Sugammadex analogue cyclodextrins as chiral selectors for enantioseparation of cathinone derivatives by capillary electrophoresis.

The present contribution describes the application of three single-isomeric cyclodextrin derivatives for the first time - Sugammadex, Subetadex and Sualphadex as chiral selectors. Their recognition ability was investigated by means of chiral capillary electrophoresis, on a pool of cathinone and amphetamine derivatives. The selectors differ in cavity sizes and in the number of ionizable groups which evidently influenced their enantioselectivity performance. Their common feature is their high isomeric purity that enabled the detailed study of the molecular association between the cathinone guest and the cyclodextrin host at the atomic level. With the aid of enantiopure cathinone derivatives, the migration order could also be determined in capillary electrophoresis. As the result of the capillary electrophoresis screening, partial or baseline chiral separation of 19 cathinones and an amphetamine derivative could be achieved, and the systematic study was performed focusing on three different pH conditions pH = 7.0, pH = 5.0 and pH = 2.5 and several different selector concentrations. Among the tested derivatives Subetadex is the best performing chiral selector, especially under acidic pH values for separating enantiomers, proven not only by capillary electrophoresis but also by 1D and 2D NMR measurements.

Comparative bioavailability study following a single dose intravenous and buccal administration of remdesivir in rabbits.

As remdesivir, the first FDA-approved drug for SARS-CoV-2 infection, can be used only for hospitalized patients due to intravenous administration, there is an urgent need of effective oral antiviral formulations to be used at early stage of infection in an outpatient setting. The present paper reports on the comparative pharmacokinetics of the electrospun nanofiber remdesivir/sulfobutyl ether beta-cyclodextrin formulation after intravenous and buccal administration. It was postulated that oral transmucosal administration avoids remdesivir from metabolic transformation and intact remdesivir can be detected in plasma, but only the active metabolite GS-441524 could be experimentally detected at a significantly lower plasma level, than that provided by the intravenous route. In buccally treated animals, the metabolite GS-441524 appeared only at 1 h after treatment, while in intravenously treated animals, GS-441524 was possible to quantify even at the first time-point of blood collection. Further optimization of formulation is required to improve pharmacokinetics of remdesivir-sulfobutyl ether beta-cyclodextrin formulation upon buccal administration.

Cyclodextrin-enabled green environmental biotechnologies.

Most of the organic compounds contaminating the environment can form inclusion complexes with cyclodextrins resulting in enhanced solubility (a benefit in soil remediation) or just the opposite: reduced mobility by sorption (a benefit in wastewater treatment). Combining biotechnologies with cyclodextrin, a renewable and biodegradable material, green environmental technologies of high efficiency were developed. For instance, the cyclodextrin-enabled soil washing/flushing technologies combined with bioremediation have been demonstrated in full-scale field experiments. The efficiency of tertiary wastewater treatment by sorption of non-biodegradable xenobiotics, such as residual pharmaceutics, was proved. The biofilm formation in fouling processes can be prevented or reduced either by applying cyclodextrin-based coatings or by manipulation of quorum sensing (bacterial communication) via capturing signal molecules.

Structural characterization of methyl-ß-cyclodextrins by high-performance liquid chromatography and nuclear magnetic resonance spectroscopy and effect of their isomeric composition on the capillary electrophoresis enantioseparation of daclatasvir.

The separation of daclatasvir and its R,R,R,R-enantiomer was studied by capillary electrophoresis using various randomly methylated ß-CDs and the single isomer heptakis(2,6-di-O-methyl)-ß-CD (2,6-DM-ß-CD) as chiral selectors in an acidic background electrolyte. Opposite enantiomer migration order was observed for randomly substituted CDs compared to 2,6-DM-ß-CD as well as methylated ß-CDs with different composition according to the specifications of the manufacturers. HPLC and NMR analyses confirmed that the presence of a high 2,6-DM-ß-CD content in the CDs enables to achieve the migration order R,R,R,R-enantiomer > daclatasvir. In contrast, products with low 2,6-DM-ß-CD isomer content and/or the presence of a large amount of methylated CD isomers, in which d-glucopyranose moieties are not substituted in either position 2 or 6, displayed the opposite enantiomer migration order daclatasvir > R,R,R,R-enantiomer. The study indicated the importance of the type and composition of derivatized CDs on chiral separations in capillary electrophoresis as well as the importance of proper quality control for cyclodextrin manufacturers. Moreover, the observed migration order could be rationalized based on the composition and substitution pattern of the CDs.

