Alkylation of cyclomaltohexaose (α-cyclodextrin, α-CD) with allyl or cinnamyl bromide, followed by peracetylation of remaining hydroxyl groups and separation of isomers, resulted in the set of peracetylated 2(I)-O-, 3(I)-O- and 6(I)-O-alkylated α-CDs in up to 27% yields. Ozonolysis or oxidative cleavage of peracetylated allyl or cinnamyl derivatives resulted in a complete set of peracetylated 2(I)-O-, 3(I)-O- and 6(I)-O-formylmethyl or carboxymethyl derivatives that are useful precursors for preparation of regioselectively monosubstituted derivatives of α-CD. Moreover, a quick method to recognize single 2(I)-O-, 3(I)-O- and 6(I)-O-monosubstituted peracetylated CDs from one another using only their (1)H NMR spectra has been proposed.

• MeSH
• acetylace MeSH
• aldehydy chemická syntéza   MeSH
• alfa-cyklodextriny chemická syntéza   chemie   izolace a purifikace   MeSH
• alkylace MeSH
• katalýza MeSH
• kyseliny karboxylové chemická syntéza   MeSH
• magnetická rezonanční spektroskopie MeSH
• oxidace-redukce MeSH
• síran měďnatý chemie   MeSH
• sloučeniny ruthenia chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aldehydy MeSH
• alfa-cyklodextriny MeSH
• kyseliny karboxylové MeSH
• ruthenium chloride MeSH Prohlížeč
• síran měďnatý MeSH
• sloučeniny ruthenia MeSH

The acylation of prednisolone 20-hydrazone with star poly(ethylene glycol) tetracarboxylic acid (M = 20,000) has been used to prepare the corresponding pH-sensitive conjugate. With α-cyclodextrin, this conjugate forms a polypseudorotaxane, which was characterised by means of (1)H NMR spectra, powder X-ray diffraction patterns and STM microscopy. The rate of acid-catalysed hydrolysis of the conjugate was studied under in vitro conditions in model media of hydrochloric acid solutions, phosphate and acetate buffers (pH 2-5.8). The acid-catalysed hydrolysis (at pH 2) of the polypseudorotaxane was ca 3.5 times slower than that of the original conjugate. After 1h in this medium, 86% of the covalently attached prednisolone remained unchanged. The prepared polypseudorotaxane represents a promising peroral transport system of prednisolone with a pH-sensitive linker with delayed acid-catalysed hydrolysis thanks to protection at the molecular level using α-cyclodextrin.

• MeSH
• alfa-cyklodextriny chemická syntéza   chemie   farmakokinetika   MeSH
• gely MeSH
• glukokortikoidy chemie   MeSH
• hydrazony chemie   MeSH
• koncentrace vodíkových iontů MeSH
• polyethylenglykoly chemická syntéza   chemie   farmakokinetika   MeSH
• pomocné látky MeSH
• prednisolon analogy a deriváty   chemická syntéza   chemie   farmakokinetika   MeSH
• příprava léků metody   MeSH
• rotaxany chemie   MeSH
• stabilita léku MeSH
• systémy cílené aplikace léků * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• alpha-cyclodextrin MeSH Prohlížeč
• gely MeSH
• glukokortikoidy MeSH
• hydrazony MeSH
• polyethylenglykoly MeSH
• pomocné látky MeSH
• prednisolon MeSH
• rotaxany MeSH
• star poly(ethylene glycol)hydrazide-prednisolone-20-hydrazone MeSH Prohlížeč

The reaction of α-amino-ω-methoxypoly(ethylene glycol) [M = 5000] or star α-amino-poly(ethylene glycol) [M = 20 000] with hemiesters of prednisolone dicarboxylic acids (succinic, glutaric, adipic, phthalic acid) has been used to prepare the corresponding conjugates. The rate of esterase catalyzed hydrolysis of the conjugates is controlled by the molecular mass of poly(ethylene glycol) and the length of the linker between prednisolone and poly(ethylene glycol) (τ(1/2)∼ 5-0.5 h). The enzymatic hydrolysis proceeds most rapidly at conjugates with linkers derived from adipic and phthalic acids. The synthesized conjugates form polypseudorotaxanes with α-cyclodextrin which were characterized by 2D NOESY NMR spectra, powder X-ray diffraction patterns and in one case also by STM microscopy. In the case of the polypseudorotaxane having the linker derived from adipic acid, the enzymatic release proceeds ca. five times slower in comparison with the rate of prednisolone release from the corresponding conjugate. The rate of prednisolone release from the carrier can be controlled by three factors: character of the linker between the polymeric carrier and prednisolone, the molecular mass of poly(ethylene glycol) and complex formation with α-cyclodextrin. The synthesized polypseudorotaxanes represent new promising transport systems intended for targeted release of prednisolone in transplanted liver.

