextrin selectivity ofPaenibacillus maceransα-CGTase could be augmented by masking subsite −7 of the active site, blocking the formation of larger cyclodextrins, particularly β-cyclodextrin. Five single mutants and three double mutants designed to remove hydrogen-bonding interactions between the enzyme and substrate at subsite −7 were constructed and characterized in detail. Although the rates of α-cyclodextrin formation varied only modestly, the rate of β-cyclodextrin formation decreased dramatically in these mutants. The increase in α-cyclodextrin selectivity was directly proportional to the increase in the ratio of theirkcatvalues for α- and β-cyclodextrin formation. The R146A/D147P and R146P/D147A double mutants exhibited ratios of α-cyclodextrin to total cyclodextrin production of 75.1% and 76.1%, approximately one-fifth greater than that of the wild-type enzyme (63.2%), without loss of thermostability. Thus, these double mutants may be more suitable for the industrial production of α-cyclodextrin than the wild-type enzyme. The production of β-cyclodextrin by these mutants was almost identical to their production of γ-cyclodextrin, which was unaffected by the mutations in subsite −7, suggesting that subsite −7 was effectively blocked by these mutations. Further increases in α-cyclodextrin selectivity will require identification of the mechanism or mechanisms by which these small quantities of larger cyclodextrins are formed.
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Healy, Bronach, Tian Yu, Daniele C. da Silva Alves, Cynthia Okeke e Carmel B. Breslin. "Cyclodextrins as Supramolecular Recognition Systems: Applications in the Fabrication of Electrochemical Sensors". Materials 14, n. 7 (28 marzo 2021): 1668. http://dx.doi.org/10.3390/ma14071668.
Testo completoAbstract (sommario):
Supramolecular chemistry, although focused mainly on noncovalent intermolecular and intramolecular interactions, which are considerably weaker than covalent interactions, can be employed to fabricate sensors with a remarkable affinity for a target analyte. In this review the development of cyclodextrin-based electrochemical sensors is described and discussed. Following a short introduction to the general properties of cyclodextrins and their ability to form inclusion complexes, the cyclodextrin-based sensors are introduced. This includes the combination of cyclodextrins with reduced graphene oxide, carbon nanotubes, conducting polymers, enzymes and aptamers, and electropolymerized cyclodextrin films. The applications of these materials as chiral recognition agents and biosensors and in the electrochemical detection of environmental contaminants, biomolecules and amino acids, drugs and flavonoids are reviewed and compared. Based on the papers reviewed, it is clear that cyclodextrins are promising molecular recognition agents in the creation of electrochemical sensors, chiral sensors, and biosensors. Moreover, they have been combined with a host of materials to enhance the detection of the target analytes. Nevertheless, challenges remain, including the development of more robust methods for the integration of cyclodextrins into the sensing unit.
20
Durand, Amaury, David Mathiron, Sébastien Rigaud, Florence Djedaini-Pilard e Frédéric Marçon. "Rapid Study on Mefloquine Hydrochloride Complexation with Hydroxypropyl-β-Cyclodextrin and Randomly Methylated β-Cyclodextrin: Phase Diagrams, Nuclear Magnetic Resonance Analysis, and Stability Assessment". Pharmaceutics 15, n. 12 (18 dicembre 2023): 2794. http://dx.doi.org/10.3390/pharmaceutics15122794.
Testo completoAbstract (sommario):
This study investigates the complexation of mefloquine hydrochloride by cyclodextrins to improve its solubility in order to design an oral solution. This approach may enhance the effectiveness of mefloquine, a drug which can be used for malaria prophylaxis and treatment in children. Mefloquine hydrochloride’s solubility was assessed in different buffer solutions, and its quantification was achieved through high-performance liquid chromatography. The complexation efficiency with cyclodextrins was evaluated, and nuclear magnetic resonance (NMR) methods were employed to determine the interactions between mefloquine and cyclodextrins. Mefloquine’s solubility increased when combined with hydroxypropyl-β-cyclodextrin (HP-β-CD) and randomly methylated β-cyclodextrin (RAMEB), with RAMEB being more effective. The drug’s solubility varied across different pH buffers, being higher in acidic buffers. Interestingly, mefloquine’s solubility decreased with a citrate buffer, possibly due to precipitation. The NMR studies highlighted non-covalent interactions between RAMEB, HP-β-CD, and mefloquine, explaining the solubilizing effect via complexation phenomena. Furthermore, the NMR experiments indicated the complexation of mefloquine by all the studied cyclodextrins, forming diastereoisomeric complexes. Cyclodextrin complexation improved mefloquine’s solubility, potentially impacting its bioavailability.
21
Murai, Hisao, Yoshinori Yamamoto e Yasumasa J. I'Haya. "Time-resolved ESR study on photochemical formation of radical pair in cyclodextrin cavities". Canadian Journal of Chemistry 69, n. 11 (1 novembre 1991): 1643–48. http://dx.doi.org/10.1139/v91-241.
Testo completoAbstract (sommario):
The photoreduction of xanthone with diethylaniline in cyclodextrin cavities was studied at 77 K and room temperature by a time-resolved ESR technique. The radical pair observed in β- and γ-cyclodextrins showed inverted spin polarization compared to that of precursor excited triplet xanthone. This result is rationalized by taking account of the fixed orientation of the radical ion pair in the cyclodextrins. Frozen aqueous solutions and dried powder-like samples provided similar results. The spectrum of the radical pair was also detected in an aqueous solution of β-cyclodextrin at room temperature. Key words: cyclodextrins, xanthone, spin polarization, radical ion-pair, time-resolved ESR.
22
Raut, Sushil Y., Alekhya S. N. Manne, Guruprasad Kalthur, Sanyog Jain e Srinivas Mutalik. "Cyclodextrins as Carriers in Targeted Delivery of Therapeutic Agents: Focused Review on Traditional and Inimitable Applications". Current Pharmaceutical Design 25, n. 4 (3 giugno 2019): 444–54. http://dx.doi.org/10.2174/1381612825666190306163602.
