Biomedical subjects

Francesco Berardi

Publications and source records attributed to Francesco Berardi.

At least 19 recordsLinked to original sources

PubMed2006

Arylmethyloxyphenyl derivatives: small molecules displaying P-glycoprotein inhibition.

Some arylmethyloxyphenyl derivatives were prepared as simplified structures of analogous arylpiperazines with high affinity toward dopaminergic D(2) and serotonergic 5-HT(1A) receptors and inhibiting P-glycoprotein (P-gp). The compounds 5b and 8b displayed good P-gp inhibition activity measured as [(3)H]vinblastine transport inhibition in the Caco-2 cell monolayer and intracellular doxorubicin accumulation in MCF7/Adr cells by flow cytometry. Compounds 5b and 8b also inhibited, dose-dependently, ATP-ase activation induced by P-gp substrate vinblastine.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2006

Is the sigma2 receptor a histone binding protein?

Starting from the high affinity sigma(2) receptor ligand 2, (PB28), we synthesized amino derivative 4 and coupled it to an NHS-ester activated sepharose stationary phase column to elute a crude protein prepared by lysed human SK-N-SH neuroblastoma cells. We characterized the SDS-PAGE gel electrophoresis stained bands by MALDI-MS and LC-MS-MS analysis. The MASCOT MS-MS ion search program led to the identification of the protein components. The six eluted proteins had a molecular weight ranging from 13 kDa to 26 kDa and were human histone proteins. A human 40S ribosomal protein S3 (SwissProt accession number: P23396) was also identified as a comigrated band. The human histone proteins that were characterized were H3.3A histone (NCBI accession number: 51859376), H2B histone (NCBI accession number: 1568557), H2A.5 histone (NCBI accession number: 70686), H1 (NCBI accession number: 22770677), and H2.1 histone (SwissProt accession number: P16403). These results disclosed a dual hypothesis about the sigma(2) receptor, that is, that it is formed by histones or that the sigma(2) ligands also bind histone proteins.

1-Naphthylamine↗

PubMed2006

The sigma-2 receptor agonist PB28 inhibits calcium release from the endoplasmic reticulum of SK-N-SH neuroblastoma cells.

In this paper we demonstrate that PB28 abolishes the Ca2+ release through the inositol 1,4,5-trisphosphate (InsP3) receptors and ryanodine receptors in SK-N-SH cells. Sigma receptors are divided into the subtypes sigma-1 and sigma-2, which are expressed in tumor cell lines and characterized by distinct pharmacological profiles. The sigma-1 receptor has been recently cloned, whereas the sigma-2 receptor is less well characterized. The endogenous ligand(s) of both subtypes remain unclear. In isolated guinea pig ileum, PB28 inhibits the contraction induced by carbachol dose dependently and in a non-competitive manner. In SK-N-SH cells PB28 challenge does not affect the intracellular Ca2+ concentration but incubation with PB28 for 45 min abolishes the cytosolic Ca2+ increases evoked by carbachol or histamine. This effect, not sensitive to cycloheximide, is caused by direct inhibition of the InsP3 receptors, since PB28 abolishes the response elicited by InsP3 administration in permeabilized SK-N-SH cells. Finally, incubation for 45 min with PB28 also abolishes the cytosolic Ca2+ increase evoked by caffeine.

Animals↗

PubMed2006

Design, synthesis, and binding affinities of potential positron emission tomography (PET) ligands for visualization of brain dopamine D3 receptors.

