Preparation and characterization of soluble branched ionic ß-cyclodextrins and their inclusion complexes with triclosan.

This study aims to synthesize, characterize and investigate the water solubility and cytotoxicity of branched anionic/cationic ß-cyclodextrins (bßCDs) obtained by reaction with epichlorohydrin and chloroacetic acid or choline chloride, respectively, by a single step polycondensation reaction. Obtained ionic bßCDs were investigated as an attempt to comparatively study anionic and cationic bßCDs. Water solubility of both ionic derivatives was similar (400 mg/mL) at neutral and basic pHs and remarkably higher than that of their neutral homologues. Additionally, a pH-dependent solubility of anionic bßCDs was observed. Cytotoxicity of ionic bßCDs was evaluated on Human colon carcinoma Caco-2 cells and high cell viability (>99%) was observed in the range of 0-100 mg/mL for anionic and cationic samples, in the same range of that of neutral and parent ß-CDs. Additionally, complexes formation capacity with triclosan, a poor water soluble antimicrobial agent, was confirmed by several techniques observing a complexation limit around 4 mg/mL for both systems and higher stability constant for anionic bßCDs than cationic derivatives.

Cationic ß-cyclodextrin polymer applied to a dual cyclodextrin polyelectrolyte multilayer system.

A polyelectrolyte multilayer film (PEM) based on cationic and anionic ß-cyclodextrin polyelectrolytes was coated onto a textile substrate for future drug delivery purposes. We firstly synthesized a novel cationic ß-cyclodextrin polymer (polyEPG-CD) by crosslinking ß-cyclodextrin (ßCD) with epichlorohydrin (EP) under basic conditions, in the presence of glycidyltrimetrylammonium chloride (GTMAC) as cationizing group. The influence of preparation conditions has been investigated in order to preferably obtain a water soluble fraction whose charge density and molecular weights were optimal for the layer-by-layer (LbL) deposition process. The different cationic cyclodextrin polymers obtained were characterized by FTIR, NMR, colloidal titration, conductimetry, thermogravimetric analysis and size exclusion chromatography. Besides, the counterpart polyelectrolyte was a ß-cyclodextrin polymer crosslinked with citric acid, polyCTR-CD, whose synthesis and characterization have been previously reported. Finally we realized the Layer by Layer (LbL) build-up of the PEM coating onto the textile support, using the dip coating method, by alternatively soaking it in cationic polyEPG-CD and anionic polyCTR-CD solutions. This multilayer self-assembly was monitored by SEM, gravimetry and OWLS in function of both polyelectrolytes concentrations and ratios. Solutions parameters such as pH, ionic strenght were also discussed.

Synthesis, characterization and application of epichlorohydrin-ß-cyclodextrin polymer.

Cyclodextrins, the macrocyclic compounds are renowned for their inclusion ability. Several chemical and polymerized derivatives of parent cyclodextrins are synthesized to improve the physicochemical/biopharmaceutical properties of drug and inclusion capacity of cyclodextrin. This review article recapitulates the potential aspects of polymerized water-soluble derivative of ß-cyclodextrin viz. epichlorohydrin-ß-cyclodextrin polymer in different areas of drug delivery. Polymerized cyclodextrin combines the advantage of the properties of polymer (high molecular weight and higher solubility) with the formation of inclusion complex with cyclodextrin. This justifies the superiority of polymerized cyclodextrin over parent cyclodextrin and some other chemically modified and non-polymerized derivatives. The use of polymerized cyclodextrin in various fields like biomedical, pharmaceutical and gene delivery is increasing day-by-day. ß-Cyclodextrin-epichlorohydrin polymer is a high molecular weight compound, which acts as an effective drug carrier for enhancing the solubility and oral bioavailability of drugs along with the increase in therapeutic efficiency. The future panorama of polymerized cyclodextrins is quite bright as they can serve as useful multifunctional tools for pharmaceutical scientists to develop and optimize drug delivery through various routes. Also, no information concerning the regulatory status and toxicity of polymerized cyclodextrins is available. So, there is a need to focus on these critical issues for resolving the problems associated with the development and commercialization of drug products.

Nitrite-mediated synthesis of chiral epichlorohydrin using halohydrin dehalogenase from Agrobacterium radiobacter AD1.

