Production of cyclodextrins using moderately heat-treated cornstarch

Cyclodextrins are very useful compounds for the food, cosmetic, pharmaceutic, and plastic industries. We developed a process for the production of cyclodextrins from moderately heat-treated cornstarch. This method had many merits. First, the cyclodextrins were not degraded by cyclodextrin glucanotransferase, because low molecular weight maltodextrins were hardly produced. Second, it was possible to remove the residual cornstarch by a simple method such as filtration or centrifugation. Third, the amount of cyclodextrin glucanotransferase used for cyclodextrin production was less than that using the traditional method. Fourth, the pretreating method was simple. And fifth, the residual starch could be used as substrate for the production of other compounds. Cyclodextrins were produced at optimum conditions: heating temperature was 65°C; heating time was 1 h; concentration of substrate was 7.5%; amount of enzyme loaded was 48 U g⁻¹ of substrate. Using these conditions, the results were as follows: the content of cyclodextrins, 50%; the conversion yield of substrate, 25%; the productivity per enzyme unit, 5.22 mg of cyclodextrins.     

Direct assay for alpha-amylase using fluorophore-modified cyclodextrins

A simple assay method for alpha-amylase was developed based on fluorophore-modified cyclodextrins (CDs). Four kinds of CD derivatives bearing a 4-amino-7-nitrobenz-2-oxa-1,3-diazole (NBD-amine) moiety were prepared as artificial substrates for the assay method. The fluorescence intensity of all the NBD-amine-modified CDs decreased upon addition of Aspergillus oryzae alpha-amylase, indicating a reduction in hydrophobicity near the NBD-amine moiety induced by hydrolysis of the CD ring. NC4gammaCD, having a gamma-CD and an amino-tetramethylene spacer, was the most sensitive substrate for the alpha-amylase assay. The initial rate of hydrolysis of NC4gammaCD displayed a liner correlation to the concentration of the alpha-amylase. NC4gammaCD was sensitive to the alpha-amylase but was not sensitive to guest compounds that were accommodated by the native CDs.     

Novel two‐stage fermentation process for bioethanol production using Saccharomyces pastorianus

Bioethanol produced from lignocellulosic materials has the potential to be economically feasible, if both glucose and xylose released from cellulose and hemicellulose can be efficiently converted to ethanol. Saccharomyces spp. can efficiently convert glucose to ethanol; however, xylose conversion to ethanol is a major hurdle due to lack of xylose‐metabolizing pathways. In this study, a novel two‐stage fermentation process was investigated to improve bioethanol productivity. In this process, xylose is converted into biomass via non‐Saccharomyces microorganism and coupled to a glucose‐utilizing Saccharomyces fermentation. Escherichia coli was determined to efficiently convert xylose to biomass, which was then killed to produce E. coli extract. Since earlier studies with Saccharomyces pastorianus demonstrated that xylose isomerase increased ethanol productivities on pure sugars, the addition of both E. coli extract and xylose isomerase to S. pastorianus fermentations on pure sugars and corn stover hydrolysates were investigated. It was determined that the xylose isomerase addition increased ethanol productivities on pure sugars but was not as effective alone on the corn stover hydrolysates. It was observed that the E. coli extract addition increased ethanol productivities on both corn stover hydrolysates and pure sugars. The ethanol productivities observed on the corn stover hydrolysates with the E. coli extract addition was the same as observed on pure sugars with both E. coli extract and xylose isomerase additions. These results indicate that the two‐stage fermentation process has the capability to be a competitive alternative to recombinant Saccharomyces cerevisiae‐based fermentations. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:300–310, 2014     

Comprehensive strategy for chiral separations using sulfated cyclodextrins in capillary electrophoresis

This review focuses on the emerging role of sulfated cyclodextrins in the capillary electrophoretic (CE) separation of chiral analytes. Since being introduced as enantioselective agents for CE in 1995, these anionic additives have continued to demonstrate remarkable application universality. The broad spectrum of chiral compounds successfully separated using this approach includes acidic, basic, neutral, and zwitterionic species. This impressive array of analyte structures is derived from a growing diversity of compound classes including pharmaceuticals, plant extracts, biomarkers, herbicides, alkaloids, fungicides, and metal ions. Moreover, literature reports highlight the minimal optimization required to achieve a successful separation. Based on these findings, sulfated cyclodextrins appear to be well suited for the development of a more universal, comprehensive separation strategy for chiral compounds. This review explores this proposition by beginning with the structure and migration properties of sulfated cyclodextrins, using applications to highlight the separating power of this technique and ending with a pragmatic, comprehensive separation strategy.     

