Enantiomeric separation of pirlindole by liquid chromatography using different types of chiral stationary phases

Enantioseparation of Cinacalcet, and its Two Related Compounds by HPLC with Self-Made Chiral Stationary Phases and Chiral Mobile Phase Additives

Background:

Cinacalcet is one of the second-generation calcimimetics which consists of a chiral center. The pharmacological effect of R-cinacalcet is 1000 times greater than that of the Scinacalcet. As mentioned in many literatures, 1-(1-naphthyl)ethylamine is used as the starting material for the synthesis of cinacalcet. The absolute structure of cinacalcet is influenced by the starting materials.

Methods:

We present the chiral separation of cinacalcet and its starting material, 1-(1-naphthyl) ethylamine along with one of its intermediates, N-(1-(naphthalen-1-yl) ethyl)-3- (3-(trifluoromethyl) phenyl) propanamide by high-performance liquid chromatography with chiral stationary phase and chiral mobile phase additives.

Results:

On vancomycin and cellulose tri 3,5-dimethylphenylcarbamate) chiral stationary phase, cinacalcet and 1-(1-naphthyl)ethylamine achieved enantioseparation under normal phase with addition of triethylamine additives, respectively. Meanwhile, 1-(1-naphthyl)ethylamine and N-(1-(naphthalen-1- yl)ethyl)-3-(3-(trifluoromethyl) phenyl) propanamide achieved enantioseparation on 1-napthalene vancomycin chiral stationary phase using D-tartaric acid, diethyl L-tartrate and diethyl D-tartrate as chiral mobile phase additives.

Conclusion:

The chiral recognition in our experiment was based on the hydrogen-bonding, dipoledipole and π-π interactions among the solutes, chiral stationary phases and chiral mobile phase additives. In addition, the space adaptability of chiral stationary phases also affected the separation efficacy.

Separation of drug enantiomers by liquid chromatography and capillary electrophoresis, using immobilized proteins as chiral selectors

Proteins display interesting chiral discrimination properties owing to multiple possibilities of intermolecular interactions with chiral compounds. This review deals with proteins which have been used as immobilized chiral selectors for the enantioseparation of drugs in liquid chromatography and capillary electrophoresis. The main procedures allowing the immobilization of proteins onto matrices, such as silica and zirconia particles, membranes and capillaries are first presented. Then the factors affecting the enantioseparation of drugs in liquid chromatography, using various protein-based chiral stationary phases (CSPs), are reviewed and discussed. Last, chiral separations already achieved using immobilized protein selectors in affinity capillary electrochromatography (ACEC) are presented and compared in terms of efficiency, stability and reproducibility.

Automated determination of pirlindole enantiomers in plasma by on-line coupling of a pre-column packed with restricted access material to a chiral liquid chromatographic column

A fully automated liquid chromatographic method has been developed for the determination of the enantiomers of pirlindole, an antidepressant drug, in human plasma. The method is based on the use of a pre-column packed with restricted access material (RAM) (LiChrospher ADS RP-4) for sample clean-up coupled to a column containing a cellulose tris-(3,5-dimethylphenylcarbamate) based chiral stationary phase (Chiralcel OD-R) for the separation and quantitative analysis of pirlindole enantiomers. A 50-microl plasma volume was injected directly onto the pre-column using a mixture of phosphate buffer (pH 5.0) and methanol (97:3; v/v) as washing liquid. By rotation of a switching valve, the analytes were then eluted in the back-flush mode with the LC mobile phase. A complete separation of pirlindole enantiomers was obtained in 22 min on the Chiralcel OD-R column, using a mobile phase made of a mixture of phosphate buffer (pH 5.0) containing 50 mM sodium perchlorate and acetonitrile (65:35; v/v). The flow-rate was 0.6 ml/min and the analytes were detected fluorometrically using 295 and 340 nm as excitation and emission wavelengths, respectively. The method was then validated and was found to be linear in the 2.5-200 ng/ml range. The limit of detection was lower than 1 ng/ml. Repeatability and intermediate precision at a concentration of 50 ng/ml were about 1.5 and 3.5%, respectively.

Chiral high-performance liquid chromatographic analysis of antifungal SCH 56592 and evaluation of its chiral inversion in animals and humans

SCH 56592 is a novel triazole antifungal agent that is active both orally and intravenously in animal models of infection. This compound is in Phase II-III clinical trials for the treatment of systemic fungal infections. SCH 56592 is a single enantiomer with four stereogenic centers; therefore, it was necessary to evaluate the possible chiral inversion of this drug candidate in animals and humans. Thus, chiral high-performance liquid chromatographic (HPLC) methods have been developed to separate SCH 56592 from its diastereomers and to evaluate its chiral inversion in rats, dogs, cynomolgus monkeys, and humans. Chiral HPLC analysis involved the use of a Chiralcel OD column set at 39 degrees C with a mobile phase of hexane-ethanol-diethylamine and a fluorescence detector set at an excitation wavelength of 270 nm and an emission wavelength of 390 nm. Plasma or serum samples were subjected to solid phase extraction on a C(2) cartridge followed by HPLC analysis. The method was sensitive with a limit of quantitation of 0.1 microg/ml in dog serum. The linearity was satisfactory, as shown by correlations of >0.997 and by visual examination of the calibration curves. The precision and accuracy were satisfactory, as indicated by coefficients of variation (CV) ranging from 1.1 to 12.1% and bias values ranging from -11.0 to 9.0%. Chiral HPLC analysis indicated that SCH 56592 was not subjected to chiral inversion in rats, dogs, cynomolgus monkeys, and humans.