We here report the synthesis of compounds structurally related to the high-affinity dopamine D(3) receptor ligand N-[4-[4-(2,3-dichlorophenyl)piperazin-1-yl]butyl]-7-methoxy-2-benzofurancarboxamide (1). All compounds were specifically designed as potential PET radioligands for brain D(3) receptors visualization, having lipophilicity within a range for high brain uptake and weak nonspecific binding (2 < ClogP < 3.5) and bearing a methoxy substituent for easy access to labeling with the positron emitter isotope (11)C. N-[4-[4-(5-methoxy-2-benzisoxazolyl)piperazin-1-yl]butyl]-4-(4-morpholinyl)benzamide (22), N-[4-[4-(5-methoxy-2-benzisoxazolyl)piperazin-1-yl]butyl]-4-(1H-imidazol-1-yl)benzamide (23), and N-[4-[4-(5-methoxy-2-benzisoxazolyl)piperazin-1-yl]butyl]-5-(2-furanyl)-1H-pyrazole-3-carboxamide (24) displayed good D(3) receptor affinities (K(i) values 38.0, 22.6, and 21.3 nM, respectively) and were selective over D(2) receptor. Moreover, compounds 22-24 were able to permeate the Caco-2 cell monolayer, differently from compound 1. Although the goal to identify potential PET radioligands with subnanomolar affinities for D(3) receptor was not achieved, the proposed strategy could be a starting point for future developments.

Animals↗

PubMed2006

Cyclohexylpiperazine derivative PB28, a sigma2 agonist and sigma1 antagonist receptor, inhibits cell growth, modulates P-glycoprotein, and synergizes with anthracyclines in breast cancer.

sigma Ligands have recently been shown to have cytotoxic activity, to induce ceramide-dependent/caspase-independent apoptosis, and to down-regulate P-glycoprotein (P-gp) mRNA levels in some mouse and human models. In this study, we verified whether a mixed sigma(2) agonist/sigma(1) antagonist, PB28, was able to have antitumor activity and to enhance anthracycline efficacy in two human breast cancer cell lines, MCF7 and MCF7 ADR, both characterized by significant sigma(2) receptor expression, by high and low sigma(1) receptor expression, and low and high P-gp expression, respectively. In both cell lines, PB28 showed high sigma(2) receptor affinity and low sigma(1) receptor affinity; furthermore, it inhibited cell growth with a clear effect at 48 hours (IC(50) in nanomolar range), a consistent time exposure-independent increase of G(0)-G(1)-phase fraction (of approximately 20% of both cell lines) and caspase-independent apoptosis (15% increased after 1-day drug exposure). PB28 also reduced P-gp expression in a concentration- and time-dependent manner ( approximately 60% in MCF7 and 90% in MCF7 ADR). We showed also a strong synergism between PB28 and doxorubicin by adopting either simultaneous or sequential schedules of the two drugs. We suggest that this synergism could depend on PB28-induced increase of intracellular accumulation of doxorubicin ( approximately 50% in MCF7 and 75% in MCF7 ADR by flow cytometry analysis). In conclusion, we suggest that the sigma(2) agonist PB28 could be an interesting antitumor agent either in monotherapy or in combination with conventional drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2006

Synthesis and binding profile of constrained analogues of N-[4-(4-arylpiperazin-1-yl)butyl]-3-methoxybenzamides, a class of potent dopamine D3 receptor ligands.

We recently reported on a series of N-[4-(4-arylpiperazin-1-yl)butyl]-3-methoxybenzamides, endowed with high affinity for dopamine D(3) receptors, but lacking of selectivity over D(4), D(2), 5-HT(1A), and alpha(1)-receptors. To improve the D(3)-receptor affinity and selectivity, without causing a considerable increasing in the lipophilicity, the flexible butyl linker was replaced by a more conformationally constrained cyclohexyl linker. The new cis- and trans-N-[4-(4-aryl-1-piperazinyl)cyclohexyl]-3-methoxybenzamides (Aryl= 2,3-di-Cl-Ph, 2-CH(3)O-Ph, 4-Cl-Ph, 2,3-di-CH(3)-Ph) were tested in-vitro for their binding affinity for D(3), D(4), D(2), 5-HT(1A), and alpha(1)-receptors. The trans- derivatives were found to be more potent at D(3) receptor than the corresponding cis- isomers, but less potent than the opened counterparts. This reflected negatively on the selectivity over the other studied receptors. Derivative trans-N-{4-[4-(2,3-dichlorophenyl)-1-piperazinyl]cyclohexyl}-3-methoxybenzamide (trans-7) showed high D(3)-receptor affinity (K(i)=0.18 nM) and a relevant selectivity over D(4), D(2), 5-HT(1A), and alpha(1)-receptors (>200-fold). This compound was characterized as a full agonist at D(3) receptor when tested in the Eu-GTP binding assay.

