Sigma receptor and aquaporin modulators: chiral resolution, configurational assignment, and preliminary biological profile of RC752 enantiomers.

The key role of chiral small molecules in drug discovery programs has been deeply investigated throughout last decades. In this context, our previous studies highlighted the influence of the absolute configuration of different stereocenters on the pharmacokinetic, pharmacodynamic and functional properties of promising Sigma receptor (SR) modulators. Thus, starting from the racemic SR ligand RC752, we report herein the isolation of the enantiomers via enantioselective separation with both HPLC and SFC. After optimization of the eco-sustainable chiral SFC method, both enantiomers were obtained in sufficient amount (tens of mg) and purity (ee up to 95%) to allow their characterization and initial biological investigation. Both enantiomers a) displayed a high affinity for the S1R subtype (Ki = 15.0 ± 1.7 and 6.0 ± 1.2 nM for the (S)- and (R)-enantiomer, respectively), but only negligible affinity toward the S2R (> 350 nM), and b) were rapidly metabolized when incubated with mouse and human hepatic microsomes. Furthermore, the activity on AQP-mediated water permeability indicated a different functional profile for the enantiomers in terms of modulatory effect on the peroxiporins gating.

Discovery of RC-752, a Novel Sigma-1 Receptor Antagonist with Antinociceptive Activity: A Promising Tool for Fighting Neuropathic Pain.

Neuropathic pain (NP) is a chronic condition resulting from damaged pain-signaling pathways. It is a debilitating disorder that affects up to 10% of the world's population. Although opioid analgesics are effective in reducing pain, they present severe risks; so, there is a pressing need for non-opioid pain-relieving drugs. One potential alternative is represented by sigma-1 receptor (S1R) antagonists due to their promising analgesic effects. Here, we report the synthesis and biological evaluation of a series of S1R antagonists based on a 2-aryl-4-aminobutanol scaffold. After assessing affinity toward the S1R and selectivity over the sigma-2 receptor (S2R), we evaluated the agonist/antagonist profile of the compounds by investigating their effects on nerve growth factor-induced neurite outgrowth and aquaporin-mediated water permeability in the presence and absence of oxidative stress. (R/S)-RC-752 emerged as the most interesting compound for S1R affinity (Ki S1R = 6.2 ± 0.9) and functional antagonist activity. Furthermore, it showed no cytotoxic effect in two normal human cell lines or in an in vivo zebrafish model and was stable after incubation in mouse plasma. (R/S)-RC-752 was then evaluated in two animal models of NP: the formalin test and the spinal nerve ligation model. The results clearly demonstrated that compound (R/S)-RC-752 effectively alleviated pain in both animal models, thus providing the proof of concept of its efficacy as an antinociceptive agent.

Novel N-(Heterocyclylphenyl)benzensulfonamide Sharing an Unreported Binding Site with T-Cell Factor 4 at the ß-Catenin Armadillo Repeats Domain as an Anticancer Agent.

Despite intensive efforts, no inhibitors of the Wnt/ß-catenin signaling pathway have been approved so far for the clinical treatment of cancer. We synthesized novel N-(heterocyclylphenyl)benzenesulfonamides as ß-catenin inhibitors. Compounds 5-10 showed strong inhibition of the luciferase activity. Compounds 5 and 6 inhibited the MDA-MB-231, HCC1806, and HCC1937 TNBC cells. Compound 9 induced in vitro cell death in SW480 and HCT116 cells and in vivo tumorigenicity of a human colorectal cancer line HCT116. In a co-immunoprecipitation study in HCT116 cells transfected with Myc-tagged T-cell factor 4 (Tcf-4), compound 9 abrogated the association between ß-catenin and Tcf-4. The crystallographic analysis of the ß-catenin Armadillo repeats domain revealed that compound 9 and Tcf-4 share a common binding site within the hotspot binding region close to Lys508. To our knowledge, compound 9 is the first small molecule ligand of this region to be reported. These results highlight the potential of this novel class of ß-catenin inhibitors as anticancer agents.

Favorable Preclinical Pharmacological Profile of a Novel Antimalarial Pyrrolizidinylmethyl Derivative of 4-amino-7-chloroquinoline with Potent In Vitro and In Vivo Activities.

