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A fast and practical chiral capillary electrophoretic method has been developed for determination of the enantiomeric purity of 2-(2′-carboxy-3′-phenylcyclopropyl)glycine (PCCG) compounds. In particular, the isomer PCCG-13, a potent selective and competitive antagonist at phospholipase D-coupled metabotropic glutamate receptors (mGluRs), was completely resolved from its enantiomer PCCG-15 by use of dimethyl-β-cyclodextrin (DMCD) as chiral selector. pH 9.0 running buffer containing 2-amino-2-methyl-1,3-propanediol (AMPD; 100mM) was a suitable medium enabling resolution of the enantiomers in a short (32.5 cm total length) poly(vinyl alcohol) (PVA)-coated capillary. Because of the suppression of the electroosmotic flow and the good peak shape, baseline resolution of the enantiomers was obtained by use of the optimum concentration of chiral selector. For quantitative purposes at impurity levels, high sample loading was required and adequate separation was obtained in the presence of 80 mM DMCD. This CE method enabled quantification of 0.3% m/m of undesired enantiomer in PCCG-13; the samples analyzed, obtained from enantioselective synthesis, proved to be of high enantiomeric purity. [ABSTRACT FROM AUTHOR]

The performance of a HSA-based HPLC column has been improved by modulating the binding properties of the anchored protein using lithocholic acid as a selective modifier in the mobile phase. In particular, retention decreased for both drugs binding to sites I or II, while the enantioselectivity was maintained for most analytes. The advantages of using lithocholic acid in the mobile phase were impressive in the case of profens, for which a considerable reduction in analysis time and a significant increase in enantioselectivity were obtained. The results were rationalized by considering lithocholic acid as a direct competitor for site II binding drugs and indirect competitor for site I binding drugs. [ABSTRACT FROM AUTHOR]

A comparison of the enantiorecognition ability of linear, neutral polysaccharides was performed on a series of basic drug racemates in acidic running buffer (pH 3.0). Dextrin 20, Dextran 70 and Pullulan were chosen as chiral selectors for their different characteristics. Dextrin 20, high-dextrose equivalent maltodextrin, showed good enantioresolution for a limited number of racemic drugs. In contrast, Dextran 70, a low-equivalent dextrose polysaccharide, exhibited poorer enantioresolution but had wider applicability allowing nine basic racemates to be resolved; in particular, at high concentrations enantioseparation of amphetamine and congeners was achieved in relatively short time. The results obtained appear to support different mechanisms of enantiorecognition for the polysaccharides studied. [ABSTRACT FROM AUTHOR]

A human serum albumin (HSA)-based HPLC column has been modified in situ by disulfiram, an alcohol-deterrent drug reported to bind cys34, the only free cysteine in HSA, under physiological conditions. The reversible and covalent binding of disulfiram was found to change the binding properties of the protein, giving rise to a new selector which performed differently from the native albumin-based stationary phase. When low concentrations of disulfiram were used as mobile phase modifier, reversible binding resulted in a cooperative allosteric effect with improved selector performance. Covalent modification resulted in markedly reduced affinity for binding of the drugs to sites I or II, while still maintaining enantioselectivity. This study has enabled the monitoring of interactions of disulfiram with potentially coadministered drugs, and the preparation of a chiral selector with different drug affinity and enantioselectivity. [ABSTRACT FROM AUTHOR]

1 H-benz[f]indene-1.3(2H)dione-bis-amidinohydrazone (benzhydrazone) inhibited incorporation ofC-glucosamine,C-fucose andC-mannose into glycoproteins of HEp-2 cells infected with various strains of herpes simplex virus 1 (HSV-1) and impaired RNA and protein synthesis to a low extent. These biochemical effects are very similar to those induced by glycosylation inhibitors such as tunicamycin, D-glucosamine and 2-deoxy-D-glucose. In contrast to these inhibitors, benzhydrazone reduced HSV glycoprotein synthesis selectively since it did not significantly modify i) the saccharide uptake into glycoproteins of uninfected and of Sindbis virus-infected cells, ii) viral growth and cell fusion in paramyxovirus-infected cells, two activities which depend on viral glycoprotein synthesis. Benzhydrazone had only minor effects on the overall metabolism of uninfected cells, since it did not alter cell growth rate, and amino acid, uridine, and hexose incorporations were about 80 per cent those of untreated cells. [ABSTRACT FROM AUTHOR]

Reversed-phase HPLC separations of basic compounds have been optimized by use of mobile phases containing 1,8-diaminooctane (DAO) as amine modifier and heptanesulfonate as counter-ion. Such studies have demonstrated the high resolution and selectivity of this chromatographic system compared with mobile phases prepared with the more widely used primary amines. With the aim of clarifying the retention mechanism involved, three sets of compounds with different structures and properties were analyzed: sulfamidics and trimethoprim, aromatic diamines and aminophenols, and a standard mixture of lipophilic basic drugs. The conditions investigated were: diaminoalkane modifier concentration, diaminoalkane modifier alkyl-chain length, nature and concentration of the counter-ion, pH of the mobile phase, concentration of the organic modifer, and the nature of the stationary phase as characterized by percentage carbon loading. Analysis of chromatographic behavior as a function of the chromatographic conditions has enabled the proposal of a mechanism of retention of the three classes of compounds. [ABSTRACT FROM AUTHOR]

The development of a selective and sensitive HPLC method for the determination of semipermanent hair colorants in cosmetic formulations is proposed. The separation and identification of N-hydroxyalkyl nitrophenylenediamines and nitroaminophenols were performed by HPLC with on-line, post-column, photochemical derivatisation, using a reversed phase, ion-pair system with 1,8-diaminooctane and heptansulfonate in the mobile phase. Two UV spectra (photoreactor on and off) were obtained for each analyte, adding information for confirming peak identity. Analyte-modified spectral properties were used to increase the method sensitivity. The proposed method was successfully applied to quality control and stability studies of cosmetic formulations. [ABSTRACT FROM AUTHOR]