Types Of Cyclodextrins Research Articles

Combination of large volume sample stacking with polarity switching and cyclodextrin electrokinetic chromatography (LVSS-PS-CDEKC) for the determination of selected preservatives in pharmaceuticals

In this study, a large volume sample stacking (LVSS) with polarity switching (PS) and cyclodextrin electrokinetic chromatography (CDEKC) method has been developed for the simultaneous separation and determination of 8 preservatives: methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), isobutylparaben (IBP), sorbic acid (SA), benzoic acid (BA), p-hydroxybenzoic acid (PHBA) in pharmaceuticals. The effects of some typical parameters such as sample volume, applied voltage, composition and pH of the running buffer and organic modifier concentration were examined and optimized. Moreover, the impact of type and concentration of cyclodextrin as electrolyte modifiers was also investigated. The detection limits of analytes for the elaborated LVSS-PS-CDEKC method were found to be in 0.8–5 ng mL−1 range, which were around 500 times lower than normal CDEKC without preconcentration technique. All analytes were completely resolved in less than 11 min in an uncoated fused-silica capillary of 75 μm internal diameter (I.D) x 50 cm length. The electrophoretic separation was performed in a 2 mM α-cyclodextrin and 25 mM tetraborate system (pH = 9.3) with an applied voltage of 25 kV. The established method was validated and confirmed to be applicable for the determination of the preservatives in a quality control of pharmaceuticals.

Eco-Friendly Tadalafil Surfactant-Free Dry Emulsion Tablets (SFDETs) Stabilized by In Situ Self-Assembled Aggregates of Natural Oil and Native Cyclodextrins.

The main principles of green chemistry and engineering were extended to pharmaceutical formulations to prepare eco-friendly surfactant-free dry emulsion tablets (SFDETs) devoid of solvents or synthetic surfactants. Surfactant-free emulsions were stabilized by in situ cyclodextrins/sweet almond oil inclusion complexes and assessed for creaming stability. Formulation variables' effects on the emulsion droplet size and tadalafil solubility were studied using 22 × 3 factorial design. The emulsions exhibited nanometric and micrometric droplet sizes. The optimized nanoemulsion was loaded with tadalafil, morphologically evaluated, and utilized for preparing lyophilized SFDETs using different gelatin/Pearlitol® ratios. The tablets were characterized and the selected formulation was subjected to storage for 6months. The emulsions prepared using β-cyclodextrin or higher concentrations of α-cyclodextrin showed little or no phase separation. Statistical analysis revealed significant influence of cyclodextrin type and amount on droplet size, while cyclodextrin type and oil volume exhibited significant effect on drug solubility. Morphological examination revealed non-aggregated spherical emulsion droplets. The prepared tablets showed satisfactory mechanical strength, short disintegration times, and enhanced drug dissolution. The selected tablet formulation (gelatin/Pearlitol®, 4:2 w/w) showed acceptable stability at 25°C/60% relative humidity. An overall conclusion claims that the absence of surfactants is expected to minimize the proposed tablets' in vivo toxicity and environmental concerns.

Complex systems that incorporate cyclodextrins to get materials for some specific applications

Cyclodextrins (CDs) are a family of biodegradable cyclic hydrocarbons composed of α-(1,4) linked glucopyranose subunits, the more common containing 6, 7 or 8 glucose units are named α, β and γ-cyclodextrins respectively. Since the discovery of CDs, they have attracted interest among scientists and the first studies were about the properties of the native compounds and in particular their use as catalysts of organic reactions. Characteristics features of different types of cyclodextrins stimulated investigation in different areas of research, due to its non-toxic and non-inmunogenic properties and also to the development of an improved industrial production. In this way, many materials with important properties have been developed. This mini-review will focus on chemical systems that use cyclodextrins, whatever linked covalently or mediated by the non covalent interactions, to build complex systems developed mainly during the last five years.

