Maria Luisa Sanna

Direct HPLC enantioseparation of omeprazole and its chiral impurities: Application to the determination of enantiomeric purity of esomeprazole magnesium trihydrate

Analytical and semipreparative high-performance liquid chromatography (HPLC) enantioseparation of the proton-pump inhibitor omeprazole (OME) and its potential organic chiral impurities were accomplished on the immobilised-type Chiralpak IA chiral stationary phase (CSP) under both polar organic and normal-phase conditions. The (S)-enantiomers were isolated with a purity of >99% ee and their absolute configuration was empirically assigned by circular dichroism (CD) spectroscopy. A chemo- and enantioselective HPLC method was validated to control the enantiomeric purity of the (S)-enantiomer of OME (ESO), an active ingredient contained in drug products, in the presence of chiral and achiral related substances. The precision, linearity and accuracy of the determination of the (R)-impurity as well as the recovery of ESO from a pharmaceutical preparation were determined. The proposed method uses the mixture methyl tert-butylether (MtBE)-ethyl acetate (EA)-ethanol (EtOH)-diethylamine (DEA) 60:40:5:0.1 (v/v/v/v) as a mobile phase. In these conditions, linearity over the concentration range 0.5-25 microg/ml for (R)-enantiomer was obtained. The limits of detection and quantification were 99 and 333 ng/ml, respectively. The intra and inter-day assay precision was less than 2% (RSD%).

3-Acetyl-2,5-diaryl-2,3-dihydro-1,3,4-oxadiazoles: a new scaffold for the selective inhibition of monoamine oxidase B.

3-Acetyl-2,5-diaryl-2,3-dihydro-1,3,4-oxadiazoles were designed, synthesized, and tested as inhibitors against human monoamine oxidase (MAO) A and B isoforms. Several compounds, obtained as racemates, were identified as selective MAO-B inhibitors. The enantiomers of some derivatives were separated by enantioselective HPLC and tested. The R-enantiomers always showed the highest activity. Docking study and molecular dynamic simulations demonstrated the putative binding mode. We conclude that these 1,3,4-oxadiazoles derivatives are promising reversible and selective MAO-B inhibitors.

Synthesis of new 3-aryl-4,5-dihydropyrazole-1-carbothioamide derivatives. An investigation on their ability to inhibit monoamine oxidase

Some differently substituted 3-aryl-4,5-dihydropyrazoles-1-carbothioamides have been synthesised with the aim to investigate their monoamine oxidase inhibitory activity. The chemical structures of the compounds have been characterized by means of their IR, (1)H NMR, (13)C NMR spectroscopic data and elemental analyses. All the active compounds showed a selective activity towards the B isoform of the enzyme, regardless of the substitution on the heterocyclic ring. The inhibition of the enzymatic activity was measured on human recombinant MAO isoforms, expressed in baculovirus infected BTI insect cells. Docking experiments were carried out with the aim to rationalize the mechanism of inhibition of the most active and selective compound.

Catalytic enantioselective Amadori–Heyns rearrangement of racemic α-hydroxy ketones with arylamines: synthesis of optically active α-arylamino ketones

A novel synthesis of optically active α-arylamino ketones through an organocatalytic enantioselective Amadori-Heyns rearrangement is described.

Application of an immobilised amylose-based chiral stationary phase to the development of new monoamine oxidase B inhibitors.

A direct HPLC enantioseparation of three new chiral oxadiazoline derivatives endowed with potential MAO-B inhibitory activity was accomplished on the immobilised Chiralpak IA chiral stationary phase. Multi-mg amounts of enantiomers with high enantiomeric purity (ee> or =98%) were rapidly collected using pure dichloromethane as eluent. The absolute configuration and chiroptical properties of the enantiomers isolated at semipreparative scale were exhaustively determined.

Semipreparative HPLC enantioseparation, chiroptical properties, and absolute configuration of two novel cyclooxygenase-2 inhibitors

A direct semipreparative HPLC enantioseparation of two chiral thiazolidinone derivatives having cyclooxygenase-2 inhibition activity was performed on the Chiralpak IA chiral stationary phase. Semipreparative amounts of enantiopure forms were collected using acetonitrile-ethanol-trifluoroacetic acid mixtures as mobile phase. The absolute configuration of both compounds was unequivocally established by single-crystal X-ray diffraction method and correlated to the chiroptical properties of isolated enantiomers.

Through scaffold modification to 3,5-diaryl-4,5-dihydroisoxazoles: new potent and selective inhibitors of monoamine oxidase B

Abstract 3,5-Diaryl-4,5-dihydroisoxazoles were synthesized and evaluated as monoamine oxidase (MAO) enzyme inhibitors and iron chelators. All compounds exhibited selective inhibitory activity towards the B isoform of MAO in the nanomolar concentration range. The best performing compound was preliminarily evaluated for its ability to bind iron II and III cations, indicating that neither iron II nor iron III is coordinated. The best compounds racemic mixtures were separated and single enantiomers inhibitory activity evaluated. Furthermore, none of the synthesised compounds exhibited activity towards MAO A. Overall, these data support our hypothesis that 3,5-diaryl-4,5-dihydroisoxazoles are promising scaffolds for the design of neuroprotective agents.