Animals↗

PubMed2005

Methyl substitution on the piperidine ring of N-[omega-(6-methoxynaphthalen-1-yl)alkyl] derivatives as a probe for selective binding and activity at the sigma(1) receptor.

The N-(6-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl and N-(6-methoxynaphthalen-1-yl)propyl derivatives as well as their upper homologous butyl derivatives of various methylpiperidines were prepared. The piperidine moiety bearing monomethyl or geminal dimethyl groups was employed as a probe to explore sigma-subtype affinities and selectivities by radioligand binding assays at sigma(1) and sigma(2) receptors and the Delta(8)-Delta(7) sterol isomerase (SI) site. 4-Methyl derivative 31 was the most potent sigma(1) ligand (K(i)=0.030 nM) with a good selectivity profile (597-fold and 268-fold relative to sigma(2) receptor and SI site, respectively), whereas 3,3-dimethyl derivative 26 (K(i)=0.35 nM) was the most selective (680-fold) relative to the sigma(2) receptor. Both compounds can be proposed as tools for PET experiments. Furthermore, the naphthalene compounds 26, 28, 31, and 33 demonstrated antiproliferative activity in rat C6 glioma cells (EC(50) = 15.0 microM for 33), revealing a putative sigma(1) antagonist activity and opening a useful perspective in tumor research and therapy.

Animals↗

PubMed2005

First structure-activity relationship study on dopamine D3 receptor agents with N-[4-(4-arylpiperazin-1-yl)butyl]arylcarboxamide structure.

Structure-affinity relationships of N-[4-(4-arylpiperazin-1-yl)butyl]arylcarboxamides as D3 receptor ligands have been well characterized but not structure-activity relationships. In a first attempt to clarify this issue, seven 1-(2,3-dichlorophenyl)piperazine derivatives and their 2-methoxyphenyl counterparts were prepared by varying the arylcarboxamide moiety. They were tested for D3 receptor binding affinities and in the Eu-GTP binding assay in order to evaluate their intrinsic activity. We have found that the intrinsic activity strongly depended on the nature of the arylcarboxamide moiety.

Amides↗

PubMed2005

11C-labeling of n-[4-[4-(2,3-dichlorophenyl)piperazin-1-yl]butyl]arylcarboxamide derivatives and evaluation as potential radioligands for PET imaging of dopamine D3 receptors.

The selective dopamine D(3) receptor ligands N-4-[4-[(2,3-dichlorophenyl)piperazin-1-yl]butyl]1-methoxy-2-naphthalencarboxamide (1) and N-4-[4-[(2,3-dichlorophenyl)piperazin-1-yl]butyl]-7-methoxy-2-benzofurancarboxamide (2) were labeled with (11)C (t(1/2) = 20.4 min) as potential radioligands for the noninvasive assessment of the dopamine D(3) neurotransmission system in vivo with positron emission tomography (PET). The radiosynthesis consisted in an O-methylation of the des-methyl precursors N-[4-[4-(2,3-dichlorophenyl)piperazin-1-yl]butyl]-1-hydroxy-2-naphthalenecarboxamide (3) and N-[4-[4-(2,3-dichlorophenyl)piperazin-1-yl]butyl]-7-hydroxy-2-benzofurancarboxamide (4) with [(11)C]methyl iodide using tBuOK/HMPA and KOH/DMSO, respectively. The radiotracers [(11)C]1 and [(11)C]2 were obtained in 35 min with over 99% radiochemical purity, 74 +/- 37 GBq/mumol of specific radioactivity, 13% and 26% radiochemical yield (EOB, decay-corrected). Distribution studies in rats demonstrated that the new tracers [(11)C]1 and [(11)C]2 cross the blood-brain barrier and localize in the brain. However, the kinetics of cerebral uptake did not reflect the regional expression of the D(3) receptors. Despite their in vitro pharmacological profile, [(11)C]1 and [(11)C]2 do not display an in vivo behavior suitable to image D(3) receptor expression using PET.

