Sulfate esters of morphine derivatives: synthesis and characterization.

Sixteen 3-O- and 6-O-sulfate esters of morphine, codeine and some of their N-methyl quaternary derivatives were synthesized by means of sulfation with pyridine-SO(3) complex and sulfuric acid/N,N'-dicyclohexylcarbodiimide. Complete (1)H- and (13)C-NMR assignments are given for each of the synthesized compounds based on one- and two-dimensional homo- and heteronuclear measurements. Comparative analysis of chiral properties by circular dichroism and optical rotatory dispersion revealed characteristic differences in the spectra due to changes in charge, polarity and intramolecular association by strong hydrogen bonds in aqueous solution.

Structure and stereochemistry of novel ecdysteroids from the roots of Serratula wolffii.

Three new natural ecdysteroids viz. 22-dehydro-20-deoxy-ajugasterone C (1), 1-hydroxy-22-deoxy-20,21-didehydro-ecdysone (2) and 22-deoxy-20,21-didehydro-ecdysone (3) were isolated from the methanol extract of the roots of Serratula wolffii. The structures of compounds 1-3 were established by various spectroscopic techniques, including one- and two-dimensional NMR, circular dichroism and mass spectroscopic methods.

Gradient HPLC separation of dehydroepiandrosterone (DHEA) from its metabolites and biological congeners: role of tetrahydrofuran in the chromatographic mechanism.

A three-step gradient reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the separation of dehydroepiandrosterone (DHEA), its sulfate ester (DHEA-S), its three C7-oxidized metabolites (7alphaOH-DHEA, 7betaOH-DHEA, 7-keto-DHEA), and its biosynthetic congeners (androstenedione, testosterone, estradiol, pregnenolone). This new method allows the quantitative characterization of DHEA metabolism and biosynthetic transformation under given physiological, pathological, or therapeutically influenced circumstances. Tetrahydrofuran probably acts as a proton acceptor coadsorbent, while isopropanol behaves as a proton donor during the separation of testosterone, estradiol, and the stereoisomers of 7-OH-DHEA.

Utility of cyclodextrins in the formulation of genistein part 1. Preparation and physicochemical properties of genistein complexes with native cyclodextrins.

Isoflavones are suitable guest molecules for inclusion complex formation with cyclodextrins (CDs). The molecular encapsulation with CDs results in a solid, molecularly dispersed form and in a significantly improved aqueous solubility of isoflavones. Genistein, a key isoflavone constituent of Ononidis spinosae radix was found to form a supramolecular, non-covalent inclusion complex with both beta-cyclodextrin (beta-CD) and gamma-cyclodextrin (gamma-CD), while it did not form a stable complex with alpha-CD.

Enantiomer separation of imidazo-quinazoline-dione derivatives on quinine carbamate-based chiral stationary phase in normal phase mode.

The normal phase mode liquid chromatographic enantiomer separation capability of a quinine tert-butyl-carbamate-type chiral stationary phase (CSP) has been investigated for a set of polar [1,5-b]-quinazoline-1,5-dione derivatives. This class of chiral heterocycles is currently under development as potential alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and/or N-methyl-D-aspartic acid (NMDA) receptor antagonists. The effect of the nature and concentration of polar modifier, i.

Three new steroids from the roots of Serratula wolffii.

Investigation of the methanol extract of the roots of Serratula wolffii resulted in an ecdysone-related compound, 2beta,3beta,20R,22R,25-pentahydroxy-5beta-cholest-6,8(14)-dien (1), a new ecdysteroid, 24-methylene-shidasterone (2), the known compound stachysterone B (3) and its 14,15-alpha-epoxide (4), a novel natural product. The structures of compounds 1-4 were established by spectral analysis ((1)H NMR, (13)C NMR, COSY, NOESY, HMQC, HMQC-TOCSY and HMBC).

Preparative-scale chromatography of ecdysteroids of Serratula wolffli andrae.

Numerous ecdysteroids are isolated from the herb of Serratula wolffii Andrae, a cultivated plant. The isolation procedure includes a variety of low-pressure liquid chromatography, thin-layer chromatography (TLC), gel chromatography, and high-performance liquid chromatography (HPLC) methods. The progress of separation is monitored by TLC, and the final proof of purity is carried out by HPLC.

Tracking of enantioselective solubility of rac-norgestrel in the presence of cyclodextrin by a CD spectroscopic method.

Dissolution of hydrophobic rac-norgestrel in aqueous gamma-cyclodextrin (gamma-CyD) and hydroxypropyl-gamma-cyclodextrin (HP-gamma-CyD) solutions was investigated, and enantioselective dissolution was observed. (-)-Norgestrel, the eutomer molecule, was dissolved to a greater extent using each of the CyDs, although the effect was more significant in the case of HP-gamma-CyD. A circular dichroism (CD) spectroscopic method based on measurement of the anisotropy factor was applied for the determination of the enantiomer ratio.

[Ecdysteroids of Silene italica ssp. nemoralis, novel approaches of ecdysteroid therapy].

Ecdysteroids are known as insect moulting hormones. They have the basic steroid structure, although their physiological effects on mammalians do not show the thymolytic and androgenic side effects of vertebrate type steroid hormones. At the same time, phytoecdysteroids can be used utilizing their anabolic and adaptogenic effects.

Liquid chromatographic enantiomer separations of novel quinazolone derivatives on quinine carbamate based chiral stationary phases using hydro-organic mobile phases.

Quinine carbamate-type weak chiral anion-exchange selectors (SOs) and the respective chiral stationary phases (CSPs) have been used for the direct liquid chromatographic enantiomer separation of a wide range of chiral acids. In the present work, we demonstrate that these CSPs can also be extended to chiral discrimination of a set of neutral polar potential NMDA (N-methyl-D-aspartic acid) and/or AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) antagonist imidazo-quinazoline-dione derivatives (selectands, SAs) using acetonitrile and methanol containing hydro-organic and buffered mobile phases. The influence of mobile phase composition, column temperature and structure variation of the SAs and SOs on retention and enantioselectivity was systematically investigated to gain insight into the overall chiral recognition mechanism.

[Enantioseparation of quinazolone derivatives using an AGP-based liquid chromatography stationary phase].

An AGP-based chiral stationary phase has been applied successfully for enantioseparation of 4(3H)-quinazolone derivatives. Chiral-AGP is proved to be an excellent selector, as optimized chromatographic conditions allow with one exception baseline resolution for the enantiomers of the potential cholecystokinin antagonist compounds (alpha = 1.19-1.

Study on the sorption properties of alpha1-acid glycoprotein (AGP)-based stationary phase modified by organic solvents.

An alpha(1)-acid glycoprotein, immobilized on silica (Chiral-AGP) is one of the most widely used chiral stationary phases for the enantiomeric separation of a wide variety of chiral drugs with several applications in the biological and clinical field. The aim of this work was to study the sorption properties of the AGP-based stationary phase, which may have crucial importance for enantioselectivity. New binding data to the mechanism of the chromatographic separation are presented.

Synthesis and stereochemistry of dispiro substituted pyridazines: application of ellipticity-absorbance ratio spectra for proving enantiomeric relationship by HPLC-CD/UV detection.

The aim of our study was to synthesize vinylic and pyrido-fused pyridazines with a spirano moiety and to investigate their stereochemistry by spectroscopic and HPLC analyses. The vinylic compounds 5 were obtained by Knoevenagel condensation of cyclohexylidene malonates 1 with pyridazinecarbaldehyde 2. Compound 5b exhibits geometric isomerism identified by NMR, HPLC, and X-ray methods.