New Quinoxaline Derivatives as Dual Pim-1/2 Kinase Inhibitors: Design, Synthesis and Biological Evaluation.

Proviral integration site for Moloney murine leukemia virus (Pim)-1/2 kinase overexpression has been identified in a variety of hematologic (e.g., multiple myeloma or acute myeloid leukemia (AML)) and solid (e.g., colorectal carcinoma) tumors, playing a key role in cancer progression, metastasis, and drug resistance, and is linked to poor prognosis. These kinases are thus considered interesting targets in oncology. We report herein the design, synthesis, structure-activity relationships (SAR) and in vitro evaluations of new quinoxaline derivatives, acting as dual Pim1/2 inhibitors. Two lead compounds (5c and 5e) were then identified, as potent submicromolar Pim-1 and Pim-2 inhibitors. These molecules were also able to inhibit the growth of the two human cell lines, MV4-11 (AML) and HCT-116 (colorectal carcinoma), expressing high endogenous levels of Pim-1/2 kinases.

Structure-based design of novel quinoxaline-2-carboxylic acids and analogues as Pim-1 inhibitors.

We identified a new series of quinoxaline-2-carboxylic acid derivatives, targeting the human proviral integration site for Moloney murine leukemia virus-1 (HsPim-1) kinase. Seventeen analogues were synthesized providing useful insight into structure-activity relationships studied. Docking studies realized in the ATP pocket of HsPim-1 are consistent with an unclassical binding mode of these inhibitors. The lead compound 1 was able to block HsPim-1 enzymatic activity at nanomolar concentrations (IC50 of 74 nM), with a good selectivity profile against a panel of mammalian protein kinases. In vitro studies on the human chronic myeloid leukemia cell line KU812 showed an antitumor activity at micromolar concentrations. As a result, compound 1 represents a promising lead for the design of novel anticancer targeted therapies.

Anti-diabetic activity of fused PPARγ-SIRT1 ligands with limited body-weight gain by mimicking calorie restriction and decreasing SGK1 expression.

A series of benzothiazol-2-one containing α-ethoxyphenylpropionic acid derivatives incorporating resveratrol or butein scaffolds were designed as fused full PPARγ agonist ligands and SIRT1-activating compounds for the treatment of type 2 diabetes (T2D) and its complications. Compound 14d displayed the best in vitro pharmacological profile with full PPARγ agonist activity (Emax = 98%, EC50 = 200 nM), SIRT1 enzymatic activation (+128%) and SGK1 expression inhibition (- 57%) which is known to limit side effects as fluid retention and body-weight gain. Compound 14d showed high efficacy in an ob/ob mice model with significant decreases in serum triglyceride, glucose and insulin levels but mostly with limited body-weight gain by mimicking calorie restriction (CR) and inhibiting SGK1 expression.

New quinolinic derivatives as melatonergic ligands: Synthesis and pharmacological evaluation.

New series of melatonergic ligands issued from two methoxy-quinolinic scaffolds (2-MQ and 3-MQ), were designed and synthesized. Herein we report the synthetic scheme and pharmacological results of the new prepared compounds. Investigation of compound 11a, the strict 2-MQ analogue, revealed the promising potential of this series. Therefore, pharmacomodulation of the acetamide function of 11a has led to compounds with different pharmacological profiles and the emergence of an MT2 selectivity. Besides, sulphonamide 11b showed the most important MT2 selectivity of this series (167 folds) while methyl and ethyl-ureas 11f and 11g represented the most potent melatonergic ligands of this study.

Synthesis and Biological Evaluation of N-[2-(4-Hydroxyphenylamino)-pyridin-3-yl]-4-methoxy-benzenesulfonamide (ABT-751) Tricyclic Analogues as Antimitotic and Antivascular Agents with Potent in Vivo Antitumor Activity.

Benzopyridothiadiazepine (2a) and benzopyridooxathiazepine (2b) were modified to produce tricyclic quinazolinone 15-18 or benzothiadiazine 26-27 derivatives. These compounds were evaluated in cytotoxicity and tubulin inhibition assays and led to potent inhibitors of tubulin polymerization. N-[2(4-Methoxyphenyl)ethyl]-1,2-dihydro-pyrimidino[2,1-b]quinazolin-6-one (16a) exhibited the best in vitro cytotoxic activity (GI50 10-66.9 nM) against the NCI 60 human tumor cell line and significant potency against tubulin assembly (IC50 0.812 µM). In mechanism studies, 16a was shown to block cell cycle in G2/M phase and to disrupt microtubule formation and displayed good antivascular properties as inhibition of cell migration, invasion, and endothelial tube formation. Compound 16a was evaluated in C57BL/6 mouse melanoma B16F10 xenograft model to validate its antitumor activity, in comparison with reference ABT-751 (1). Compound 16a displayed strong in vivo antitumor and antivascular activities at a dose of 5 mg/kg without obvious toxicity, whereas 1 needed a 10-fold higher concentration to reach similar effects.