• MeSH
• alfa-cyklodextriny chemie   MeSH
• cyklodextriny chemie   MeSH
• molekulární struktura MeSH
• poloxamer chemie   MeSH
• polyethylenglykoly chemie   MeSH
• prednisolon chemie   MeSH
• rastrovací tunelová mikroskopie MeSH
• rotaxany chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• alpha-cyclodextrin MeSH Prohlížeč
• cyklodextriny MeSH
• poloxamer MeSH
• polyethylenglykoly MeSH
• prednisolon MeSH
• pseudopolyrotaxane MeSH Prohlížeč
• rotaxany MeSH

The compounds I-IV derived from α-D-cyclodextrin moiety by bridging and/or interconnecting with various patterns of disulfide bonds were chosen as models for the spectroscopic study of conformation of the disulfide bridge. The energy gap between the disulfide and cyclodextrin's electronic transitions allows us to investigate absorption and electronic circular dichroism spectra without disturbing spectral overlaps with amides or aromatic amino acids in peptides or proteins. Raman optical activity (ROA) spectra were measured and the bands due to S-S and C-S stretching motion identified. Comparison with the quantum mechanical calculations of simple models indicates that sense of disulfide twist follows sign of the measured S-S ROA band.

• MeSH
• alfa-cyklodextriny chemie   MeSH
• cirkulární dichroismus MeSH
• disulfidy chemie   MeSH
• molekulární struktura MeSH
• Ramanova spektroskopie MeSH
• vibrace * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• disulfidy MeSH

Template-free oxidative dimerization of 6(I), 6(III), 6(V)-trisulfanyl-alpha-cyclodextrin proceeds with a remarkable efficiency (> or =94%) yielding an unprecedented duplex alpha-cyclodextrin triply bridged with disulfide linkages whose structure has been confirmed by X-ray analysis.

• MeSH
• alfa-cyklodextriny chemická syntéza   chemie   MeSH
• disulfidy chemie   MeSH
• emulze chemie   MeSH
• koncentrace vodíkových iontů MeSH
• krystalografie rentgenová MeSH
• polymery chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• alpha-cyclodextrin MeSH Prohlížeč
• disulfidy MeSH
• emulze MeSH
• polymery MeSH

The rigid duplex cyclodextrin 6 composed of two alpha-cyclodextrin macrocycles connected with two disulfide bonds in "transannular" (C6(I), C6(IV)) positions was prepared from partially debenzylated alpha-cyclodextrin 1 in four steps in 73% overall yield. In the last key step involving oxidative coupling of the thiol 5, predominance of the target duplex 6 can be attained under conditions of thermodynamic control. The structure of duplex cyclodextrin was established by MS as well as 2-D NMR methods and confirmed by a single-crystal X-ray analysis. The ability of the duplex cyclodextrin 6 to bind alpha,omega-alkanediols (C9-C14) and 1-alkanols (C9 and C10) was studied by isothermal titration calorimetry in aqueous solutions. The stability constants of the complexes gradually increase with the alkyl chain length and reach an unprecedently high value of K = 8.6 x 10(9) M(-1) for 1,14-tetradecanediol. It was found that the doubly bridged dimer 6 exhibits higher binding affinity toward the series of alpha,omega-alkanediols than the singly bridged analogue 10 by about 2 orders of magnitude in K (M(-1)) or 3.1-3.3 kcal/mol in deltaG(o), the enhancement being due to enthalpic factors. Theoretical calculations using DFT-D methods suggest that the enthalpic contribution stems from dispersion interactions.

• MeSH
• alfa-cyklodextriny chemická syntéza   chemie   MeSH
• alkoholy chemie   MeSH
• dimerizace MeSH
• disulfidy chemie   MeSH
• krystalografie rentgenová MeSH
• molekulární konformace MeSH
• molekulární modely MeSH
• termodynamika MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• alkoholy MeSH
• alpha-cyclodextrin MeSH Prohlížeč
• disulfidy MeSH