Nanoencapsulation of Hydrophobic Food Flavor Ingredients and Their Cyclodextrin Inclusion Complexes

Preservation of hydrophobic, volatile, food flavor ingredients during processing is a foremost concern for food manufacturers. Nanoencapsulation is a method, which enables achieving enhanced thermal stability, solubility, and antioxidant activity of flavors. Among the available techniques for nanoencapsulation, electrohydrodynamic technique and encapsulation of flavors in nanofibers give the opportunity to achieve enhanced efficiency and higher surface-to-volume ratio, with a more compact size equipment and a cost-effective process. Cyclodextrins have the potential to be used as nanocarriers with the capability to form complexes with various non-polar flavor molecules. The formed cyclodextrin inclusion complexes (ICs) can be included into biopolymers or can be electrospun to form a polymer-free nanofiber. Natural and modified types of cyclodextrins can be applied for encapsulation and development of inclusion complexes with flavor molecules. Higher thermal stability was achievable with γ-CD-ICs in most of the studied cases, due to larger size of the cavity, and higher strength of the formed complex. From the modified types of cyclodextrins, formed ICs of Mβ-CD showed higher stability, due to rigid structure of the molecule and HPβ-CD enabled achieving higher antioxidant properties, due to less strength of the formed complex and possibility for hydrogen donation. In comparison with polymeric nanofibers, polymer-free systems enabled higher loading of flavors. Concluding from the reported studies, electrospun nanofibers prepared from flavors and their CD-ICs can give the possibility to achieve higher thermal stability, enhanced solubility, antioxidant, and antibacterial properties together with prolonged shelf life of foods and can be applied in food processing and packaging.

Influence of Inclusion Complexation and Skin Microporation on Enhancement of Transdermal Permeation of Raloxifene Hydrochloride

The aim of the present investigation was to develop an inclusion complex-based hydrogel for transdermal delivery of raloxifene hydrochloride. Inclusion complexation was tried using two types of cyclodextrins, β-cyclodextrin and hydroxypropyl-β-cyclodextrin. Kneading, co-precipitation, solvent evaporation and freeze drying were the methods explored for preparing inclusion complexs. The prepared complexes were characterized using differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray powder diffraction and both in vitro and ex vivo drug release studies. Kneading method was found to be the most suitable for preparing the inclusion complexes. Phase solubility studies indicated that β-cyclodextrin gave rise to Bs type of curve while hydroxypropyl-β-cyclodextrin resulted in Ap type of curve. The stability constants (K1:1) obtained for β-cyclodextrin and hydroxypropyl-β-cyclodextrin were 1572 and 2960, respectively. Complexation efficiency of hydroxypropyl-β-cyclodextrin was higher than that of β-cyclodextrin. Differential scanning calorimetry, Fourier transform infrared spectroscopy and X-ray powder diffraction studies indicated the superiority of hydroxypropyl-β-cyclodextrin for complexing raloxifene hydrochloride. In vitro and ex vivo studies showed that highest drug release occurred from inclusion complex prepared with hydroxypropyl-β-cyclodextrin with a ratio of 1:2.5. Histopathology studies revealed that the developed hydrogel was non-irritant and micropores were clearly visible for the microporated skin.

Preparation of Cyclodextrin Type Stationary Phase Based on Graphene Oxide and Its Application in Enantioseparation and Hydrophilic Interaction Chromatography

