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.

Synthesis and biological evaluation of 9-oxo-9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile analogues as potential inhibitors of deubiquitinating enzymes.

High-throughput screening highlighted 9-oxo-9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile (1) as an active inhibitor of ubiquitin-specific proteases (USPs), a family of hydrolytic enzymes involved in the removal of ubiquitin from protein substrates. The chemical behavior of compound 1 was examined. Moreover, the synthesis and in vitro evaluation of new compounds, analogues of 1, led to the identification of potent and selective inhibitors of the deubiquitinating enzyme USP8.

Semagacestat, a gamma-secretase inhibitor for the potential treatment of Alzheimer's disease.

Eli Lilly & Co is developing semagacestat, an inhibitor of the gamma-secretase enzyme. This enzyme is pivotal in the generation of beta-amyloid (A beta), a neurotoxic endogenous peptide believed to be involved in the pathogenesis of Alzheimer's disease (AD). In animals, semagacestat reduced A beta levels in the plasma, CSF and brain; however, studies have not reported on cognitive effect of this compound. Phase I clinical trials in healthy volunteers have evaluated doses ranging from 5 to 140 mg/day and phase II trials in patients with AD have evaluated doses ranging from 30 to 140 mg/day for up to 14 weeks. Trials in both healthy volunteers and patients with AD have demonstrated a dose-dependent inhibition of plasma A beta levels, and a recent trial in healthy volunteers demonstrated a robust, dose-dependent inhibition of newly generated A beta in the CSF after single oral doses. The main adverse events involved the gastrointestinal tract. In 2008, two large phase III clinical trials in patients with mild-to-moderate AD were initiated by Eli Lilly. Semagacestat is the most advanced gamma-secretase inhibitor and represents a major hope among therapies designed to slow the rate of cognitive decline of patients with AD.

Medicinal chemistry and therapeutic potential of muscarinic M3 antagonists.

Muscarinic acetylcholine receptors belong to the G-protein-coupled receptors family. Currently five different receptor subtypes have been identified and cloned. M3 receptor subtypes are coupled to G(q) family proteins and increase phosphatidyl inositol hydrolysis and calcium release from internal stores. They are widely distributed both in the central nervous system and in the periphery. At the central level, M3 receptor subtypes are involved in modulation of neurotransmitter release, temperature homeostasis, and food intake, while in the periphery they induce smooth muscle contraction, gland secretion, indirect relaxation of vascular smooth muscle, and miosis. The main therapeutic applications of M3 antagonists include overactive bladder (OAB), chronic obstructive pulmonary disease (COPD), and pain-predominant irritable bowel syndrome (IBS). The introduction of selective M3 antagonists has not improved clinical efficacy compared with the old non-selective antimuscarinics but has reduced the rate of adverse events mediated by the blockade of cardiac M2 receptors (tachycardia) and central M1 receptors (cognitive impairment). Improved tolerability has been obtained also with controlled release or with inhaled formulations. However, there is still a need for safer M3 antagonists for the treatment of COPD and better-tolerated and more effective compounds for the therapy of OAB. New selective muscarinic M3 antagonists currently in early discovery and under development have been designed to address these issues. However, as M3 receptors are widely located in various tissues including salivary glands, gut smooth muscles, iris, and ciliary muscles, further clinical improvements may derive from the discovery and the development of new compounds with tissue rather than muscarinic receptor subtype selectivity.

Chemistry strategies in early drug discovery: an overview of recent trends.

In the scenario of a continuous request for better drugs in shorter times, medicinal chemists must face the challenging task of preparing new patentable molecules, combining high activity and selectivity, drug-likeness and good pharmacokinetic properties. Multiparametric optimization requires a substantial improvement of the efficacy and throughput of the early discovery process, leading to a significant revolution in organic synthesis and chemistry technologies. Chemists are searching for ways to simplify synthetic protocols, for example, by the use of polymer-assisted solution-phase synthesis, microwave-assisted organic synthesis and flow chemistry. Organic synthesis is benefiting of fast and robust reactions, with breakthrough approaches often entailing the privileged use of multicomponent reactions, click chemistry and ring-closing metathesis.

Gamma-secretase modulation and its promise for Alzheimer's disease: a medicinal chemistry perspective.