Cluster anions of boron are built up on three-center two-electron bonds in contrast to naturally occurring compounds and their synthetic analogs. Methanol works as a solvent and as a competing agent, which advantageously adjusts reasonable strength of their interaction with native CDs in water-organic BGE. The highest methanol concentration preserving chiral discrimination of atropoisomers of individual anions is approximately 35, 55 and 75% v/v for alpha-, beta- and gamma-CD, respectively. alpha-CD separates anionic 7, 8-nido-dicarbaundecaborate clusters with small exo-skeletal substituents. beta-CD separates anions of all four tested structural types. The efficiency of separation of a compound with alpha- or beta-CD is always markedly lower than the separation efficiency at the absence of a CD in BGE. The efficiency of separation of a compound with beta-CD is always lower than the efficiency of separation of the compound with alpha-CD. gamma-CD was proved to be unsuitable as a chiral selector because in BGEs with gamma-CD, effective mobilities of analytes as well as their differences continuously decrease. The decrease was ascribed to the decomposition of the gamma-CD. The assessment of analytical prospect of alpha- and beta-CDs as chiral selectors for chiral separations of boron cluster anions requires knowledge of stability of individual CDs at the conditions of analyses and recognition of the chance to eliminate low separation efficiency.

• MeSH
• alfa-cyklodextriny chemie   izolace a purifikace   MeSH
• anionty chemie   MeSH
• beta-cyklodextriny chemie   izolace a purifikace   MeSH
• cyklodextriny MeSH
• elektroforéza kapilární metody   MeSH
• elektrolyty chemie   MeSH
• gama-cyklodextriny chemie   izolace a purifikace   MeSH
• hydrofobní a hydrofilní interakce MeSH
• methanol chemie   MeSH
• senzitivita a specificita MeSH
• sloučeniny boru chemie   MeSH
• stereoizomerie MeSH
• voda chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• anionty MeSH
• beta-cyklodextriny MeSH
• cyklodextriny MeSH
• elektrolyty MeSH
• gama-cyklodextriny MeSH
• methanol MeSH
• sloučeniny boru MeSH
• voda MeSH

In background electrolyte (BGE) with the optimal methanol concentration of 30% (v/v), the ion with -NCS group bonded to a cluster boron atom exhibits the strongest interaction with alpha-cyclodextrin and the highest separation selectivity. Interaction of ions with alkyl or thioalkyl group weakens with the increasing substituent size. The ion with phenyl group exhibits the weakest interaction. Bonding of a group to boron atom weakens the ion interaction with alpha-cyclodextrin. Second substituent further weakens the interaction with alpha-cyclodextrin. Separation efficiency is lower at the presence of alpha-cyclodextrin than at its absence. This separation efficiency loss, amounts up to 90%.

• MeSH
• alfa-cyklodextriny chemie   MeSH
• anionty izolace a purifikace   MeSH
• borany chemie   MeSH
• senzitivita a specificita MeSH
• stereoizomerie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• alpha-cyclodextrin MeSH Prohlížeč
• anionty MeSH
• borany MeSH

Eight phenolic acids were analyzed by capillary zone electrophoresis. On-line analyte preconcentration was carried out by hydrodynamic injection of large volume of sample followed by removal of the bulk of the low conductivity sample matrix by polarity switching. The optimal electrolyte system consisted of 50mM sodium tetraborate of pH 9.0 (adjusted with 0.1 M phosphoric acid) containing 2% of alpha-cyclodextrin. The separations were carried out with a fused silica capillary (effective length 50 cm, i.d. 50 microm) and monitored at 200 nm. Under optimized preconcentration conditions (sample injection 99 s at 100 mbar and the polarity switching time 1.0 min) linear calibration ranges (0.1-2.0 microg/ml, R=0.9979-0.9995), favourable limits of detection (0.01-0.025 microg/ml) and good repeatability of the peak areas (R.S.D.: 2.76-5.69%, n=6) were achieved.

• MeSH
• alfa-cyklodextriny chemie   MeSH
• elektroforéza kapilární metody   MeSH
• hydroxybenzoáty analýza   MeSH
• kalibrace MeSH
• koncentrace vodíkových iontů MeSH
• reprodukovatelnost výsledků MeSH
• senzitivita a specificita MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• alpha-cyclodextrin MeSH Prohlížeč
• hydroxybenzoáty MeSH
• phenolic acid MeSH Prohlížeč

• MeSH
• alfa-cyklodextriny chemie   MeSH
• aminokyseliny chemie   MeSH
• chemické modely MeSH
• chemie organická metody   MeSH
• krystalografie rentgenová metody   MeSH
• molekulární konformace MeSH
• molekulární modely MeSH
• nanotechnologie metody   MeSH
• nanotrubičky chemie   MeSH
• peptidy chemie   MeSH
• vodíková vazba MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alfa-cyklodextriny MeSH
• alpha-cyclodextrin MeSH Prohlížeč
• aminokyseliny MeSH
• peptidy MeSH