Synthesis and biological evaluation of novel pyrazoline-based aromatic sulfamates with potent carbonic anhydrase isoforms II, IV and IX inhibitory efficacy.

Herein we report the synthesis of a new series of aromatic sulfamates designed considering the sulfonamide COX-2 selective inhibitors celecoxib and valdecoxib as lead compounds. These latter were shown to possess important human carbonic anhydrase (CA, EC 4.2.1.1) inhibitory properties, with the inhibition of the tumor-associated isoform hCA IX likely being co-responsible of the celecoxib anti-tumor effects. Bioisosteric substitution of the pyrazole or isoxazole rings from these drugs with the pyrazoline one was considered owing to the multiple biological activities ascribed to this latter heterocycle and paired with the replacement of the sulfonamide of celecoxib and valdecoxib with its equally potent bioisoster sulfamate. The synthesized derivatives were screened for the inhibition of four human carbonic anhydrase isoforms, namely hCA I, II, IV, and IX. All screened sulfamates exhibited great potency enhancement in inhibiting isoform II and IV, widely involved in glaucoma (KIs in the range of 0.4-12.4 nM and 17.7 and 43.3 nM, respectively), compared to the lead compounds, whereas they affected the tumor-associated hCA IX as potently as celecoxib.

Peptide welding technology - A simple strategy for generating innovative ligands for G protein coupled receptors.

Based on their high selectivity of action and low toxicity, naturally occurring peptides have great potential in terms of drug development. However, the pharmacokinetic properties of peptides, in particular their half life, are poor. Among different strategies developed for reducing susceptibility to peptidases, and thus increasing the duration of action of peptides, the generation of branched peptides has been described. However, the synthesis and purification of branched peptides are extremely complicated thus limiting their druggability. Here we present a novel and facile synthesis of tetrabranched peptides acting as GPCR ligands and their in vitro and vivo pharmacological characterization. Tetrabranched derivatives of nociceptin/orphanin FQ (N/OFQ), N/OFQ related peptides, opioid peptides, tachykinins, and neuropeptide S were generated with the strategy named peptide welding technology (PWT) and characterized by high yield and purity of the desired final product. In general, PWT derivatives displayed a pharmacological profile similar to that of the natural sequence in terms of affinity, pharmacological activity, potency, and selectivity of action in vitro. More importantly, in vivo studies demonstrated that PWT peptides are characterized by increased potency associated with long lasting duration of action. In conclusion, PWT derivatives of biologically active peptides can be viewed as innovative pharmacological tools for investigating those conditions and states in which selective and prolonged receptor stimulation promotes beneficial effects.

A diastereoselective synthesis of Cebranopadol, a novel analgesic showing NOP/mu mixed agonism.

A diastereoselective synthesis of the title compound as a single E diastereomer has been efficiently accomplished by assembling the featured pyrano-indole scaffold of the spiro[cyclohexane-dihydropyrano[3,4-b]-indole]-amine framework through an oxa-Pictet-Spengler reaction, promoted by a cheap and green Zeolite catalyst. Basic pharmacological experiments demonstrate that Cebranopadol acts as a mixed nociception/orphanin FQ (NOP) and mu (MOP) opioid receptor agonist useful for treatment of chronic pain.

Structure- and conformation-activity studies of nociceptin/orphanin FQ receptor dimeric ligands.

The peptide nociceptin/orphanin FQ (N/OFQ) and the N/OFQ receptor (NOP) constitute a neuropeptidergic system that modulates various biological functions and is currently targeted for the generation of innovative drugs. In the present study dimeric NOP receptor ligands with spacers of different lengths were generated using both peptide and non-peptide pharmacophores. The novel compounds (12 peptide and 7 nonpeptide ligands) were pharmacologically investigated in a calcium mobilization assay and in the mouse vas deferens bioassay. Both structure- and conformation-activity studies were performed. Results demonstrated that dimerization did not modify the pharmacological activity of both peptide and non-peptide pharmacophores. Moreover, when dimeric compounds were obtained with low potency peptide pharmacophores, dimerization recovered ligand potency. This effect depends on the doubling of the C-terminal address sequence rather than the presence of an additional N-terminal message sequence or modifications of peptide conformation.