Abstract Graphene oxide (GO) was covalently coupled to the surface of amino silica gel by amide bond. β-cyclodextrin (β-CD) was further chemically bonded with GO to prepare a novel chiral stationary phase. The resulting material was characterized by Fourier transform-infrared (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental analysis and thermogravimetric analysis (TGA). The separation of seven enantiomers was improved in varying degrees. Meanwhile, the stationary phase showed typical characteristics of hydrophilic interaction chromatography (HILIC), and four small nucleoside molecules were separated with the mobile phase of methanol-acetonitrile-water (45:45:10, V/V) in the HILIC mode. In addition, the separation mechanism of the stationary phase was further explored by studying the effects of mobile phase composition, temperature and pH value on the analyte retention. The low temperature was conducive to the separation of analytes at 20–60 °C. The addition of protonated solvent methanol significantly decreased the retention time of the four analytes. The change of pH affected the degree of protonation of the analyte, the interaction between analytes and the stationary phase, and retention time of analytes. The results showed that GO and β-CD played a synergistic effect in the chiral resolution of the chromatographic stationary phase. The retention of analytes in HILIC was attributed to their mixed-mode retention mechanisms including hydrophilic interaction, electrostatic interaction, hydrogen bonding, π-π stacking and so on.

English

The aim of this study was to enhance the solubility and dissolution rate of sulfamethoxazole (SMZ) by preparing the inclusion complexes with β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HPβ-CD) and γ-cyclodextrin (γ-CD). The effect of the type of cyclodextrins used for the preparation of complexes, on the in vitro dissolution profiles and solubilities in different mediums (pH 4.5 and 7.0) was also evaluated. The interaction between SMZ and cyclodextrins in solution was studied by the phase-solubility method. Inclusion complexation was confirmed by the results from the studies of infrared spectoroscopy (IR) and differential scanning calorimetry (DSC). The effect of water-soluble polymers, that is, polyethylene glycols 4000, 10000, 20000 and non-ionic surfactants, that is, polysorbate 20, 40 and 60 on the complexation of SMZ with CDs were also investigated by the same methods. The rates of release of the active material from the complexes were determined from dissolution studies using USP XXII paddle method. As a result of this study, it was found that the solubility of SMZ was significantly enhanced by inclusion of β-CD, especially when the water soluble additives are added (from 0.086 to 0.377 mg/ml with SMZ:β-CD:PEG20000). Key words: Cyclodextrins, sulfamethoxazole, solubility, dissolution rate.

Valorization of Olive Pomace-Based Nutraceuticals as Antioxidants in Chemical, Food, and Biological Models.

Waste remaining after the production of olive oil (olive pomace) is known to contain significant amounts of phenolic compounds that exert different types of biological activities, primarily acting as antioxidants. In this work, a sustainable approach that combines ultrasound-assisted extraction with food-grade solvents and encapsulation with different types of cyclodextrins was used to prepare olive pomace-based polyphenol rich extracts that were tested as antioxidants in various chemical, food, and biological model systems. Encapsulation with cyclodextrins had a significant positive impact on the chemical composition of obtained extracts and it positively affected their antioxidant activity. Observed effects can be explained by an increased content of polyphenols in the formulations, specific physical properties of encapsulated compounds improving their antioxidant activity in complex food/physiological environment, and enhanced interaction with natural substrates. Depending on the applied model, the tested samples showed significant antioxidant protection in the concentration range 0.1–3%. Among the investigated cyclodextrins, hydroxypropyl-β-cyclodextrin and randomly methylated-β-cyclodextrin encapsulated extracts showed particularly good antioxidant activity and were especially potent in oil-in-water emulsion systems (1242 mg/g and 1422 mg/g of Trolox equivalents, respectively), showing significantly higher antioxidant activity than Trolox (reference antioxidant). In other models, they provided antioxidant protection comparable to commonly used synthetic antioxidants at concentration levels of 2–3%.