Testo completoAbstract (sommario):
The objective of the article is to provide a comprehensive review on the application of cyclodextrin complexation in the delivery of drugs, bioactive molecules or macromolecules, with more emphasis on targeted drug delivery. Classically the cyclodextrins have been considered only as a means of improving the solubility of drugs; however, many attempts have been made to use cyclodextrins as drug delivery carriers. The cyclodextrin surface can be modified with various ligands for active targeting of drugs. It can also be passively targeted through various triggering mechanisms like thermal, magnetic, pH dependent, light dependent, ultrasound, etc. A comprehensive literature review has been done in the area of drug delivery using cyclodextrins. Applications of inclusion complexes in the drug delivery through various routes with examples are discussed. This review focuses on receptor mediated active targeting as well as stimuli responsive passive targeting of drugs/genes by using cyclodextrins. The article provides a detailed insight of the use of cyclodextrins and their derivatives on the targeted delivery of the drugs/genes.
23
Easton, CJ, S. Kassara, SF Lincoln e BL May. "Amino Substituents as a Probe of Reactions of Phenyl Acetates With Cyclodextrins". Australian Journal of Chemistry 48, n. 2 (1995): 269. http://dx.doi.org/10.1071/ch9950269.
Testo completoAbstract (sommario):
The effects of α- and β- cyclodextrin and 6A-amino-6A-deoxy-α- and -β- cyclodextrin on the rates of reactions of m- and p-nitrophenyl acetate, in borate buffer at pH 10.0 and 298.2 K, show that the amino substituents of the modified cyclodextrins have only a modest influence on the dissociation constants of the complexes formed with each ester and the first-order rate constants for the reactions of complexed m-nitrophenyl acetate. By contrast, the amino substituents significantly increase the rate constants for the reactions of complexes of p- nitrophenyl acetate. These results indicate that one mode of inclusion of p-nitrophenyl acetate in α- and β- cyclodextrin has the ester oxycarbonyl group in the vicinity of the cyclodextrin primary hydroxy groups. While this mode of inclusion in the unmodified cyclodextrins does not lead to reaction and has not been detected previously for that reason, in analogous complexes of the amino-substituted cyclodextrins, the nucleophilic amino group is proximate to the carboxy group of the ester and reaction proceeds. There is no kinetic evidence for this mode of inclusion of m-nitrophenyl acetate. This interpretation of the kinetic effects is consistent with the extent of acetamide formation in reactions of the esters with the amino-substituted cyclodextrins.
24
Vranić, Edina, e Alija Uzunović. "Dissolution Studies of Physical Mixtures of Indomethacin with Alpha- and Gamma-Cyclodextrins". Bosnian Journal of Basic Medical Sciences 10, n. 3 (20 agosto 2010): 197–203. http://dx.doi.org/10.17305/bjbms.2010.2685.
Testo completoAbstract (sommario):
Oral administration of indomethacin has been limited by its poor water solubility. Cyclodextrins have been recognized as potential candidates to overcome the poor solubility of indomethacin through the formation of inclusion complexes.The aim of our study was to compare the dissolution profiles of pure indomethacin and its mixtures with α- and γ-cyclodextrins The inclusion complexes of indomethacin with α- and γ-cyclodextrins were prepared by direct mixing in dissolution vessel. Fixed volumes of the dissolution medium were withdrawn at 0,5; 1 and 4 hours. Dissolution tests were performed on the USP Apparatus 2, rotating speed 100 rpm at 37±0,5°C, 500 ml, distilled water and 0,1 M HCl solution). Quantification of dissolved indomethacin was performed by UV/VIS spectrophotometric method at the absorption maximum around 320 nm.The results were expressed as relative dissolution rate (ratio between indomethacin dissolved from its physical mixtures with α- and γ-cyclodextrins and that dissolved the pure drug).Relative dissolution rates of indomethacin in combination with α- and γ-cyclodextrins at the end of testing were in the range of 91,66 to 337,14 % (for α- cyclodextrin) and in the range of 128,57 to 301,92 % (for γ-cyclodextrin).The complexation of indomethacin with α- and γ-cyclodextrins resulted in the enhancement of dissolution rate.
25
Cabal, Jiří. "Hydrolytic Reactions of Methylfluorophosphonates with Cyclodextrins". Collection of Czechoslovak Chemical Communications 60, n. 7 (1995): 1162–69. http://dx.doi.org/10.1135/cccc19951162.
Testo completoAbstract (sommario):
Reactions of three methylfluorophosphonates (isopropyl, 1,2,2-trimethylpropyl, and cyclohexyl) with α-, β- and γ-cyclodextrins were investigated. The cyclodextrins were found to react with stereoisomers of the methylfluorophosphonates at different rates depending on the location of the substituents at the phosphorus atom. The dependence of the rate increase on cyclodextrin concentration showed a saturation effect. The reactivity of the inclusion complexes of the cyclodextrins with the methylfluorophosphonates depended on the size of the alkyl part of the phosphonate molecule as well as on the size of the cavity of the cyclodextrins. Dependences of the reaction rates on temperature and pH of the reaction medium were recorded. Kinetic data have been used to evaluate the cyclodextrins as the catalysts.
26
Easton, Christopher J., Stephen F. Lincoln, Bruce L. May e John Papageorgiou. "Reactions of Amino-Substituted Cyclodextrins with 2-Arylpropanoic Acid Derivatives". Australian Journal of Chemistry 50, n. 5 (1997): 451. http://dx.doi.org/10.1071/c97034.
Testo completoAbstract (sommario):
Reactions of 6A-amino-6A-deoxy-β-cyclodextrin and 3A-amino-3A-deoxy-(2AS,3AS)-β-cyclodextrin with the 3-nitrophenyl esters of 2-phenylpropanoic acid and Ibuprofen occur with only low diastereoselectivity, to afford the corresponding arylpropanamido-substituted cyclodextrins. These amides are also formed by decarboxylation of corresponding malonates, again with only low diastereoselectivity. The n.m.r. spectra of the amido-substituted cyclodextrins indicate that the aryl substituent is included within the cyclodextrin annulus at low temperature, but becomes dissociated from the cavity as the temperature is increased.