The 4-aminoquinoline drugs, such as chloroquine (CQ), amodiaquine or piperaquine, are still commonly used for malaria treatment, either alone (CQ) or in combination with artemisinin derivatives. We previously described the excellent in vitro activity of a novel pyrrolizidinylmethyl derivative of 4-amino-7-chloroquinoline, named MG3, against P. falciparum drug-resistant parasites. Here, we report the optimized and safer synthesis of MG3, now suitable for a scale-up, and its additional in vitro and in vivo characterization. MG3 is active against a panel of P. vivax and P. falciparum field isolates, either alone or in combination with artemisinin derivatives. In vivo MG3 is orally active in the P. berghei, P. chabaudi, and P. yoelii models of rodent malaria with efficacy comparable, or better, than that of CQ and of other quinolines under development. The in vivo and in vitro ADME-Tox studies indicate that MG3 possesses a very good pre-clinical developability profile associated with an excellent oral bioavailability, and low toxicity in non-formal preclinical studies on rats, dogs, and non-human primates (NHP). In conclusion, the pharmacological profile of MG3 is in line with those obtained with CQ or the other quinolines in use and seems to possess all the requirements for a developmental candidate.

Targeting the Grb2 cSH3 domain: Design, synthesis and biological evaluation of the first series of modulators.

Growth factor receptor bound protein 2 (Grb2) is an adaptor protein featured by a nSH3-SH2-cSH3 domains. Grb2 finely regulates important cellular pathways such as growth, proliferation and metabolism and a minor lapse of this tight control may totally change the entire pathway to the oncogenic. Indeed, Grb2 is found overexpressed in many tumours type. Consequently, Grb2 is an attractive therapeutic target for the development of new anticancer drug. Herein, we reported the synthesis and the biological evaluation of a series of Grb2 inhibitors, developed starting from a hit-compound already reported by this research unit. The newly synthesized compounds were evaluated by kinetic binding experiments, and the most promising derivatives were assayed in a short panel of cancer cells. Five of the newly synthesized derivatives proved to be able to bind the targeted protein with valuable inhibitory concentration in one-digit micromolar concentration. The most active compound of this series, derivative 12, showed an inhibitory concentration of about 6 µM for glioblastoma and ovarian cancer cells, and an IC50 of 1.67 for lung cancer cell. For derivative 12, the metabolic stability and the ROS production was also evaluated. The biological data together with the docking studies led to rationalize an early structure activity relationship.

Novel Aryl Sulfonamide Derivatives as NLRP3 Inflammasome Inhibitors for the Potential Treatment of Cancer.

The NLRP3 inflammasome is a critical component of innate immunity that senses diverse pathogen- and host-derived molecules. However, its aberrant activation has been associated with the pathogenesis of multiple diseases, including cancer. In this study, we designed and synthesized a series of aryl sulfonamide derivatives (ASDs) to inhibit the NLRP3 inflammasome. Among these, compounds 6c, 7n, and 10 specifically inhibited NLRP3 activation at nanomolar concentrations without affecting the activation of the NLRC4 and AIM2 inflammasomes. Furthermore, we demonstrated that these compounds reduce interleukin-1ß (IL-1ß) production in vivo and attenuate melanoma tumor growth. Moreover, metabolic stability in liver microsomes of 6c, 7n, and 10 was studied along with plasma exposure in mice of the most interesting compound 6c. Therefore, we generated potent NLRP3 inflammasome inhibitors, which can be considered in future medicinal chemistry and pharmacological studies aimed at developing a new therapeutic approach for NLRP3 inflammasome-driven cancer.

Novel S1R agonists counteracting NMDA excitotoxicity and oxidative stress: A step forward in the discovery of neuroprotective agents.

