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.

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.

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.

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.

Design, synthesis and pharmacological evaluation of novel naphthalenic derivatives as selective MT(1) melatoninergic ligands.

Novel heterodimer analogues of melatonin were synthesized, when agomelatine (1) and various aryl units are linked via a linear alkyl chain through the methoxy group. The compounds were tested for their actions at melatonin receptors. Several of these ligands are MT(1)-selective with nanomolar or subnanomolar affinity. In addition, while most of the derivatives behave as partial agonists on one or both receptor subtypes, N-[2-(7-{4-[6-(1-methoxycarbonylethyl)naphthalen-2-yloxy]butoxy}naphthalen-1-yl)ethyl]acetamide (36), a subnanomolar MT(1) ligand with an 11-fold preference over MT(2) receptors, is a full antagonist on both receptors. Our results also confirm that the selectivity seen for the MT(1) receptor arises predominantly from steric factors and is not a consequence of the bridging of melatonin receptor dimers.

Benzopyridooxathiazepine derivatives as novel potent antimitotic agents.

Herein, we describe the structure-activity relationship study of a new 1-(arylalkyl)-11H-benzo[f]-1,2-dihydropyrido[3,2,c][1,2,5]oxathiazepine 5,5-dioxide series of antimitotic agents. The pharmacological results obtained from previous works allowed us to identify compound 1 as a new cytotoxic agent inhibiting tubulin polymerization. We have undertaken the synthesis of its non-methylated analogue 7 and have extended our investigations to a novel, structurally related benzopyridooxathiazepine dioxide series. Among all analogues synthesized in this study, compound 10b was the most promising, being 12-fold more potent than compound 1. Its activity over a panel of five tumoral cell lines was in the nanomolar range for all of the histological types tested and flow cytometric studies performed on L1210 cells showed an accumulation of the cells in the G2/M phases of the cell cycle with a significant percentage of tetraploid cells (8N DNA content). This interesting pharmacological profile, resulting from inhibition of tubulin polymerization, encouraged us to perform preliminary in vivo studies.

Antioxidant activity of benzoxazolinonic and benzothiazolinonic derivatives in the LDL oxidation model.

A series of benzazolone compounds were synthesized utilizing benzoxazolinonic and benzothiazolinonic heterocycles as the building unit. The antioxidant activity of these compounds was determined by inhibition of lipid peroxidation. The oxidation of LDL was induced in the presence of CuSO(4) or 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH). The protective action of these compounds against the cytotoxicity was 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). The best antioxidant activities were observed for phenolic compounds 13 and 14b with ratio R=2.5, 3.2 (5microM). Both of these test substances increased the cell viability significantly as indicated by MTT assay and LDH release assay.

Design and synthesis of 3-phenyltetrahydronaphthalenic derivatives as new selective MT2 melatoninergic ligands. Part II.

Following our studies of the melatoninergic receptors, we have developed new tetrahydronaphthalenic derivatives of melatonin that have been tested as selective melatonin receptors ligands. Regarding the role of the phenyl substituent to obtain selective ligands, modulation of selectivity and activity have been achieved by modifications of the acyl group and substitutions on the phenyl ring. Ten of the seventeen evaluated derivatives have MT(2) receptor affinity similar to that of melatonin. Moreover, we have achieved remarkable MT(2) selectivity over MT(1) (selectivity >100) and have been able to further extend the RSA of the tetrahydrophthalenic series. However, the compounds presented here display partial agonist or antagonist behavior instead of full agonist.

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

Benzofuranic analogues of MCA-NAT (5-methoxycarbonylamino-N-acetyltryptamine) have been synthesized and evaluated as melatonin receptor ligands. Introduction of a methoxycarbonylamino substituent in the C-5 position of the benzofurane nucleus obtains MT(3) selective ligands. This selectivity can be modulated with suitable variations of the C-5 position and the acyl group on the C-3 side chain.

Synthesis of 3-phenylnaphthalenic derivatives as new selective MT(2) melatoninergic ligands.

A series of naphthalenic analogues of melatonin were prepared and evaluated as melatonin receptor MT(2) selective ligands. Activity and MT(2) selectivity can be modulated with suitable variations of the C-3 phenyl and the acyl group on the C-1 side chain. Surprisingly, in contrast with what had been previously described in other series (2-benzylindoles, 2-benzylbenzofurans and 3-phenyltetralins), the presence of a C-3 phenyl with a functional group on the meta position seems to be primordial for MT(2) affinity and selectivity. Indeed, N-[2-(3-(3-hydroxymethylphenyl)-7-methoxynaphth-1-yl)ethyl]acetamide (21) is one of the best MT(2) selective ligands described until now and behaves as an antagonist.

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.

The strange case of Dr HDL and Mr HDL: does a NO's story illuminate the mystery of HDL's dark side uncovered by Dr HDL's drug targeting CETP?

Recently, the first large-scale morbidity and mortality trial (ILLUMINATE) to evaluate the cardiovascular end points of a CETP inhibitor (torcetrapib) has been prematurely stopped because the mortality was significantly increased in the treated group. Why torcetrapib caused excess death is not known. Based on the fact that HDL interacts with endothelial nitric oxyde synthase (eNOS) and nitric oxide (NO) secretion, which partly controlled blood pressure and than torcetrapib could increase blood pressure among some patients, we hypothesize that CETP inhibition could have significantly inhibit eNOS. CETP inhibition would have enlarged HDL size resulting in a deficit in the interaction between HDL and the Scavenger Receptor class B type I (SR-BI), which is an important link between HDL and eNOS activation. We suggest than the deficit in NO secretion would have been sufficient among all patients to induce a destabilization of the plaques of atheroma, but could have induced a pathogenic increase in blood pressure only in patients whose eNOS activity was naturally weak due to genetic polymorphisms of this enzyme. We also hypothesize that the increase in HDL levels, induced by CETP inhibition, coupled with the capacity of HDL to induce endothelin-1 secretion would have aggravated the cardiovascular risks under this CETP inhibitor treatment.

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 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 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.

Novel benzopyridothiadiazepines as potential active antitumor agents.

The synthesis of novel thiadiazepine derivatives, that could be considered as constraint analogues of E-7010, are reported. These molecules were evaluated for their antiproliferative activity toward the murine L1210 leukemia cell line. Flow cytometric studies performed on L1210 cells with the most cytotoxic compounds showed an accumulation of the cells in the G2/M phases of the cell cycle with a significant percentage of tetraploid cells (8N DNA content). Submicromolar cytotoxicities were observed with compounds 2b, 4b, 4e, 4g, and 4i. Two of them, compounds 2b and 4b, were found to be potent inhibitors of tubulin polymerization with IC50 of respectively 3.8 and 2.4 microM compared to 2.4 microM for desoxypodophyllotoxin. A 4-methoxyphenylethyl substitution on the pyridinyl nitrogen of the benzopyridothiadiazepine was found to be essential for the antiproliferative activity. The in vitro activities of compounds 2b and 4b make benzopyridothiadiazepine dioxides a promising new class of tubulin binders which warrant further in vivo evaluation.

New antiproliferative benzoindolinothiazepines derivatives.

New benzoindolinothiazepines containing a piperazine moiety are described as potent antiproliferative agents against PC3 human prostatic cell lines. This activity could be explained by an accumulation of cells in G1 phase.

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.