Synthesis and pharmacological evaluation of multifunctional tacrine derivatives against several disease pathways of AD.

A novel series of tacrine derivatives were designed and synthesized by combining caffeic acid (CA), ferulic acid (FA) and lipoic acid (LA) with tacrine. The antioxidant study revealed that all the hybrids have much more antioxidant capacities compared to CA. Among these compounds, 1b possessed a good ability to inhibit the ß-amyloid protein (Aß) self-aggregation, sub-micromole acetylcholinesterase (AChE)/butyrylcholinesterase (BuChE) inhibitory, modest BACE1 inhibitory. Moreover, compound 1b also was a DPPH radical scavenger and copper chelatory as well as had potent neuroprotective effects against glutamate-induced cell death with low toxicity in HT22 cells. Our findings suggest that the compound 1b might be a promising lead multi-targeted ligand and worthy of further developing for the therapy of Alzheimer's disease.

Synthesis and evaluation of multi-functional NO-donor/insulin-secretagogue derivatives for the treatment of type II diabetes and its cardiovascular complications.

Although there is a significant effort in the discovery of effective therapies to contrast both the pathological endocrine and metabolic aspects of diabetes and the endothelial dysfunction associated with this disease, no hypoglycemic drug has been proven to defeat the cardiovascular complications associated with type II diabetes. The aim of this research was to design new compounds exhibiting a double profile of hypoglycemic agents/NO-donors. The synthesis of molecules obtained by the conjunction of NO-donor moieties with two oral insulin-secretagogue drugs (repaglinide and nateglinide) was reported. NO-mediated vasorelaxing effects of the synthesized compounds were evaluated by functional tests on isolated endothelium-denuded rat aortic rings. The most potent molecule (4) was tested to evaluate the hypoglycemic and the anti-ischemic cardioprotective activities. This study indicates that 4 should represent a new insulin-secretagogue/NO-donor prodrug with an enhanced cardiovascular activity, which may contrast the pathological aspects of diabetes and endowed of cardioprotective activity.

Synthesis and biological evaluation of 2'-oxo-2,3-dihydro-3'H- spiro[chromene-4,5'-[1,3]oxazolidin]-3'yl]acetic acid derivatives as aldose reductase inhibitors.

Aldose reductase (ARL2) is the first enzyme in the polyol pathway which catalyzes the NADPH-dependent reduction of glucose to sorbitol. Its involvement on diabetic complications makes this enzyme a challenge therapeutic target widely investigated to limit and/or prevent them. On this basis, a limited series of 4-spiro-oxazolidinone-benzopyran derivatives (1-7) were synthesized to evaluate them as potential ARL2 inhibitors. The activity was determined spectrophotometrically by monitoring the oxidation of NADPH catalyzed by ALR2. Within the series of compounds, the 4-methoxy derivative 1b showed to be the most active compound, exhibiting inhibitory levels in the submicromolar range. In addition, the activity against the aldehyde reductase isoform (ARL1) was also evaluated. Unlike sorbinil (reference drug) that lack of selectivity towards the two enzyme all the tested compounds resulted to be devoid of ARL1 inhibitory activity (IC(50) > 10 µM), thus proving to be selective.

Synthesis and in-vitro antitumour activity of new naphthyridine derivatives on human pancreatic cancer cells.

OBJECTIVES: The aim of the study was to evaluate the antitumour effect in vitro of newly synthesized 7-substituted 2,3-dihydro-1,8-naphthyridines. METHODS: Characterization tools included cell viability assay, caspase 3/7 induction, DNA fragmentation, fibroblast growth factor type 1 receptor kinase inhibition, and in-vitro antiangiogenic analysis. KEY FINDINGS: Treatment of MIA PaCa-2 human pancreatic cancer cells with test compounds showed time- and concentration-dependent cytotoxicity with IC50 values in the micromolar range. Compounds with an aminoalkyl or a diaminoalkyl side chain at the 7-position exhibited remarkable cytotoxicity, whereas the presence of a methyl group or a cyclic amine in the same position led to a significant decrease in their biological activity. Cytotoxicity screening demonstrated that the most active was compound 11 (mean 50% inhibition of cell proliferation (IC50) 11 mum). This compound had an in-vitro antitumour efficacy superior to 5-fluorouracil (the lowest cell viability value after treatment (E(max)) 0.2% and 19%, respectively) and proved to be less toxic than 5-fluorouracil against non-cancerous human oral epithelial cells. In addition, compound 11 induced apoptosis in MIA PaCa-2 cells and it was able to promote antiangiogenic effects in vitro. Finally, its cytotoxicity was enhanced in pancreatic cancer cells stimulated with fibroblast growth factor, while no substantial effect was observed on human bronchial smooth muscle cells stimulated with the same growth factor. CONCLUSIONS: These findings suggest that 1,8-naphthyridine derivatives are a promising class of compounds in cancer research. In particular, the antitumour activity of compound 11 is worth further investigation.

