Francesco Campagna

Design, synthesis and biological evaluation of indane-2-arylhydrazinylmethylene-1,3-diones and indol-2-aryldiazenylmethylene-3-ones as β-amyloid aggregation inhibitors

Biological screening of (hetero)aromatic compounds allowed the identification of some novel inhibitors of Abeta(1-40) aggregation, bearing indane and indole rings as common scaffolds. Molecular decoration of lead compounds led to inhibitors exhibiting a potency, measured by the Thioflavin T fluorimetric assay, ranging from high to low micromolar IC(50). The 2-(p-isopropylphenyldiazenylmethylene)indolone derivative 6c resulted as the most potent aggregation inhibitor exhibiting an IC(50) of 1.4 muM, with complete lack of fibril formation as confirmed by transmission electron microscopy. Structure-activity relationships suggested that binding to the Abeta peptide may be largely guided by pi-stacking and hydrogen bond interactions.

1,3-Dialkyl-8-(hetero)aryl-9-OH-9-deazaxanthines as potent A2B adenosine receptor antagonists: Design, synthesis, structure-affinity and structure-selectivity relationships

A number of 1,3-dialkyl-8-(hetero)aryl-9-OH-9-deazaxanthines were prepared and evaluated as ligands of recombinant human adenosine receptors (hARs). Several 1,3-dipropyl derivatives endowed with nanomolar binding affinity at hA(2B) receptors, but poor selectivity over hA(2A), hA(1) and hA(3) AR subtypes were identified. A comparison with the corresponding 7-OH- and 7,9-unsubstituted-deazaxanthines revealed that 9-OH-9-deazaxanthines are more potent hA(2B) ligands with lower partition coefficients and higher water solubility compared to the other two congeneric classes of deazaxanthines. An optimization of the para-substituent of the 8-phenyl ring of 9-OH-9-deazaxanthines led to the discovery of compound 38, which exhibited outstanding hA(2B) affinity (Ki=1.0 nM), good selectivity over hA(2A), hA(1) and hA(3) (selectivity indices=100, 79 and 1290, respectively) and excellent antagonist potency in a functional assay on rat A(2B) (pA(2B)=9.33).

Synthesis of new heterocyclic ring systems: indeno[2,1-b]-benzo[g]indolizine and indeno[1',2':5,4]pyrrolo[2,1-a]phthalazine

Some derivatives of the title heterocycles have been prepared by a «one step» synthesis from 2-hydroxy-2-acylmethylene-1,3-indandiones, tosyl chloride and isoquinoline or phthalazine. The synthesis of new indeno[2,1-b]indolizine derivatives performed by using pyridine as base is also reported

Design, synthesis and biological evaluation of benzo[e][1,2,4]triazin-7(1H)-one and [1,2,4]-triazino[5,6,1-jk]carbazol-6-one derivatives as dual inhibitors of beta-amyloid aggregation and acetyl/butyryl cholinesterase

Alzheimers disease (AD) onset and progression are associated with the dysregulation of multiple and complex physiological processes and a successful therapeutic approach should therefore address more than one target. Two new chemical entities, the easily accessible heterocyclic scaffolds 1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (benzotriazinone I) and 2-phenyl-6H-[1,2,4]triazino[5,6,1-jk]carbazol-6-one (triazafluoranthenone II), were explored for their multitarget-directed inhibition of beta-amyloid (Aβ) fibrillization and acetyl- (AChE) and/or butyryl- (BChE) cholinesterase, three valuable targets for AD therapy. Introduction of appropriate amine substituents at positions 6 and 5 on scaffold I and II, respectively, allowed the preparation of a series of compounds that were tested as Aβ(1-40) aggregation and cholinesterase inhibitors. Potent inhibitors of Aβ self-aggregation were discovered and among them benzotriazinone 7 exhibited an outstanding IC(50) equal to 0.37 μM. Compounds bearing a basic amine linked to the heterocyclic scaffold through a linear alkyl chain of varying length also afforded good ChE inhibitors. In particular, benzotriazinone 24 and triazafluoranthenone 38 were endowed with an interesting multiple activity, the former displaying IC(50) values of 1.4, 1.5 and 1.9 μM on Aβ aggregation and AChE and BChE inhibition, respectively, and the latter showing IC(50) values of 1.4 and an outstanding 0.025 μM in the Aβ aggregation and BChE inhibition, respectively. Benzotriazinone 24 and triazafluoranthenone 29, selected owing to their suitable aqueous solubility and Aβ aggregation inhibition, were submitted to a time course kinetic assay followed with thioflavin T (ThT) spectrofluorimetry, circular dichroism (CD) and transmission electron microscopy (TEM). Experimental data indicated that 24 acted at a low concentration ratio (10 μM 24 vs. 50 μM Aβ), stabilizing the unstructured Aβ peptide and inhibiting fibrillogenesis, and that 29 also acted as fibrillization inhibitor, but likely enhancing and stabilizing the β-sheet arrangement of Aβ to yield protofibrillar species as detected by TEM.