Complexation and enhancement of temozolomide solubility with cyclodextrins

ABSTRACT Temozolomide is a poorly soluble anti-cancer drug used in the treatment of some brain cancers. Following literature reports about the enhancement of solubility and stability for these kinds of drugs upon complexation with cyclodextrins, we aimed to form an inclusion complex between temozolomide and the different types of cyclodextrins (CDs) to enhance its solubility. In this study, three different cyclodextrins (β -CD, hydroxyl-β-CD and γ-CD) were used, and changes in solubility was measured by UV-Vis Spectroscopy and HPLC. Morphological changes upon complexation were shown by the Scanning Electron Microscope (SEM), and weight loss profiles with respect to temperatures which were unique to the compounds were shown by Thermogravimetric Analysis. Changes in heat release profiles were shown by Differential Scanning Calorimeter (DSC). Drug solubility was measured to be increased to around 25% for 1:1 molar ratio for all used CD complexations. Changes of morphology, heat release and weight loss profiles are consistent with the formation of an inclusion complex between CDs and temozolomide. In this study, success was shown in the enhancement of temozolomide solubility upon complexation with different types of CDs. It has been demonstrated that cyclodextrins can be used as complexing agents for poorly soluble anti-cancer drugs, increasing their solubility and hence drug availability.

Amisulpride-CD-Loaded Liposomes: Optimization and In Vivo Evaluation.

Amisulpride (AMS) is an atypical antipsychotic agent used for the treatment of schizophrenia. The effect of different variables, i.e., the type of cyclodextrins (CDs), ratio of drug/CDs, and type of loading on the prepared AMS-CD liposomes (single and double loaded) was studied by applying 23 full factorial design. Double-loaded liposomes are loaded with AMS-hydroxyl propyl-β-cyclodextrin (HP-β-CD) in the aqueous phase and free drug in the lipophilic bilayer, while single-loaded liposomes are loaded only with AMS-HP-β-CD in the aqueous phase. Entrapment efficiency, particle size, polydespersibility, and zeta potential were selected as dependent variables. Design Expert® software was used to obtain an optimized formulation with high entrapment efficiency (64.55 ± 1.27%), average particle size of 40.1 ± 2.77nm, polydespersibility of 0.44 ± 0.37, and zeta potential of - 48.8 ± 0.28. Optimized formula was evaluated for in vitro release, surface morphology and stability study was also conducted. AMS-HP-β-CD in double-loaded liposomes exhibited higher drug release than those in the conventional liposomes and in the single-loaded liposomes. The maximum plasma concentration (Cmax) of AMS in optimized AMS-HP-β-CD double-loaded liposomal formulation increased by 1.55- and 1.29-fold, as compared to the commercial tablets and conventional liposomes, respectively. However, the relative bioavailability of AMS double-loaded liposomes was 1.94- and 1.28-folds of commercial tablet and conventional liposomes, respectively.

Design, characterization and comparison of materials based on β and γ cyclodextrin covalently connected to microporous silica for environmental analysis

Determination of organic pollutants in environmental samples presents great difficulties due to the lack of sensitivity and selectivity in many of the existing analytical methods. In this work, the efficiency of materials based on silica structures containing bounded γ-cyclodextrin has been evaluated to determinate phenolic compounds and polycyclic aromatic hydrocarbons in air and water samples, respectively, in comparison with materials made of β-cyclodextrin. According to the results obtained for the material characterization, the new γ-cyclodextrin solid phase does not apparently present any porosity when used in air samples, but it has been shown to work efficiently for the preconcentration of polycyclic aromatic hydrocarbons in water, with recoveries around 80%. In addition, the use of the β-cyclodextrin material for phenolic compounds sampling can be highlighted with recoveries between 83% and 95%, and recoveries for 4-vinylphenol and 2-methoxy-4-vinylphenol have been especially improved in comparison with the use of materials containing trapped β-cyclodextrin in our previous researches. The observed phenomena can be explained on the basis of the analyte molecules size and the diameter of the cyclodextrin cavities, the influence of the cyclodextrin type in the material structure as well as on the interactions taking place with the pollutants and the influence of the matrix type in the retention and desorption mechanisms.