Monoaryl-substituted salicylaldoximes as ligands for estrogen receptor beta.

Salicylaldoximes possess a hydrogen-bonded pseudocyclic A' ring in place of the typical phenolic A ring that is characteristic of most estrogen receptor (ER) ligands. Monoaryl-substituted salicylaldoximes were obtained by replacing the phenol moiety (ring A) of the ERbeta pharmacophore with the pseudocycle A' ring, which has previously been shown to behave as a bioequivalent of phenols in nonselective ER ligands. In this series, small substituents (CH 3, CN, Cl) were introduced into the central phenyl scaffold. An efficient sequential halogen-selective double cross-coupling reaction was developed for the synthesis of the methyl-substituted ER ligand. The measured ERbeta affinity proved to be very sensitive to the effect of central core substituents. The binding affinities of the compounds herein reported were in good agreement with the results of computational docking analysis. The chloro-substituted derivative showed the highest beta affinity and selectivity, and it also proved to be an ERbeta partial agonist with an EC 50 of 11 nM.

Allosteric inhibition of [(125I)] ET-1 binding to ET(A) receptors by aldoxime and hydroxamic acid derivatives.

Endothelin-1 (ET-1), a potent vasoconstrictor peptide, exerts its physiological effects by binding and activating specific G protein-coupled receptors, named ET(A) and ET(B). An unique property of ET-1 is its ability to bind almost irreversibly to its receptors. Aspirin and salicylic acid (SA) are allosteric inhibitors of ET-1 binding to ET(A) receptors. Dihalogenated derivatives of SA have been identified as more potent allosteric inhibitors than aspirin. In this study, disubstituted benzohydroxamic acid, benzaldoximes and dihalosalicylic acid dimers were synthesized and tested as inhibitors of [(125)I]ET-1 binding to ET(A) receptors in rat embryonic cardiomyocyte (H9c2 cell) membranes. Some dihalosalicylic acid dimers 2h showed good inhibitory activity, the most active compounds are the hydroxamic acids derived from anthranilic acid. Among these compounds, the 3, 5-diiodo-2-aminobenzohydroxamic acid e compound 2a is three-folds more potent as inhibitor of [(125I)] ET-1 binding to ET(A) receptors than the 3; 5-diiodosalicylic acid reported in literature. Most aryl aldoximes in this study were biologically inactive as inhibitors of [(125I)] ET-1 binding to ET(A) receptors.

3-[(Aryl)(4-fluorobenzyloxy)methyl]piperidine derivatives: high-affinity ligands for the serotonin transporter.

The structural requirements for high-affinity binding at the serotonin transporter (SERT) have been investigated through the preparation of some 3-[(aryl)(4-fluorobenzyloxy)methyl]piperidine derivatives. The affinity of synthesised piperidinic compounds (1-4) at the SERT was evaluated by displacement of [3H]-paroxetine binding. Derived inhibition constant (Ki) values were in the same order of magnitude as that of fluoxetine, ranging between 2 and 400 nM. To better define the profiles of these compounds as potential antidepressants, binding affinity for 5-HT1A receptors and alpha2-adrenoceptors was also investigated by competition experiments using [3H]8-hydroxy-2-(dipropylamino)tetralin ([3H]8-OH-DPAT) and [3H]rauwolscine as radiolabelled ligands, respectively. Inhibition data indicate that compounds 1-4 possess a very weak affinity for these receptors. The high affinity of compound 1 for SERT indicates that it is worth investigating further.