Novel method of niosome generation using supercritical carbon dioxide part I: process mechanics

Abstract

A novel method for the production of non-ionic surfactant vesicles (niosomes) using an rapid expansion of supercritical solution (RESS)-based process coupled with a gas ejector is presented along with an investigation of parameters affecting niosome morphology, size and encapsulation efficiency of a 0.2?M d-glucose solution in Tris buffer at physiological pH. The solubility of the non-ionic surfactant polyoxyethylene(4) sorbitan monostearate in SC-CO₂ was determined at three pressures (10, 15 and 20?MPa) and three temperatures (40, 50 and 60?°C). Mole fraction of Tween61 in the vapor phase increased with pressure at 40?°C, but did not change with pressure at 50 or 60?°C. Solubility data were correlated using the Peng–Robinson equation of state (PREOS) with the Panagiotopoulos and Reid mixing rule. Vesicles were either multilamellar or unilamellar, depending on the degree of precipitation of the lipid formulation at the point of aqueous cargo introduction. Vesicle particle size distributions were bimodal, with the 80–99% of the liposomal volume contributed niosomes ranging in size from 3 to 7?μm and the remaining niosomes ranging from 239 to 969?nm, depending on the system configuration. Encapsulation efficiency as high as 28% using the gas ejector to introduce the glucose cargo solution was achieved. Vesicle particle size and encapsulation efficiency were shown to be dependent on cargo droplet formation.     

Biotechnological applications of cyclodextrins

Cyclodextrins (CDs) are a family of cyclic oligosaccharides that are composed of alpha-1,4-linked glucopyranose subunits. Cyclodextrins are produced from starch by enzymatic degradation. These macrocyclic carbohydrates with apolar internal cavities can form complexes with and solubilize many normally water-insoluble compounds. This review describes recent applications of CDs in pharmaceuticals with a major emphasis on drug delivery systems. The utility of these water-soluble cyclic glucans in a variety of foods, flavors cosmetics, packaging and textiles is elaborated. The role of these compounds in biocatalysis is also discussed. Cyclodextrins are used in separation science because they have been shown to discriminate between positional isomers, functional groups, homologues and enantiomers. This property makes them a useful agent for a wide variety of separations.     

Applications of modified cyclodextrins

One of the key areas of importance in biotechnology and bioengineering is molecular complexation (MC). MC is useful in selectivity, separation, and solubilization of biomolecules. While many complex, natural MC agents exist, such as proteins and antibodies, relatively few engineered MC materials are available. Inorganic, insoluble MC agents, such as zeolites, are widely used in petroleum catalysis. Carbon Buckminster fullerenes ("bucky balls") can complex small neutral molecules, but are relatively insoluble and difficult to manufacture. Crown ethers have been used for molecular complexation, but are costly to synthesize and have limited capacities.One class of highly useful MC agents are cyclodextrins (CDs). These naturally-occurring, water-soluble cyclic glucans are used in a variety of food, pharmaceutical, and analytical applications. Due to the availability of multiple reactive hydroxyl groups, the functionality of CDs can be greatly increased through chemical modification. A host of new applications are being explored, including enzyme mimicry, molecular recognition, chromatographic separation, and solubilization. This review describes recent applications of modified cyclodextrins in bioprocessing and medicine.     

Enzymatic production of cyclodextrins

Cyclodextrins (CD) are enzymatically modified starches with a wide range of applications in food, pharmaceutical and chemical industries, agriculture and environmental engineering. They are produced from starch via enzymatic conversion using cyclodextrin glycosyl transferases (CGTases) and partly alpha-amylases. Due to its low solubility in water, separation and purification of beta-CD is relatively easy compared to alpha- and gamma-CD. In recent years more economic processes for gamma-CD and especially alpha-CD production have been developed using improved CGTases and downstream processing. New purification steps, e.g. affinity adsorption, may reduce the use of complexing agents. The implementation of thermostable CGTases can simplify the production process and increase the selectivity of the reaction. A tabular overview of alpha-CD production processes is presented.     

