Synthesis and biological evaluation of imidazo[1,2-a]pyrimidines and imidazo[1,2-a]pyridines as new inhibitors of the Wnt/ß-catenin signaling.

Wnt/ß-catenin signaling plays an important role in the regulation of embryonic development and tumorigenesis. Since its deregulation results in severe human diseases, especially cancer, the Wnt signaling pathway constitutes a promising platform for pharmacological targeting of cancer. In this study we synthesized a series of imidazo[1,2-a]pyrimidines and imidazo[1,2-a]pyridines and identified some derivatives that were able to inhibit the Wnt/ß-catenin signaling pathway in a luciferase reporter assay and cell proliferation in selected cancer cell lines, endowed with APC or ß-catenin gene mutations. The most active compounds significantly downregulate the expression of Wnt target genes such as c-myc and cyclin D1. Further studies indicated that these compounds function independently of GSK-3ß activity. More importantly, in vivo experiments, carried out on a Wnt-reporter zebrafish model indicate, in particular for compounds 4c and 4i as the most active compounds, an activity comparable to that of the reference compound IWR1, suggesting their potential use not only as small molecule inhibitors of the Wnt/ß-catenin signal in Wnt driven cancers, but also in other Wnt-related diseases.

Ca(2+) release-activated Ca(2+) channel inhibitors.

Ca(2+) release-activated Ca(2+) (CRAC) channels are becoming important targets for therapeutic intervention in several areas of disease, including immunology, allergy and cancer. In parallel to the progression towards reliable methods for measuring CRAC currents and their inhibition, patents have been generated by several companies. In this Patent Review, an analysis of the patents in the CRAC channel inhibition filed is presented. A discussion of the biological methods used in the patents is included. The general interest in this area is growing fast with almost 80% of the patents issued after 2010.

Allosteric modulators of human A2B adenosine receptor.

BACKGROUND: Among adenosine receptors (ARs) the A2B subtype exhibits low affinity for the endogenous agonist compared with the A1, A2A, and A3 subtypes and is therefore activated when concentrations of adenosine increase to a large extent following tissue damages (e.g. ischemia, inflammation). For this reason, A2B AR represents an important pharmacological target. METHODS: We evaluated seven 1-benzyl-3-ketoindole derivatives (7-9) for their ability to act as positive or negative allosteric modulators of human A2B AR through binding and functional assays using CHO cells expressing human A1, A2A, A2B, and A3 ARs. RESULTS: The investigated compounds behaved as specific positive or negative allosteric modulators of human A2B AR depending on small differences in their structures. The positive allosteric modulators 7a,b and 8a increased agonist efficacy without any effect on agonist potency. The negative allosteric modulators 8b,c and 9a,b reduced agonist potency and efficacy. CONCLUSIONS: A number of 1-benzyl-3-ketoindole derivatives were pharmacologically characterized as selective positive (7a,b) or negative (8c, 9a,b) allosteric modulators of human A2B AR. GENERAL SIGNIFICANCE: The 1-benzyl-3-ketoindole derivatives 7-9 acting as positive or negative allosteric modulators of human A2B AR represent new pharmacological tools useful for the development of therapeutic agents to treat pathological conditions related to an altered functionality of A2B AR.

Modulation of A2B adenosine receptor by 1-Benzyl-3-ketoindole derivatives.

We have disclosed a series of 1-benzyl-3-ketoindole derivatives acting as either positive or negative modulators of the human A(2B) adenosine receptor (A(2B) AR) depending on small differences in their side chain. The new compounds were designed taking into account structural similarities between AR antagonists and ligands of the GABA(A)/benzodiazepine receptor. All compounds resulted totally inactive at A(2A) and A3 ARs and showed small (8a,b) or none (7a,b, 8c and 9a,b) affinity for A1 AR. When tested on A(2B) AR-transfected CHO cells, 7a,b and 8a acted as positive modulators, whereas 8b,c and 9a,b acted as negative modulators, enhancing or weakening the NECA-induced increase of cAMP levels, respectively. Compounds 7-9 might be regarded as useful biological and pharmacological tools to explore the therapeutic potential of A(2B) AR modulators, while their 3-ketoindole scaffold might be taken as a reference to design new analogs.

Tertiary amides with a five-membered heteroaromatic ring as new probes for the translocator protein.

In this study novel ligands of the translocator protein (TSPO), characterized by a five-membered aromatic heterocycle (i.e. oxazole, isoxazole, oxadiazole), a phenyl ring, and an amide side chain of carboxy or acetic type, were designed using a previously reported pharmacophore/topological model. Most of compounds showed significant TSPO binding affinity (K(i) values in the nanomolar/submicromolar range), the highest being displayed by oxazolacetamides 6. A number of compounds were tested for their ability to inhibit the proliferation/viability of human glioblastoma cell line U87MG. The dose-time dependent cell response to treatment with 6d demonstrated the specificity of the observed effect. The ability of 6d to induce mitochondrial membrane dissipation (ΔΨm) substantiates the intracellular pro-apoptotic mechanism activated by ligand binding to TSPO.

Derivatives of benzimidazol-2-ylquinoline and benzimidazol-2-ylisoquinoline as selective A1 adenosine receptor antagonists with stimulant activity on human colon motility.

A number of quinolines and isoquinolines connected in various ways to a substituted benzimidazol-2-yl system were synthesized and evaluated as novel antagonists of adenosine receptors (ARs) by competition experiments using human A(1), A(2A), and A(3) ARs. The new compounds were designed based on derivatives of 2-(benzimidazol-2-yl)quinoxaline, previously reported as potent and selective antagonists of A(1) and A(3) ARs. Among these, 3-[4-(ethylthio)-1H-benzimidazol-2-yl]isoquinoline 4b exhibited the best combination of potency toward the A(1) AR (K(i) =1.4 nM) and selectivity against the A(2A) (K(i) >10 µM), A(2B) (K(i)>10 µM), and A(3) ARs (K(i)>1 µM). Functional experiments in circular smooth muscle preparations of isolated human colon showed that 4b behaves as a potent and selective antagonist of the A(1) AR in the neuromuscular compartment of this intestinal region. Biological and pharmacological data suggest that 4b is a suitable starting point for the development of novel agents endowed with stimulant properties on colonic activity.

Inhibition of MDR1 activity in vitro by a novel class of diltiazem analogues: toward new candidates.

The reversal of multidrug resistance by 22 molecules [8-aryl-8-hydroxy-5-R'-8H-[1,4]thiazino[3,4-c][1,2,4]oxadiazol-3-ones (1a-i) and 8-aryl-8-alkoxy-5-methyl-8H-[1,4]thiazino[3,4-c][1,2,4]oxadiazol-3-ones (2a-m)] related to myocardial-calcium-channel-modulator diltiazem was studied in multidrug resistant A2780/DX3 and their sensitive counterpart A2780 cells. MTT, cytofluorimetry assays, and fluorescence microscopy analyses were used to define activity and accumulation of doxorubicin with or without the diltiazem-like modulators. Of the 22 molecules, 1a, 2f, 2g, and 2m were able to overcome the established criteria for the selection in A2780/DX3 cells (IC(50) reduction > or = 25%), but only 2f, 2g, and 2m caused a significant increase of intracellular accumulation of doxorubicin. In conclusion, experiments lead to the identification of three diltiazem-like molecules able to increase the intracellular accumulation of doxorubicin by inhibiting the MDR1 function, thus potentiating its antiproliferative activity in multidrug resistant A2780/DX3 cells.