Synthesis and In Vivo Imaging of N-(3-[11C]Methoxybenzyl)-2-(3-Methoxyphenyl)ethylaniline as a Potential Targeting Agent for P-glycoprotein.

PURPOSE: The plasma membrane P-glycoprotein (Pgp) is an efflux transporter involved in multidrug resistance and in the onset of neurodegenerative disease. Its function and most mechanisms of action are still under investigation. We developed a C-11-labeled 2-arylethylphenylamine-([11C]AEPH) derivative for positron emission tomography (PET), as a novel probe to better understand the activity and the function of Pgp in vivo. PROCEDURES: The synthetic procedure and the quality control of the selected lead compound, [11C]AEPH-1, were set up and optimized. The biodistribution and the dynamic extraction in target organs of [11C]AEPH-1 were studied in vivo by PET in healthy rats at baseline and after pre-treatment with a Pgp inhibitor (tariquidar). RESULTS: In vivo dynamic imaging was consistent with the results of ex vivo extraction on explanted organs. An adequate stability for in vivo studies, as well as a high activity of [11C]AEPH-1 in intestine and barrier tissues, has been demonstrated. Results of the blockade study showed a decrease of uptake after the pre-treatment, indicating a behavior attributable to a Pgp ligand. CONCLUSIONS: The suitable pharmacokinetics and the specificity tested in the pre-treated animals have indicated the potentiality of this AEPH derivative to act as Pgp ligand, providing new opportunities for further studies on expression and function of this important efflux transporter in the fields of neurology and oncology.

Locking PDK1 in DFG-out conformation through 2-oxo-indole containing molecules: Another tools to fight glioblastoma.

The phosphoinositide-dependent kinase-1 (PDK1) is one of the main components of the PI3K/Akt pathway. Also named the "master kinase" of the AGC family, PDK1 plays a critical role in tumorigenesis, by enhancing cell proliferation and inhibiting apoptosis, as well as in cell invasion and metastasis formation. Although there have been done huge efforts in discovering specific compounds targeting PDK1, nowadays no PDK1 inhibitor has yet entered the clinic. With the aim to pick out novel and potent PDK1 inhibitors, herein we report the design and synthesis of a new class of molecules obtained by merging the 2-oxo-indole nucleus with the 2-oxo-pyridonyl fragment, two moieties with high affinity for the PDK1 hinge region and its DFG-out binding site, respectively. To this purpose, a small series of compounds were synthesised and a tandem application of docking and Molecular Dynamic (MD) was employed to get insight into their mode of binding. The OXID-pyridonyl hybrid 8, possessing the lower IC50 (IC50 = 112 nM), was also tested against recombinant kinases involved in the PI3K/PDK1/Akt pathway and was subjected to vitro studies to evaluate the cytotoxicity and the inhibition of tumour cell migration. All together the results let us to consider 8, as a lead compound of a new generation of PDK1 inhibitors and encourage us to further studies in this direction.

Design and synthesis of 2-oxindole based multi-targeted inhibitors of PDK1/Akt signaling pathway for the treatment of glioblastoma multiforme.

Aggressive behavior and diffuse infiltrative growth are the main features of Glioblastoma multiforme (GBM), together with the high degree of resistance and recurrence. Evidence indicate that GBM-derived stem cells (GSCs), endowed with unlimited proliferative potential, play a critical role in tumor development and maintenance. Among the many signaling pathways involved in maintaining GSC stemness, tumorigenic potential, and anti-apoptotic properties, the PDK1/Akt pathway is a challenging target to develop new potential agents able to affect GBM resistance to chemotherapy. In an effort to find new PDK1/Akt inhibitors, we rationally designed and synthesized a small family of 2-oxindole derivatives. Among them, compound 3 inhibited PDK1 kinase and downstream effectors such as CHK1, GS3Kα and GS3Kß, which contribute to GCS survival. Compound 3 appeared to be a good tool for studying the role of the PDK1/Akt pathway in GCS self-renewal and tumorigenicity, and might represent the starting point for the development of more potent and focused multi-target therapies for GBM.