Comparative Enantioseparation of Amlodipine by HPLC and Capillary Electrophoresis

Abstract Objective: The purpose of this study was to separate the enantiomers of amlodipine by High Performance Liquid Chromatography (HPLC) using ovomucoid (OVM) as chiral selector, respectively by Capillary Electrophoresis (CE) using cyclodextrines and to evaluate the analytical performance of the both proposed methods. Material and methods: HPLC enantioseparation of amlodipine was performed on an HPLC Agilent Technologies 1100 series using as chiral stationary phase an Ultron ES OVM, 150x4.6 mm column with ovomucoid as chiral selector. The stereoselective CE analysis of amlodipine was achieved on Agilent Technologies 7100 CE using uncoated fused-silica capillaries 48 cm x 50 mm and different type of cyclodextrins as chiral selectors. Results: A mobile phase consisting of 80% Na2HPO4 10 mM at a pH level of 5.0 and 20% ACN, isocratic elution at a flow of 1 ml/min turned to be the optimal experimental conditions for HPLC analysis (R=5.51; α=1.71) with retention times shorter than 10 minutes for the two isomers, tR (S-AML) = 4.63 (min); tR (R-AML) = 5.54 (min). The migration times for amlodipine enantiomers were tm (S-AML) = 8.15 (min) and tm (R-AML)= 8.45 (min) and the optimum CE conditions have proven to be a buffer solution containing 25 mM H3PO4 at pH 3.0 and 20 mM α-CD as chiral selector and a capillary temperature set at 15°C (R=1.51; α=1.03). Conclusion: The analytical performances of the chromatographic method using OVM as chiral selector are superior to the electrophoretic analysis method but the CE method is more economical and may represent an alternative to the HPLC chromatographic separation.

Inhibition of cyclodextrins on the activity of α-amylase

α-amylase activity influences both flour fermentation process and the quality of the fermented products due to its ability of breaking starch into smaller units. The inhibition of cyclodextrins on α-amylase activity was investigated in this paper. Experiment results showed that hydrophobic cavity size was an intrinsic factor during the inhibition processing. Among three types of cyclodextrin (α-, β- and γ-), β-type exhibited the most significant inhibitory activity toward α-amylase. The optimal inhibitory parameters were indicated to be pH 5.9, concentration of β-cyclodextrins 1 mmol/L, reaction temperature 45 °C and reaction time 60 min. Results suggested that the endogenous fluorescence of α-amylase was inhibited by cyclodextrins. Circular dichroism spectrum indicated that the secondary structure of α-amylase, including α-helices, β-sheets and random coils, was changed by cyclodextrins. All the results in this paper aim to provide a further understanding for α-amylase in the industry application.

Host-Guest Interactions of α−Mangostin with (α,β,γ)−Cyclodextrins: Semi-Empirical Quantum Mechanical Methods of PM6 and PM7

Objective: This study aimed to investigate the molecular interactions, geometrical properties, encapsulation process and calculated energy of the inclusion complexes system between α−mangostin (guest) with α−cyclodextrin, β−cyclodextrin and γ-cyclodextrin (hosts) in an aqueous environment using the semi-empirical quantum mechanical methods of PM6 and PM7. Materials and Methods: Molecular docking simulation and semi-empirical quantum mechanical calculations of PM6 and PM7 were employed to identify the molecular interactions between α−mangostin and three types of cyclodextrin. Results: The inclusion complex formation energy values of all α−mangostin/cyclodextrin that obtained by the semiempirical PM7 method were significantly lower than complexation energy obtained by the semi-empirical PM6 method. Conclusion: The inclusion complex of α−mangostin/γ−cyclodextrin is the most favorable pathway of inclusion complex formation of α−mangostin with cyclodextrin because it has the highest negative value of free binding energy (ΔG) and complexation energy (ΔE) compared to α−mangostin/α−cyclodextrin and α−mangostin/ β−cyclodextrin. Key words: Alpha mangostin, Cyclodextrin, Host-guest interactions, PM6, PM7.