In the current study, the haloalcohol dehalogenase HheC gene from Agrobacterium radiobacter AD1 was synthesized and expressed in Escherichia coli. After purification using Ni-nitrilotriacetic acid affinity chromatography, HheC was used in the synthesis of chiral epichlorohydrin in the presence of NO2⁻. The optimal pH, temperature, and NO2⁻ concentration for enantioselectivity are 5.0, 37°C, and 60 mM, respectively. The maximum velocity and Michaelis constant values for (S)-epichlorohydrin are 714.3 µmol min⁻¹ mg⁻¹ and 17.2 mM, respectively, whereas those for (R)-epichlorohydrin are 166.8 µmol min⁻¹ mg⁻¹ and 29.0 mM, respectively. Under optimal conditions, (R)-epichlorohydrin with 99% enantiomeric excess was obtained after an 18 Min reaction; the yield reached 41%, which is the highest amount obtained for chiral epichlorohydrin synthesis using haloalcohol dehalogenase. In addition, (R)-epichlorohydrin with 99% enantiomeric excess was successfully obtained from 1,3-dichloro-2-propanol by the ring opening of racemic epichlorohydrin in the presence of NO2⁻ after the ring closure of 1,3-dichloro-2-propanol with HheC. To the best of our knowledge, the current study is the first report on the kinetic resolution of epichlorohydrin with NO2⁻ and synthesis of chiral epichlorohydrin with 99% enantiomeric excess from 1,3-dichloro-2-propanol by combining ring closure of 1,3-dichloro-2-propanol and ring opening of racemic epichlorohydrin.

Enantioselective hydrolysis of racemic epichlorohydrin using an epoxide hydrolase from Novosphingobium aromaticivorans.

Previously we reported that an epoxide hydrolase (EHase) from Novosphingobium aromaticivorans could preferentially hydrolyze (R)-styrene oxide. In this study, we demonstrate that the purified NEH could be also effective in chiral resolution of racemic epichlorohydrin (ECH). Particularly, the purified NEH showed excellent hydrolyzing activity toward ECH to complete the reaction at a short period of incubation time. Enantiopure (S)-ECH could be obtained with a high enantiopurity of more than 99.99% enantiomeric excess (ee) and yield of 20.7% (theoretical, 50%). The chiral resolution of the purified NEH toward ECH was not susceptible to substrate inhibition by 500 mM racemic ECH.

Evaluation of artificial chaperoning behavior of an insoluble cyclodextrin-rich copolymer: solid-phase assisted refolding of carbonic anhydrase.

Insoluble beta-cyclodextrin (beta-CD) copolymers have been used for the refolding of thermally and/or chemically denatured carbonic anhydrase with refolding yield of 40% using 300 mg of the copolymer/ml refolding solution containing 0.042 mg/ml protein. In an attempt to enhance the refolding yield with lower quantities of the copolymer, a new beta-CD-rich copolymer with higher beta-CD content was synthesized. Regarding the need for rapid stripping of the detergent molecules from the detergent-protein complexes formed in the capture step of the technique (artificial chaperone-assisted refolding), experimental variables (e.g. copolymer and the protein contents) were optimized to improve the refolding yields along with depressing the aggregate formation. In addition, comparative studies using different ionic detergents and the copolymer were conducted to get a more comprehensive understanding of the detergent's tail length in the stripping step of the process. Our results indicated that under the optimal developed refolding environment, the denatured CA was refolded with a yield of 75% using only 5mg of the copolymer/1.2 ml refolding solution containing 0.0286 mg/ml protein. Taking into account the recycling potential of the copolymer, the new resin, with significant cost-cutting capability, is a suitable candidate for industrial applications.

[Synthesis of phosphobetaine--a derivative of long-chain tertiary aliphatic amine with epichlorohydrin]. / Synteza fosforanobetainy--pochodnej dlugolancuchowej trzeciorzedowej aminy alifatycznej z epichlorohydryna.

Synthesis of a new surface active agent, a phosphobetaine derivative of tertiary amines with C12-22 long chains and sodium 3-chloro-2-hydroxypropyl phosphate has been elaborated. The reactants were applied at the molar ratio of 1:1.3. The obtained compounds was found to possess high surfactant and antimicrobial activities.