Molecular interactions in remdesivir-cyclodextrin systems.

Remdesivir (REM) is the first antiviral drug (Veklury™) approved by the Food and Drug Administration for the therapy of COVID-19. Due to its poor water solubility, the preparation of Veklury™ requires a suitable solubilizing excipient at pH 2 conditions. For this purpose, the final formulation contains the randomly substituted sulfobutylether-ß-cyclodextrin (SBEßCD) as a complexing agent. Herein, extensive NMR spectroscopic study with various cyclodextrin (CD) derivatives were conducted to understand the interactions in SBEßCD - REM systems at the molecular level. The pKa value of REM has been determined experimentally for the first time, as the protonation state of the aminopyrrolo-triazine moiety can play a key role in CD-REM inclusion complex formation as SBEßCD has permanent negative charges. The UV-pH titration experiments yielded a pKa of 3.56, thus the majority of REM bears a positive charge at pH 2.0. NMR experiments were performed on ß- and γCD derivatives to determine complex stabilities, stoichiometries and structures. The stability constants were determined by nonlinear curve fitting based on 1H NMR titrations at pH 2.0, while Job's method was used to determine the stoichiometries. ßCD complexes were one order of magnitude more stable than their γCD counterparts. Sulfobutylation resulted in a significant increase in stability and the single isomer derivatives showed unexpectedly high stability values (logK = 4.35 for REM - per-6-SBEßCD). In the case of ßCDs, the ethylbutyl-moiety plays a key role in complexation immersing into the ßCD cavity, while the phenoxy-moiety overtakes and drives the inclusion of REM in the case of γCDs. This is the first comprehensive study of REM-CD complexation, allowing the design of new CD derivatives with tailored stabilities, thereby aiding the formulation or production and even the analytical characterization of REM.

Cyclodextrins Exert a Ligand-like Current Inhibitory Effect on the KV1.3 Ion Channel Independent of Membrane Cholesterol Extraction.

Cyclodextrins (CDs) are cyclic oligosaccharides capable of forming water-soluble complexes with a variety of otherwise poorly soluble molecules including cholesterol and different drugs. Consistently, CDs are widely used in research and clinical practice to deplete cholesterol from cellular membranes or to increase solubility and bioavailability of different pharmaceuticals at local concentrations in the millimolar range. Effects of CDs exerted on cellular functions are generally thought to originate from reductions in cholesterol levels. Potential direct, ligand-like CD effects are largely neglected in spite of several recent studies reporting direct interaction between CDs and proteins including AMP-activated protein kinase, ß-amyloid peptides, and α-synuclein. In this study, by using patch-clamp technique, time-resolved quantitation of cholesterol levels and biophysical parameters and applying cholesterol-extracting and non-cholesterol-extracting CDs at 1 and 5 mM concentrations, we provide evidence for a previously unexplored ligand-like, cholesterol-independent current inhibitory effect of CDs on KV1.3, a prototypical voltage-gated potassium channel with pathophysiological relevance in various autoimmune and neurodegenerative disorders. Our findings propose that potential direct CD effects on KV channels should be taken into consideration when interpreting functional consequences of CD treatments in both research and clinical practice. Furthermore, current-blocking effects of CDs on KV channels at therapeutically relevant concentrations might contribute to additional beneficial or adverse effects during their therapeutic applications.

Complexation of daclatasvir by single isomer methylated ß-cyclodextrins studied by capillary electrophoresis, NMR spectroscopy and mass spectrometry.