Neuropeptide S receptor ligands: a patent review (2005-2016).

INTRODUCTION: Neuropeptide S (NPS) is a 20-residue peptide and endogenous ligand of the NPS receptor (NPSR). This receptor was a formerly orphan GPCR whose activation increases calcium and cyclic adenosine monophosphate levels. The NPS/NPSR system is expressed in several brain regions where it controls important biological functions including locomotor activity, arousal and sleep, anxiety, food intake, memory, pain, and drug addiction. Areas covered: This review furnishes an updated overview of the patent literature covering NPSR ligands since 2005, when the first example of an NPSR antagonist was disclosed. Expert opinion: Several potent NPSR antagonists are available as valuable pharmacological tools despite showing suboptimal pharmacokinetic properties in vivo. The optimization of these ligands is needed to speed up their potential clinical advancement as pharmaceuticals to treat drug addiction. In order to support the design of novel NPSR antagonists, we performed a ligand-based conformational analysis recognizing some structural requirements for NPSR antagonism. The identification of small-molecule NPSR agonists now represents an unmet challenge to be addressed. These molecules will allow investigation of the beneficial effects of selective NPSR activation in a large panel of psychiatric disorders and to foresee their therapeutic potential as anxiolytics, nootropics, and analgesics.

DOES hemopressin bind metal ions in vivo?

Hemopressin is a neuropeptide, derived from the degradation of the α(1)-chain of hemoglobin, and possesses several pharmacologic properties, such as the ability to block cannabinoid CB1 receptor activity, to cause dose-dependent hypotension and to inhibit food intake. Actually, human hemopressin (PVNFKLLSH) is only the precursor of a class of longer peptides, called "Pepcans", which bear additional residues at their amino-terminus and possess slightly different chemical and biological properties with respect to hemopressin. The presence of a histidyl residue and the free terminal amine imparts to hemopressin and its derivatives good binding properties towards transition metal ions. In this paper, we present a wide investigation on the complex-formation equilibria of human hemopressin and three analogues towards the Cu(ii) and Ni(ii) ions. The study showed that the main coordination site is always the amino terminus (if not protected), while the C-terminal histidine acts only as an anchoring site for the metal ions at acidic pH, with the formation of a macrochelate complex. The presence of additional residues in N-terminal position produces significant differences in the protonation and complex-formation behaviors of these peptides, which can be explained in terms of charge of the ligand and coordination environment. Although the participation of metal ions in the biological activity of hemopressin and Pepcans has not yet been demonstrated, the data reported here can help to shed light on the mechanisms governing the action of these neuropeptides in vivo.

Design, Synthesis, and Biological Characterization of Novel Mitochondria Targeted Dichloroacetate-Loaded Compounds with Antileukemic Activity.

The mitochondrial kinase inhibitor dichloroacetate (DCA) has recently received attention in oncology due to its ability to target glycolysis. However, DCA molecule exhibits poor bioavailability and cellular uptake with limited ability to reach its target mitochondria. To overcome these biases, we have synthesized novel DCA-loaded compounds. The selection of the most promising therapeutic molecule was evaluated by combining in vitro assays, to test the antitumoral potential on leukemic cells, and a preliminary characterization of the molecule stability in vivo, in mice. Among the newly synthesized compounds, we have selected the multiple DCA-loaded compound 10, characterized by a tertiary amine scaffold, because it exhibited enhanced (>30-fold) in vitro antitumor activity with respect to DCA and increased in vivo stability. On the basis of these results, we believe that compound 10 should be considered for further preclinical evaluations for the treatment of cancers and/or other diseases characterized by altered metabolic origin.

Bv8/prokineticin 2 is involved in Aß-induced neurotoxicity.