ENHANCEMENT OF SOLUBILITY OF RILPIVIRINE BY INCLUSION COMPLEXATION WITH CYCLODEXTRINS

Rilpivirine having lowest water solubility indicates class II drugs of BCS. These classes of drugs could potentially exhibit dissolution rate limited absorption. The objective of the present study is to improve the solubility and dissolution of Rilpivirine through inclusion complexation with βCD and HPβCD. Solid binary systems of Rilpivirine with βCD and HPβCD were prepared by solvent evaporation and kneading methods at 1:1 and 1:2 M ratios. The prepared solid binary systems were studied in solution state by phase solubility, in vitro dissolution rate and solid state by FTIR and XRD. The dissolution parameters were studied by using dissolution software PCP Disso V3. The drug content was uniform in all the solid binary systems with low SD and CV values. The apparent stability constant indicates there is a 1:1 stochiometric complex with βCD and HPβCD. The formation of inclusion complexes with βCD and HPβCD in the solid state were confirmed by FTIR, XRD. The dissolution data clearly suggest drug release was method dependent and type of cyclodextrin. The dissolution of solid binary systems obeyed first-order kinetics and model fitted with Hixon crowel. A true inclusion complex of Rilpivirine was observed with βCD and HPβCD. Dissolution properties of solid binary systems were superior then rilpivirine alone and its corresponding physical mixtures. Overall dissolution rate was solvent evaporation > kneaded binary systems > physical mixture > pure drug. One-way ANOVA results suggest the DE30 and DE60 values were significantly higher (P<0.05) in solid binary systems when compared to physical mixture and pure drug.

SYNTHESIS OF GOLD NANOPARTICLES BY TETRACHLOROAURATE REDUCTION WITH CYCLODEXTRINS

One-step synthesis of gold nanoparticles functionalized with α-, β- and γ-cyclodextrins was carried out using a synthetic method of direct tetrachloroaurate reduction in alkaline solutions. The two experimental conditions studied were direct heating and microwave irradiation. This is the first publication comparing the characteristics of gold nanoparticles produced using three cyclodextrins under different conditions. The resulting nanoparticles were characterized by absorbance spectra, FTIR spectra, dynamic light scattering data and transmission electron microscopy images. The reducing ability of cyclodextrins increased in the following order: β-cyclodextrin < α-cyclodextrin < γ-cyclodextrin. Therefore, γ-cyclodextrin was the most active reductant and the only cyclodextrin that was able to reduce tetrachloroaurate at room temperature. In this case, nanoparticles were observed only after 4 days of storage. The nanoparticle size was dependent on the cyclodextrin type and correlated with the difference in the reducing ability. Using microwave irradiation, most of nanoparticles were found to be free nanoparticles. Using direct heating, aggregates formed due to the high ionic strength of the solution after prolonged boiling. Therefore, nanoparticles synthesized by direct heating were less stable during storage than those synthesized by microwave irradiation.

Exploring halide anion affinities to native cyclodextrins by mass spectrometry and molecular modelling.

The binding affinities of cyclodextrins complexation with chlorine (Cl-), bromine (Br-) and iodine (I-), were measured by mass spectrometric titrimetry, and the fitting of the binding constants was based on the concentration measurement of the cyclodextrin equilibrium. The binding constants (lg Ka) for α-, β- or γ-cyclodextrin with Cl- were 3.99, 4.03 and 4.11, respectively. The gas-phase binding affinity of halide anions for native cyclodextrins was probed by collision-induced dissociation. In collision-induced dissociation, the centre-of-mass frame energy results revealed that in the gas phase, for the same type of cyclodextrin, the stability of the complexes decreased in order: Cl > Br > I, and for the same halide anion, the binding stability of the complex with α-, β- or γ-cyclodextrin decreased in the order: γ-cyclodextrin >β-cyclodextrin > α-cyclodextrin. The density functional theory calculations showed that halide anion binding on the primary face had a lower energy than the secondary face and hydrogen bonding was the main driving force for complex formation. The higher stability of the γ-cyclodextrin complex with the Cl anion can be attributed to the higher charge density of the Cl anion and better flexibility of γ-cyclodextrin.

