Strong induction of iodothyronine deiodinases by chemotherapeutic selenocompounds.

The biological activity of thyroid hormones (TH) is regulated by selenoenzymes of the iodothyronine deiodinase (DIO) family catalysing TH activating and inactivating reactions. Besides TH metabolism, several studies indicate an important role of DIO isoenzymes in tumorigenesis and cancer growth. It is therefore of therapeutic importance to identify modulators of DIO expression. We have synthesized and studied a series of selenocompounds containing a methyl- or benzyl-imidoselenocarbamate backbone. One of these novel compounds had chemotherapeutic activities in a murine xenograft tumour model by an unknown mechanism. Therefore, we tested their effects on DIO expression in vitro. In HepG2 hepatocarcinoma cells, DIO1 activity was strongly (up to 10-fold) increased by the methyl- but not by the corresponding benzyl-imidoselenocarbamates. Steady-state mRNA levels remained unaltered under these conditions indicating a post-transcriptional mode of action. The effects were further characterized in HEK293 cells stably expressing DIO1, DIO2 or DIO3. Even within the artificial genetic context of the expression vectors, all three DIO isoenzymes were up-regulated by the methyl- and to a lesser extent by the benzyl-imidoselenocarbamates. Consistent stimulating effects were observed with methyl-N,N'-di(quinolin-3-ylcarbonyl)-imidoselenocarbamate (EI201), a selenocompound known for its anti-tumour activity. DIO inducing effects were unrelated to the intracellular accumulation of selenium, yet the precise mode of action remains elusive. Collectively, our data highlight that these selenocompounds may constitute interesting pharmacological compounds for modifying DIO expression potentially affecting the balance between cell differentiation and proliferation.

Innovative lead compounds and formulation strategies as newer kinetoplastid therapies.

The protozoan diseases leishmaniasis, human African trypanosomiasis (HAT) and Chagas disease (CD) are responsible for substantial global morbidity and mortality in tropical and subtropical regions. Environmental changes, drug resistance and immunosuppression are contributing to the emergence and spread of these diseases. In the absence of safe and efficient vaccines, chemotherapy, together with vector control, remains the most important measure to control kinetoplastid diseases. Nevertheless, the current chemotherapeutic treatments are clearly inadequate because of their toxic effects, generation of resistances as well as route and schedules of administration not adapted to the field-conditions. This review overlooks the strategies that can be addressed to meet immediately the patient needs such as the reconsideration of current regimens of administration and the rational combination of drugs in use. In the medium-long term, due to new methodologies of medicinal-chemistry, the screening from natural products and the identification of new therapeutic targets, new lead compounds have great chance to advance through the drug development pipeline to clinic. Modern pharmaceutical formulation strategies and nanomedicines also merit a place in view of the benefits of a single dose of liposomal Amphotericin B (AmBisome®) against visceral leishmaniasis. BBB-targeted nanodevices could be suited for selective delivery of drugs against HAT encephalitic phase. Bioadhesive nanoparticles can be proposed to enhance the bioavailability of drugs after oral administration by reason of improving the drug solubility, and permeability across the intestinal epithelia.

The quinoline imidoselenocarbamate EI201 blocks the AKT/mTOR pathway and targets cancer stem cells leading to a strong antitumor activity.

Methylimidoselenocarbamates have previously proven to display potent antitumor activities. In the present study we show that these compounds act as multikinase inhibitors. We found that the most effective compound, quinoline imidoselenocarbamate EI201, inhibits the PI3K/AKT/mTOR pathway, which is persistently activated and contributes to malignant progression in various cancers. EI201 blocked the phosphorylation of AKT, mTOR and several of its downstream regulators (p70S6K and 4E-BP1) and ERK1/2 in PC-3, HT-29 and MCF-7 cells in vitro, inducing both autophagy and apoptosis. EI201 also contributes to the loss of maintenance of the selfrenewal and tumorigenic capacity of cancer stem cells (CSCs). 0.1 µmol/L EI201 triggered a reduction in size and number of tumorspheres in PC-3, HT-29 and MCF-7 cells and 4 µmol/L induced the elimination of almost all the tumorspheres in the three studied cell lines. In addition, EI201 suppressed almost 80% prostate tumor growth in vivo (p < 0.01) compared to controls at a relatively low dose (10 mg/kg) in a mouse xenograft model. There was a significant decrease in the subcutaneous primary tumor [18F]-FDG uptake (76.5% reduction, p < 0.05) and in the total tumor burden (76.8% reduction, p < 0.05) after EI201 treatment compared to vehicle control, without causing toxicity in mice. Taken together, our results support further development of EI201 as a novel multi-kinase inhibitor that may be useful against cancers with aberrant upregulation of PI3K/AKT and MAPK signaling pathways.