In capillary electrophoresis an enantioseparation of daclatasvir (DCV) was observed in case of heptakis(2,6-di-O-methyl)-ß-CD, heptakis(2-O-methyl)-ß-CD and ß-CD, while two peaks with a plateau were noted for heptakis(2,3,6-tri-O-methyl)-ß-CD and heptakis(2,3-di-O-methyl)-ß-CD indicating a slow equilibrium. Heptakis(6-O-methyl)-ß-CD and heptakis(3-O-methyl)-ß-CD yielded broad peaks. Nuclear magnetic resonance experiments including nuclear Overhauser effect-based techniques revealed inclusion complex formation for all CDs with the biphenyl ring of DCV within the cavity and the valine-pyrrolidine moieties protruding from the torus. However, in case of heptakis(2,6-di-O-methyl)-ß-CD, heptakis(2-O-methyl)-ß-CD and ß-CD higher order structures with 1:3 stoichiometry were concluded, where the valine moieties enter additional CD molecules via the secondary side. Heptakis(2,3,6-tri-O-methyl)-ß-CD and heptakis(2,3-di-O-methyl)-ß-CD yielded primarily 1:1 complexes. Higher order complexes between DCV and heptakis(2,6-di-O-methyl)-ß-CD were corroborated by mass spectrometry. Complex stoichiometry was not the reason for the slow equilibrium yielding the plateau observed in capillary electrophoresis, but structural characteristics of the CDs especially complete methylation of the secondary rim.

Carboxymethyl-γ-cyclodextrin, a novel selective relaxant binding agent for the reversal of neuromuscular block induced by aminosteroid neuromuscular blockers: an ex vivo laboratory study.

BACKGROUND: Residual neuromuscular block at the end of surgery may compromise the patient's safety. The risk of airway complications can be minimized through monitoring of neuromuscular function and reversal of neuromuscular block if needed. Effective reversal can be achieved with selective relaxant binding agents, however, sugammadex is the only clinically approved drug in this group. We investigated the concentration-response properties of a novel selective relaxant binding agent, carboxymethyl-γ-cyclodextrin for the reversal of neuromuscular block. We evaluated the hypothesis that it is equally potent for reversing neuromuscular block as sugammadex. METHODS: Phrenic nerve - hemidiaphragm tissue preparations were isolated from male Wistar rats and suspended in a tissue holder allowing electrical stimulation of the nerve and monitoring of muscle contraction force. Concentration-response relationships were constructed for the neuromuscular blocking agents rocuronium, pipecuronium, and vecuronium. The half-effective concentrations of sugammadex and carboxymethyl-γ-cyclodextrin for reversal of neuromuscular block were determined. RESULTS: The half effective concentrations (95% confidence interval, CI) were 7.50 (6.93-8.12) µM for rocuronium, 1.38 (1.33-1.42) µM for pipecuronium, and 3.69 (3.59-3.80) µM for vecuronium. The half effective concentrations (95% CI) of carboxymethyl-γ-cyclodextrin and sugammadex were 35.89 (32.67-39.41) µM and 3.67 (3.43-3.92) µM, respectively, for the reversal of rocuronium-induced block; 10.14 (9.61-10.70) µM and 0.67 (0.62-0.74) µM, respectively, for the reversal of pipecuronium-induced block; and 376.1 (341.9-413.8) µM and 1.45 (1.35-1.56) µM, respectively, for the reversal of vecuronium-induced block. CONCLUSIONS: Carboxymethyl-γ-cyclodextrin is an effective, but less potent agent for reversal of neuromuscular block than sugammadex.

Sulfobutylether-beta-cyclodextrin-enabled antiviral remdesivir: Characterization of electrospun- and lyophilized formulations.

Veklury™ by Gilead Sciences, Inc., containing antiviral drug, remdesivir (REM) has received emergency authorization in the USA and in Europe for COVID-19 therapy. Here, for the first time, we describe details of the non-covalent, host-guest type interaction between REM and the solubilizing excipient, sulfobutylether-beta-cyclodextrin (SBECD) that results in significant solubility enhancement. Complete amorphousness of the cyclodextrin-enabled REM formulation was demonstrated by X-ray diffraction, thermal analysis, Raman chemical mapping and electron microscopy/energy dispersive spectroscopy. The use of solubilizing carbohydrate resulted in a 300-fold improvement of the aqueous solubility of REM, and enhanced dissolution rate of the drug enabling the preparation of stable infusion solutions for therapy. 2D ROESY NMR spectroscopy provided information on the nature of REM-excipient interaction and indicated the presence of inclusion phenomenon and the electrostatic attraction between anionic SBECD and nitrogen-containing REM in aqueous solution.