27
Belyakova, L. A. "Encapsulation of benzene carboxylic acids using cyclodextrins". Himia, Fizika ta Tehnologia Poverhni 12, n. 1 (30 marzo 2021): 40–51. http://dx.doi.org/10.15407/hftp12.01.040.
Testo completoAbstract (sommario):
The encapsulation of medicinal substances in various polymers is a common way to increase their thermal, hydrolytic, and chemical stability. However, the bioavailability of the encapsulated drugs decreases. The solution to this important problem can be the preparation of nanocapsules of medicinal substances using complexing agents, for example, cyclodextrins. The purpose of this work is to study the possibility of encapsulation of benzoic, salicylic, and β-resorcylic acids using α- and β-cyclodextrins. The interaction of benzene carboxylic acids with cyclodextrins in aqueous solutions at 20–30 оС has been studied by spectrophotometry. The formation of complexes with a composition of 1:1 in the cyclodextrin – benzene carboxylic acid systems has been proven. The stability constants of the complexes and the main thermodynamic parameters of complex formation have been calculated. It has been shown that the nature of changes in the spectral characteristics of benzene carboxylic acids in the presence of cyclodextrins can be used to predict the possibility of aromatic organic compounds encapsulation. The determining role of the complementarity of geometric parameters of cyclodextrins and benzene carboxylic acids in the preparation of inclusion complexes with features of nanocapsules has been found. The prospects of using β-cyclodextrin for encapsulation of benzene carboxylic acids have been demonstrated. The complexes of β-cyclodextrin with benzene carboxylic acids were synthesized and studied by IR spectroscopy, X-ray analysis and derivatography. The formation of two types of complexes in the β-cyclodextrin – benzene carboxylic acid system was established. The first type of complexes is formed due to nonspecific interactions between the hydrophobic cavity of β-cyclodextrin and the benzene carboxylic acid molecule, the second type is due to specific interactions between the functional groups of molecules. Benzoic and salicylic acids form nanocapsules with β-cyclodextrin, and their hydrolytic and thermal stability increases. Complexes of the second type acquire the properties of a new compound: β-resorcylic acid loses its individuality, forming strong supramolecular structures with β-cyclodextrin.
28
Kazlauskaite, Jurga Andreja, Liudas Ivanauskas e Jurga Bernatoniene. "Cyclodextrin-Assisted Extraction Method as a Green Alternative to Increase the Isoflavone Yield from Trifolium pratensis L. Extract". Pharmaceutics 13, n. 5 (26 aprile 2021): 620. http://dx.doi.org/10.3390/pharmaceutics13050620.
Testo completoAbstract (sommario):
Trifolium pratense L. is receiving increasing attention due to the isoflavones it contains, which have been studied for their benefits to human health. A common problem with isoflavone aglycones is a rather low water solubility and limited pharmaceutical applications. The use of excipients, such as cyclodextrins in the production of isoflavone rich extracts, could become one of the new strategies for the extraction of target compounds. The aim of this study was to evaluate an eco-friendly method using the effects of α-, β- and γ-cyclodextrins for isoflavone solubilization in plant extracts in comparison to a standard extract without excipients. Extractions of red clover were prepared using ultrasound-assisted combined with thermal hydrolysis and heat reflux. It was determined that cyclodextrins significantly increased the isoflavones aglycone yields. By increasing cyclodextrins in the extraction media from 1 to 5%, the daidzin concentration increased on average by 1.06 (α-cyclodextrins), 1.4 (β-cyclodextrins) and 1.25 (γ-cyclodextrins) times. Genistein concentration increased using α- and γ-cyclodextrins (1.28 and 1.12 times, α- and γ-cyclodextrins, respectively), but decreased using β-cyclodextrins. The results showed that the cyclodextrin-assisted extraction enhanced the yields of isoflavones from red clover, which suggests using cyclodextrins as a green alternative and a cost-effective method to increase its pharmaceutical application.
29
Yannakopoulou, Konstantina, Laszlo Jicsinszky, Crysie Aggelidou, Nikolaos Mourtzis, Tanisha M. Robinson, Adiamseged Yohannes, Ekaterina M. Nestorovich, Sergey M. Bezrukov e Vladimir A. Karginov. "Symmetry Requirements for Effective Blocking of Pore-Forming Toxins: Comparative Study with α-, β-, and γ-Cyclodextrin Derivatives". Antimicrobial Agents and Chemotherapy 55, n. 7 (9 maggio 2011): 3594–97. http://dx.doi.org/10.1128/aac.01764-10.
Testo completoAbstract (sommario):
ABSTRACTWe compared the abilities of structurally related cationic cyclodextrins to inhibitBacillus anthracislethal toxin andStaphylococcus aureusα-hemolysin. We found that both β- and γ-cyclodextrin derivatives effectively inhibited anthrax toxin action by blocking the transmembrane oligomeric pores formed by the protective antigen (PA) subunit of the toxin, whereas α-cyclodextrins were ineffective. In contrast, α-hemolysin was selectively blocked only by β-cyclodextrin derivatives, demonstrating that both symmetry and size of the inhibitor and the pore are important.
30
Kazlauskaite, Jurga Andreja, Liudas Ivanauskas, Mindaugas Marksa e Jurga Bernatoniene. "The Effect of Traditional and Cyclodextrin-Assisted Extraction Methods on Trifolium pratense L. (Red Clover) Extracts Antioxidant Potential". Antioxidants 11, n. 2 (21 febbraio 2022): 435. http://dx.doi.org/10.3390/antiox11020435.
