E. Bossù

Determination of silymarine in the extract from the dried silybum marianum fruits by high performance liquid chromatography and capillary electrophoresis

Silybine (SBN), isosilybine (ISBN), silycristine (SCN), silydianine (SDN), and taxifoline (TXF) are the main active flavanoids, generally found in the dried fruits of silybum marianum. The concentrations of these compounds, excepted TXF, are all together usually expressed as silymarine content. In this paper the determination of the silymarine titre was made by high performance liquid chromatography (HPLC), and high performance capillary electrophoresis (HPCE). Two reversed stationary phases, RP-18 and RP-8, were observed comparing the resolutions of all considered flavanoids with each stationary phases. The HPCE was carried out considering the possible improvement in the resolution of SBN, CN, SDN and TXF using, 8-cyclodextrines or organic modifier. The qualitative and quantitative data obtained by HPLC and HPCE were compared.

Enantioseparation and anti-rhinovirus activity of 3-benzylchroman-4-ones

In a series of homo-isoflavonoids, chloro-substituted rac-3-benzylchroman-4-ones (3 d-f) showed an antiviral in vitro activity against selected picornaviruses. In order to study the anti-rhinovirus activity of each stereoisomer, racemic mixtures of 3 d and 3 e were successfully resolved by high-performance liquid chromatography, using a Whelk-O 1 column as chiral stationary phase. The CD spectra confirm that the two eluates of each compound are enantiomers but do not allow the assignment of their absolute configurations. The antiviral activity of the isomers and their racemates was tested in vitro against human rhinovirus serotype 1B and 14 infection, by means of the plaque reduction assay. All homoisoflavonoids tested exhibited an inhibitory effect on rhinovirus replication with an activity depending on virus serotype and compound. The two enantiomers of each compound and the corresponding racemate were equipotent, clearly showing that the configuration of the chiral center in position 3 does not influence the activity against both rhinovirus serotypes.

Determination of the binding of a β2-blocker drug, frusemide and ceftriaxone to serum proteins by capillary zone electrophoresis

Abstract A modified Hummel-Dreyer method was used to study the binding of drugs with serum proteins by high performance capillary electrophoresis. The study was carried out to check the possible interaction between serum proteins and a highly selective β 2 -blocker, ICI 118551 (ICI). To prove the suitability of the method the protein binding of frusemide and ceftriaxone, drugs previously investigated, was also studied. The analyses were carried out by injecting a solution of sα 1 -acidic glycoprotein ( α 1 -AGP) or human serum albumin in 70 mM NaH 2 PO 4 : Na 2 HPO 4 (pH 7.4) buffer into an uncoated fused silica capillary filled with the same buffer. In the capillary, maintained at a working temperature of 35°C, a known amount of the ICI, frusemide or ceftriaxone was added. The method allows the bound drug to be determined directly.

LTB4 as marker of 5-LO inhibitory activity of two new N-ω-ethoxycarbonyl-4-quinolones

The supposed 5-LO inhibitory activity of two N-ω-ethoxycarbonyl-4-quinolones was tested determining leukotriene B4 (LTB4) in RBL-1 cell cultures, pretreated with the two compounds of interest. LTB4, obtained by solid-phase extraction (SPE) from celle cultures supernatants, was determined by micellar electrokinetic chromatography (MEKC). The analysis was performed using an uncoated capillary, filled with borate buffer at pH 8.3, containing 12.5 mM SDS as micelles generator. Therefore, following the decreasing of LTB4 it was possible to verify the 5-LO inhibitory activity of two quinolone derivatives. To asses the suitability of the use of LTB4 as marker of the activity of the new compounds, the analysis was repeated using quercetin, a well known 5-LO inhibitor.

Human α1-glycoprotein acid as chiral selector in the enantioseparation of midodrine and deglymidodrine racemates by HPLC

Human alpha1-acid glycoprotein (alpha1-AGP) has been used as a chiral stationary phase (CSP) for the enantioseparation of midodrine and deglymidodrine racemates in the same HPLC run. The imobilized AGP resulted as the best chiral selector for the enantioresolution of two compounds. Due to the modification of alpha1-AGP characters as a result of changing the composition of the mobile phase, an attempt study of the watery mobile phase (ionic strength and pH of the buffer, nature and concentration of the organic modifier) allowed for an increase in the enantioselectivity of the chromatographic system and an optimization of the resolution base-line of both enantiomeric pairs.

Analysis of non-benzodiazepinic anxiolytic agents by capillary zone electrophoresis

A simple capillary electrophoretic method was developed for the analysis of a new generation of serotonergic anxiolytics and their related substances: zalospirone, gepirone, ipsapirone and buspirone. All compounds run in a Tris/phosphate buffer at pH 3 as cations and the experimental conditions allowed good resolution of four drugs and their principal impurities. The analyses were made using two different kinds of capillary. The suitability of CZE and HPLC methods for the analysis of these non-benzodiazepinic anxiolytic agents and their impurities was compared.

Analysis of ticlopidine and related impurities by capillary electrophoresis

Capillary electrophoresis has been used to analyse ticlopidine and its main impurities in bulk material. The minimum detectable amount of impurities was determined and the electrophoretic conditions used were discussed. The proposed method is also suitable to analyse the drug in plasma.

Chromatographic resolution and pharmacological investigation of some imidazole derivatives

Some N-phenylethylimidazoles have a chiral carbon atom in their structure. These compounds were obtained by non-stereoselective synthesis and their pharmacological activity was always tested on the racemic mixtures. The proposed HPLC method allowed the chiral resolution of RF29, denzimol and reduced nafimidone by using a Chiracel OD-H column. The enantiomers of each compound were separately collected and their pharmacological activity was tested on the guinea pig ileum and the rabbit jejunum.

Chromatographic resolution and pharmacological investigation of ICI 118551, a new β2-blocker

Abstract ICI 118551, a highly selective β 2 -blocking compound, and its threo isomer, one of the possible impurities of drug, were resolved by high-performance liquid chromatography on a chiral stationary phase. The enantiomers of ICI 118551 were separately collected and the β 2 -blocking activity of each isomer was tested on the guinea pig trachea.