Sigma-1 receptor (S1R) has been considered a promising therapeutic target for several neurodegenerative diseases and S1R agonists have shown neuroprotective activity against glutamate excitotoxicity and oxidative stress. Starting from a previously identified low nanomolar S1R agonist, in this work we prepared and tested novel benzylpiperidine/benzylpiperazine-based compounds designed by applying a ring opening strategy. Among them, 4-benzyl-1-(2-phenoxyethyl)piperidine 6b (S1R Ki = 0.93 nM) and 4-benzyl-1-(3-phenoxypropyl)piperidine 8b (S1R Ki = 1.1 nM) emerged as high affinity S1R ligands and showed selectivity over S2R and N-methyl-d-aspartate receptor (NMDAR). Candidate compounds behaved as potent S1R agonists being able to enhance the neurite outgrowth induced by nerve growth factor (NGF) in PC12 cell lines. In SH-SY5Y neuroblastoma cell lines they exhibited a neuroprotective effect against rotenone- and NMDA-mediated toxic insults. The neuroprotective activity of 6b and 8b was reverted by co-treatment with an S1R antagonist, PB212. Compounds 6b and 8b were tested for cytotoxicity in-vitro against three human cancer cell lines (A549, LoVo and Panc-1) and in-vivo zebrafish model, resulting in a good efficacy/safety profile, comparable or superior to the reference drug memantine. Overall, these results encourage further preclinical investigations of 6b and 8b on in-vivo models of neurodegenerative diseases.

RS6077 induces mitotic arrest and selectively activates cell death in human cancer cell lines and in a lymphoma tumor in vivo.

We synthesized a new inhibitor of tubulin polymerization, the pyrrole (1-(7H-pyrrolo[2,3- d]pyrimidin-4-yl)-1H-pyrrol-3-yl)(3,4,5-trimethoxy-phenyl)methanone 6 (RS6077). Compound 6 inhibited the growth of multiple cancer cell lines, with IC50 values in the nM range, without affecting the growth of non-transformed cells. The novel agent arrested cells in the G2/M phase of the cell cycle in both transformed and non-transformed cell lines, but single cell analysis by time-lapse video recording revealed a remarkable selectivity in cell death induction by compound 6: in RPE-1 non-transformed cells mitotic arrest induced was not necessarily followed by cell death; in contrast, in HeLa transformed and in lymphoid-derived transformed AHH1 cell lines, cell death was effectively induced during mitotic arrest in cells that fail to complete mitosis. Importantly, the agent also inhibited the growth of the lymphoma TMD8 xenograft model. Together these findings suggest that derivative 6 has a selective efficacy in transformed vs non-transformed cells and indicate that the same compound has potential as novel therapeutic agent to treat lymphomas. Compound 6 showed good metabolic stability upon incubation with human liver microsomes.

Induction of Ferroptosis in Glioblastoma and Ovarian Cancers by a New Pyrrole Tubulin Assembly Inhibitor.

We synthesized new aroyl diheterocyclic pyrrole (ARDHEP) 15 that exhibited the hallmarks of ferroptosis. Compound 15 strongly inhibited U-87 MG, OVCAR-3, and MCF-7 cancer cells, induced an increase of cleaved PARP, but was not toxic for normal human primary T lymphocytes at 0.1 µM. Analysis of the levels of lactoperoxidase, malondialdehyde, lactic acid, total glutathione, and ATP suggested that the in vivo inhibition of cancer cell proliferation by 15 went through stimulation of oxidative stress injury and Fe2+ accumulation. Quantitative polymerase chain reaction analysis of the mRNA expression in U-87 MG and SKOV-3 tumor tissues from 15-treated mice showed the presence of Ptgs2/Nfe2l2/Sat1/Akr1c1/Gpx4 genes correlated with ferroptosis in both groups. Immunofluorescence staining revealed significantly lower expressions of proteins Ki67, CD31, and ferroptosis negative regulation proteins glutathione peroxidase 4 (GPX4) and FTH1. Compound 15 was found to be metabolically stable when incubated with human liver microsomes.

Novel analgesic/anti-inflammatory agents: 1,5-Diarylpyrrole nitrooxyethyl sulfides and related compounds as Cyclooxygenase-2 inhibitors containing a nitric oxide donor moiety endowed with vasorelaxant properties.

