Elisabetta Armani

Bis(L-amino acid amidato)copper(II) complexes as chiral eluents in the enantiomeric separation of D,L-dansylamino acids by reversed-phase high-performance liquid chromatography

Copper(II) complexes of L-amino acylamides (Phe, Val, Tyr, Ala) when added to the eluent (water-acetonitrile) in reversed-phase high-performance liquid chromatography (C18) are able to perform enantiomeric separation of dansylamino acids. The lipophilicity and bulk of the ligand greatly affect the stereoselectivity and the elution order of the enantiomers. The type and concentration of the copper complexes, pH and eluent polarity were examined in order to get some insights into the separation mechanism. This may be consistent with a ligand-exchange mechanism, probably occurring on the organic phase of the column, where the enantioselective complex is adsorbed. Mixtures of D,L-dansylamino acids were well separated by isocratic and gradient elution.

Copper(II) complexes of diamino-diamido-type ligands as chiral eluents in the enantiomeric separation of D,L-dansylamino acids by reversed-phase high-performance liquid chromatography

For purpose of studying the mechanism of chiral recognition in high-performance liquid chromatography (HPLC) (reversed phase), a model system is proposed, i.e., copper(II) complexes of diamino-diamido-type ligands containing L-amino acids (AA-NN-n) which added to the eluent are able to perform the enantiomeric resolution of dansylamino acids on C8 and C18 columns. Being potentially tetradentate, this system should be more liable to give an apical or outer-sphere interaction with the enantiomer rather than a simultaneous dechelation of two binding sites, as in the classical ligand-exchange mechanism. This model allows the variation of several parameters, such as the structural and electronic features of the initial complexes, their relative stabilities and lipophilicities and their correlation with enantioselectivity in HPLC.

CHF6001 I: a novel highly potent and selective phosphodiesterase 4 inhibitor with robust anti-inflammatory activity and suitable for topical pulmonary administration.

This study examined the pharmacologic characterization of CHF6001 [(S)-3,5-dichloro-4-(2-(3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl)-2-(3-(cyclopropylmethoxy)-4-(methylsulfonamido)benzoyloxy)ethyl)pyridine 1-oxide], a novel phosphodiesterase (PDE)4 inhibitor designed for treating pulmonary inflammatory diseases via inhaled administration. CHF6001 was 7- and 923-fold more potent than roflumilast and cilomilast, respectively, in inhibiting PDE4 enzymatic activity (IC50 = 0.026 ± 0.006 nM). CHF6001 inhibited PDE4 isoforms A–D with equal potency, showed an elevated ratio of high-affinity rolipram binding site versus low-affinity rolipram binding site (i.e., >40) and displayed >20,000-fold selectivity versus PDE4 compared with a panel of PDEs. CHF6001 effectively inhibited (subnanomolar IC50 values) the release of tumor necrosis factor-α from human peripheral blood mononuclear cells, human acute monocytic leukemia cell line macrophages (THP-1), and rodent macrophages (RAW264.7 and NR8383). Moreover, CHF6001 potently inhibited the activation of oxidative burst in neutrophils and eosinophils, neutrophil chemotaxis, and the release of interferon-γ from CD4+ T cells. In all these functional assays, CHF6001 was more potent than previously described PDE4 inhibitors, including roflumilast, UK-500,001 [2-(3,4-difluorophenoxy)-5-fluoro-N-((1S,4S)-4-(2-hydroxy-5-methylbenzamido)cyclohexyl)nicotinamide], and cilomilast, and it was comparable to GSK256066 [6-((3-(dimethylcarbamoyl)phenyl)sulfonyl)-4-((3-methoxyphenyl)amino)-8-methylquinoline-3-carboxamide]. When administered intratracheally to rats as a micronized dry powder, CHF6001 inhibited liposaccharide-induced pulmonary neutrophilia (ED50 = 0.205 μmol/kg) and leukocyte infiltration (ED50 = 0.188 μmol/kg) with an efficacy comparable to a high dose of budesonide (1 μmol/kg i.p.). In sum, CHF6001 has the potential to be an effective topical treatment of conditions associated with pulmonary inflammation, including asthma and chronic obstructive pulmonary disease.

Novel Class of Benzoic Acid Ester Derivatives as Potent PDE4 Inhibitors for Inhaled Administration in the Treatment of Respiratory Diseases

The first steps in the selection process of a new anti-inflammatory drug for the inhaled treatment of asthma and chronic obstructive pulmonary disease are herein described. A series of novel ester derivatives of 1-(3-(cyclopropylmethoxy)-4-(difluoromethoxy)phenyl)-2-(3,5-dichloropyridin-4-yl) ethanol have been synthesized and evaluated for inhibitory activity toward cAMP-specific phosphodiesterase-4 (PDE4). In particular, esters of variously substituted benzoic acids were extensively explored, and structural modification of the alcoholic and benzoic moieties were performed to maximize the inhibitory potency. Several compounds with high activity in cell-free and cell-based assays were obtained. Through the evaluation of opportune in vitro ADME properties, a potential candidate suitable for inhaled administration in respiratory diseases was identified and tested in an in vivo model of pulmonary inflammation, proving its efficacy.

Functionalized pyrazoles and pyrazolo[3,4-d]pyridazinones: Synthesis and evaluation of their phosphodiesterase 4 inhibitory activity

A series of pyrazoles and pyrazolo[3,4-d]pyridazinones were synthesized and evaluated for their PDE4 inhibitory activity. All the pyrazoles were found devoid of activity, whereas some of the novel pyrazolo[3,4-d]pyridazinones showed good activity as PDE4 inhibitors. The most potent compounds in this series showed an IC(50) in the nanomolar range. The ability to inhibit TNF-alpha release in human PBMCs was determined for two representative compounds, finding values in the sub-micromolar range. SARs studies demonstrated that the best arranged groups around the heterocyclic core are 2-chloro-, 2-methyl- and 3-nitrophenyl at position 2, an ethyl ester at position 4 and a small alkyl group at position 6. Molecular modeling studies performed on a representative compound allowed to define its binding mode to the PDE4B isoform.

Discovery and optimization of thiazolidinyl- and pyrrolidinyl- derivatives as inhaled PDE4 inhibitors for respiratory diseases

Phosphodiesterase 4 (PDE4) is a key cAMP-metabolizing enzyme involved in the pathogenesis of inflammatory disease, and its pharmacological inhibition has been shown to exert therapeutic efficacy in chronic obstructive pulmonary disease (COPD). Herein, we describe a drug discovery program aiming at the identification of novel classes of potent PDE4 inhibitors suitable for pulmonary administration. Starting from a previous series of benzoic acid esters, we explored the chemical space in the solvent-exposed region of the enzyme catalytic binding pocket. Extensive structural modifications led to the discovery of a number of heterocycloalkyl esters as potent in vitro PDE4 inhibitors. (S*,S**)-18e and (S*,S**)-22e, in particular, exhibited optimal in vitro ADME and pharmacokinetics properties and dose-dependently counteracted acute lung eosinophilia in an experimental animal model. The optimal biological profile as well as the excellent solid-state properties suggest that both compounds have the potential to be effective topical agents for treating respiratory inflammatory diseases.