Amides↗

PubMed2005

Correlation between sigma2 receptor protein expression and histopathologic grade in human bladder cancer.

Sigma2 (sigma2) receptor proteins are overexpressed in several tissues and tumour cell lines. Although the biomolecular mechanism of this overexpression must be elucidated, sigma2 receptor was considered a potential biomarker for monitoring solid tumour proliferation. In this study, we verified first sigma2 receptor overexpression by saturation analysis with radioligand in six human bladder cancer specimens, then if a possible correlation could be established between sigma2 overexpression and tumour tissue stage and grade. The results displayed that sigma2 receptor protein was normally expressed in human bladder and overexpressed in the case of high-grade transitional cell carcinomas. Moreover, these receptors were undetected in a low-grade squamous cell carcinoma and in a very rare form of anaplastic, large cells plasmacytoid cancer.

Aged↗

PubMed2005

Design and synthesis of long-chain arylpiperazines with mixed affinity for serotonin transporter (SERT) and 5-HT(1A) receptor.

A new generation of antidepressant agents could be represented by compounds with mixed activity as serotonin transporter (SERT) inhibitors and 5-HT(1A) receptor antagonists. We report here on the synthesis and evaluation of SERT and 5-HT(1A) receptor affinity of long-chain arylpiperazines obtained either by modifying 6-nitroquipazine into a long-chain arylpiperazine or by inserting a modified 6-nitroquipazine moiety or other structures endowed with SERT affinity into a long-chain arylpiperazine with 5-HT(1A) affinity. Among the compounds studied, 2-[4-(2-methoxyphenyl)piperazin-1-yl]-N-(6-nitro-2-quinolyl)ethylamine (21) and 1-(5-bromo-1,2,3,4-tetrahydronaphthalen-1-yl)-3-[4-(2-methoxyphenyl)-piperazin-1-yl]-1-propanone (24) showed good affinity values for SERT and 5-HT(1A) receptors (SERT: K(i) (inhibition constant)=71.8 and 62.8 nM; 5-HT(1A)K(i)=14.2 and 0.82 nM, respectively).

Animals↗

PubMed2005

Distribution of sigma receptors in EMT-6 cells: preliminary biological evaluation of PB167 and potential for in-vivo PET.

Sigma(1) and sigma(2) receptors have been detected in many tissues and are highly expressed in several tumour cell lines from various tissues. The high level of expression observed for sigma receptors and their involvement in cell proliferation and apoptosis has led to the development of several sigma ligands in order to obtain a molecular probe for in-vivo diagnostic imaging techniques such as positron emission tomography (PET) and single photon emission computerized tomography (SPECT). The EMT-6 cells implanted in mice were a good model for evaluating the proliferation of solid tumours by in-vivo PET. Moreover, we developed the sigma ligand PB167, a cyclohexylpiperazine derivative, previously evaluated for sigma(2) receptor affinity and activity in standard protocols. The related results encouraged us to verify if this compound could be developed as a radiotracer for in-vivo PET in order to visualize sigma(2) receptors expressed in EMT-6 cells when implanted in mice. This perspective was thought to be favourable because PB167 bears a methoxy substituent on the tetraline nucleus, an easy point for (11)C labelling. The aims of this preliminary study were both to assess the relative distribution of sigma(1) and sigma(2) receptors in EMT-6 cells and to verify if PB167 could be developed as a sigma(2) radiotracer for in-vivo PET. The results showed that both sigma(1) and sigma(2) receptors were overexpressed in EMT-6 cells and that the ligand PB167 can be positively considered for radiosynthesis preparation in order to suitably visualize sigma(2) receptors by the in-vivo PET technique and correlate their presence to tumour proliferation.