Selenium and clinical trials: new therapeutic evidence for multiple diseases.

The understanding of the essential role of selenium (Se) in human health has increased substantially in recent decades. Micronutrient deficiencies are very common in the general population and may be even more common in patients with different pathologies due to genetic or environmental causes and prescription drug use. Selenium is used by people in the prevention and/or treatment of different disorders including cardiovascular disease, osteoarthritis, rheumatoid arthritis, hypothyroidism, stroke, atherosclerosis, cancer susceptibility and treatment, HIV, AIDS, neuronal diseases such as Alzheimer or amyotrophic lateral sclerosis, pancreatitis, depression, and diabetes amongst others. Several mechanisms have been suggested to mediate the biological effects of Se and these include antioxidant defence systems, synthesis and stability of metabolites that act as intermediates implicated in diverse selenoproteins expression pathways oxidative metabolism, immune system modulation, DNA intercalators, kinase regulation, enzymatic cofactor, and gene expression. A number of clinical trials in recent years have provided convincing evidence of the central role of this element, either alone or in combination with other micronutrients or antioxidants, in the prevention and treatment of multiple diseases. Based on these studies this review focuses on the advances made so far in the study of mechanisms and applications of selenium compounds that could be suitable for chronic diseases.

New 1-aryl-3-(4-arylpiperazin-1-yl)propane derivatives, with dual action at 5-HT1A serotonin receptors and serotonin transporter, as a new class of antidepressants.

In a search toward new and efficient antidepressants, 1-aryl-3-(4-arylpiperazin-1-yl)propane derivatives were designed, synthesized, and evaluated for 5-HT reuptake inhibition and 5-HT1A receptor antagonism. This dual pharmacological profile should lead, in principle, to a rapid and pronounced enhancement in serotoninergic neurotransmission and consequently to a more efficacious treatment of depression. The design was based on coupling structural moieties related to inhibition of serotonin reuptake, such as gamma-phenoxypropylamines, to arylpiperazines, typical 5-HT1A ligands. In binding studies, several compounds showed affinity at the 5-HT transporter and 5-HT1A receptors. Antidepressant-like activity was initially assayed in the forced swimming test with those compounds with Ki < 200 nM in both binding studies. Functional characterization was performed by measuring the intrinsic effect on rectal temperature in mice and also the antagonism to 8-OH-DPAT-induced hypothermia. The most efficacious compounds (12f, 23gE, 28a, and 28b) were further explored for their ability to antagonize 8-OH-DPAT-induced inhibition of forskolin-stimulated cAMP formation in a cell line expressing the 5-HT1A receptor. Furthermore, the antidepressant-like properties of 12f, 28a, and 28b, which exhibited 5-HT1A receptor antagonistic property in the latter study, were also evaluated in the learned helplessness test in rats. Among these three compounds, 28b (1-benzo[b]thiophene-3-yl)-3-[4-(2-methoxyphenyl)-1-ylpropan-1-ol) showed the higher affinity at both the 5-HT transporter and 5-HT1A receptors (Ki = 20 nM in both cases) and was also active in the other pharmacological tests. Such a pharmacological profile could lead to a new class of antidepressants with a dual mechanism of action and a faster onset of action.

New 3-[4-(aryl)piperazin-1-yl]-1-(benzo[b]thiophen-3-yl)propane derivatives with dual action at 5-HT1A serotonin receptors and serotonin transporter as a new class of antidepressants.

