Discovery of a Novel Chemo-Type for TAAR1 Agonism via Molecular Modeling.

The search for novel effective TAAR1 ligands continues to draw great attention due to the wide range of pharmacological applications related to TAAR1 targeting. Herein, molecular docking studies of known TAAR1 ligands, characterized by an oxazoline core, have been performed in order to identify novel promising chemo-types for the discovery of more active TAAR1 agonists. In particular, the oxazoline-based compound S18616 has been taken as a reference compound for the computational study, leading to the development of quite flat and conformationally locked ligands. The choice of a "Y-shape" conformation was suggested for the design of TAAR1 ligands, interacting with the protein cavity delimited by ASP103 and aromatic residues such as PHE186, PHE195, PHE268, and PHE267. The obtained results allowed us to preliminary in silico screen an in-house series of pyrimidinone-benzimidazoles (1a-10a) as a novel scaffold to target TAAR1. Combined ligand-based (LBCM) and structure based (SBCM) computational methods suggested the biological evaluation of compounds 1a-10a, leading to the identification of derivatives 1a-3a (hTAAR1 EC50 = 526.3-657.4 nM) as promising novel TAAR1 agonists.

Small Molecule Tyrosine Kinase Inhibitors (TKIs) for Glioblastoma Treatment.

In the last decade, many small molecules, usually characterized by heterocyclic scaffolds, have been designed and synthesized as tyrosine kinase inhibitors (TKIs). Among them, several compounds have been tested at preclinical and clinical levels to treat glioblastoma multiforme (GBM). GBM is the most common and aggressive type of cancer originating in the brain and has an unfavorable prognosis, with a median survival of 15-16 months and a 5-year survival rate of 5%. Despite recent advances in treating GBM, it represents an incurable disease associated with treatment resistance and high recurrence rates. For these reasons, there is an urgent need for the development of new pharmacological agents to fight this malignancy. In this review, we reported the compounds published in the last five years, which showed promising activity in GBM preclinical models acting as TKIs. We grouped the compounds based on the targeted kinase: first, we reported receptor TKIs and then, cytoplasmic and peculiar kinase inhibitors. For each small molecule, we included the chemical structure, and we schematized the interaction with the target for some representative compounds with the aim of elucidating the mechanism of action. Finally, we cited the most relevant clinical trials.

Anti-Survival Effect of SI306 and Its Derivatives on Human Glioblastoma Cells.

Glioblastoma (GBM) is the most common adult brain tumor and, although many efforts have been made to find valid therapies, the onset of resistance is the main cause of recurrence. Therefore, it is crucial to identify and target the molecular mediators responsible for GBM malignancy. In this context, the use of Src inhibitors such as SI306 (C1) and its prodrug (C2) showed promising results, suggesting that SI306 could be the lead compound useful to derivate new anti-GBM drugs. Therefore, a new prodrug of SI306 (C3) was synthesized and tested on CAS-1 and U87 human GBM cells by comparing its effect to that of C1 and C2. All compounds were more effective on CAS-1 than U87 cells, while C2 was the most active on both cell lines. Moreover, the anti-survival effect was associated with a reduction in the expression of epidermal growth factor receptor (EGFR)WT and EGFR-vIII in U87 and CAS-1 cells, respectively. Collectively, our findings demonstrate that all tested compounds are able to counteract GBM survival, further supporting the role of SI306 as progenitor of promising new drugs to treat malignant GBM.

Synthetic Heterocyclic Derivatives as Kinase Inhibitors Tested for the Treatment of Neuroblastoma.

In the last few years, small molecules endowed with different heterocyclic scaffolds have been developed as kinase inhibitors. Some of them are being tested at preclinical or clinical levels for the potential treatment of neuroblastoma (NB). This disease is the most common extracranial solid tumor in childhood and is responsible for 10% to 15% of pediatric cancer deaths. Despite the availability of some treatments, including the use of very toxic cytotoxic chemotherapeutic agents, high-risk (HR)-NB patients still have a poor prognosis and a survival rate below 50%. For these reasons, new pharmacological options are urgently needed. This review focuses on synthetic heterocyclic compounds published in the last five years, which showed at least some activity on this severe disease and act as kinase inhibitors. The specific mechanism of action, selectivity, and biological activity of these drug candidates are described, when established. Moreover, the most remarkable clinical trials are reported. Importantly, kinase inhibitors approved for other diseases have shown to be active and endowed with lower toxicity compared to conventional cytotoxic agents. The data collected in this article can be particularly useful for the researchers working in this area.