Testo completoAbstract (sommario):
Red clover is the subject of numerous studies because of its antioxidant properties, the positive influence of isoflavones on the health, and its potential use in the prevention and treatment of chronic diseases. The right excipients, such as cyclodextrins, can increase the profile of valuable phenolic compounds in extraction media to obtain rich in antioxidants, extracts that can be used in nutraceuticals production. The aim of this study was to investigate and compare the total phenolic content, flavonoid content, and antioxidant activity of red clover aerial parts, aqueous and ethanolic extracts prepared using traditional and cyclodextrins-assisted methods. The antioxidant activity of the extracts was established using ABTS, DPPH, FRAP, and ABTS-post column methods. It was determined that cyclodextrins significantly increased total phenolic content (compared with control)—using β-cyclodextrin 20.29% (in aqueous samples); γ-cyclodextrin 22.26% (in ethanolic samples). All the samples prepared with excipients demonstrated a strong relationship between total phenolic content and DPPH assay. Study showed that for extraction with water, the highest amounts of phenolic compounds, flavonoids and antioxidant activity will be achieved with β-cyclodextrin, but extractions with ethanol will give the best results with γ-cyclodextrin. Therefore, cyclodextrins are a great and safe tool for obtaining rich, red clover flower extracts that are high in antioxidant activity, which can be used in the pharmaceutical industry for nutraceuticals production.
31
Delyagina, E. S., A. A. Garibyan e I. V. Terekhova. "Comparative Analysis of the Effect of Native and Polymeric β-Cyclodextrins on the Solubility and Membrane Permeability of Baricitinib". Журнал физической химии 97, n. 8 (1 agosto 2023): 1218–24. http://dx.doi.org/10.31857/s0044453723080046.
Testo completoAbstract (sommario):
A study is performed of the effect native and polymeric β-cyclodextrins have on the solubility and membrane permeability of baricitinib, a new generation immunomodulator. It is found that native and polymeric β-cyclodextrins exhibit the same solubilizing effect in relation to baricitinib, while their effect on the membrane permeability of the drug differs. The increased solubility of baricitinib is due to the formation of inclusion complexes that have the same stability but are enthalpy-entropy stabilized in native β-cyclodextrin and enthalpy stabilized in polymeric β-cyclodextrin. The effect cyclodextrins on baricitinib’s coefficients of permeability of through a model membrane is discussed in terms of complexation, changes in the viscosity of the medium, and the state of the water boundary layer near the membrane’s surface.
32
Rusznyák, Ágnes, Mercédesz Palicskó, Milo Malanga, Éva Fenyvesi, Lajos Szente, Judit Váradi, Ildikó Bácskay et al. "Cellular Effects of Cyclodextrins: Studies on HeLa Cells". Molecules 27, n. 5 (28 febbraio 2022): 1589. http://dx.doi.org/10.3390/molecules27051589.
Testo completoAbstract (sommario):
Cyclodextrins are high molecular weight, hydrophilic, cyclic, non-reducing oligosaccharides, applied as excipients for the improvement of the solubility and permeability of insoluble active pharmaceutical ingredients. On the other hand, beta-cyclodextrins are used as cholesterol sequestering agents in life sciences. Recently, we demonstrated the cellular internalization and intracellular effects of cyclodextrins on Caco-2 cells. In this study, we aimed to further investigate the endocytosis of (2-hydroxylpropyl)-beta-(HPBCD) and random methylated-beta-cyclodextrin (RAMEB) to test their cytotoxicity, NF-kappa B pathway induction, autophagy, and lysosome formation on HeLa cells. These derivatives were able to enter the cells; however, major differences were revealed in the inhibition of their endocytosis compared to Caco-2 cells. NF-kappa B p65 translocation was not detected in the cell nuclei after HPBCD or RAMEB pre-treatment and cyclodextrin treatment did not enhance the formation of autophagosomes. These cyclodextrin derivates were partially localized in lysosomes after internalization.
33
Musilová, Lenka, Aleš Mráček, Eduarda F. G. Azevedo, Artur J. M. Valente, Ana M. T. D. P. V. Cabral, Ana C. F. Ribeiro e Miguel A. Esteso. "Interactions between Sodium Hyaluronate and β-Cyclodextrin as Seen by Transport Properties". International Journal of Molecular Sciences 24, n. 3 (2 febbraio 2023): 2889. http://dx.doi.org/10.3390/ijms24032889.
Testo completoAbstract (sommario):
Knowledge of mass transport parameters, diffusion, and viscosity of hyaluronic acid (HA) in the presence of cyclodextrins is of considerable importance for areas such as food packaging and drug delivery, among others. Despite a number of studies investigating the functionalization of HA or the corresponding sodium salt by cyclodextrins, only a few studies have reported the effect of cyclodextrins on the mass transport of HA in the presence of these oligosaccharides. Here, we report the tracer binary and ternary interdiffusion coefficients of sodium hyaluronate (NaHy) in water and aqueous β-cyclodextrin solutions. The diffusion behavior of sodium hyaluronate was dependent on the reduced viscosity of NaHy, which, in turn, presented a concave dependence on concentration, with a minimum at approximately 2.5 g dm−3. The significant decrease in the limiting diffusion coefficient of NaHy (at most 45%) at NaHy concentrations below 1 g dm−3 in the presence of β-cyclodextrin, taking water as the reference, allowed us to conclude that NaHy strongly interacted with the cyclodextrin.
34
Rassu, Giovanna, Silvia Fancello, Marta Roldo, Milo Malanga, Lajos Szente, Rossana Migheli, Elisabetta Gavini e Paolo Giunchedi. "Investigation of Cytotoxicity and Cell Uptake of Cationic Beta-Cyclodextrins as Valid Tools in Nasal Delivery". Pharmaceutics 12, n. 7 (12 luglio 2020): 658. http://dx.doi.org/10.3390/pharmaceutics12070658.
Testo completoAbstract (sommario):
Cyclodextrin polymers have high applicability in pharmaceutical formulations due to better biocompatibility, solubility enhancement, loading capacity and controlled drug release than their parent, cyclodextrins. The cytotoxicity and cell uptake of new cationic beta-cyclodextrin monomers and polymers were evaluated as suitable materials for nasal formulations and their protective effects on cells exposed to hydrogen peroxide were studied. PC12 and CACO-2 cells were selected as the neuronal- and epithelial-type cells, respectively, to mimic the structure of respiratory and olfactory epithelia of the nasal cavity. All cationic beta-cyclodextrin polymers tested showed dose- and time-dependent toxicity; nevertheless, at 5 µM concentration and 60 min of exposure, the quaternary-ammonium-beta-cyclodextrin soluble polymer could be recognized as nontoxic. Based on these results, a fluorescently labelled quaternary-ammonium-beta-cyclodextrin monomer and polymer were selected for uptake studies in CACO-2 cells. The monomeric and polymeric beta-cyclodextrins were internalized in the cytoplasm of CACO-2 cells; the cationic monomer showed higher permeability than the hydroxypropyl-beta-cyclodextrin, employed as comparison. Therefore, these cationic beta-cyclodextrins showed potential as excipients able to improve the nasal absorption of drugs. Furthermore, amino-beta-cyclodextrin and beta-cyclodextrin soluble polymers were able to reduce oxidative damage in PC12 and CACO-2 cells and thus could be studied as bioactive carriers or potential drugs for cell protection against oxidative stress.