Bv8/Prokineticin 2 (PROK2) is a bioactive peptide initially discovered as a regulator of gastrointestinal motility. Among multiple biological roles demonstrated for PROK2, it was recently established that PROK2 is an insult-inducible endangering mediator for cerebral damage. Aim of the present study was to evaluate the PROK2 and its receptors' potential involvement in amyloid beta (Aß) neurotoxicity, a hallmark of Alzheimer's disease (AD) and various forms of traumatic brain injury (TBI). Analyzing primary cortical cultures (CNs) and cortex and hippocampus from Aß treated rats, we found that PROK2 and its receptors PKR1 and PKR2 mRNA are up-regulated by Aß, suggesting their potential involvement in AD. Hence we evaluated if impairing the prokineticin system activation might have protective effect against neuronal death induced by Aß. We found that a PKR antagonist concentration-dependently protects CNs against Aß(1-42)-induced neurotoxicity, by reducing the Aß-induced PROK2 neuronal up-regulation. Moreover, the antagonist completely rescued LTP impairment in hippocampal slices from 6 month-old Tg2576 AD mice without affecting basal synaptic transmission and paired pulse-facilitation paradigms. These results indicate that PROK2 plays a role in cerebral amyloidosis and that PROK2 antagonists may represent a new approach for ameliorating the defining pathology of AD.

Critical role for prokineticin 2 in CNS autoimmunity.

OBJECTIVE: To investigate the potential role of prokineticin 2 (PK2), a bioactive peptide involved in multiple biological functions including immune modulation, in CNS autoimmune demyelinating disease. METHODS: We investigated the expression of PK2 in mice with experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS), and in patients with relapsing-remitting MS. We evaluated the biological effects of PK2 on expression of EAE and on development of T-cell response against myelin by blocking PK2 in vivo with PK2 receptor antagonists. We treated with PK2 immune cells activated against myelin antigen to explore the immune-modulating effects of this peptide in vitro. RESULTS: Pk2 messenger RNA was upregulated in spinal cord and lymph node cells (LNCs) of mice with EAE. PK2 protein was expressed in EAE inflammatory infiltrates and was increased in sera during EAE. In patients with relapsing-remitting MS, transcripts for PK2 were significantly increased in peripheral blood mononuclear cells compared with healthy controls, and PK2 serum concentrations were significantly higher. A PK2 receptor antagonist prevented or attenuated established EAE in chronic and relapsing-remitting models, reduced CNS inflammation and demyelination, and decreased the production of interferon (IFN)-γ and interleukin (IL)-17A cytokines in LNCs while increasing IL-10. PK2 in vitro increased IFN-γ and IL-17A and reduced IL-10 in splenocytes activated against myelin antigen. CONCLUSION: These data suggest that PK2 is a critical immune regulator in CNS autoimmune demyelination and may represent a new target for therapy.

In vitro and in vivo pharmacological characterization of a neuropeptide S tetrabranched derivative.

The peptide welding technology (PWT) is a novel chemical strategy that allows the synthesis of multibranched peptides with high yield, purity, and reproducibility. With this approach, a tetrabranched derivative of neuropeptide S (NPS) has been synthesized and pharmacologically characterized. The in vitro activity of PWT1-NPS has been studied in a calcium mobilization assay. In vivo, PWT1-NPS has been investigated in the locomotor activity (LA) and recovery of the righting reflex (RR) tests. In calcium mobilization studies, PWT1-NPS behaved as full agonist at the mouse NPS receptor (NPSR) being threefold more potent than NPS. The selective NPSR antagonists [ (t) Bu-D-Gly(5)]NPS and SHA 68 displayed similar potency values against NPS and PWT1-NPS. In vivo, both NPS (1-100 pmol, i.c.v.) and PWT1-NPS (0.1-100 pmol, i.c.v.) stimulated mouse LA, with PWT1-NPS showing higher potency than NPS. In the RR assay, NPS (100 pmol, i.c.v.) was able to reduce the percentage of mice losing the RR after diazepam administration and their sleep time 5 min after the i.c.v. injection, but it was totally inactive 2 h after the injection. On the contrary, PWT1-NPS (30 pmol, i.c.v.), injected 2 h before diazepam, displayed wake-promoting effects. This PWT1-NPS stimulant effect was no longer evident in mice lacking the NPSR receptor. The PWT1 technology can be successfully applied to the NPS sequence. PWT1-NPS displayed in vitro a pharmacological profile similar to NPS. In vivo PWT1-NPS mimicked NPS effects showing higher potency and long-lasting action.