Pyrazole[3,4-d]pyrimidine derivatives loaded into halloysite as potential CDK inhibitors.

Uncontrolled cell proliferation is a hallmark of cancer as a result of rapid and deregulated progression through the cell cycle. The inhibition of cyclin-dependent kinases (CDKs) activities is a promising therapeutic strategy to block cell cycle of tumor cells. In this work we reported a new example of nanocomposites based on halloysite nanotubes (HNTs)/pyrazolo[3,4-d]pyrimidine derivatives (Si306 and Si113) as anticancer agents and CDK inhibitors. HNTs/Si306 and HNTs/Si113 nanocomposites were synthesized and characterized. The release kinetics were also investigated. Antitumoral activity was evaluated on three cancer cell lines (HeLa, MDA-MB-231 and HCT116) and the effects on cell cycle arrest in HCT116 cells were evaluated. Finally, molecular dynamics simulations were performed of the complexes between Si113 or Si306 and the active site of both CDK 1 and 2.

Insights into RNA-dependent RNA Polymerase Inhibitors as Antiinfluenza Virus Agents.

BACKGROUND: Influenza is a seasonal disease that affects millions of people every year and has a significant economic impact. Vaccines are the best strategy to fight this viral pathology, but they are not always available or administrable, prompting the search for antiviral drugs. RNA-dependent RNA polymerase (RdRp) recently emerged as a promising target because of its key role in viral replication and its high conservation among viral strains. DISCUSSION: This review presents an overview of the most interesting RdRp inhibitors that have been discussed in the literature since 2000. Compounds already approved or in clinical trials and a selection of inhibitors endowed with different scaffolds are described, along with the main features responsible for their activity. RESULTS: RdRp inhibitors are emerging as a new strategy to fight viral infections and the importance of this class of drugs has been confirmed by the FDA approval of baloxavir marboxil in 2018. Despite the complexity of the RdRp machine makes the identification of new compounds a challenging research topic, it is likely that in the coming years, this field will attract the interest of a number of academic and industrial scientists because of the potential strength of this therapeutic approach.

An Update on JAK Inhibitors.

Janus kinases (JAKs) are a family of non-receptor tyrosine kinases, composed by four members, JAK1, JAK2, JAK3 and TYK2. JAKs are involved in different inflammatory and autoimmune diseases, as well as in malignancies, through the activation of the JAK/STAT signalling pathway. Furthermore, the V617F mutation in JAK2 was identified in patients affected by myeloproliferative neoplasms. This knowledge prompted researchers from academia and pharmaceutical companies to investigate this field in order to discover small molecule JAK inhibitors. These efforts recently afforded to the market approval of four JAK inhibitors. Despite the fact that all these drugs are pyrrolo[2,3-d]pyrimidine derivatives, many compounds endowed with different heterocyclic scaffolds have been reported in the literature as selective or multi-JAK inhibitors, and a number of them is currently being evaluated in clinical trials. In this review we will report many representative compounds that have been published in articles or patents in the last five years (period 2013-2017). The inhibitors will be classified on the basis of their chemical structure, focusing, when possible, on their structure activity relationships, selectivity and biological activity. For every class of derivatives, compounds disclosed before 2013 that have entered clinical trials will also be briefly reported, to underline the importance of a particular chemical scaffold in the search for new inhibitors.

Recent Studies on Ponatinib in Cancers Other Than Chronic Myeloid Leukemia.

Ponatinib is a third line drug for the treatment of chronic myeloid leukemia patients, especially those that develop the gatekeeper mutation T315I, which is resistant to the first and the second line drugs imatinib, nilotinib, dasatinib and bosutinib. The compound was first identified as a pan Bcr-Abl and Src kinase inhibitor. Further studies have indicated that it is a multitargeted inhibitor that is active on FGFRs, RET, AKT, ERK1/2, KIT, MEKK2 and other kinases. For this reason, the compound has been evaluated on several cancers in which these kinases play important roles, including thyroid, breast, ovary and lung cancer, neuroblastoma, rhabdoid tumours and in myeloproliferative disorders. Ponatinib is also being tested in clinical trials to evaluate its activity in FLT3-ITD acute myelogenous leukemia, head and neck cancers, certain type of lung cancer, gastrointestinal stromal tumours and other malignancies. In this review we report the most recent preclinical and clinical studies on ponatinib in cancers other than CML, with the aim of giving a complete overview of this interesting compound.