Synthesis of triazoloquinazolinone based compounds as tubulin polymerization inhibitors and vascular disrupting agents.

A series of 1-phenyl-[1,2,4]triazolo[4,3-a]quinazolin-5-ones designed as conformationally restricted CA-4 analogues, were tested for their tubulin polymerization and growth inhibitory activities. The 3-hydroxy-4-methoxy derivatives 11d and 12d are potent inhibitors of tubulin assembly but only the N-methylated amid counterpart 12d possesses potent anticancer activity in a large panel of cancer cell lines. Upon treatment with compound 12d, remarkable cell shape changes as cell migration and tube formation were elicited in HUVECs, consistent with vasculature damaging activity.

Melatonergic ligands: Design, synthesis and pharmacological evaluation of novel series of naphthofuranic derivatives.

Following our research for new melatonergic ligands, herein we report the design, synthesis and biological evaluation of new series of naphthofuranic derivatives as MT1 and MT2 ligands. Binding affinity results of the prepared compounds revealed good binding affinities at both melatonin receptor subtypes. Particularly, compound 6a behaved as an MT1 partial agonist and MT2 full agonist and exhibited an excellent binding affinity at MT2 (Ki = 0.09 nM). In addition, lateral chain displacement from position 1 to 2 of the furan core had no effect on the binding affinity at both MT1 and MT2, while elongation of this side chain, led to decreased melatonergic binding affinities.

Synthesis and pharmacological evaluation of dual ligands for melatonin (MT1/MT2) and serotonin 5-HT2C receptor subtypes (II).

In this paper we report the investigation of C-3 and ß-acetamide positions of agomelatine analogues. Concomitant insertion of a hydroxymethyl in the ß-acetamide position and aliphatic groups in C-3 position produced a positive effect on both melatonin (MT1, MT2) and serotonin (5-HT2C) binding affinities. In particular, the allyl 6b and ethyl 15a represented the more interesting compounds of this series. Furthermore, the introduction of methyl cycloalkyl groups (compounds 11a, 12a) exhibited no change in both MT2 and 5-HT2C binding affinities while a decrease of MT1 binding affinity occurred leading to an MT2 selectivity. Finally, the acetamide modulation has led to methyl thiourea 11h, with a weak MT2 selectivity.

New melatonin (MT1/MT2) ligands: design and synthesis of (8,9-dihydro-7H-furo[3,2-f]chromen-1-yl) derivatives.

Herein we describe the synthesis of novel tricyclic analogues issued from the rigidification of the methoxy group of the benzofuranic analogue of melatonin as MT1 and MT2 ligands. Most of the synthesized compounds displayed high binding affinities at MT1 and MT2 receptors subtypes. Compound 6b (MT1, Ki=0.07nM; MT2, Ki=0.08nM) exhibited with the vinyl 6c and allyl 6d the most interesting derivatives of this series. Functional activity of these compounds showed full agonist activity with EC50 in the nanomolar range. Compounds 6a (EC50=0.8nM and Emax=98%) and 6b (EC50=0.2nM and Emax=121%) exhibited good pharmacological profiles.

Synthesis and pharmacological evaluation of a series of the agomelatine analogues as melatonin MT1 /MT2 agonist and 5-HT2C antagonist.

Agomelatine is a naphthalenic analogue of melatonin that is in clinical use for the treatment of major depressive disorders. Interestingly, while agomelatine exhibits potent affinity for melatonin receptors, it binds with only moderate affinity to the serotonin 5-HT2C receptor. Optimization of agomelatine toward this target could further potentiate its clinical efficacy. To explore this hypothesis and to access derivatives in which a key point of agomelatine metabolism is blocked, a series of naphthalenic derivatives was designed and synthesized as novel analogues of agomelatine. Most of the prepared compounds exhibited good binding affinity at the melatonin MT1 and MT2 receptor subtypes. Two compounds, an acetamide and an acrylamide derivative, exhibited good binding affinities at both the human melatonin (MT) receptors and the serotonin 5-HT2C receptor subtype, with pKi values of 7.96 and 7.95 against MT1, 7.86 and 8.68 against MT2, and 6.64 and 6.44 against 5-HT2C, respectively.