Self-assemblies of amphiphilic cyclodextrins

Cyclodextrins are natural cyclic oligosaccharides widely used as “molecular cages” in the pharmaceutical, agrochemical, food and cosmetical industries. The optimization of their pharmacological properties has led to the synthesis of numerous analogues. Amphiphilic derivatives were designed to improve the cell targeting of the drug-containing cyclodextrin cavities through their transportation in the organism, within self-assembling systems. Amphiphilic cyclodextrins can self-assemble into water-soluble aggregates such as mono or polydisperse micelles, or insert in lipid membranes and liposomes. Polysubstituted amphiphilic cyclodextrins are briefly reviewed, and monosubstituted derivatives of native and methylated β-cyclodextrins are presented in more details, with an emphasis on their self-organization within lipid membranes. Presented at the joint biannual meeting of the SFB-GEIMM-GRIP, Anglet France, 14–19 October, 2006.     

Novel biocatalytic process of N-substituted acrylamide synthesis

The enzymatic synthesis of N-substituted acrylamides (N-isopropyl acrylamide and N, N-dimethylaminopropyl acrylamide) was demonstrated for the first time. The Rhodococcus erythropolis 37 strain, exhibiting acylamidase activity, was used as a source of enzyme, and water-dissolved acrylamide and isopropylamine/dimethylaminopropylamine served as substrates. The optimum conditions for the synthesis of acrylamide N-substitutes were determined using N-isopropyl acrylamide. The yield of the product was maximum at pH 9.5–10.5, substrate (acrylamide/isopropylamine) ratio within the range from 1.3: 1 to 2: 1, and absolute substrate concentrations of 8.0 (acrylamide) and 4.0% (isopropylamine). These conditions allowed for the synthesis of 22 g/L of N-isopropyl acrylamide.     

Study of the inclusion complexes of aromatic molecules with cyclodextrins using ionspray mass spectrometry

The formation of inclusion complexes between cyclodextrins (cyclohexa-, cyclohepta-, and cyclooctamylose) and either 1-anilinonaphthalene-8-sulfonate or 2-p-toluidinylnaphthalene-6-sulfonate was investigated by ionspray mass spectrometry operated both in the positive and in the negative ion mode. This soft ionisation technique allowed the detection of the inclusion complexes; the presence of false positives was excluded by increasing the voltage at the orifice which caused breakage of the electrostatic adducts and some fragmentation of the free cyclodextrin molecules, but left the inclusion complexes intact. The spectra recorded in the negative mode showed the presence of complexes formed by two cyclodextrin molecules and one aromatic molecule; such stoichiometry was not detected in the positive mode.     

Spectrofluorometric analytical applications of cyclodextrins

Cyclodextrins (CDs) are a family of cyclic oligosaccharides composed of α‐(1,4)‐linked glucopyranose subunits. The most important feature of CDs is their ability to form inclusion complexes (host–guest complexes) with a very wide range of solid, liquid and gaseous compounds by a molecular complexation. During the last decade, a considerable number of research papers has been focused on the use of CDs to enhance fluorescence intensity of different analytes and to develop CD‐induced spectrofluorimetric method. In this review, the various spectrofluorimetric methods based on host–inclusion complex are presented. Copyright © 2013 John Wiley & Sons, Ltd.     

New approach for selective separation of dilute products from simulated clostridial fermentation broths using cyclodextrins

The ability of cyclodextrins (CD) to form crystalline insoluble complexes with organics was explored in this study in view of a selective separation of dilute products obtainable from three clostridial fermentation systems. To this purpose, a product or a product mixture at a concentration of 0.150 mM each were treated with alpha-CD or beta-CD (0.150 mM) in aqueous solutions as well as in a nutrient broth as a simulated fermentation medium. In the acetone-butanol-ethanol system, and in the butanol-iso-propanol system, alpha-CD was found to precipitate selectively 48% and 46% butanol after 1 h agitation at 30 degrees C. However, beta-CD was found to be superior for the butyric acid-acetic acid system because it selectively precipitated 100% butyric acid under the same conditions. Cooling the three product system with alpha-CD to 4 degrees C for 24 h increased significantly the crop of precipitates but decreased the selectivity for either butanol or butyric acid. Cyclodextrins were thus shown to offer potentially a new exciting possibility for downstream processing of low-concentration fermentation products.     

