Many new chemotherapeutic agents are under preclinical investigation and, despite efforts to more selectively target cancer cells, limitations such as toxicity and inherent resistance are often encountered. Therefore, alternative strategies are needed to treat cancer and overcome such limitations. We describe novel cyclohexylpiperazine derivatives, designed as mixed affinity ligands for sigma (s) receptors and human D8– D7 sterol isomerase (HSI) ligands, which also exhibit P-glycoprotein (P-gp) inhibitory activity, with the aim of exploiting the antiproliferative effects mediated by s and HSI sites while overcoming P-gp-mediated resistance. All of the compounds displayed high affinities for s receptors and HSI sites, P-gp inhibitory activity, and s2 receptor agonist antiproliferative activity. Antiproliferative activity was also tested in PC-3 cells to establish s1 and HSI contribution. Compound cis-11, which displayed the best antiproliferative and P-gp inhibitory activities, was coadministered with 0.1 mm doxorubicin in MDCK-MDR1 cells. Compound cis-11 caused 70% and 90% cell death when coadministered at 30 mm and 50 mm, respectively. When administered alone, cis-11 resulted in 50% cell death, demonstrating its single agent antitumor properties in a tumor cell line overexpressing P-gp.

New fluorescent derivatives for s receptors were designed and synthesized. To achieve this purpose, a 4-nitro-2,1,3-benzoxadiazole fluorescent tag was connected through a piperazine linker to a modified skeleton derived from selected s receptor agonists or antagonists. Compounds 5g, 7b, 7e and 7g displayed high s1 affinity and low s1/s2 selectivity (Kis1 ranging from 31.6 nM to 48.5 nM, Kis1/s2 ¼ 5–18), while compound 5d exhibited high s2 affinity and selectivity (Kis2 ¼ 56.8 nM, Kis1 > 5000 nM). Binding affinity studies revealed that compounds 5d, 5g, 7b, 7e and 7g showed no affinity towards several receptors including opioid, dopaminergic, serotonergic, adrenergic, muscarinic, histaminergic, N-methyl-D-aspartate (NMDA), NMDA receptor channel, or dopamine and serotonine transporters. The fluorescent properties, cellular uptake and confocal microscopy studies on 5d suggest a potential use of this probe to further clarify the molecular role of s2 receptor subtypes in normal and cancer cells.

CSCs are responsible for the high rate of recurrence and chemoresistance of different types of cancer. The current antineoplastic agents able to inhibit bulk replicating cancer cells and radiation treatment are not efficacious toward CSCs since this subpopulation has several intrinsic mechanisms of resistance. Among these mechanisms, the expression of ATP-Binding Cassette (ABC) transporters family and the activation of different signaling pathways (such as Wnt/β-catenin signaling, Hedgehog, Notch, Akt/PKB) are reported. Therefore, considering ABC transporters expression on CSCs membranes, compounds able to modulate MDR could induce cytotoxicity in these cells disclosing an exciting and alternative strategy for targeting CSCs in tumor therapy. The next challenge in the cure of cancer relapse may be a multimodal strategy, an approach where specific CSCs targeting drugs exert simultaneously the ability to circumvent tumor drug resistance (ABC transporters modulation) and cytotoxic activity toward CSCs and the corresponding differentiated tumor cells. The efficacy of suggested multimodal strategy could be probed by using several scaffolds active toward MDR pumps on CSCs isolated by tumor specimens.

A series of alkyloxyquinoline derivatives has been developed to evaluate the relationship between P-gp potency and lipophilicity. The results show a satisfactory lipophilicity-activity correlation although a series of derivatives showing higher P-gp potency is needed in order to confirm this hypothesis.