New radioligands for describing the molecular pharmacology of MT1 and MT2 melatonin receptors.

Melatonin receptors have been studied for several decades. The low expression of the receptors in tissues led the scientific community to find a substitute for the natural hormone melatonin, the agonist 2-[125I]-iodomelatonin. Using the agonist, several hundreds of studies were conducted, including the discovery of agonists and antagonists for the receptors and minute details about their molecular behavior. Recently, we attempted to expand the panel of radioligands available for studying the melatonin receptors by using the newly discovered compounds SD6, DIV880, and S70254. These compounds were characterized for their affinities to the hMT1 and hMT2 recombinant receptors and their functionality in the classical GTPS system. SD6 is a full agonist, equilibrated between the receptor isoforms, whereas S70254 and DIV880 are only partial MT2 agonists, with Ki in the low nanomolar range while they have no affinity to MT1 receptors. These new tools will hopefully allow for additions to the current body of information on the native localization of the receptor isoforms in tissues.

Synthesis, antiproliferative activity and tubulin targeting effect of acridinone and dioxophenothiazine derivatives.

The synthesis of new acridinone and dioxophenothiazine derivatives along with their tubulin polymerization inhibitory and antiproliferative activities is reported. The analysis of correlation for cytotoxic and antitubulin potential of tested compounds showed that 4-methoxyphenylethyl derivatives 18a and 19a were highly cytotoxic but were regarded to have no significant antitubulin activity. However, the introduction of a 3-hydroxy substituent leading to compounds 18e and 19e, strongly increased the antitubulin potential but was associated with a loss of the antiproliferative activity. Modeling studies, topoisomerase inhibition assays and cell cycle analysis have been performed to better investigate the mechanism of action of such compounds.

Novel conformationally constrained analogues of agomelatine as new melatoninergic ligands.

Novel conformationally restricted analogues of agomelatine were synthesized and pharmacologically evaluated at MT1 and MT2 melatoninergic receptors. Replacement of the N-acetyl side chain of agomelatine by oxathiadiazole-2-oxide (compound 3), oxadiazole-5(4H)-one (compound 4), tetrazole (compound 5), oxazolidinone (compound 7a), pyrrolidinone (compound 7b), imidazolidinedione (compound 12), thiazole (compounds 13 and 14) and isoxazole moieties (compound 15) led to a decrease of the melatoninergic binding affinities, particularly at MT1. Compounds 7a and 7b exhibiting nanomolar affinity towards the MT2 receptors subtypes have shown the most interesting pharmacological results of this series with the appearance of a weak MT2-selectivity.

Effect of oxime ether incorporation in acyl indole derivatives on PPAR subtype selectivity.

Compounds that simultaneously activate peroxisome proliferator-activated receptor (PPAR) subtypes α and γ have the potential to effectively treat dyslipidemia and type 2 diabetes (T2D) in a single pharmaceutically active molecule. The frequently observed side effects of selective PPARγ agonists, such as edema and weight gain, were expected to be overcome by using additive PPARα activity, leading to dual PPARα/γ agonists with balanced activity for both subtypes. Herein we report the discovery, synthesis, and optimization of a new series of α-ethoxyphenylpropionic acid bearing 5- or 6-substituted indoles. The incorporation of oxime ethers on the carbonyl portion of the benzoyl group can bring the PPARα/γ potency ratio equal to or slightly greater than one, as is the case for compounds 20 c and 21 a. Compound 20 c shows high efficacy in an ob/ob mouse model of T2D and dyslipidemia, similar to that of rosiglitazone and tesaglitazar, but with a significant increase in body weight gain. In contrast, compound 21 a, less potent as a dual PPARα/γ activator than 20 c, showed an interesting pharmacological profile, as it elicits a decrease in body weight relative to reference compounds.

Design, synthesis and pharmacological evaluation of new series of naphthalenic analogues as melatoninergic (MT1/MT2) and serotoninergic 5-HT2C dual ligands (I).