Structural characterization of fondaparinux interaction with per-6-amino-beta-cyclodextrin: An NMR and MS study.

The highly anionic synthetic pentasaccharide fondaparinux (FDPX) - representing the antithrombin binding sequence of heparin - is in clinical use as a potent anticoagulant. Contrary to the unfractionated heparin, FDPX lacks potent antidote completely reversing its anticoagulant activity, therefore it is of great importance to identify new structures exhibiting strong intermolecular interactions towards FDPX. The polycationic heptakis(6-amino-6-deoxy)-beta-cyclodextrin (NH2-ß-CD) can serve as an excellent model compound to mimic these interactions between the oppositely charged oligosaccharides. Herein, extensive NMR spectroscopic and nano-electrospray ionization mass spectrometric (nESI-MS) studies were conducted to understand the molecular-level interactions in the FDPX - NH2-ß-CD systems. NMR experiments were performed at pD 7.4 and 2.0. Job's method of continuous variation and 1H NMR titration experiments suggested the formation of FDPX∙NH2-ß-CD complex at pD 7.4, while the presence of multiple complexes was assumed at pD 2.0. Stability constants were determined by separate 1H NMR titrations, yielding log ß11=3.65 ± 0.02 at pD 7.4, while log ß11 ≥ 4.9 value suggested a high-affinity system at pD 2.0. 2D NOESY NMR studies indicated spatial proximities between the anomeric resonance α-l-iduronic acid residue and the cyclodextrin's methylene unit in the proximity of the cationic amino function. Acidic degradation of FDPX was investigated by NMR and MS for the first time in detail confirming that desulfation occurs involving one to two sulfate moieties. The desulfation of FDPX was inhibited by the cationic cyclodextrin in the case of equimolar ratio at pD 2.0. This is the first report on the stabilizing effect of cyclodextrin complexation on heparin degradation.

Comparative analysis of the full set of methylated ß-cyclodextrins as chiral selectors in capillary electrophoresis.

The chiral separation ability of the full library of methylated-ß-cyclodextrins towards pharmacologically significant racemic drugs including basic compounds was studied by chiral CE. The syntheses of all the methylated, single isomer ß-cyclodextrins were revised and optimized and the aqueous solubility of the derivatives was unambiguously established. The three most relevant commercially available methylated isomeric mixtures were also included in the screening, so a total of ten various methylated CDs were investigated. The effects of the selector concentration on the enantiorecognition properties at acidic pH were investigated. Among the dimethylated ß-cyclodextrins, the heptakis (2,6-di-O-methyl)-ß-cyclodextrin isomer (2,6-DIMEB) resulted to be the most versatile chiral selector. Terbutaline was selected as a model compound for the in-depth investigation of host-guest enantiodiscrimination ability. The association constants between the two terbutaline enantiomers and 2,6-DIMEB were determined in order to support that the enantioseparation is driven by differences is host-guest binding. The migration order of the enantiomers was confirmed by performing spiking experiments with the pure enantiomers. 1D and 2D NMR spectroscopy was applied to the 2,3-, and 2,6-DIMEB/terbutaline systems to rationalize at molecular level the different enantioseparation ability of the dimethylated ß-cyclodextrin selectors.

Separation of brombuterol enantiomers in capillary electrophoresis with cyclodextrin-type chiral selectors and investigation of structure of selector-selectand complexes using nuclear magnetic resonance spectroscopy.

The major goal of this study was to determine the affinity pattern of brombuterol (BB) enantiomers toward various cyclodextrins (CD) and to evaluate the potential of NMR spectroscopy for understanding fine mechanisms of interactions between CDs and BB enantiomers. Separation of BB enantiomers was performed in a fused-silica capillary using a phosphate buffer, pH 2.5, at the room temperature in the normal polarity mode. It was shown once again that CE in combination with NMR spectroscopy represents a very sensitive tool for studies of affinity patterns and structure of CD complexes with chiral guests. Although opposite affinity patterns of BB enantiomers were observed toward native ß- and γ-CDs, no significant differences between the structures of the complexes of these two CDs with BB were detected by NMR spectroscopy. In contrary to this, the opposite affinity pattern of BB enantiomers toward ß-CD and its two sulfated derivatives, heptakis (2,3-O-diacetyl-6-sulfo)-ß-CD (HDAS-ß-CD) and heptakis (2-O-methyl-3,6-di-O-sulfo)-ß-CD (HMDS-ß-CD) was associated with major differences in the structure of the complexes. In addition, it was shown again that HMDS-ß-CD provides separation of enantiomers without formation of inclusion-type complex with the chiral analyte.