35
Li, Shujing, Li Yuan, Bing Zhang, Wei Zhou, Xinrui Wang e Dongsheng Bai. "Photostability and antioxidant activity studies on the inclusion complexes of trans-polydatin with β-cyclodextrin and derivatives". RSC Advances 8, n. 46 (2018): 25941–48. http://dx.doi.org/10.1039/c8ra04778b.
Testo completo
36
Rusznyák, Ágnes, Milo Malanga, Éva Fenyvesi, Lajos Szente, Judit Váradi, Ildikó Bácskay, Miklós Vecsernyés et al. "Investigation of the Cellular Effects of Beta- Cyclodextrin Derivatives on Caco-2 Intestinal Epithelial Cells". Pharmaceutics 13, n. 2 (25 gennaio 2021): 157. http://dx.doi.org/10.3390/pharmaceutics13020157.
Testo completoAbstract (sommario):
Cyclodextrins are widely used excipients for increasing water-solubility, delivery and bioavailability of lipophilic drugs. By using fluorescent cyclodextrin derivatives, we showed previously that cyclodextrins are able to enter Caco-2 intestinal cells by endocytosis, but the influence of different fluorescent labeling on the same cyclodextrin derivative has not been studied. The consequences of the cellular internalization of cyclodextrins have not been revealed yet either. The aims of this study were to compare the cellular internalization of fluorescein- and rhodamine-labeled (2-hydroxypropyl)-, (HPBCD) and randommethyl-β-cyclodextrins (RAMEB) and to investigate the intracellular effects of these derivatives on Caco-2 cells. Stimulation of the NF-kappa B pathway and autophagy and localization of these derivatives in lysosomes were tested. The endocytosis of these derivatives was examined by fluorescence microscopy and flow cytometry. Both fluorescein- and rhodamine-labeled derivatives entered the cells, therefore the type of the fluorescent labeling did not influence their internalization. Cyclodextrin pretreatment did not activate the translocation of the p65 subunit of the NF-kappa B heterodimer into the cell nuclei from the cytoplasm. After HPBCD or RAMEB treatment, formation of the autophagosomes did not increase compared to the control sample and at the same time these derivatives could be detected in lysosomes after internalization.
37
Lemli, Beáta, Péter Vilmányi, Eszter Fliszár-Nyúl, Balázs Zoltán Zsidó, Csaba Hetényi, Lajos Szente e Miklós Poór. "Testing Serum Albumins and Cyclodextrins as Potential Binders of the Mycotoxin Metabolites Alternariol-3-Sulfate, Alternariol-9-Monomethylether and Alternariol-9-Monomethylether-3-Sulfate". International Journal of Molecular Sciences 23, n. 22 (18 novembre 2022): 14353. http://dx.doi.org/10.3390/ijms232214353.
Testo completoAbstract (sommario):
Alternaria mycotoxins, including alternariol (AOH), alternariol-9-monomethylether (AME), and their masked/modified derivatives (e.g., sulfates or glycosides), are common food contaminants. Their acute toxicity is relatively low, while chronic exposure can lead to the development of adverse health effects. Masked/modified metabolites can probably release the more toxic parent mycotoxin due to their enzymatic hydrolysis in the intestines. Previously, we demonstrated the complex formation of AOH with serum albumins and cyclodextrins; these interactions were successfully applied for the extraction of AOH from aqueous matrices (including beverages). Therefore, in this study, the interactions of AME, alternariol-3-sulfate (AS), and alternariol-9-monomethylether-3-sulfate (AMS) were investigated with albumins (human, bovine, porcine, and rat) and with cyclodextrins (sulfobutylether-β-cyclodextrin, sugammadex, and cyclodextrin bead polymers). Our major results/conclusions are the following: (1) The stability of mycotoxin–albumin complexes showed only minor species dependent variations. (2) AS and AMS formed highly stable complexes with albumins in a wide pH range, while AME–albumin interactions preferred alkaline conditions. (3) AME formed more stable complexes with the cyclodextrins examined than AS and AMS. (4) Beta-cyclodextrin bead polymer proved to be highly suitable for the extraction of AME, AS, and AMS from aqueous solution. (5) Albumins and cyclodextrins are promising binders of the mycotoxins tested.
38
ZHEKOVA, BORIANA Y., e VESELIN S. STANCHEV. "Reaction Conditions for Maximal Cyclodextrin Production by Cyclodextrin Glucanotransferase from Bacillus megaterium". Polish Journal of Microbiology 60, n. 2 (2011): 113–18. http://dx.doi.org/10.33073/pjm-2011-015.
Testo completoAbstract (sommario):
The effect of the reaction conditions (substrate concentration, enzyme dosage, and pH) on cyclodextrin production by cyclodextrin glucanotransferase from Bacillus megaterium was investigated by applying mathematical modeling methods. Adequate models were developed and they were used for determination of the optimal conditions for maximal formation of beta-cyclodextrins at minimal concentrations of a- and gamma-cydclodextrins. The main factor affecting the ratio of the products was pH of the reaction mixture. At pH 9 the enzyme formed mainly beta- and y-cyclodextrins and the ratio a:beta:gamma was 2.6:83.5:13.9; at pH 5 the ratio changed to 8.6:84.6:6.8. Mathematical models were used for determination of the conditions for maximal conversion of the substrate into cyclodextrins. 45.88% conversion of starch was achieved at 5% substrate concentration, 3.5 U/g enzyme dosage, and pH 7.4.