Synthesis, antifungal activity, and molecular modeling studies of new inverted oxime ethers of oxiconazole.

Some new oxime ethers of types 7 and 8, in which the methyleneaminoxy group, C=N-O, of oxiconazole 6 is in an inverted atomic sequence, were synthesized and tested for their antifungal activities. Among them, the type 7 compounds, such as the N-ethoxy-morpholino-substituted derivatives 7l-o (Table 1), showed good antifungal properties against the Candida strains tested, with minimum inhibitory concentration (MIC) values similar to those of the reference drug 6. A remarkable result was obtained with these types of azoles, which had shown a cidal character against Candida albicans, while the reference drug oxiconazole was only fungistatic in the same tests. This fact may be seen from a comparison of the MIC values with those of the minimum fungicidal concentration (MFC) values for most of the type 7 compounds assayed that have shown differences between the MIC and the MFC, which are lower than three double diluitions. A simple molecular modeling of the P450 14-alpha-sterol demethylase from C. albicans (Candida P450DM) was built in order to understand how the structural differences between type 7 compounds and oxiconazole 6 can induce different antifungal profiles. The results of this work seem to confirm that it is possible to reverse the atomic sequence of the methyleneaminoxy group, C=N-O, of 6, obtaining new imidazoles possessing good antifungal properties.

Conformationally restrained analogues of sympathomimetic catecholamines. Synthesis and adrenergic activity of 5,6- and 6,7-dihydroxy-3,4-dihydrospiro[naphthalen-1(2H)-2',5'-morpholines].

The 5,6- (10a) and 6,7-dihydroxy-3,4-dihydrospiro[naphthalen-1(2H)-)-2',5'-morpholine](11a) and their N-isopropyl derivatives (10b and 11b) (DDSNMs), which can be viewed as the result of the combination of the structure of the 2-(3,4-dihydroxyphenyl)morpholine 5a or 5b (DPMs) with the structure of the corresponding 1-(aminomethyl)-5,6-dihydroxy- (8a or 8b) or 1-(aminomethyl)-6,7-dihydroxy-1,2,3,4-tetrahydro-1-naphthalen-ol (9a or 9b) (1-AMDTNs) were synthesised. The new compounds DDSNMs 10a,b and 11a,b were assayed for their alpha- and beta-adrenergic properties by means of binding experiments and functional tests and the results were compared with those obtained for catecholamines 1a, b and the previously described morpholine (5) and tetrahydronaphthalene (8, 9) derivatives. The affinity and activity indices thus obtained indicate in general a low ability of the new compounds 10 and 11 to interact with the alpha- and beta-adrenoceptors, which, in all cases, was lower than that of the corresponding morpholine (5) and tetrahydronaphthalene (8, 9) analogues.

Aryl-substituted methyleneaminoxymethyl (MAOM) analogues of diarylcyclopentenyl cyclooxygenase-2 inhibitors: effects of some structural modifications on their biological properties.

The (E)-[2-(4-aminosulfonylphenyl)-1-cyclopentenyl-1-methyliden]-(arylmethyloxy)amines (6a,b), which are the sulfonamidic analogues of the previously described methylsulfonyl derivatives 5a,b, and their corresponding sulfides (7a,b) and sulfoxides (8a,b) were synthesised in order to obtain information about the role played by these different sulphur-containing groups in the cyclooxygenase-2 inhibitory activity of this class of compounds. In addition, other chemical manipulations concerning the oxime-ether substituent of this type of derivatives were affected by preparing compounds 9a,b, which present a methyl group on the oximic carbon of the oxime-ether chain of 5a,b, and compounds 10 and 11, in which the atomic sequence (C=NOCH(2)) of the MAOMM of 8b and 5b, respectively, is inverted. Compounds 6-11 were tested in vitro for their inhibitory activity towards COX-1 and COX-2 by measuring prostaglandin E2 (PGE2) production in U937 cell lines and activated J774.2 macrophages, respectively. Some of the new compounds showed an appreciable in vitro COX-2 inhibitory activity, with IC(50) values in the microM (7a,b, 8a and 9b) or sub-microM (8b) range. This last compound was also assayed in vivo for its antiinflammatory activity by means of the carrageenan-induced paw edema test in rats. No inhibitory effects were detected up to dose of 30 mg kg(-1) orally administered.