Separation of terbutaline enantiomers in capillary electrophoresis with cyclodextrin-type chiral selectors and investigation of structure of selector-selectand complexes.

The affinity pattern of terbutaline enantiomers towards various cyclodextrins was studied using capillary electrophoresis. The affinity pattern of terbutaline enantiomers was the same towards all studied cyclodextrins except heptakis(2-O-methyl-3,6-di-O-sulfo)-ß-CD. Nuclear magnetic resonance spectroscopy was used for understanding of fine structural mechanisms of interactions of ß-cyclodextrin and its two sulfated derivatives with the enantiomers of terbutaline. The structure of terbutaline complexes with all 3 cyclodextrins studied was different from each other. In confirmation with our earlier studies it was shown again that capillary electrophoresis represents very sensitive technique for studies of affinity patterns in cyclodextrin complexes with chiral guests. Other instrumental (e.g. NMR spectroscopy and X-ray diffraction analysis) and theoretical techniques, although very useful for obtaining the information regarding the stoichiometry, binding constants and structure of intermolecular complexes, as well as about the forces involved in selector-selectand binding and chiral recognition, may sometimes fail to properly sense those fine differences in the affinity patterns. Therefore, it is recommended to use capillary electrophoresis in order to examine correctness of affinity pattern determined for intermolecular complexes of cyclodextrins with guest molecules by other instrumental or computation techniques.

Novel medium-throughput technique for investigating drug-cyclodextrin complexation by pH-metric titration using the partition coefficient method.

The present study was aimed to develop a medium-throughput screening technique for investigation of cyclodextrin (CD)-active pharmaceutical ingredient (API) complexes. Dual-phase potentiometric lipophilicity measurement, as gold standard technique, was combined with the partition coefficient method (plotting the reciprocal of partition coefficients of APIs as a function of CD concentration). A general equation was derived for determination of stability constants of 1:1 CD-API complexes (K1:1,CD) based on solely the changes of partition coefficients (logPo/wN-logPappN), without measurement of the actual API concentrations. Experimentally determined logP value (-1.64) of 6-deoxy-6[(5/6)-fluoresceinylthioureido]-HPBCD (FITC-NH-HPBCD) was used to estimate the logP value (≈ -2.5 to -3) of (2-hydroxypropyl)-ß-cyclodextrin (HPBCD). The results suggested that the amount of HPBCD can be considered to be inconsequential in the octanol phase. The decrease of octanol volume due to the octanol-CD complexation was considered, thus a corrected octanol-water phase ratio was also introduced. The K1:1,CD values obtained by this developed method showed a good accordance with the results from other orthogonal methods.

Fast further purification of diastereomeric salts of a nonracemic acid by gas antisolvent fractionation.

A novel, green possibility of the further purification of the diastereomeric salt of 4-chloromandelic acid and 1-phenylethane-1-amine was developed. Gas antisolvent method using supercritical carbon dioxide was applied for the first time to precipitate the diastereomeric salts with increased purity followed by the supercritical fluid extraction of the dissolved diastereomers. The RR-salt can be purified to >99%, while fractionation-based purification of the SR-salt is limited to ~80%. The limiting initial diastereomeric excess correlates strongly with the atmospheric melting eutectic composition of the same salts, which suggests that despite the fast precipitation, the diastereomeric excess of the solid product is not kinetically determined. The efficiency of the diastereomeric enrichment is in the same range as that of the atmospheric reference experiments; however, technological advantages provided by the antisolvent precipitation method such as fast processing and dry product obtained suggest that this novel procedure is a promising alternative to the atmospheric methods.

Characterization of a single-isomer carboxymethyl-beta-cyclodextrin in chiral capillary electrophoresis.