1-Cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperazine 1 (PB28) and 2- Methoxy-5-methyl-N-[4-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)butyl]benzamide 2 (RHM-1) represent leads for tumor diagnosis, given their high affinity at sigma2 receptors. With the purpose of obtaining good candidates for s2 PET tracers development, hybrid structures between 1 and 2 were designed. Excellent sigma1/sigma2 selectivities were reached when 6,7-dimethoxytetrahydroisoquinolinewas linked to an omethoxy substituted arylamide (11a, 12a, 15a), and for these benzamides an intramolecular H-bond in the active conformation at the s sites, was hypothesized. However these excellent s2 ligands were accompanied by interaction with P-gp, which may limit their use as sigma2 receptor PET agents when tumors overexpress P-gp. Compound 15a whose P-gp interaction was just moderate represents an interesting tool for the development of sigma2 PET tracers useful in tumors overexpressing P-gp.

A set of basic aryl-group-containing compounds was synthesized with the aim of developing potent and selective P-glycoprotein (P-gp) modulators that are able to reverse multidrug resistance (MDR). The natures of the spacer (dicyclohexylamine or dialkylamine) and the aryl moieties were modified to investigate selectivity and the mechanism of P-gp interaction. The inhibitory activities of the compounds toward P-gp, multidrug resistance-associated protein 1 (MRP1), and breast cancer resistance protein (BCRP), the most relevant ATP binding cassette (ABC) transporters for MDR, were evaluated. The mechanism of P-gp interaction for each compound was investigated with three biological assays: apparent permeability (Papp ) determination (B→A/A→B) in Caco-2 cell monolayers, ATP cell depletion, and inhibition of Calcein-AM transport in MDCK-MDR1 cells. These assays allowed us to estimate the selectivity of the compounds for the three efflux pumps and to identify the structural requirements that define the P-gp-interaction profile. All dicyclohexylamine derivatives were found to be P-gp substrates, whereas one dialkylamine derivative was shown to be a P-gp inhibitor. The good MRP1 activity of one cis/cis isomer highlighted this as a lead candidate for the development of MRP1 ligands.

Inverse agonists are useful active ingredient of drugs clinically used to treat diseases mainly involving receptors endowed with nonendogenous agonist induced activity (constitutive or basal activity). SP-1e and SP-1g are the first two potent and highly selective β3-adrenoceptor inverse agonists [EC50=181 nM (IA=- 64%) and 136 nM (IA=-73%), respectively], which their peculiar activity seems due to the absolute configurations of the two stereogenic centres present in each molecule. Rat proximal colon motility measurements allowed their further pharmacological characterization and pA2 values determination by Schild analysis (7.89 and 8.16, respectively). The purpose of our work is a further characterization of our novel β3-adrenoceptor agonists (SP-1a-d, SP-1f,1h) and inverse agonists (SP-1e and SP1g) on rat proximal colon motility and a confirmation of their inverse agonist nature in a more complex system like the functional test on rat proximal colon. Male Wistar rats segment of the proximal colon were placed in organ baths containing Krebs solution. Muscle tension was recorded isotonically. Cumulative β3-AR agonists doses experiments were performed for each test compound: isoprenaline, BRL37344, SP-1a-d, SP-1f and SP-1h were dissolved in Krebs. The EC50 values of each agonists and pA2 of inverse agonists were determined. SP-1a-d, SP-1f and SP-1h in rat colon have a muscle relaxing effect thus confirming their partial agonist activity found in CHO-K1 cell line. SP-1e and SP-1g behaved as antagonists with pA2 values of 7.89 and 8.16, espectively. In conclusion, experiments carried out by using isolated rat proximal colon allowed us to determine the pA2 values of the two β3-AR inverse agonists and add knowledge on the behavior of a novel set of compounds and their possible value as agents useful whenever is necessary to also control the colon motility.