Novel process for the production of cellulolytic enzymes

A novel process for the production of extracellular carboxymethylcellulase (CMCase) and xylanase by fermentation under nonaseptic or nonsterile conditions is described. The fermentation process is carried out under very acidic conditions of pH 2.0 by using a acidophilic cellulolytic fungus. Microbial contamination is avoided or minimized to an insignificant level under this acid pH condition. The culture medium for this production consists of a carbon source from cellulosics or lignocellulosics, such as Na-CMC, xylan, Avicel cellulose, cellulose powder, alpha-cellulose, sawdust, etc., or a mixture of the forementioned together with simple ingredients such as (NH(4))(2)SO(4), K(2)HPO(4), MgSO(4) and NaNO(3). The fermentation is carried out at room temperature (28-30 degrees C), under aerobic conditions, and without controlling the pH. The CMCase and xylanase produced are stable under very simple storage conditions, such as in the fresh culture medium not containing the substrate for a period of 3 days, at any temperature from 0 to 30 degrees C. These extracellular enzymes have an optimum pH around 3, with the best range of pH from 2.0 to 3.6, for any temperature between 15 and 60 degrees C. The optimum temperatures are 55 degrees C for CMCase activity and 25-50 degrees C for xylanase activity, at any pH between 2.0 and 5.2. The apparent Michaelis constants Km are 2.6 and 1.5 mg/mL for CMCase and xylanase of the culture filtrate, respectively.     

Enantioselective host-guest complexation of Ru(II) trisdiimine complexes using neutral and anionic derivatized cyclodextrins

Enantioselective host-guest complexation between five racemic Ru(II) trisdiimine complexes and eight derivatized cyclodextrins (CDs) has been examined by NMR techniques. The appearance of non-equivalent complexation-induced shifts of between the Δ and Λ-enantionomers of the Ru(II) trisdiimine complexes and derivatized CDs is readily observed by NMR. In particular, sulfobutyl ether-β-cyclodextrin sodium salt (SBE-β-CD), R-naphtylethyl carbamate β-cyclodextrin (RN-β-CD), and S-naphtylethyl carbamate β-cyclodextrin (SN-β-CD) showed good enantiodiscrimination for all five Ru complexes examined, which indicates that aromatic and anionic derivatizing groups are beneficial for chiral recognition. The complexation stoichiometry between SBE-β-CD and [Ru(phen)₃]²⁺ was found to be 1:1 and binding constants reveal that Λ-[Ru(phen)₃]²⁺ binds more strongly to SBE-β-CD than the Δ-enantiomer. Correlations between this NMR method and separative techniques based on CDs as chiral discriminating agents (i.e., selectors) are discussed in detail.     

Enhanced extracellular production of trans-resveratrol in Vitis vinifera suspension cultured cells by using cyclodextrins and methyljasmonate

In this work, the effect of different inducing factors on trans-resveratrol extracellular production in Monastrell grapevine suspension cultured cells is evaluated. A detailed analysis provides the optimal concentrations of cyclodextrins, methyljasmonate and UV irradiation dosage, optimal cell density, elicitation time and sucrose content in the culture media. The results indicate that trans-resveratrol production decreases as the initial cell density increases for a constant elicitor concentration in Monastrell suspension cultured cells treated with cyclodextrins individually or in combination with methyljasmonate; the decrease observed in cell cultures elicited with cyclodextrins alone is far more drastic than those observed in the combined treatment. trans-Resveratrol extracellular production observed by the joint use of cyclodextrins and methyljasmonate (1,447.8 ± 60.4 μmol trans-resveratrol g⁻¹ dry weight) is lower when these chemical compounds are combined with UV light short exposure (669.9 ± 45.2 μmol trans-resveratrol g⁻¹ dry weight). Likewise, trans-resveratrol production is dependent on levels of sucrose in the elicitation medium with the maximal levels observed with 20 g l⁻¹ sucrose and the joint action of cyclodextrins and 100 μM methyljasmonate. The sucrose concentration did not seem to limit the process although it affects significantly the specific productivity since the lowest sucrose concentration is 10 g l⁻¹, the highest productivity is reached (100.7 ± 5.8 μmol trans-resveratrol g⁻¹ dry weight g⁻¹ sucrose) using cyclodextrins and 25 μM methyljasmonate.     

The binding of cocaine to cyclodextrins

Cocaine binds into beta-cyclodextrin, but not detectably into alpha- or gamma-cyclodextrin, in water solution. NMR studies indicate the geometry of the complex, which is confirmed by molecular mechanics calculations and binding studies on cocaine analogues and cyclodextrin dimers.