Structure-activity relationships of 2-Aryl-2,5-dihydropyridazino[4,3-b]indol-3(3H)-ones at the benzodiazepine receptor

A large series of 2-aryl-2,5-dihydropyridazino[4,3-b]indol-3(3H)ones (PIs) carrying properly selected substituents at the indole and N2-phenyl rings was prepared and tested as central benzodiazepine receptor (BZR) ligands and potential (anti)convulsant agents. Stereoelectronic requirements for high receptor affinity were detected by means of 2-D and 3-D QSAR analyses. BZR affinities and pharmacological profiles of the compounds were examined in comparison with some other pyridazinoindolones recently described by us and with pyrazoloquinoline (PQ) analogues. An anticonvulsant activity greater than PQs was generally observed for PIs. Notably, in the test of audiogenically induced seizures, one compound showed a potency comparable to that of diazepam.

Synthesis and antibacterial activity of pyridazino[4,3-b]indole-4-carboxylic acids carrying different substituents at N-2

The synthesis and the in vitro evaluation of antibacterial activity of new pyridazino[4,3-b]indole-4-carboxylic acids 2-4, 6 against some selected representative of Gram-positive and Gram-negative bacteria are reported. The role of the lipophilicity in the modulation of the antibacterial activity of the tested compounds is discussed. All the synthesized compounds appear quite weak against Gram-positive bacteria, whereas have no significant activity against Gram-negative bacteria. Only derivative 2g possesses an interesting activity against Gram-positive bacteria.

2-Aryl-2,5-dihydropyridazino[4,3-b]lindol-3(3H)-ones: Novel rigid planar benzodiazepine receptor ligands

A series of 2-aryl-2,5-dihydropyridazino[4,3-b]indol-3(3H)-ones 5 were prepared and evaluated for their ability to inhibit radioligand binding to BZR, and to prevent sound and pentylenetetrazole (PTZ) induced seizures in mice. The biological and pharmacological results are discussed in the light of some recently proposed pharmacophore models and compared through molecular orbital and molecular modeling studies to those obtained from the close pyrazoloquinoline analogs 6.

Benzodiazepine Receptor Affinities, Behavioral, and Anticonvulsant Activity of 2-Aryl-2,5-dihydropyridazino[4,3-b]indol- 3(3H)-ones in Mice

The anticonvulsant properties of 1,4-benzodiazepines (BDZs), pyrazoloquinolones (CGS), 2-aryl-2,5-dihydropyridazino[4, 3-b]indol-3(3H)-ones (PIs) 1 1i 1d 1f 1e 1b 1c 1h, and 1a, the latter being inactive against audiogenic seizures. Some PIs 1 and abecarnil showed anticonvulsant properties against seizures induced by PTZ with a potency lower than that observed in audiogenic seizures. The pharmacological actions of 1d, 1f, and 1i were significantly reduced by a treatment with flumazenil (8.24 micromol/kg IP), suggesting a clear involvement of benzodiazepine mechanisms in the anticonvulsant activity of these compounds or their metabolites. The anticonvulsant activity of 1d, 1f, and 1i was also evaluated against seizures induced by two beta-carbolines namely methyl-beta-carboline-3-carboxylate (beta-CCM) and methyl-6, 7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM), in DBA/2 mice: they gave better protection against seizures induced by beta-CCM than the ones by DMCM. The potency of various BDZs and PIs as inhibitors of specific [3H]flumazenil binding to neuronal membranes, was also evaluated. The radioligand binding study, carried out on stable cell lines expressing definite combinations of benzodiazepine receptor subunits, demonstrated that 1b, 1e, 1d, and 1h have preferential interaction with alpha(1), beta(3), gamma(2), receptor subtypes.

Synthesis and antibacterial activity of 2-aryl-2,5-dihydro-3(3H)-oxo-pyridazino[4,3-b]indole-4-carboxylic acids.

The in vitro antibacterial and antifungal activities of a series of pyridazinoindolonic acids II against some selected representative of Gram-positive, Gram-negative bacteria and fungi have been investigated. Some interesting observations among the structural features necessary for high antibacterial activity are presented and discussed.

Synthesis and biological evaluation of pyridazino[4,3-b]indoles and indeno[1,2-c]pyridazines as new ligands of central and peripheral benzodiazepine receptors.

A large number of pyridazino[4,3-b]indoles and indeno[1,2-c]pyridazines were synthesised and tested to evaluate their binding affinities at both central (CBR) and peripheral (PBR) benzodiazepine receptors. Relatively good PBR binding affinities were found for ligands belonging to the 3-arylmethyloxy-pyridazinoindole series, whereas only 2-aryl-indenopyridazines 7a, 8a and 10a display a weak binding affinity for CBR. To find out the main structural determinants affecting PBR affinity, a molecular modelling study based on the comparative analysis of the three-dimensional properties of four properly selected derivatives 24a, 3b, 18a and 10d, with those of highly active and selective PBR ligands, taken as reference, was performed.