Structure activity studies of nociceptin/orphanin FQ(1-13)-NH2 derivatives modified in position 5.

Nociceptin/orphanin FQ (N/OFQ) is a heptadecapeptide acting as the endogenous ligand of the N/OFQ peptide receptor (NOP). N/OFQ(1-13)-NH2 is the shortest N/OFQ sequence maintaining the same potency and efficacy as the natural peptide. Thus N/OFQ(1-13)-NH2 was used as chemical template for investigating the structure activity relationship of threonine in position 5. 28 [X(5)]N/OFQ(1-13)-NH2 derivatives, in which Thr was substituted with natural and unnatural residues, were synthesized and characterized pharmacologically for their effects at the human NOP receptor. Two different functional assays were used: agonist stimulated [(35)S]GTPγS binding in cell membranes and calcium mobilization in whole cells co-expressing chimeric G proteins. All [X(5)]N/OFQ(1-13)-NH2 derivatives behaved as full NOP agonists showing large differences in their potency. There was an excellent correlation between the results obtained in the two assays. The results of this study suggest that: position 5 does not play a pivotal role in receptor activation; the secondary alcoholic function of Thr is not important for receptor binding; side chain size, lipo/hydrophilic balance as well as hydrogen bond capability are also not crucial for receptor binding; an aliphatic amino function positively charged with at least 3 carbon atom distance from the peptide backbone has a huge disrupting effect on receptor binding. In conclusion this study demonstrates that a simple ethyl side chain as in compound 23 is sufficient in N/OFQ position 5 for maintaining bioactivity.

Prokineticin 2 upregulation in the peripheral nervous system has a major role in triggering and maintaining neuropathic pain in the chronic constriction injury model.

The new chemokine Prokineticin 2 (PROK2) and its receptors (PKR1 and PKR2) have a role in inflammatory pain and immunomodulation. Here we identified PROK2 as a critical mediator of neuropathic pain in the chronic constriction injury (CCI) of the sciatic nerve in mice and demonstrated that blocking the prokineticin receptors with two PKR1-preferring antagonists (PC1 and PC7) reduces pain and nerve damage. PROK2 mRNA expression was upregulated in the injured nerve since day 3 post injury (dpi) and in the ipsilateral DRG since 6 dpi. PROK2 protein overexpression was evident in Schwann Cells, infiltrating macrophages and axons in the peripheral nerve and in the neuronal bodies and some satellite cells in the DRG. Therapeutic treatment of neuropathic mice with the PKR-antagonist, PC1, impaired the PROK2 upregulation and signalling. This fact, besides alleviating pain, brought down the burden of proinflammatory cytokines in the damaged nerve and prompted an anti-inflammatory repair program. Such a treatment also reduced intraneural oedema and axon degeneration as demonstrated by the physiological skin innervation and thickness conserved in CCI-PC1 mice. These findings suggest that PROK2 plays a crucial role in neuropathic pain and might represent a novel target of treatment for this disease.

A novel and facile synthesis of tetra branched derivatives of nociceptin/orphanin FQ.

Branched peptides have been found to be useful in several research fields however their synthesis and purification is complicated. Here we present a novel and facile synthesis of tetra branched derivatives of nociceptin/orphanin FQ (N/OFQ). Three N/OFQ tetra branched derivatives were prepared using novel cores (PWT1, PWT2 and PWT3) containing a maleimido moiety. [Cys(18)]N/OFQ-NH2 was linked to the cores via thiol-Michael reaction characterized by high yield and purity of the desired final product. In the electrically stimulated mouse vas deferens PWT-N/OFQ derivatives mimicked the inhibitory action of the natural sequence showing similar maximal effects and 3 fold higher potencies. The NOP selective antagonist SB-612111 antagonized the effects of N/OFQ and PWT derivatives with similar pKB values (8.02-8.48). In vivo after supraspinal administration PWT2-N/OFQ stimulated food intake in mice mimicking the action of N/OFQ. Compared to the natural peptide PWT2-N/OFQ was 40 fold more potent and elicited larger effects. These findings suggest that the PWT chemical strategy can be successfully applied to biologically active peptides to generate, with unprecedented high purity and yield, tetra branched derivatives displaying an in vitro pharmacological profile similar to that of the natural sequence associated, in vivo, to increased potency and effectiveness.