Synthesis and biological evaluation of a library of hybrid derivatives as inhibitors of influenza virus PA-PB1 interaction.

The limited treatment options against influenza virus along with the growing public health concerns regarding the continuous emergence of drug-resistant viruses make essential the development of new anti-flu agents with novel mechanisms of action. One of the most attractive targets is the interaction between two subunits of the RNA-dependent RNA polymerase, PA and PB1. Herein we report the rational design of hybrid compounds starting from a 3-cyano-4,6-diphenylpyridine scaffold recently identified as disruptor of PA-PB1 interactions. Guided by the previously reported SAR data, a library of amino acid derivatives was synthesized. The biological evaluation led to the identification of new PA-PB1 inhibitors, that do not show appreciable toxicity. Molecular modeling shed further lights on the inhibition mechanism of these compounds.

Pyrrolo[2,3-d]Pyrimidines as Kinase Inhibitors.

The pyrrolo[2,3-d]pyrimidine nucleus is a deaza-isostere of adenine, the nitrogenous base of ATP, and is present in many ATP-competitive inhibitors of different kinases. In the last few years the number of articles and patents that have appeared involving this type of inhibitors has dramatically increased and some compounds have been approved for the treatment of inflammatory or myeloproliferative diseases. Other derivatives are currently being evaluated in clinical trials. This review deals with pyrrolo[2,3- d]pyrimidine derivatives active as kinase inhibitors that have been reported in the literature from 2011 to 2016, with a particular interest on the recently patented compounds. The molecules are classified depending on the inhibited kinase, focusing on their chemical structures.

Identification of new pyrrolo[2,3-d]pyrimidines as Src tyrosine kinase inhibitors in vitro active against Glioblastoma.

In the last few years, several pyrrolo-pyrimidine derivatives have been either approved by the US FDA and in other countries for the treatment of different diseases or are currently in phase I/II clinical trials. Herein we present the synthesis and the characterization of a novel series of pyrrolo[2,3-d]pyrimidines, compounds 8a-j, and their activity against Glioblastoma multiforme (GBM). Docking studies and MM-GBSA analysis revealed the ability of such compounds to efficiently interact with the ATP binding site of Src. Enzymatic assays against a mini-panel of kinases (Src, Fyn, EGFR, Kit, Flt3, Abl, AblT315I) have been performed, showing an unexpected selectivity of our pyrrolo[2,3-d]pyrimidines for Src. Finally, the derivatives were tested for their antiproliferative potency on U87 GBM cell line. Compound 8h showed a considerable cytotoxicity effect against U87 cell line with an IC50 value of 7.1 µM.

Anticonvulsive Activity in Audiogenic DBA/2 Mice of 1,4-Benzodiazepines and 1,5-Benzodiazepines with Different Activities at Cerebellar Granule Cell GABAA Receptors.

Herein, we tested in a model of generalized reflex epilepsy in mice different 1,4-benzodiazepines and 1,5-benzodiazepines with agonistic activity at the GABAA receptor population contributing to the peak component of the chloride current elicited by GABA in cerebellar granule cells (CGCs) in culture. The substances have all higher lipophilia than clobazam, an antiepileptic drug well known and used in human therapy. This ensures that they all can pass relatively easily the blood-brain barrier (BBB). The benzodiazepines were administered intraperitoneally (i.p.) and tested for their activity against sound-induced tonic and clonic seizures in a genetic model of experimental epilepsy, the DBA/2 mouse. Our data demonstrates an interesting inverse correlation between the ED50s and the efficacy (E %) of the drugs in increasing the peak chloride current elicited by GABA in cerebellar granule cells in culture. There is indication of the existence of a threshold of E % above which the increase of ED50 with increasing E % becomes linear. This is statistically significant for the clonic phase, whereas it is at the limit of significance for the tonic one. A possible interpretation of these results is that in this epilepsy model, projections from the cerebellum exert a convulsion prevention activity.

Analogs, formulations and derivatives of imatinib: a patent review.

INTRODUCTION: The Bcr-Abl inhibitor imatinib was approved in 2001 for chronic myeloid leukemia therapy, and dramatically changed the lives of patients affected by this disease. Since it also inhibits platelet derived growth factor receptor (PDGFR) and c-Kit, imatinib is used for various other tumors caused by abnormalities of one or both these two enzymes. AREAS COVERED: This review presents an overview on imatinib formulations and derivatives, synthetic methodologies and therapeutic uses that have appeared in the patent literature since 2008. EXPERT OPINION: Innovative imatinib formulations, such as nanoparticles containing the drug, will improve its bioavailability. Moreover, oral solutions or high imatinib content tablets or capsules will improve patient compliance. Some solid formulations and innovative syntheses that have appeared in the last few years will reduce the cost of the drug, offering big advantages for poor countries. Some recently patented efficacious imatinib derivatives are in preclinical studies and could enter clinical trials in the next few years. Overall, Bcr-Abl inhibitors constitute a very appealing research field that can be expected to expand further.