Animals↗

PubMed2004

Structure-affinity relationship study on N-(1,2,3,4-tetrahydronaphthalen-1-yl)-4-aryl-1-piperazinealkylamides, a new class of 5-hydroxytryptamine7 receptor agents.

A series of N-(1,2,3,4-tetrahydronaphthalen-1-yl)-4-aryl-1-piperazinealkylamides was prepared and their affinity for serotonin (5-hydroxytryptamine, 5-HT) 5-HT7, 5-HT(1A), and 5-HT(2A) receptors was measured by in vitro binding assays. In relation to 5-HT7 receptor affinity, receptor binding studies indicated that (i) the optimal alkyl chain length was five methylenes, (ii) an unsubstituted 1,2,3,4-tetrahydronaphthalenyl nucleus was preferred, and (iii) the substitution pattern of the aryl ring linked to the piperazine ring played a crucial role. Several compound with high affinity for 5-HT7 receptors were identified. Among them, 4-(2-methoxyphenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (28), 4-(2-acetylphenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (34), 4-(2-methylthiophenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (44), 4-(2-hydroxyphenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (46), and 4-(2-methylphenyl)-N-(1,2,3,4-tetrahydronaphthalen-1-yl)-1-piperazinehexanamide (49) were assayed for the 5-HT7 receptor-mediated relaxation of substance P-induced guinea pig ileum contraction. Compounds 28, 44, and 49 behaved as full agonists and compound 34 as a partial agonist, whereas derivative 46 acted as an antagonist. Among the compounds presented here, it emerged that 44 was identified as a potent 5-HT7 receptor agonist (Ki = 0.22 nM, EC50 = 2.56 microM), endowed with selectivity over 5-HT(1A) and 5-HT(2A) receptors (200-fold and >1000-fold, respectively).

Amides↗

PubMed2004

Antiproliferative and cytotoxic effects of some sigma2 agonists and sigma1 antagonists in tumour cell lines.

To establish the activity of sigma ligands at sigma1 and sigma2 receptor, we chose two tumour cell lines, the human SK-N-SH neuroblastoma and the rat C6 glioma lines, which express sigma2 receptors at a high density and sigma1 receptors in their high-affinity or low-affinity state. We tested the sigma2 receptor agonist PB28 and the sigma2 antagonist AC927, and (+)-pentazocine and NE100 as agonist and antagonist, respectively, at sigma1 receptors, with regard to antiproliferative and cytotoxic effects. In addition, 1,3-di(2-tolyl)guanidine (DTG) and haloperidol were tested as reference compounds displaying nearly equipotent sigma affinity (sigma2>sigma1 and sigma1>sigma2, respectively). In both SK-N-SH and C6 cells, PB28 and NE100 displayed the most potent results both in antiproliferative and cytotoxic assay while AC927 and (+)-pentazocine were inactive in both assays. The cytotoxic and antiproliferative effects of DTG and haloperidol reflected their sigma1 antagonist activity and sigma2 agonist activity. Moreover, our results in the tumour cell lines correlated well with those for sigma2 activity found previously in a functional assay in the guinea-pig bladder. These findings establish a new model for evaluating both sigma2 and sigma1 receptor activity of sigma ligands, which could be useful for developing new ligands having mixed sigma2 agonist/sigma1 antagonist activity as potential antineoplastic agents.

Animals↗

PubMed2004

4-(tetralin-1-yl)- and 4-(naphthalen-1-yl)alkyl derivatives of 1-cyclohexylpiperazine as sigma receptor ligands with agonist sigma2 activity.