In this work, the synthesis, characterization, and chiral capillary electrophoretic study of heptakis-(2,3-di-O-methyl-6-O-carboxymethyl)-ß-CD (HDMCM), a single-isomer carboxymethylated CD, are presented. The pH-dependent and selector concentration-dependent enantiorecognition properties of HDMCM were investigated and discussed herein. The enantioseparation was assessed applying a structurally diverse set of noncharged, basic, and zwitterionic racemates. The increase in the selector concentration and gross negative charge of HDMCM improved the enantioseparation that could be observed in the majority of the cases. HDMCM was also successfully applied as BGE additive in NACE using a methanol-based system in order to prove the separation selectivity features and to highlight the broad applicability of HDMCM. Over 25 racemates showed partial or baseline separation with HDMCM under the conditions investigated, among which optimal enantiomer migration order was found for the four stereoisomers of tadalafil, tapentadol, and dapoxetine, offering the possibility of a chiral CE method development for chiral purity profiling of these drugs.

Design and evaluation of artificial receptors for the reversal of neuromuscular block.

Applying patient friendly and cost-efficient medications in healthcare will be a real challenge in the 21st century. Sugammadex is a selective, yet expensive agent used for the post-surgical reversal of neuromuscular block since 2008. A wide library of cyclodextrin-based follow-ups, having potentially similar affinity towards target aminosteroid type neuromuscular blocking agents has been established. Almost 20 compounds were assessed with respect to in vitro affinity against three commonly applied drugs. Based on the capillary electrophoretic screening, carboxymethylated and sulfobutylated gamma-cyclodextrin derivatives have the potential to be promising lead molecules for their affinity towards pipecuronium was identical or even superior to Sugammadex. Carboxymethylated gamma-cyclodextrin showed efficient and complete reversal of the pipecuronium induced neuromuscular block in an ex vivo rat diaphragm experiment.

Separation of enilconazole enantiomers in capillary electrophoresis with cyclodextrin-type chiral selectors and investigation of structure of selector-selectand complexes by using nuclear magnetic resonance spectroscopy.

In the present study, the enantiomer migration order (EMO) of enilconazole in the presence of various cyclodextrins (CDs) was investigated by capillary electrophoresis (CE). Opposite EMO of enilconazole were observed when ß-CD or the sulfated heptakis(2-O-methyl-3,6-di-O-sulfo)-ß-CD (HMDS-ß-CD) was used as the chiral selectors. Nuclear magnetic resonance (NMR) spectroscopy was used to study the mechanism of chiral recognition between enilconazole enantiomers and those two cyclodextrins. On the basis of rotating frame nuclear Overhauser (ROESY) experiments, the structure of an inclusion complex between enilconazole and ß-CD was derived, in which (+)-enilconazole seemed to form a tighter complex than the (-)-enantiomer. This correlates well with the migration order of enilconazole enantiomers observed in CE. No evidence of complexation between enilconazole and HMDS-ß-CD could be gathered due to lack of intermolecular nuclear Overhauser effect (NOE). Most likely the interaction between enilconazole and HMDS-ß-CD leads to formation of a shallow external complex that is sufficient for separation of enantiomers in CE but cannot be evidenced based on ROESY experiment. Thus, in this particular case CE documents the presence of intermolecular interactions which are at least very difficult to be evidenced by other instrumental techniques.

A Novel Approach for the Control of Inflammatory Pain: Prostaglandin E2 Complexation by Randomly Methylated ß-Cyclodextrins.