As part of our ongoing interest in developing new melatoninergic ligands bearing the same pharmacological profile as agomelatine, we focused our attention on this compound as a lead. Several chemical modifications have been performed on positions C-3 and 8 of the naphthalene ring determined as primary targets for the agomelatine metabolism. Herein we report the modulation of the positions C-3 and 7 in addition of the amide side chain because of this later prominent role in the affinity profile of such ligands. Synthesized compounds were then biologically evaluated at human cloned melatoninergic and serotoninergic receptors and showed different binding affinity and intrinsic activity profiles. Compounds bearing fluoroacetamide group (compounds 4 and 5) showed a high melatoninergic binding affinity particularly towards MT(1) receptor subtype. Thus, the fluoroacetamide 4 exhibited a good melatoninergic (MT(1)/MT(2)) binding affinity (70 pM) higher than the lead. Moreover, other compounds (10a, 10e, 16, 17 and 18) issued from these modulations behaved as MT(1) and MT(2) agonists and exhibited a sub-nanomolar binding affinity towards these receptors. However, only compounds 10e, 17 and 18 showed a sub-nanomolar binding affinity at 5-HT(2C) higher than the agomelatine.

Antioxydant activity of ß-carboline derivatives in the LDL oxidation model.

A series of ß-carboline compounds were synthesized, starting from compound GWC22, their antioxidant activity was determined by inhibition of lipid peroxidation. The oxidation of LDL was induced in the presence of CuSO4 or 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH). The protective actions of these compounds against the cytotoxicity were evaluated with lactate dehydrogenase (LDH) activity in bovine aortic endothelial cells (BAECs) and cellular vitality by measuring mitochondrial activity in the presence of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). Most of compounds showed an higher antioxidant activity than GWC22 derivative (R=1.6 for 5 µM CuSO4). The best antioxidant activities are phenolic and benzyloxy derivatives with ratio R=1.9 to 2.8 for 1 µM CuSO4. These substances have protective actions and increase significantly the cell viability.

Design and synthesis of naphthalenic derivatives as new ligands at the melatonin binding site MT3.

Naphthalenic analogs of MCA-NAT (5-methoxycarbonylamino-N-acetyltryptamine) have been synthesized and evaluated as melatonin receptor ligands. Introduction of a methoxycarbonylamino substituent at the C-7 position of the naphthalenic nucleus yields MT3 selective ligands. This selectivity can be modulated with suitable variations of the C-7 position and the acyl group on the C-1 side chain. We identified new series of compounds with affinity for the MT3 binding site in the nanomolar range, and singled out a selective ligand, (N-[2-(7-methylsulfamoyl-naphth-1-yl)ethyl]acetamide (17), with a Ki of 4.9 nM and selectivity of 1024 and 2040 versus MT1 and MT2 receptors respectively.

Preparation and pharmacological evaluation of a novel series of 2-(phenylthio)benzo[b]thiophenes as selective MT2 receptor ligands.

A series of N-(2-(5-fluoro-2-(4-fluorophenylthio)benzo[b]thiophen-3-yl)ethyl)acylamides was synthesized and evaluated for binding affinity and intrinsic activity at melatonin receptors. The affinity of each compound for the melatonin receptors was determined by binding studies on cloned human MT1 and MT2 receptors expressed in CHO cells. Agonist and antagonist potency was measured on the [35S]GTPγS binding assay for the most interesting compounds. The new derivatives 8-14 showed modest to high selectivity (between 4 and 220) for MT2 receptors. The most selective compound, N-(2-(5-fluoro-2-(4-fluorophenylthio)benzo[b]thiophen-3-yl)ethyl)but-3-enamide (14), an MT2 ligand with affinity for the MT2 receptor similar to that of melatonin and a 220-fold preference over MT1 receptors, acts as a partial agonist. In addition, N-(2-(5-fluoro-2-(4-fluorophenylthio)benzo[b]thiophen-3-yl)ethyl)propionamide (9), a nanomolar MT2 ligand with a good selectivity ratio (MT1/MT2=51) shows antagonist activity on both melatonin receptors.

Synthesis, biological evaluation and docking studies of 4-amino-tetrahydroquinazolino[3,2-e]purine derivatives.

The synthesis of new 4-amino-tetrahydroquinazolino[3,2-e]purine derivatives along with their activity in cell-free enzymatic assays on Src is reported. Some compounds emerged as moderately active inhibitors of the enzyme and showed antiproliferative effects on the murine leukemia L1210 cell line. Docking studies have been also performed to analyze the binding mode of compounds under study and to identify the structural determinants of their interaction. Therefore, this study provides a new promising scaffold with moderate enzymatic inhibitory activities for further development of new anticancer drugs targeting Src tyrosine kinase.