39
Jessen, Cecilie Høgfeldt, Jesper Bendix, Theis Brock Nannestad, Heloisa Bordallo, Martin Jæger Pedersen, Christian Marcus Pedersen e Mikael Bols. "CO2 complexation with cyclodextrins". Beilstein Journal of Organic Chemistry 19 (17 luglio 2023): 1021–27. http://dx.doi.org/10.3762/bjoc.19.78.
Testo completoAbstract (sommario):
Carbon dioxide (CO2) emissions from industrial processes, power generation, and transportation contribute significantly to global warming and climate change. Carbon capture and storage (CCS) technologies are essential to reduce these emissions and mitigate the effects of climate change. Cyclodextrins (CDs), cyclic oligosaccharides, are studied as potential CO2 capture agents due to their unique molecular structures and high selectivity towards CO2. In this paper we have investigated binding efficiency of a number of cyclodextrins towards CO2. It is found that the crystal structure of α-cyclodextrin with CO2 has a 1:1 stoichioimetry and that a number of simple and modified cyclodextrins bind CO2 in water with a Kg of 0.18–1.2 bar−1 (7–35 M−1) with per-O-methyl α-cyclodextrin having the highest CO2 affinity.
40
Kean, Suzanna D., Christopher J. Easton e Stephen F. Lincoln. "Metallo-β-cyclodextrins of 6A-(2-(2-(2-Aminoethylamino)-ethylamino)ethylamino)-6A-deoxy-β-cyclodextrin and 6A-Deoxy-6A-(1,4,7,10-tetraazacyclododecan-1-yl)-β-cyclodextrin: Their Formation and Complexation of (R)- and (S)-Tryptophan and Tryptophanate in Aqueous Solution". Australian Journal of Chemistry 53, n. 5 (2000): 375. http://dx.doi.org/10.1071/ch00052.
Testo completoAbstract (sommario):
The binary metallo-β-cyclodextrins formed by 6A-(2-(2-(2-aminoethylamino)ethylamino)ethylamino)-6A-deoxy-β-cyclodextrin, [M(βCDtrien)]2+, where M2+ = Ni2+, Cu2+ and Zn2+, are characterized by log(K/dm3 mol-1) = 11.500.02, 10.700.07 and 9.400.01, respectively, in aqueous solution at 298.2 K and I = 0.1 mol dm-3 (NaClO4), where K is the stability constant. For those formed by 6A-deoxy-6A-(1,4,7,10-tetraazacyclododecan-1-yl)-β-cyclodextrin, [M(βCDcyclen)]2+, where M2+ = Cu2+ and Zn2+, log(K/dm3 mol-1) = 13.610.02 and 11.620.04, respectively. The ternary metallo-β-cyclodextrins formed by [M(βCDtrien)]2+ and (R)- and (S)-tryptophanate, [M(βCDtrien)((R)-Trp)]+ and [M(βCDtrien)((S)-Trp)]+ are characterized by log(K/dm3 mol-1) = 6.900.04 and 6.790.04, 8.20.3 and 7.90.2, and 6.640.08 and 7.010.07, respectively, where M2+ = Ni2+, Cu2+ and Zn2+. For the ternary metallo-β-cyclodextrins formed by [M(βCDcyclen)]2+ and (R)- and (S)-tryptophanate, [M(βCDcyclen)((R)-Trp)]+ and [M(βCDcyclen)((S)-Trp)]+, log(K/dm3 mol-1) = 6.840.06 and 6.850.06, and 4.950.05 and 4.940.04, respectively, where M2+ = Cu2+ and Zn2+. Other binary and ternary metallo-β-cyclo-dextrins are also formed. Binary complexes formed by the substituted β-cyclodextrins are exemplified by βCDcyclen.(R)-Trp- and βCDcyclen.(S)-Trp- for which log(Kd/m3 mol-1) = 3.690.04 and 3.950.03, respectively. These data are discussed together with those from the literature characterizing other metallo-β-cyclodextrin and substituted β-cyclodextrin systems.
41
Dumanski, Paul G., Christopher J. Easton, Stephen F. Lincoln e Jamie S. Simpson. "Effect of Cyclodextrins on Electrophilic Aromatic Bromination in Aqueous Solution". Australian Journal of Chemistry 56, n. 11 (2003): 1107. http://dx.doi.org/10.1071/ch03102.
Testo completoAbstract (sommario):
Cyclodextrins act as molecular reactors to change the ratios of the products of reactions of anisole, acetanilide, 3-methylanisole, and 3-methylacetanilide with pyridinium dichlorobromate. With anisole and acetanilide, bromination at the para position is favoured over ortho substitution, and the effect is greatest with α-cyclodextrin. In the reactions of the methylanisole and methylacetanilide, the cyclodextrins afford higher yields of monobrominated products and less of the di- and tribromides, and β-cyclodextrin has the greatest effect. These outcomes can be attributed to inclusion of the substrates within the cyclodextrins restricting access of the reagent adjacent to the methoxy and acetamido groups. The yields of 4-bromoanisole, 4-bromoacetanilide, 4-bromo-3-methylanisole, and 4-bromo-3-methylacetanilide are thus increased from 73 to 94, 55 to 98, 37 to 86, and 39 to 72%, respectively. Perhaps more significantly, the quantities of the corresponding by-products are substantially reduced, from 27 to 6, 45 to 2, 63 to 14, and 61 to 28%. Since the reactions occur readily in water at ambient temperature, the cyclodextrins make them very efficient.
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Rajput, Kiransinh N., Kamlesh C. Patel e Ujjval B. Trivedi. "β-Cyclodextrin Production by Cyclodextrin Glucanotransferase from an Alkaliphile Microbacterium terrae KNR 9 Using Different Starch Substrates". Biotechnology Research International 2016 (25 agosto 2016): 1–7. http://dx.doi.org/10.1155/2016/2034359.