Several 1-cyclohexylpiperazine derivatives related to sigma(2) receptor ligand 1-cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperazine (33, K(i) = 0.34 nM) were synthesized and tested in radioligand binding assays, to attempt a structure-affinity relationship study. Intermediate alkyl chain length and methoxyl group position on the tetralin nucleus were varied. A few naphthalene analogues were also prepared. High affinities were found in sigma(2) receptor binding for almost all compounds, some of which displayed K(i) values in subnanomolar range, but low sigma(2)/sigma(1) selectivities were found. The highest sigma(2) affinities were displayed by compounds with an intermediate alkyl chain of three (32 and 43) or five methylenes (39 and 46). Quite high sigma(1) receptor affinity was found for compounds with a four-methylene chain; 36 (K(i) = 0.036 nM) and 45 (K(i) = 0.22 nM) displaying good sigma(1)/sigma(2) selectivity (406- and 139-fold, respectively). Moreover, homologues of compound 33 displayed also satisfactory selectivities over dopamine D(2)-like, serotonin 5-HT(3), and adrenergic alpha(1) receptors. These compounds and a few others were tested in the inhibition of the electrically evoked contractions in guinea pig bladder and were demonstrated to be full sigma(2) agonists. The activity values correlated well to the affinity scale (EC(50) in microM range). 33 and related compounds are proposed as a class of potential antineoplastic and PET diagnosis agents.

Animals↗

PubMed2004

Studies on 1-arylpiperazine derivatives with affinity for rat 5-HT7 and 5-HT1A receptors.

Several 1-aryl-4-(2-arylethyl)piperazine derivatives were synthesized and tested in-vitro for their binding affinity for 5-HT(7) and 5-HT(1A) receptors. These compounds displayed 5-HT(7 )receptor affinity ranging between K(i) = 474 nM and K(i) = 8.2 nM, besides high affinity for the 5-HT(1A) receptor. Intrinsic activity of the most potent compounds was assessed. 4-[2-(3-Methoxyphenyl)ethyl]-1-(2-methoxyphenyl)piperazine (16) and 1-(1,2-benzisoxazol-3-yl)-4-[2-(3-methoxyphenyl)ethyl]piperazine (20) (K(i) = 24.5 and 8.2 nM, respectively) behaved as partial agonist and full agonist, respectively, when tested for 5-HT(7) receptor-mediated relaxation of substance P-induced guinea-pig ileum contraction.

Animals↗

PubMed2003

A new method for evaluating sigma(2) ligand activity in the isolated guinea-pig bladder.

We demonstrated the presence of sigma(2) receptors in the guinea-pig ileum by saturation analysis and extended our investigation to guinea-pig bladder and rat bladder. In functional assays of the isolated tissues in organ baths, sigma(2) receptor ligands inhibited electrically evoked contractions in both guinea-pig bladder and ileum and a linear correlation was found between sigma(2) receptor affinity and sigma(2) receptor activity values of selected compounds. The sigma(2) activity of these compounds in the presence of desensitised sigma(1) receptors both in bladder and ileum was also tested. On the basis of our results, we propose the electrically stimulated guinea-pig bladder as a new method for evaluating sigma(2) activity.

Animals↗

PubMed2003

Synthesis of chiral 1-[omega-(4-chlorophenoxy)alkyl]-4-methylpiperidines and their biological evaluation at sigma1, sigma2, and sterol delta8-delta7 isomerase sites.

Sumitomo's patented sigma ligand 1-[3-(4-chlorophenoxy)propyl]-4-methylpiperidine (15), which has been claimed as agent for CNS disorders and neuropathies, and its lower homologue 12 were prepared along with related chiral (4-chlorophenoxy)alkylpiperidines. They were tested at sigma1, sigma2, and sterol Delta8-Delta7 isomerase (SI) sites by in vitro radioligand binding assays, to evaluate the influence of a chiral center in the alkyl chain on the selective sigma(1) binding relative to other sigma family sites. Generally high sigma1-site affinities were found, so that the chirality introduced by a methyl substitution resulted in slight differences. Nevertheless, the shorter oxyethylenic chain was beneficial to increase sigma1 selectivity. However, the (-)-(S)-4-methyl-1-[2-(4-chlorophenoxy)-1-methylethyl]piperidine ((-)-(S)-17) reached the highest sigma1 affinity (K(i) = 0.34 nM) and the best selectivity relative to the sigma2 site (547-fold). Compound (-)-(S)-17 displayed also a moderate selectivity (11-fold) relative to the SI site.

Animals↗