The design of compounds able to combine the selective inhibition of cyclooxygenase-2 (COX-2) with the release of nitric oxide (NO) is a promising strategy to achieve potent anti-inflammatory agents endowed with an overall safer profile and reduced toxicity upon gastrointestinal and cardiovascular systems. With the aim of generating novel and selective COX-2 inhibiting NO-donors (CINOD) and encouraged by the promising results obtained with our nitrooxy- and hydroxyethyl ethers 11 and 12 reported in previous works, we shifted our attention on the synthesis of isosteric thioanalogs nitrooxy- and hydroxy ethyl sulfides 13a-c and 14a-c, respectively, along with their oxidation products nitrooxy- and hydroxyethyl sulfoxides 15a-c and 16a-c, respectively, also referred to as thio-CINOD. Preliminary data and metabolic analysis highlighted how the isosteric substitution of the ethereal oxygen atom of 11a-c with sulfur in compounds 13a-c, independently from the presence and the number of fluorine atoms in N1-phenyl ring, leads to new selective and highly potent COX-2 inhibitors, capable to induce vasorelaxant responses in vivo. The same behavior is observed with their oxidized counterparts nitrooxyethyl sulfoxides 15a-c, in which the oxidation state of the sulfur atom and the presence of the additional oxygen atom play a substantial role in enhancing compounds activity and vasorelaxation. In addition, the screened compounds proved significantly efficacious in mouse models of inflammation and nociception at the dose of 20 mg/kg.

Givinostat-Liposomes: Anti-Tumor Effect on 2D and 3D Glioblastoma Models and Pharmacokinetics.

Glioblastoma is the most common and aggressive brain tumor, associated with poor prognosis and survival, representing a challenging medical issue for neurooncologists. Dysregulation of histone-modifying enzymes (HDACs) is commonly identified in many tumors and has been linked to cancer proliferation, changes in metabolism, and drug resistance. These findings led to the development of HDAC inhibitors, which are limited by their narrow therapeutic index. In this work, we provide the proof of concept for a delivery system that can improve the in vivo half-life and increase the brain delivery of Givinostat, a pan-HDAC inhibitor. Here, 150-nm-sized liposomes composed of cholesterol and sphingomyelin with or without surface decoration with mApoE peptide, inhibited human glioblastoma cell growth in 2D and 3D models by inducing a time- and dose-dependent reduction in cell viability, reduction in the receptors involved in cholesterol metabolism (from -25% to -75% of protein levels), and reduction in HDAC activity (-25% within 30 min). In addition, liposome-Givinostat formulations showed a 2.5-fold increase in the drug half-life in the bloodstream and a 6-fold increase in the amount of drug entering the brain in healthy mice, without any signs of overt toxicity. These features make liposomes loaded with Givinostat valuable as potential candidates for glioblastoma therapy.

Discovery of Reversible Inhibitors of KDM1A Efficacious in Acute Myeloid Leukemia Models.

Lysine-specific demethylase 1 (LSD1 or KDM1A) is a FAD-dependent enzyme that acts as a transcription corepressor or coactivator by regulating the methylation status of histone H3 lysines K4 and K9, respectively. KDM1A represents an attractive target for cancer therapy. While, in the past, the main medicinal chemistry strategy toward KDM1A inhibition was based on the optimization of ligands that irreversibly bind the FAD cofactor within the enzyme catalytic site, we and others have also identified reversible inhibitors. Herein we reported the discovery of 5-imidazolylthieno[3,2-b]pyrroles, a new series of KDM1A inhibitors endowed with picomolar inhibitory potency, active in cells and efficacious after oral administration in murine leukemia models.

Anti-tumor Efficacy Assessment of the Sigma Receptor Pan Modulator RC-106. A Promising Therapeutic Tool for Pancreatic Cancer.