Study of the Interaction of 1,4- and 1,5-Benzodiazepines with GABAA Receptors of Rat Cerebellum Granule Cells in Culture.

The effects of a classical 1,4-benzodiazepine agonist, such as diazepam, its catabolite N-desmethyl-diazepam (nordiazepam), and 1,5-benzodiazepines such as clobazam and RL 214 (a triazolobenzodiazepine previously synthesized in our labs) were evaluated on native GABAA receptors of cerebellar granule cells in culture. The parameter studied was the increase of GABA-activated chloride currents caused by these substances. The contributions of α6 ß2/3 γ2 and α1 α6 ß2/3 γ2 receptor subtypes to the increase of GABA-activated chloride current were investigated by comparing the effects of such substances in the presence vs. the absence of furosemide. Furosemide is in fact able to block such receptors. It was found that the percent enhancement of peak GABA-activated current doubled for diazepam, clobazam, and RL 214. However, it did not change for N-desmethyl-diazepam. These results indicate that diazepam, clobazam, and RL 214 interact exclusively with α1 ß2/3 γ2 receptors, while N-desmethyl-diazepam seems to interact with not only α1- but also α6-containing receptors.

1,8-Naphthyridines IX. Potent anti-inflammatory and/or analgesic activity of a new group of substituted 5-amino[1,2,4]triazolo[4,3-a][1,8]naphthyridine-6-carboxamides, of some their Mannich base derivatives and of one novel substituted 5-amino-10-oxo-10H-pyrimido[1,2-a][1,8]naphthyridine-6-carboxamide derivative.

A new group of 5-(alkylamino)-9-isopropyl[1,2,4]triazolo[4,3-a][1,8]naphthyridine derivatives bearing a CONHR group at the 6-position (1c-g), designed to obtain new effective analgesic and/or anti-inflammatory agents, were synthesized and tested along with three new 9-alkyl-5-(4-alkyl-1-piperazinyl)-N,N-diethyl [1,2,4]triazolo[4,3-a][1,8]naphthyridine-6-carboxamides (2b-d). Besides, a new class of analogues of compounds 1 and 2, bearing a Mannich base moiety at the 9-position (12a-d), as well as the novel N,N-diethyl-5-(isobutylamino)-8-methyl-10-oxo-10H-pyrimido[1,2-a][1,8]naphthyridine-6-carboxamide (15) were prepared and tested. Compounds 1c-g exhibited very interesting anti-inflammatory properties in rats, whereas compounds 2b-d and 15 proved to be endowed with prevalent analgesic activity frequently associated with sedative effects in mice. On the contrary, the Mannich bases 12a-d resulted inactive. The most effective (80% inhibition of oedema) and potent (threshold dose 1.6 mg kg(-1) with 31% inhibition of oedema) anti-inflammatory compound 1d did not show gastrolesive effects following 100 mg kg(-1) oral administration in rats.

Fine molecular tuning at position 4 of 2H-chromen-2-one derivatives in the search of potent and selective monoamine oxidase B inhibitors.

The effects on the inhibition potencies of monoamine oxidase isoforms A (MAO-A) and B (MAO-B) depending upon changes in the physicochemical properties (size, shape, H-bonding, lipophilicity, etc.) of substituents at the C4 position of 2H-chromen-2-one derivatives were extensively investigated, and the results significantly added to our knowledge on this class of MAO inhibitors. All the 67 examined compounds showed high MAO-B selectivity, some of them achieving potency in the low nanomolar range. In particular, the 7-metachlorobenzyloxy-4-oxyacetamido-2H-chromen-2-one (entry 62) showed single digit nanomolar MAO-B potency (IC50 = 3.1 nM) and high selectivity over the MAO-A isoform (selectivity ratio = 7244). The great variety of the investigated substituents at C4 of the 2H-chromen-2-one nucleus, combined with binding models generated from docking studies carried out on selected compounds, allowed us to shed light on the main molecular requirements for potent and selective MAO-B inhibition, highlighting the dominant role of the steric effects. Interestingly, many of the designed substituents could be metabolically related to each other (e.g., CH3/CH2OH/CHO/COOH; NH2/NHCH3, NHAc), and therefore the results obtained may help in predicting the in vivo activity of some putative metabolites of lead MAO-B inhibitors.