Testo completoAbstract (sommario):
Cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) is an important member of α-amylase family which can degrade the starch and produce cyclodextrins (CDs) as a result of intramolecular transglycosylation (cyclization). β-Cyclodextrin production was carried out using the purified CGTase enzyme from an alkaliphile Microbacterium terrae KNR 9 with different starches in raw as well as gelatinized form. Cyclodextrin production was confirmed using thin layer chromatography. Six different starch substrates, namely, soluble starch, potato starch, sago starch, corn starch, corn flour, and rice flour, were tested for CD production. Raw potato starch granules were found to be the best substrate giving 13.46 gm/L of cyclodextrins after 1 h of incubation at 60°C. Raw sago starch gave 12.96 gm/L of cyclodextrins as the second best substrate. To achieve the maximum cyclodextrin production, statistical optimization using Central Composite Design (CCD) was carried out with three parameters, namely, potato starch concentration, CGTase enzyme concentration, and incubation temperature. Cyclodextrin production of 28.22 (gm/L) was achieved with the optimized parameters suggested by the model which are CGTase 4.8 U/L, starch 150 gm/L, and temperature 55.6°C. The suggested optimized conditions showed about 15% increase in β-cyclodextrin production (28.22 gm/L) at 55.6°C as compared to 24.48 gm/L at 60°C. The degradation of raw potato starch granules by purified CGTase was also confirmed by microscopic observations.
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Kontogiannidou, Eleni, Martina Ferrari, Asteria-Danai Deligianni, Nikolaos Bouropoulos, Dimitrios A. Andreadis, Milena Sorrenti, Laura Catenacci et al. "In Vitro and Ex Vivo Evaluation of Tablets Containing Piroxicam-Cyclodextrin Complexes for Buccal Delivery". Pharmaceutics 11, n. 8 (8 agosto 2019): 398. http://dx.doi.org/10.3390/pharmaceutics11080398.
Testo completoAbstract (sommario):
In the current study, the development of mucoadhesive tablets for buccal delivery of a non-steroidal anti-inflammatory drug was investigated. Binary complexes with piroxicam and cyclodextrins (β-cyclodextrin (β-CD), methylated-β-cyclodextrin (Me-β-CD), and hydroxypropyl-β-cyclodextrin (HP-β-CD)) were prepared by the co-evaporation method. All formulations were characterized by means of differential scanning calorimetry, infrared spectroscopy and powder X-ray diffractometry. Mucoadhesive tablets of binary systems were formulated by direct compression using chitosan as mucoadhesive polymer. The in vitro release profiles of tablets were conducted in simulated saliva and, the drug permeation studies, across porcine buccal mucosa. The results suggest that the rank order effect of cyclodextrins for the drug release was Me-β-CD > HP-β-CD > β-CD, whereas the ex vivo studies showed that the tablets containing chitosan significantly increased the transport of the drug compared to their free complexes. Finally, histological assessment revealed loss of the superficial cell layers, which might be attributed to the presence of cyclodextrins.
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Meier-Augenstein, Wolfram, Barend V. Burger, Hendrik S. C. Spies e Wina J. G. Burger. "Conformational Analyses of Alkylated β-Cyclodextrins by NMR Spectroscopy". Zeitschrift für Naturforschung B 47, n. 6 (1 giugno 1992): 877–86. http://dx.doi.org/10.1515/znb-1992-0618.
Testo completoAbstract (sommario):
β-Cyclodextrin was derivatized with 1-bromoalkanes of different chain lengths. The yield as well as the purity of the resulting cyclodextrin derivatives were improved by using solvent mixtures instead of pure solvents. The heptakis(2,6-di-O-alkyl)- and heptakis(2,3,6-tri-O-alkyl)-β-cyclodextrins were studied by means of NMR spectroscopy employing one-dimensional as well as two-dimensional NMR techniques. Analysis of the NMR data showed that only in completely derivatized β-cyclodextrins the cyclodextrin torus undergoes a conformational change. Best separation factors were found for the cyclodextrin derivative with the highest internal mobility as determined from the corresponding NT1-values, the validity of which was confirmed by NOE determinations. Therefore, 13C relaxation times could be used as a measure of the efficiency and usefulness of a given cyclodextrin derivative as an enantioselective stationary phase.
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Poulson, Benjamin Gabriel, Qana A. Alsulami, Abeer Sharfalddin, Emam F. El Agammy, Fouzi Mouffouk, Abdul-Hamid Emwas, Lukasz Jaremko e Mariusz Jaremko. "Cyclodextrins: Structural, Chemical, and Physical Properties, and Applications". Polysaccharides 3, n. 1 (28 dicembre 2021): 1–31. http://dx.doi.org/10.3390/polysaccharides3010001.
Testo completoAbstract (sommario):
Due to their unique structural, physical and chemical properties, cyclodextrins and their derivatives have been of great interest to scientists and researchers in both academia and industry for over a century. Many of the industrial applications of cyclodextrins have arisen from their ability to encapsulate, either partially or fully, other molecules, especially organic compounds. Cyclodextrins are non-toxic oligopolymers of glucose that help to increase the solubility of organic compounds with poor aqueous solubility, can mask odors from foul-smelling compounds, and have been widely studied in the area of drug delivery. In this review, we explore the structural and chemical properties of cyclodextrins that give rise to this encapsulation (i.e., the formation of inclusion complexes) ability. This review is unique from others written on this subject because it provides powerful insights into factors that affect cyclodextrin encapsulation. It also examines these insights in great detail. Later, we provide an overview of some industrial applications of cyclodextrins, while emphasizing the role of encapsulation in these applications. We strongly believe that cyclodextrins will continue to garner interest from scientists for many years to come, and that novel applications of cyclodextrins have yet to be discovered.
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Varan, Gamze. "Cyclodextrin in Vaccines: Enhancing Efficacy and Stability". Future Pharmacology 3, n. 3 (24 agosto 2023): 597–611. http://dx.doi.org/10.3390/futurepharmacol3030038.