Introduction: Pancreatic cancer (PC) is one of the most lethal tumor worldwide, with no prognosis improvement over the past 20-years. The silent progressive nature of this neoplasia hampers the early diagnosis, and the surgical resection of the tumor, thus chemotherapy remains the only available therapeutic option. Sigma receptors (SRs) are a class of receptors proposed as new cancer therapeutic targets due to their over-expression in tumor cells and their involvement in cancer biology. The main localization of these receptors strongly suggests their potential role in ER unfolded protein response (ER-UPR), a condition frequently occurring in several pathological settings, including cancer. Our group has recently identified RC-106, a novel pan-SR modulator with good in vitro antiproliferative activities toward a panel of different cancer cell lines. In the present study, we investigated the in vitro properties and pharmacological profile of RC-106 in PC cell lines with the aim to identify a potential lead candidate for the treatment of this tumor. Methods: Pancreatic cancer cell lines Panc-1, Capan-1, and Capan-2 have been used in all experiments. S1R and TMEM97/S2R expression in PC cell lines was quantified by Real-Time qRT-PCR and Western Blot experiments. MTS assay was used to assess the antiproliferative effect of RC-106. The apoptotic properties of RC-106 was evaluated by TUNEL and caspase activation assays. GRP78/BiP, ATF4, and CHOP was quantified to evaluate ER-UPR. Proteasome activity was investigated by a specific fluorescent-based assay. Scratch wound healing assay was used to asses RC-106 effect on cell migration. In addition, we delineated the in vivo pharmacokinetic profile and pancreas distribution of RC-106 in male CD-1 mice. Results: Panc-1, Capan-1, and Capan-2 express both SRs. RC-106 exerts an antiproliferative and pro-apoptotic effect in all examined cell lines. Cells exposure to RC-106 induces the increase of the expression of ER-UPR related proteins, and the inhibition of proteasome activity. Moreover, RC-106 is able to decrease PC cell lines motility. The in vivo results show that RC-106 is more concentrated in pancreas than plasma. Conclusion: Overall, our data evidenced that the pan-SR modulator RC-106 is an optimal candidate for in vivo studies in animal models of PC.

New 6- and 7-heterocyclyl-1H-indole derivatives as potent tubulin assembly and cancer cell growth inhibitors.

We designed new 3-arylthio- and 3-aroyl-1H-indole derivatives 3-22 bearing a heterocyclic ring at position 5, 6 or 7 of the indole nucleus. The 6- and 7-heterocyclyl-1H-indoles showed potent inhibition of tubulin polymerization, binding of colchicine to tubulin and growth of MCF-7 cancer cells. Compounds 13 and 19 inhibited a panel of cancer cells and the NCI/ADR-RES multidrug resistant cell line at low nanomolar concentrations. Compound 13 at 50 nM induced 77% G2/M in HeLa cells, and at 20 nM caused 50% stable arrest of mitosis. As an inhibitor of HepG2 cells (IC50 = 20 nM), 13 was 4-fold superior to 19. Compound 13 was a potent inhibitor of the human U87MG glioblastoma cells at nanomolar concentrations, being nearly one order of magnitude superior to previously reported arylthioindoles. The present results highlight 13 as a robust scaffold for the design of new anticancer agents.

In vivo and in vitro ADMET profiling and in vivo pharmacodynamic investigations of a selective α7 nicotinic acetylcholine receptor agonist with a spirocyclic Δ2-isoxazoline molecular skeleton.

(±)-3-Methoxy-1-oxa-2,7-diaza-7,10-ethanospiro[4.5]dec-2-ene sesquifumarate (±)-1 was previously characterized as the most selective agonist at α7 neuronal nicotinic acetylcholine receptors in a series of spirocyclic quinuclidinyl-Δ2-isoxazoline derivatives. In this study, we performed different in vitro biological assays aimed at characterizing the ADMET properties of (±)-1. Then, we tested the compound in vivo in behavioral studies including classical novel object recognition and inhibitory avoidance tests in the rat, and a spatial memory assay in zebrafish involving a rapid T-maze task. The results indicated an overall favorable profile for (±)-1 in view of potential therapeutic applications targeting the central nervous system.

In Vivo and In Vitro Activities and ADME-Tox Profile of a Quinolizidine-Modified 4-Aminoquinoline: A Potent Anti-P. falciparum and Anti-P. vivax Blood-Stage Antimalarial.

Natural products are a prolific source for the identification of new biologically active compounds. In the present work, we studied the in vitro and in vivo antimalarial efficacy and ADME-Tox profile of a molecular hybrid (AM1) between 4-aminoquinoline and a quinolizidine moiety derived from lupinine (Lupinus luteus). The aim was to find a compound endowed with the target product profile-1 (TCP-1: molecules that clear asexual blood-stage parasitaemia), proposed by the Medicine for Malaria Venture to accomplish the goal of malaria elimination/eradication. AM1 displayed a very attractive profile in terms of both in vitro and in vivo activity. By using standard in vitro antimalarial assays, AM1 showed low nanomolar inhibitory activity against chloroquine-sensitive and resistant P. falciparum strains (range IC50 16-53 nM), matched with a high potency against P. vivax field isolates (Mean IC50 29 nM). Low toxicity and additivity with artemisinin derivatives were also demonstrated in vitro. High in vivo oral efficacy was observed in both P.berghei and P. yoelii mouse models with IC50 values comparable or better than those of chloroquine. The metabolic stability in different species and the pharmacokinetic profile in the mouse model makes AM1 a compound worth further investigation as a potential novel schizonticidal agent.