GABAA Receptors of Cerebellar Granule Cells in Culture: Interaction with Benzodiazepines.

GABAA receptor mediated inhibition plays an important role in modulating the input/output dynamics of cerebellum. A characteristic of cerebellar GABAA receptors is the presence in cerebellar granule cells of subunits such as α6 and δ which give insensitivity to classical benzodiazepines. In fact, cerebellar GABAA receptors have generally been considered a poor model for testing drugs which potentially are active at the benzodiazepine site. In this overview we show how rat cerebellar granule cells in culture may be a useful model for studying new benzodiazepine site agonists. This is based on the pharmacological separation of diazepam-sensitive α1 ß2/3 γ2 receptors from those which are diazepam-insensitive and contain the α6 subunit. This is achieved by utilizing furosemide/Zn2+ which block α6 containing and incomplete receptors.

Synthesis, in vitro antiplatelet activity and molecular modelling studies of 10-substituted 2-(1-piperazinyl)pyrimido[1,2-a]benzimidazol-4(10H)-ones.

The multistep preparation of the new 10-substituted 2-(1-piperazinyl)pyrimido[1,2-a]benzimidazol-4(10H)-ones 6a-o, and of the two isomers 10-ethyl-2-(diethylamino)pyrimido[1,2-a]benzimidazol-4(10H)-one 6p and 10-ethyl-4-(diethylamino)pyrimido[1,2-a]benzimidazol-2(10H)-one 13, as well as the in vitro evaluation of their inhibitory activity on human platelet aggregation induced in platelet-rich plasma by ADP, collagen or the Ca(2+) ionophore A23187 were here described. Nine out of fifteen 2-(1-piperazinyl)derivatives (6g-o) showed good inhibitory properties towards all the platelet aggregation agonists used. Moreover, a molecular modelling study has been performed on two of the best compounds of this series (6i and 6o) to confirm in silico their interactions with the catalytic site of human platelet PDE3, using the X-ray data of the PDE3B isoform in complex with an inhibitor.

1,8-Naphthyridines VIII. Novel 5-aminoimidazo[1,2-a] [1,8]naphthyridine-6-carboxamide and 5-amino[1,2,4]triazolo[4,3-a] [1,8]naphthyridine-6-carboxamide derivatives showing potent analgesic or anti-inflammatory activity, respectively, and completely devoid of acute gastrolesivity.

On the basis of the very interesting pharmacological properties shown by the 5-amino[1,2,4]triazolo[4,3-a][1,8]naphthyridine-6-carboxamide derivatives 1, previously described by us, we have now prepared the 5-aminoimidazo[1,2-a][1,8]naphthyridine-6-carboxamide derivatives 2a-o (a new structural class) whose tricyclic system is isosteric to that of compounds 1. Both compounds 2 and some new properly substituted compounds 1 (1f-k) now synthesized were tested in vivo for their analgesic and anti-inflammatory activities: on the whole, compounds 2 showed notable analgesic properties, whereas many compounds 1 exhibited a very potent anti-inflammatory activity, coupled to scarce analgesic activity. All the effective compounds proved to be completely devoid of acute gastrolesivity (gastric damage) in rats (at the 200 mg kg(-1) oral dose).

1,8-Naphthyridines VI. Synthesis and anti-inflammatory activity of 5-(alkylamino)-N,N-diethyl[1,2,4]triazolo[4,3-a][1,8]naphthyridine-6-carboxamides with a new substitution pattern on the triazole ring.

On the basis of the good anti-inflammatory properties shown by the 9-alkyl-N,N-dialkyl-5-(alkylamino)[1,2,4]triazolo[4,3-a][1,8]naphthyridine-6-carboxamides 1, a series of analogues of such compounds, in which the 9-alkyl substituent was replaced by an ester or amide group (compounds 3a-i), was prepared and tested (inhibition of carrageenan-induced paw edema in the rat). Also two 5-(N-alkyl,N-acylamino) derivatives (compounds 4a,b) were synthesized and evaluated for the same purpose. Even though the general trend for these new [1,2,4]triazolo[4,3-a][1,8]naphthyridine derivatives was a decrease in activity compared with compounds 1, some of the new synthesized compounds exhibited still good anti-inflammatory properties.