A new convenient synthetic method and preliminary pharmacological characterization of triazinediones as prokineticin receptor antagonists.

A new efficient synthetic method to obtain prokineticin receptor antagonists based on the triazinedione scaffold is described. In this procedure the overall yield improves from 13% to about 54%, essentially for two factors: 1) N-(chlorocarbonyl) isocyanate is no more used, it represents the yield limiting step with an average yield not exceeding 30%. 2) The Mitsunobu reaction is not involved in the new synthetic scheme avoiding the use of time and solvent consuming column chromatography. All synthesized triazinediones were preliminary pharmacologically screened in vivo for their ability to reduce the Bv8-induced thermal hyperalgesia. In this assay all compounds displayed EC50 values in the picomolar-subpicomolar range, some triazinediones containing a 4-halogen substituted benzyl group in position 5 showed the best activity. The analogues containing a 4-fluorine atom (PC-7) and a 4-bromobenzyl group (PC-25) resulted 10 times more potent than the reference PC-1 that bears a 4-ethylbenzyl group. While the 4-trifluoromethylbenzyl substituted analog (PC-27) was 100 times more potent as compared to PC1.

N-carbamidoyl-4-((3-ethyl-2,4,4-trimethylcyclohexyl)methyl)benzamide enhances staurosporine cytotoxic effects likely inhibiting the protective action of Magmas toward cell apoptosis.

We recently demonstrated that Magmas overexpression protects GH-secreting rat pitutitary adenoma cell lines from apoptosis by inhibiting cytochrome c release from mitochondria after treatment with staurosporine, strongly suggesting a role of Magmas in preventing apoptosis. The aim of this study was to produce a drug that, by inhibiting Tim16, may sensitize chemoresistant tumor cell to proapoptotic stimuli. We synthesized six compounds and challenged their sensitizing effects toward the proapoptotic effects of staurosporine in the TT cell line, derived from a human medullary thyroid carcinoma. We found that compound 5, devoid of the planarity in the aliphatic part of the lead 1, is not cytotoxic but enhances the proapoptotic effects of staurosporine by reducing MMP activation. Compound 5 may be useful for cancer treatment in association with chemotherapeutic drugs, possibly allowing a reduction of the chemotherapeutic agent effective dose.

Optimization of peptides that target human thymidylate synthase to inhibit ovarian cancer cell growth.

Thymidylate synthase (TS) is a target for pemetrexed and the prodrug 5-fluorouracil (5-FU) that inhibit the protein by binding at its active site. Prolonged administration of these drugs causes TS overexpression, leading to drug resistance. The peptide lead, LR (LSCQLYQR), allosterically stabilizes the inactive form of the protein and inhibits ovarian cancer (OC) cell growth with stable TS and decreased dihydrofolate reductase (DHFR) expression. To improve TS inhibition and the anticancer effect, we have developed 35 peptides by modifying the lead. The d-glutamine-modified peptide displayed the best inhibition of cisplatin-sensitive and -resistant OC cell growth, was more active than LR and 5-FU, and showed a TS/DHFR expression pattern similar to LR. Circular dichroism spectroscopy and molecular dynamics studies provided a molecular-level rationale for the differences in structural preferences and the enzyme inhibitory activities. By combining target inhibition studies and the modulation pattern of associated proteins, this work avenues a concept to develop more specific inhibitors of OC cell growth and drug leads.

Effect of δ-opioid receptor activation on BDNF-TrkB vs. TNF-α in the mouse cortex exposed to prolonged hypoxia.