Toward the identification of neuroprotective agents: g-scale synthesis, pharmacokinetic evaluation and CNS distribution of (R)-RC-33, a promising SIGMA1 receptor agonist.

AIM: Nowadays, there is a great interest in the therapeutic potential of sigma1 receptor ligands for treating different CNS pathologies. Our previous investigations led to identify (R)-RC-33 as a potent and selective S1R agonist. RESULTS: Herein, we report the gram-scale synthesis, pharmacokinetic profile and CNS distribution of (R)-RC-33 in the mouse to determine the most suitable dosage schedule for in vivo administration. For comparative purposes, the same experiments were also performed with PRE-084, the most widely used S1R agonist commonly in pharmacological experiments. DISCUSSION: (R)-RC-33 shows a similar pharmacokinetic profile and a better CNS distribution when compared with PRE-084. CONCLUSION: (R)-RC-33 may be a promising candidate for in vivo studies in animal models of neurodegenerative diseases.

Synthesis, biological characterization and molecular modeling insights of spirochromanes as potent HDAC inhibitors.

In the last decades, inhibitors of histone deacetylases (HDAC) have become an important class of anti-cancer agents. In a previous study we described the synthesis of spiro[chromane-2,4'-piperidine]hydroxamic acid derivatives able to inhibit histone deacetylase enzymes. Herein, we present our exploration for new derivatives by replacing the piperidine moiety with various cycloamines. The goal was to obtain highly potent compounds with a good in vitro ADME profile. In addition, molecular modeling studies unravelled the binding mode of these inhibitors.

New Indole Tubulin Assembly Inhibitors Cause Stable Arrest of Mitotic Progression, Enhanced Stimulation of Natural Killer Cell Cytotoxic Activity, and Repression of Hedgehog-Dependent Cancer.

We designed 39 new 2-phenylindole derivatives as potential anticancer agents bearing the 3,4,5-trimethoxyphenyl moiety with a sulfur, ketone, or methylene bridging group at position 3 of the indole and with halogen or methoxy substituent(s) at positions 4-7. Compounds 33 and 44 strongly inhibited the growth of the P-glycoprotein-overexpressing multi-drug-resistant cell lines NCI/ADR-RES and Messa/Dx5. At 10 nM, 33 and 44 stimulated the cytotoxic activity of NK cells. At 20-50 nM, 33 and 44 arrested >80% of HeLa cells in the G2/M phase of the cell cycle, with stable arrest of mitotic progression. Cell cycle arrest was followed by cell death. Indoles 33, 44, and 81 showed strong inhibition of the SAG-induced Hedgehog signaling activation in NIH3T3 Shh-Light II cells with IC50 values of 19, 72, and 38 nM, respectively. Compounds of this class potently inhibited tubulin polymerization and cancer cell growth, including stimulation of natural killer cell cytotoxic activity and repression of Hedgehog-dependent cancer.

New pyrrole derivatives with potent tubulin polymerization inhibiting activity as anticancer agents including hedgehog-dependent cancer.

We synthesized 3-aroyl-1-arylpyrrole (ARAP) derivatives as potential anticancer agents having different substituents at the pendant 1-phenyl ring. Both the 1-phenyl ring and 3-(3,4,5-trimethoxyphenyl)carbonyl moieties were mandatory to achieve potent inhibition of tubulin polymerization, binding of colchicine to tubulin, and cancer cell growth. ARAP 22 showed strong inhibition of the P-glycoprotein-overexpressing NCI-ADR-RES and Messa/Dx5MDR cell lines. Compounds 22 and 27 suppressed in vitro the Hedgehog signaling pathway, strongly reducing luciferase activity in SAG treated NIH3T3 Shh-Light II cells, and inhibited the growth of medulloblastoma D283 cells at nanomolar concentrations. ARAPs 22 and 27 represent a new potent class of tubulin polymerization and cancer cell growth inhibitors with the potential to inhibit the Hedgehog signaling pathway.