BACKGROUND: Inhibitors of cyclooxygenase, which block the formation of prostaglandin (PG) E2, are the standard treatment of inflammatory pain. These drugs, however, have serious gastrointestinal, renal, and cardiovascular side effects that limit their clinical use. Cyclodextrins are neutral glucose oligomers that form a hydrophilic outer and a hydrophobic interior cavity used to carry hydrophilic substances. Methyl-ß-cyclodextrins are used currently in several drugs as enhancers and also to deliver PGs. We therefore hypothesized that randomly methylated ß-cyclodextrins (RAMEB) could be used for pain treatment. METHODS: An in silico screening for important inflammatory mediators (eg, PGE2, substance P, bradykinin, and calcitonin gene-related peptide) was performed to predict the probability of these molecules binding to RAMEB. Thereafter, a comprehensive in vitro study investigated the complexation affinity of the best target toward RAMEB or its RAMEB-fraction L (FL) using capillary electrophoresis.Wistar rats were injected intraplantarly with complete Freund's adjuvant (CFA) for 96 hours to induce inflammatory hyperalgesia. Subsequently, rats were treated intraplantarly or intravenously either with RAMEB or RAMEB FL and compared with the respective controls. Parecoxib was used as positive control. Mechanical (paw pressure threshold, PPT) and thermal (paw withdrawal latency) nociceptive thresholds were determined before injection and at the indicated time points thereafter. Paw tissue was collected after treatments, and PGE2 and PGD2 contents were measured. Analysis of variance was used for data analysis followed by appropriate post hoc comparisons. RESULTS: In silico screening indicated that PGE2, with the highest affinity, was the best candidate for RAMEB binding. Likewise, in capillary electrophoresis experiments, RAMEB had a high affinity to form inclusion complexes with the PGE2 (stability constant [K], 360 1/M; 95% confidence interval [C]: 347.58-372.42 M). Local treatment with RAMEB alleviated CFA-induced mechanical (PPT: 76.25 g; 95% CI: 56.24-96.25 g) and thermal hyperalgesia (PPT: 8.50 seconds; 95% CI: 6.76-10.23 seconds). Moreover, a systemic administration of RAMEB decreased CFA-induced mechanical (PPT: 126.66 g; 95% CI: 114.54-138.77 g) and thermal hyperalgesia (paw withdrawal latency: 11.47 seconds; 95% CI: 9.26-13.68 seconds). RAMEB FL resulted in greater in vitro PGE2-binding capacity and decreased PG content as well as hyperalgesia in vivo to a similar extent. Motor activity of the rats was not altered by RAMEB or RAMEB FL. CONCLUSIONS: Capture of PGs by cyclodextrins could be a novel and innovative tool for the treatment of inflammatory pain and bypassing some unwanted side effects of cyclooxygenase inhibitors.

Comparative evaluation of the chiral recognition potential of single-isomer sulfated beta-cyclodextrin synthesis intermediates in non-aqueous capillary electrophoresis.

The enantioselectivity of neutral single-isomer synthetic precursors of sulfated-ß-cyclodextrins was studied. Four neutral single-isomer cyclodextrins substituted on the secondary side with acetyl and/or methyl functional groups, heptakis(2-O-methyl-3,6-dihydroxy)-ß-cyclodextrin (HM-ß-CD), heptakis(2,3-di-O-acetyl-6-hydroxy)-ß-cyclodextrin (HDA-ß-CD), heptakis(2,3-di-O-methyl-6-hydroxy)-ß-cyclodextrin (HDM-ß-CD), heptakis(2-O-methyl-3-O-acetyl-6-hydroxy)-ß-cyclodextrin (HMA-ß-CD), and their sulfated analogs the negatively charged heptakis(2,3-di-O-methyl-6-sulfato)-ß-cyclodextrin (HDMS-ß-CD) and heptakis(2,3-di-O-acetyl-6-sulfato)-ß-cyclodextrin (HDAS-ß-CD) were investigated by non-aqueous capillary electrophoresis in the view of enantiodiscrimination for various drugs and related pharmaceutical compounds. The focus of the present work was on the chiral selectivity studies of the neutral derivatives, which are the synthesis intermediates of the sulfated products. The chiral recognition experiments proved that among the neutral compounds the HMA-ß-CD shows remarkable enantioselectivity towards chiral guests in non-aqueous capillary electrophoresis, while HM-ß-CD, HDA-ß-CD and HDM-ß-CD failed to resolve any of the 25 studied racemates under the applied experimental conditions. In order to get deeper insight into the molecular interactions between the studied single-isomer cyclodextrin and chiral fluoroquinolones (ofloxacin, gatifloxacin and lomefloxacin) and ß-blockers (propranolol), 1H and ROESY NMR experiments were performed. The 2-O-methylation in combination with the 3-O-acetylation of the host was evidenced to exclusively carry the essential spatial arrangement for chiral recognition.