Testo completoAbstract (sommario):
Cyclodextrins, a family of cyclic oligosaccharides, have received considerable interest in the field of pharmaceuticals due to their unique molecular structure and versatile properties. In the context of vaccines, cyclodextrins can effectively encapsulate antigens, ensuring their protection from degradation and improving their immunogenicity. Cyclodextrins offer stability advantages to vaccines by preventing the degradation of labile vaccine components during storage and transportation. Furthermore, cyclodextrins can serve as adjuvants, potentiating the immune response triggered by vaccines. Their unique structure and interaction with the immune system enhance the recognition of antigens by immune cells, leading to an improved activation of both innate and adaptive immune responses. This adjuvant effect contributes to the development of robust and long-lasting immune protection against targeted pathogens. Owing to the distinctive attributes inherent to nanoparticles, their integration into vaccine formulations has assumed an imperative role. Through the encapsulation of vaccine antigens/adjuvants within cyclodextrin nanoparticles, the potency and stability of vaccines can be notably enhanced. In particular, the capacity of amphiphilic cyclodextrins to form nanoparticles through self-assembly without surfactants or co-solvents is a captivating prospect for their application as carrier systems for antigens. In conclusion, cyclodextrins present a promising platform for enhancing the efficacy and stability of vaccines. Their ability to encapsulate antigens, stabilize labile vaccine components and act as adjuvants demonstrates their potential to revolutionize vaccine formulation and delivery. Further research and development in this field will facilitate the translation of cyclodextrin-based vaccine technologies into practical and impactful immunization strategies, ultimately benefiting global health and disease prevention.
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Braga, Susana Santos, Jéssica S. Barbosa, Nádia E. Santos, Firas El-Saleh e Filipe A. Almeida Paz. "Cyclodextrins in Antiviral Therapeutics and Vaccines". Pharmaceutics 13, n. 3 (19 marzo 2021): 409. http://dx.doi.org/10.3390/pharmaceutics13030409.
Testo completoAbstract (sommario):
The present review describes the various roles of cyclodextrins (CDs) in vaccines against viruses and in antiviral therapeutics. The first section describes the most commonly studied application of cyclodextrins—solubilisation and stabilisation of antiviral drugs; some examples also refer to their beneficial taste-masking activity. The second part of the review describes the role of cyclodextrins in antiviral vaccine development and stabilisation, where they are employed as adjuvants and cryopreserving agents. In addition, cyclodextrin-based polymers as delivery systems for mRNA are currently under development. Lastly, the use of cyclodextrins as pharmaceutical active ingredients for the treatment of viral infections is explored. This new field of application is still taking its first steps. Nevertheless, promising results from the use of cyclodextrins as agents to treat other pathologies are encouraging. We present potential applications of the results reported in the literature and highlight the products that are already available on the market.
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Djordjevic, Dragan, Mile Novakovic e Sandra Konstantinovic. "The application of cyclodextrins in textile area". Chemical Industry 60, n. 9-10 (2006): 259–68. http://dx.doi.org/10.2298/hemind0610259d.
Testo completoAbstract (sommario):
The application of Cyclodextrins for textiles was reviewed in this paper. Cyclodextrins are crystalline, water soluble, cyclic, non-reducing oligosaccharides consisting of six, seven, or eight glucopyranose units. Cyclodextrins are known as products which are able to form inclusion complexes. The ability of Cyclodextrins to form inclusion complexes can be used, e.g., to remove malodor from textile materials, etc. Furthermore, some modifications of the parent Cyclodextrins are possible. The derivatives can be reactive (e.g. cyclodextrin with a monochlorotriazinyl group), more hydrophilic (by means of hydrophilic side groups, such as hydroxypropyl and hydroxyethyl), less hydrophilic (by means of lipophilic side groups, such as ethylhexyl glycidyl) or ionic (by means of ionic side groups, such as hydroxypropyl trimethyl ammonium chloride).The methods for treating textiles are thus quite simple. The method using anchor-bearing Cyclodextrins is especially useful, since no fixation agent is needed, enabling they use of conventional textile treatment techniques and equipment. Furthermore, this method has virtually no limitations with respect to the textile materials that can be used.
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Seilkhanov, Tulegen M., Assel Yu Ten, Khaidar S. Tassibekov, Olzhas T. Seilkhanov, Tolganay Ye Zharkynbek, Bagila G. Tursynova e Valentina K. Yu. "Supramolecular cyclodextrin complexes of biologically active nitrogen heterocycles". Chemical Bulletin of Kazakh National University 112, n. 3 (8 ottobre 2024): 22–33. http://dx.doi.org/10.15328/cb1379.
Testo completoAbstract (sommario):
The review is devoted to the rapidly developing field of modern supramolecular chemistry - cyclodextrin complexes of biologically active nitrogen heterocycles, such as piperidines, piperazines, morpholines and pyridines. Interest in cyclodextrin complexes is growing due to the search and construction of supramolecular assemblies for targeted drug delivery. The latter is achieved as a result of supramolecular self-assembly, based on the principles of molecular recognition, and is one of the areas of modern chemistry, leading to the creation of new materials with new properties. This review fully demonstrates the ongoing scientific and practical interest in the problem of encapsulation with cyclodextrins, including nanoencapsulation. Encapsulation with cyclodextrins provides a wide range of advantages: obtaining solid dosage forms from liquid ones, stabilizing and protecting active substances from the adverse effects of external factors, increasing solubility, increasing bioavailability, reducing toxicity, prolonging action, etc. The presented review includes recent advances in the field of supramolecular complexes of biologically active nitrogen heterocycles with cyclodextrins and concludes with a discussion and identification of future promising directions for research. The review presents the results of supramolecular self-assembly of biologically active azaheterocycles with cyclodextrins.
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Welliver, Mark, e John P. McDonough. "Anesthetic Related Advances with Cyclodextrins". Scientific World JOURNAL 7 (2007): 364–71. http://dx.doi.org/10.1100/tsw.2007.83.
Testo completoAbstract (sommario):
Cyclodextrins encapsulate and electrostatically bind to lipophilic molecules. The exterior of cyclodextrins are water-soluble and maintain aqueous solubility despite encapsulation of non-aqueous soluble molecules. This unique ability to encapsulate lipophilic molecules and maintain water solubility confers numerous pharmacologic advantages for both drug delivery and removal. Cyclodextrins, a component part of supramolecular chemistry, may be in its infancy of anesthetic application but recent advances have been described as novel and revolutionary. A review of current research coupled with an understanding of cyclodextrin properties is necessary to fully appreciate the current uses and future potentials of these unique molecules.