We investigated whether δ-opioid receptor (DOR)-induced neuroprotection involves the brain-derived neurotrophic factor (BDNF) pathway. We studied the effect of DOR activation on the expression of BDNF and other proteins in the cortex of C57BL/6 mice exposed to hypoxia (10% of oxygen) for 1-10 days. The results showed that: (1) 1-day hypoxia had no appreciable effect on BDNF expression, while 3- and 10-day hypoxia progressively decreased BDNF expression, resulting in 37.3% reduction (p < 0.05) after 10-day exposure; (2) DOR activation with UFP-512 (1 mg/kg, i.p., daily) partially reversed the hypoxia-induced reduction of BDNF expression in the 3- or 10-day exposed cortex; (3) DOR activation partially reversed the hypoxia-induced reduction in functional TrkB (140-kDa) and attenuated hypoxia-induced increase in truncated TrkB (90-kDa) in the 3- or 10-day hypoxic cortex; and (4) prolonged hypoxia (10 days) significantly increased TNF-α level and decreased CD11b expression in the cortex, which was completely reversed following DOR activation; and (5) there was no significant change in pCREB and pATF-1 levels in the hypoxic cortex. We conclude that prolonged hypoxia down-regulates BDNF-TrkB signaling leading to an increase in TNF-α in the cortex, while DOR activation up-regulates BDNF-TrkB signaling thereby decreasing TNF-α levels in the hypoxic cortex.

δ-Opioid receptor activation modified microRNA expression in the rat kidney under prolonged hypoxia.

Hypoxic/ischemic injury to kidney is a frequently encountered clinical problem with limited therapeutic options. Since microRNAs are differentially involved in hypoxic/ischemic events and δ-opioid receptor (DOR) activation is known to protect against hypoxic/ischemic injury, we speculated on the involvement of DOR activation in altering the microRNA (miRNA) expression in kidney under hypoxic condition. We selected 31 miRNAs based on microarray data for quantitative PCR analysis. Among them, 14 miRNAs were significantly altered after prolonged hypoxia, DOR activation or a combination of both. We found that 1) DOR activation alters miRNA expression profiles in normoxic conditions; 2) hypoxia differentially alters miRNA expression depending on the duration of hypoxia; and 3) DOR activation can modify hypoxia-induced changes in miRNA expression. For example, 10-day hypoxia reduced the level of miR-212 by over 70%, while DOR activation could mimic such reduction even in normoxic kidney. In contrast, the same stress increased miR-29a by >100%, which was reversed following DOR activation. These first data suggest that hypoxia comprehensively modifies the miRNA profile within the kidney, which can be mimicked or modified by DOR activation. Ascertaining the targeted pathways that regulate the diverse cellular and molecular functions of miRNA may provide new insights into potential therapies for hypoxic/ischemic injury of the kidney.

Synthesis, pharmacological evaluation and conformational investigation of endomorphin-2 hybrid analogues.

This study reports on new pharmacologically active endomorphin-2 analogues, incorporating ß(2)-hPhe, ß(3)-hPhe and ß(3)-hTic unnatural amino acids in the place of the Phe(3)-Phe(4)residues. Such α, ß-hybrid analogues were designed to exploit the great potential of ß-amino acids in generating conformational variation at the key positions 3 and 4, with the aim of evaluating the effect on the opioid binding affinity. Ligand-stimulated binding assays indicated that some analogues retained a significant affinity, especially for the δ receptor. (1)H NMR and molecular modelling suggested the predominance of bent structures for all compounds. The molecular docking with the µ-opioid receptor model was also performed, highlighting a common binding mode for active compounds and helping to rationalize the observed structure-activity data.

Structural and biological exploration of phe(3)-phe(4)-modified endomorphin-2 peptidomimetics.

This study reports on our ongoing investigation on hybrid EM-2 analogues, in which the great potential of ß-amino acids was exploited to generate multiple conformational modifications at the key positions 3 and 4 of the parent peptide. The effect on the opioid binding affinity was evaluated, by means of ligand stimulated binding assays, which indicated a high nanomolar affinity toward the µ-receptor, with appreciable µ/δ selectivity, for some of the new compounds. The three-dimensional properties of the high affinity µ opioid receptor (MOR) ligands were investigated by proton nuclear magnetic resonance, molecular dynamics, and docking studies. In solution, the structures showed extended conformations, which are in agreement with the commonly accepted pharmacophore model for EM-2. From docking studies on an active form of the MOR model, different ligand-receptor interactions have been identified, thus confirming the ability of active compounds to assume a biologically active conformation.