Synthesis and affinity for serotonin and dopamine transporters of some benzophenone oxime ether derivatives.

In a previous study, we reported the synthesis of several 3-(methylenaminoxymethyl)-substituted piperidine derivatives and their ability to interfere with the transmission mediated by biogenic amines. The present study describes the preparation of some new oxime derivatives and their capacity to inhibit serotonin (SERT) and dopamine (DAT) transporters expressed at the level of the rabbit cortex and the striatal membranes, respectively. All the compounds showed K(i) values in the micromolar range on both transporters.

Synthesis and COX-2 inhibitory properties of N-phenyl- and N-benzyl-substituted amides of 2-(4-methylsulfonylphenyl)cyclopent-1-ene-1-carboxylic acid and of their pyrazole, thiophene and isoxazole analogs.

Some N-phenyl- (7a-10a) and N-benzyl-substituted (7b-10b) amido analogs of cyclooxygenase (COX-2) selective tricyclic non-steroidal anti-inflammatory drugs have been synthesized with the aim to obtain information on the structural requirements for the COX-inhibitory activity. Compounds 7-10 were tested in vitro for their inhibitory properties only towards COX-2 enzyme by measuring prostaglandin E2 (PGE2) production on activated J774.2 macrophages. Some of the new compounds (7a, 8a, 9a and 9b) showed a modest activity, with percentage inhibition values near 30% at a concentration of 10 microM. These data have been tentatively explained by a conformational study which indicates that at least the N-phenyl-substituted amides 7a-9a present steric hindrances which may prevent a good interaction with COX-2 active site.

SAR study on arylmethyloxyphenyl scaffold: looking for a P-gp nanomolar affinity.

Starting from the previously developed P-gp ligands 1a and 1b (EC50 = 0.25 µM and 0.65 µM, respectively), new arylmethyloxyphenyl derivatives have been synthesized as P-gp modulators in order to investigate: (i) the effect of small electron-donor groups (OMe) (5-11), (ii) the effect of the replacement of methoxy groups with an electron-withdrawal substituent (Cl) on C-ring (13) (iii) the effect induced by the replacement of C-ring with heteroaromatic cycles such as thiophene and pyrimidine (13, 15, 16), (iv) the effect induced by molecular constriction on C ring (14, 17, 18) on P-gp modulating activity. The results demonstrated that P-gp inhibition potency is strongly correlated to the number of methoxy groups in the A-ring whereas the methoxylation of C-ring seems to poorly affect P-gp activity. The best result was found for compound 10 that displays a nanomolar affinity (EC50 = 7.1 nM) towards P-gp pump and, in the meantime lacks of activity against MRP1 pump.

Synthesis of Novel 3,5-Disubstituted-2-oxindole Derivatives As Antitumor Agents against Human Nonsmall Cell Lung Cancer.

This study was aimed at investigating the antitumor activity of novel 2-oxindole derivatives against a well-characterized human nonsmall cell lung cancer (NSCLC) cell line. Test compounds produced an antiproliferative activity in the low micromolar/submicromolar range of concentrations and significantly induced typical apoptotic morphology with cell shrinkage, nuclear condensation and fragmentation, and rupture of cells into debris in a relatively low percentage of A549 cells. Cell cycle arrest occurred at the G1/S phase (1a and 2), and Akt phosphorylation was significantly inhibited at Thr308 and Ser473. The most active compound (1a) has an IC50 6-fold lower than the Akt inhibitor, perifosine. These data suggest that the new compounds may be cytostatic and may have maximum clinical effects in NSCLC patients who do not respond to EGFR inhibitors. These findings prompt us to further explore the oxindole structure as leading scaffold to design new molecules with potent antitumor activity against NSCLC.

Synthesis, molecular docking and binding studies of selective serotonin transporter inhibitors.