The cation-selective exhaustive injection and sweeping capillary electrophoresis method for the analysis of chlorpheniramine enantiomers in rat plasma

Chlorpheniramine is a potent antihistaminic administered as a racemic mixture, while its clinical activity is mainly associated with the S-enantiomer. In this study, a sensitive and rapid on-line preconcentration capillary electrophoresis (CE) method, cation-selective exhaustive injection (CSEI) and sweeping method was established and validated for the analysis of two chlorpheniramine enantiomers. Parameters influencing separation and enhancement efficiency were investigated, including cyclodextrin (CD) types and concentration, background electrolyte pH, type and content of organic modifier, injection time of water plug, injection time and voltage of sample. A zone of 30mM Tris buffer at pH 3.5 without chiral selector was injected into the capillary followed by a 3s water plug, allowing for the analytes to be electrokinetically injected at a voltage of 10kV for 80s. A 30mM Tris buffer at pH 3.5 consisting of 20mM sulfated-β-cyclodextrin (S-β-CD) and 5% methanol was found to be highly efficient for the separation of the two enantiomers. The present method manifested that high sensitivity (0.025μg/mL for the thethe lower limit of quantification), satisfactory accuracy (89.2%–95.0%) and precision (relative standard deviation within 8.4%) were achieved as well as favourable stability. The extraction recoveries of two enantiomers were both above 72.5%. Finally, the developed method was successfully applied to pharmacokinetic study of the two enantiomers in rat plasma after oral administration of racemic chlorpheniramine.

Phase transition of a microemulsion upon addition of cyclodextrin – applications in drug delivery

This study reports on the impact of cyclodextrin addition on the phase behavior of microemulsion systems. Three distinct oil-in-water microemulsions were formulated and subjected to increasing concentrations of various cyclodextrins. The prepared formulations underwent visual, textural and microscopic characterization followed by the evaluation of their in vitro drug release and ex vivo tissue retention behavior. Combining microemulsions with cyclodextrins resulted in either phase separation or transition into a liquid crystalline state depending on the concentration and type of cyclodextrin utilized. Formulations combined with α-cyclodextrin consistently demonstrated transition into a liquid crystalline state as confirmed by polarized light and cryo-scanning electron microscopy. In these cases, cyclodextrin addition was also positively correlated with an increase in formulation hardness, adhesiveness and turbidity. Release and clearance studies revealed that drug diffusion from the microemulsions could be slowed and tissue retention prolonged by increasing the cyclodextrin content. These findings pave the way for the development of novel cyclodextrin-microemulsion-based liquid crystalline formulations in a variety of sustained drug delivery applications.

Purification and properties of beta-cyclomaltodextrin glucanotransferase from Bacillus flexus SV 1.

Cyclomaltodextrin glucanotransferase is a unique enzyme that degrades starch into cyclic oligosaccharides called cyclodextrins, which have numerous applications in various industries such as pharmaceutical, textile, agricultural, cosmetics etc. Due to its wide applications, microorganism producing one type of cyclodextrin is of interest as it simplifies the down streaming process of separating mixture of cyclodextrins. In the present study, β-CGTase was isolated from Bacillus flexus SV 1 and biochemically characterized. Enzyme was purified by starch adsorption followed by DEAE cellulose column chromatography which resulted in a fold purification of 6.1, with a yield of 44.07%. Molecular weight of the purified enzyme was found to be 96.68 kDa, enzyme was monomeric in nature with a Km and Vmax of 0.08976 μmol mL-1 and 585.1 μmol/ml/min, respectively. Optimum pH and temperature of the purified enzyme was found to be 8.0 and 60 °C. Ca2+ showed significant increase in enzyme activity. The inhibition of enzyme by EDTA indicates that CGTase is a metalloenzyme. CGTase produced majorly β-CD and was alkalotolarent and active at high temperatures which is a promising candidate for various industries such as textile, food, agriculture, and pharmaceuticals.