Gamma-secretase modulation holds the promise for the development of a disease-modifying therapy for Alzheimer's disease (AD). This novel concept of manipulating the cleavage specificity of the gamma secretase enzyme by pharmacological means implies that steady state levels of the potentially disease-causing amyloid-beta(1-42) peptide can be lowered without the undesired side effects associated with full inhibition of this aspartyl-type protease. Following on from the initial discovery that certain non-steroidal anti-inflammatory drugs (NSAIDs) exhibit properties characteristic of gamma secretase modulators, this class of compounds has been extensively studied and exploited, leading to the discovery of NSAIDs derivatives endowed with improved potency for the reduction of amyloid-beta(1-42) peptide production. In addition, a very limited number of non-NSAID derived gamma secretase modulators has also been recently claimed in the patent literature, suggesting that only a restricted number of pharmacophores might be involved in the modulation of gamma-secretase.

Discovery of diaryl imidazolidin-2-one derivatives, a novel class of muscarinic M3 selective antagonists (Part 1).

Pharmacophore-based structural identification, synthesis, and structure-activity relationships of a new class of muscarinic M3 receptor antagonists, the diaryl imidazolidin-2-one derivatives, are described. The versatility of the discovered scaffold allowed for several structural modifications that resulted in the discovery of two distinct classes of compounds, specifically a class of tertiary amine derivatives (potentially useful for the treatment of overactive bladder by oral administration) and a class of quaternary ammonium salt derivatives (potentially useful for the treatment of respiratory diseases by the inhalation route of administration). In this paper, we describe the synthesis and biological activity of tertiary amine derivatives. For these compounds, selectivity for the M3 receptor toward the M2 receptor was crucial, because the M2 receptor subtype is mainly responsible for adverse systemic side effects of currently marketed muscarinic antagonists. Compound 50 showed the highest selectivity versus M2 receptor, with binding affinity for M3 receptor Ki = 4.8 nM and for M2 receptor Ki = 1141 nM. Functional in vitro studies on selected compounds confirmed the antagonist activity toward the M3 receptor and functional selectivity toward the M2 receptor.

Discovery of diaryl imidazolidin-2-one derivatives, a novel class of muscarinic M3 selective antagonists (Part 2).

Synthesis and biological activity of a novel class of quaternary ammonium salt muscarinic M3 receptor antagonists, showing high selectivity versus the M2 receptor, are described. Selected compounds exhibited potent anticholinergic properties, in isolated guinea-pig trachea, and good functional selectivity for trachea over atria. In vivo, the same compounds potently inhibited acetylcholine-induced bronchoconstriction after intratracheal administration in the guinea pig.

Solution phase synthesis of a library of tetrasubstituted pyrrole amides.

An efficient strategy for the solution-phase parallel synthesis of a library of pyrrole-amides is described. Key reactions include functional homologation of beta-ketoesters with a set of aldehydes followed by oxidation to produce a series of differently substituted 1,4-dicarbonyl compounds. Rapid cyclization using a microwave-assisted Paal-Knorr reaction provided a set of 24 pyrrole esters that were further functionalized through a trimethylaluminum-mediated aminolysis to obtain a larger library of 288 diverse pyrrole-3-amides. The tetrasubstitution allows a good exploration of the chemical space around the central pyrrole core. The last step was entirely automated with a Bohdan Myriad personal synthesizer.

Synthesis and biological activity of flurbiprofen analogues as selective inhibitors of beta-amyloid(1)(-)(42) secretion.

Flurbiprofen, a nonsteroidal antiinflammatory drug (NSAID), has been recently described to selectively inhibit beta-amyloid(1)(-)(42) (Abeta42) secretion, the most toxic component of the senile plaques present in the brain of Alzheimer patients. The use of this NSAID in Alzheimer's disease (AD) is hampered by a significant gastrointestinal toxicity associated with cyclooxygenase (COX) inhibition. New flurbiprofen analogues were synthesized, with the aim of increasing Abeta42 inhibitory potency while removing anti-COX activity. In vitro ADME developability parameters were taken into account in order to identify optimized compounds at an early stage of the project. Appropriate substitution patterns at the alpha position of flurbiprofen allowed for the complete removal of anti-COX activity, while modifications at the terminal phenyl ring resulted in increased inhibitory potency on Abeta42 secretion. In rats, some of the compounds appeared to be well absorbed after oral administration and to penetrate into the central nervous system. Studies in a transgenic mice model of AD showed that selected compounds significantly decreased plasma Abeta42 concentrations. These new flurbiprofen analogues represent potential drug candidates to be developed for the treatment of AD.

Cell penetrable peptoid carrier vehicles: synthesis and evaluation.

Using a highly efficient solid-phase route a series of fluorescein conjugated peptoid oligomers were synthesised and observed to display remarkable cell penetrating properties, offering the possibility of highly efficient cellular targeting.