Generations of modulators of the efflux pump P-glycoprotein (P-gp) have been produced as tools to counteract the Multidrug Resistance (MDR) phenomenon in tumor therapy, but clinical trials were not successful so far. With the aim of contributing to the development of novel P-gp modulators, we started from recently studied high-affinity sigma-2 (σ2) receptor ligands that showed also potent interaction with P-gp. For σ2 receptors high-affinity binding, a basic N-atom is a strict requirement. Therefore, we reduced the basic character of the N-atom present in these ligands, and we obtained potent P-gp modulators with poor or null σ2 receptor affinity. We also evaluated whether modulation of P-gp by these novel compounds involved consumption of ATP (as P-gp substrates do), as a source of energy to support the efflux. Surprisingly, even small structural changes resulted in opposite behavior, with amide 13 depleting ATP, in contrast to its isomer 18. Two compounds, 15 and 25, emerged for their potent activity at P-gp, and deserve further investigations as tools for P-gp modulation.

Here we report the design, synthesis, and 5-HT7 receptor affinity of a set of 1-(3-biphenyl)- and 1-(2-biphenyl)piperazines. The effect on 5-HT7 affinity of various substituents on the second (distal) phenyl ring was analyzed. Several compounds showed 5-HT7 affinities in the nanomolar range and >100-fold selectivity over 5-HT1A and adrenergic α1 receptors. 1-[2-(4-Methoxyphenyl)phenyl]piperazine (9a) showed 5-HT7 agonist properties in a guinea pig ileum assay but blocked 5-HT-mediated cAMP accumulation in 5-HT7-expressing HeLa cells.

The aim of the present work was to compare the mucoadhesive and efflux pump P-glycoprotein (P-gp) interacting properties of chitosan (CS)- and glycolchitosan (GCS)-based thiomers and corresponding unmodified parent polymers. For this purpose, the glycol chitosan-N-acetyl-cysteine (GCS-NAC) and glycol chitosan-glutathione (GCS-GSH) thiomers were prepared under simple and mild conditions. Their mucoadhesive characteristics were studied by turbidimetric and zeta potential measurements. The P-gp interacting properties were evaluated measuring the effects of thiolated- and unmodified-polymers on the bidirectional transport (BA/AB) of rhodamine-123 across Caco-2 cells as well as in the calcein-AM and ATPase activity assays. Although all the thiomers and unmodified polymers showed optimal-excellent mucoadhesive properties, the best mucoadhesive performances have been obtained by CS and CS-based thiomers. Moreover, it was found that the pretreatment of Caco-2 cell monolayer with GCS-NAC or GCS restores Rho-123 cell entrance by inhibiting P-gp activity. Hence, GCS-NAC and GCS may constitute new biomaterials useful for improving the bioavailability of P-gp substrates.

Compounds 8a–d have been designed as bioisosters of tariquidar for imaging P-gp expression and density by PET. The results displayed that compounds 8b and 8d could be considered potential P-gp/BCRP ligands suitable as 11C and 18F radiotracers, respectively.

Starting from the previously developed P-gp ligands 1a and 1b (EC50 ¼ 0.25 mM and 0.65 mM, respectively), new arylmethyloxyphenyl derivatives have been synthesized as P-gp modulators in order to investigate: (i) the effect of small electron-donor groups (OMe) (5e11), (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 ¼ 7.1 nM) towards P-gp pump and, in the meantime lacks of activity against MRP1 pump.

The development of P-glycoprotein (P-gp) ligands remains of considerable interest mostly for investigating protein structure and transport mechanism. In the last years many ligands, belonging to different generations, have been tested for modulating P-gp activity. Aim of the present work is to perform SAR studies on tetrahydroisoquinoline derivatives in order to design potent and selective P-gp ligands. For this purpose the effect of bioisosteric replacement and the role of flexibility have been investigated and four series of tetrahydroisoquinoline ligands have been developed: a) 2-aryoxazole bioisosteres; b) elongated analogues; c) 2H-Chromene and d) 2-biphenyl derivatives. Obtained results showed that both 2-biphenyl derivative 20b and elongated derivative 6g behaved as strong P-gp substrates. In conclusion important items have been highlighted for developing potent and selective P-gp ligands providing a solid starting point for further optimization.