With the aim of obtaining compounds possessing high SERT selectivity, in the present work we synthesized and studied the inhibition of serotonin (SERT), dopamine (DAT) and norepinephrine (NET) transporters by docking studies and experimental binding measurements of a series of 4-(aryl)piperidin-3-one O-4-benzyl oxime hydrochlorides (1-10) of both E and Z configuration. E configuration compounds showed high SERT binding affinities (K(i) = 10-98 nM) and high SERT selectivities over both NET and DAT. The molecular docking studies allowed a rationalization of the molecular basis of drug-SERT interactions both of the synthesized compounds and paroxetine and fluoxetine used as reference antidepressant drugs.

Therapeutic potential of sulindac hydroxamic acid against human pancreatic and colonic cancer cells.

The non-steroidal anti-inflammatory drug (NSAID) sulindac exhibits cyclooxygenase (COX)-dependent and COX-independent chemopreventive properties in human cancer. The present study was aimed at investigating whether the hydroxamic acid substitution for the carboxylic acid group could enhance the in vitro antitumor and antiangiogenic activities of sulindac. Characterization tools used on this study included analyses of cell viability, caspase 3/7 induction, DNA fragmentation, and gene expression. Our findings demonstrate that the newly synthesized hydroxamic acid derivative of sulindac and its sulfone and sulfide metabolites were characterized by a good anticancer activity on human pancreatic and colon cancer cells, both in terms of potency (IC(50) mean values from 6 ± 1.1 µM to 64 ± 1.1 µM) and efficacy (E(max) of ∼100%). Hydroxamic acid derivatives trigger a higher degree of apoptosis than carboxylic acid counterparts, increase bax/bcl-2 expression ratio and induce caspase 3/7 activation. Most notably, these compounds significantly inhibit proangiogenic growth factor-stimulated proliferation of vascular endothelial cell (HUVEC) at sub-micromolar concentrations. Our data also provide evidence that the COX-active metabolite of sulindac hydroxamic acid were the most active of the series and selective inhibition of COX-1 but not COX-2 can mimic its effects, suggesting that COX inhibition could only play a partial role in the mechanism of compound action. In conclusion, these data demonstrate that substitution of the carboxylic acid group with the hydroxamic acid moiety enhances in vitro antiproliferative, proapoptotic and antiangiogenic properties of sulindac, therefore increasing the therapeutic potential of this drug.

Novel transthyretin amyloid fibril formation inhibitors: synthesis, biological evaluation, and X-ray structural analysis.

Transthyretin (TTR) is one of thirty non-homologous proteins whose misfolding, dissociation, aggregation, and deposition is linked to human amyloid diseases. Previous studies have identified that TTR amyloidogenesis can be inhibited through stabilization of the native tetramer state by small molecule binding to the thyroid hormone sites of TTR. We have evaluated a new series of beta-aminoxypropionic acids (compounds 5-21), with a single aromatic moiety (aryl or fluorenyl) linked through a flexible oxime tether to a carboxylic acid. These compounds are structurally distinct from the native ligand thyroxine and typical halogenated biaryl NSAID-like inhibitors to avoid off-target hormonal or anti-inflammatory activity. Based on an in vitro fibril formation assay, five of these compounds showed significant inhibition of TTR amyloidogenesis, with two fluorenyl compounds displaying inhibitor efficacy comparable to the well-known TTR inhibitor diflunisal. Fluorenyl 15 is the most potent compound in this series and importantly does not show off-target anti-inflammatory activity. Crystal structures of the TTR:inhibitor complexes, in agreement with molecular docking studies, revealed that the aromatic moiety, linked to the sp(2)-hybridized oxime carbon, specifically directed the ligand in either a forward or reverse binding mode. Compared to the aryl family members, the bulkier fluorenyl analogs achieved more extensive interactions with the binding pockets of TTR and demonstrated better inhibitory activity in the fibril formation assay. Preliminary optimization efforts are described that focused on replacement of the C-terminal acid in both the aryl and fluorenyl series (compounds 22-32). The compounds presented here constitute a new class of TTR inhibitors that may hold promise in treating amyloid diseases associated with TTR misfolding.