Inhibition of drug efflux pumps such as P-glycoprotein (P-gp) is an approach toward combating multidrug resistance, which is a significant hurdle in current cancer treatments. To address this, N-substituted aryloxymethyl pyrrolidines were designed and synthesized in their homochiral forms in order to investigate the stereochemical requirements for the binding site of Pgp. Our study provides evidence that the chiral property of molecules could be a strategy for improving the capacity for interacting with P-gp, as the most active compounds of the series stereoselectively modulated this efflux pump. The naphthalene- 1-yl analogue (R)-2-[(2,3-dichlorophenoxy)methyl]-1- (naphthalen-1-ylmethyl)pyrrolidine) [(R)-7a] emerged foremost for its potency and stereoselectivity toward P-gp, with the S enantiomer being nearly inactive. The modulation of P-gp by (R)-7a involved consumption of ATP, thus demonstrating that the compound behaves as a P-gp substrate.

Starting from two carbocyclic analogs, a series of 3,3-dimethylpiperidine derivatives was prepared and tested in radioligand binding assays at r1 and r2 receptors, and at D8–D7 sterol isomerase (SI) site. The novel compounds mostly bear heterocyclic rings or bicyclic nucleus of differing lipophilicities. Compounds 18a and 19a,b demonstrated the highest r1 affinity (Ki = 0.14–0.38 nM) with a good selectivity versus r2 binding. Among them, 18a had the lowest ClogD value (3.01) and only 19b was selective versus SI too. Generally, it was observed that more planar and hydrophilic heteronuclei conferred a decrease in affinity for both r receptor subtypes.

Four mexiletine analogues have been tested for their antiarrhythmic, inotropic, and chronotropic effects on isolated guinea pig heart tissues and to assess calcium antagonist activity, in comparison with the parent compound mexiletine. All analogues showed from moderate to high antiarrhythmic activity. In particular, three of them (1b,c,e) were more active and potent than the reference drug, while exhibiting only modest or no negative inotropic and chronotropic effects and vasorelaxant activity, thus showing high selectivity of action. All compounds showed no cytotoxicity and 1b,c,d did not impair motor coordination. All in, these new analogues exhibit an interesting cardiovascular profile and deserve further investigation.

Copper is an essential trace element for the human body since it is a cofactor of several enzymes and proteins and plays a pivotal role in several biological functions (e.g., respiration, protection from oxidative damage, iron metabolism, etc.), also including the central nervous system development and functioning (e.g., synthesis of neurotransmitters, myelination, activation of neuropeptides, etc.). Therefore, copper dysmetabolism is associated with different toxic effects, mainly represented by oxidative stress, and it has been reported in many neurodegenerative disorders, such as Wilson's disease, Menkes disease, Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. This paper shows a detailed report of how copper is involved in the pathophysiology of these diseases. Moreover, a hint on novel therapeutic approaches based on restoring copper homeostasis through metal chelators will be pointed out.

L'invenzione riguarda una nuova classe di composti con elevata affinità e selettività verso la glicoproteina P. L'invenzione riguarda anche l'utilizzo di tali composti nella diagnosi in vivo di malattie neurodegenerative e come medicamenti per la prevenzione e il trattamento di malattie neurodegenerative che coinvolgono la glicoproteina P.

A series of N-(1,2,3,4-tetrahydronaphthalen-1-yl)-4-aryl-1-piperazinealkylamides was prepared and their affinity for serotonin 5-HT7, 5-HT1A, and 5-HT2A receptors was measured using 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 selected for further substitutions; and (iii) the substitution pattern of the aryl ring linked to the piperazine ring played a significant 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), 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, compound 34 as a partial agonist, whereas derivative 46 acted as an antagonist.

The invention relates to a new class of compounds with high affinity and selectivity towards P-glycoprotein. The invention also relates to the utilization of such compounds in the in vivo diagnosis of neurodegenerative diseases and as medicaments for use in the prevention and treatment of neurodegenerative disease involving P-glycoprotein.