A series of new 3-[4-(aryl)piperazin-1-yl]-1-(benzo[b]thiophen-3-yl)propane derivatives were synthesized in an attempt to find a new class of antidepressant drugs with dual activity at 5-HT1A serotonin receptors and serotonin transporter. Title compounds were evaluated for in vitro activity on 5-HT1A receptor and 5-HT transporter. They show high nanomolar affinity for both activities, and in particular, compounds 1-(5-chlorobenzo[b]thiophen-3-yl)-3-[4-(2-methoxyphenyl)piperazin-1-yl]propan-1-ol (7) and 1-(5-fluorobenzo[b]thiophen-3-yl)-3-[4-(2-methoxyphenyl)piperazin-1-yl]propan-1-ol (8) show values (nM) of K(i)=30 and 2.3 for 5-HT1A receptors and K(i)=30 and 12 for serotonin transporters, respectively. In GTPgammaS binding assays, compound 8 revealed antagonist properties to 5-HT1A receptors. Such a pharmacological profile could lead to potent antidepressant agents with new dual mechanism of action.

Design, synthesis and biological evaluation of new 3-[(4-aryl)piperazin-1-yl]-1-arylpropane derivatives as potential antidepressants with a dual mode of action: serotonin reuptake inhibition and 5-HT1A receptor antagonism.

It has been suggested that the combination of a selective serotonin reuptake inhibitor (SSRI) and a 5-HT1A receptor antagonist may facilitate the onset of the SSRIs antidepressant action. Accordingly, we describe the synthesis of a series of new 3-[(4-aryl)piperazin-1-yl]-1-arylpropane derivatives with structural modifications performed in Ar1, Ar2 and Z (Z is different functional groups) to obtain the sought dual activity. Compounds were evaluated for in vitro affinity at 5-HT1A receptors and 5-HT transporter. The antidepressant-like activity of derivatives with the higher affinity was assessed initially using the forced swimming test (FST). Compound 1-(2,4-dimethylphenyl)-3-[(2-methoxyphenyl)piperazin-1-il]-1-propa none (III.1.a) showed the best antidepressant-like activity which was further confirmed in the learned helplessness test.

Synthesis and 5-HT3 affinity of new 3-substituted indoles at central nervous system.

A series of 3-imino and 3-aminomethyl-N-methylindoles, in which the amine substituents were 3-quinuclidyl and 1-adamantyl groups, were synthesized and their in vitro affinity towards 5-HT3 central receptors evaluated. Of the nine compounds tested, three caused displacement of 3H-BRL 43694 binding to 5-HT3. 2-Chloro-3-(3-quinuclidylimino)-1-methylindole, 4, was the most potent compound with an IC50 = 5.15 10(-8) M. Moreover, the monoamine oxidase inhibition activity was tested and three compounds were shown to be MAO inhibitors, their IC50 was in the range of that of (-)-Deprenyl. Again, 4 was the most potent compound. Structure-activity relationships within the series are briefly discussed.

Hypoxia-selective agents derived from 2-quinoxalinecarbonitrile 1,4-di-N-oxides. 2.

Hypoxic cells are an important target for antitumor therapy because tumors are typically characterized by such cells. Virtually all tumors which are present as solid masses contain hypoxic cells, while normal cells generally have an adequate supply of oxygen. Accordingly, antitumor agents can be made selective for tumors by virtue of high activity under hypoxic conditions. The initial purpose of this work was to determine the influence of different groups in position 3. Thus, the synthesis of some 3-NH-substituted derivatives (2a, 3a, 4a) starting from 3-amino-2-quinoxalinecarbonitrile 1,4-di-N-oxide (1a) is described. Reductive deamination of compounds 1a-k provides the 2-quinoxalinecarbonitriles 5a-k, which are more potent, while selectivity is maintained or increased in some derivatives. The compound 7-(4-nitrophenyl)-2-quinoxalinecarbonitrile 1,4-di-N-oxide (5k) is 150-fold more potent than tirapazamine (3-amino-1,2,4- benzotriazine 1,4-di-N-oxide), which has been used as a standard. Three derivatives (5g,i,k) show a hypoxic cytotoxicity ratio (HCR) > or = 200, better than that of tirapazamine (HCR = 75) in V79 cells. Replacement of the 3-amino group by chlorine affords the potent but nonselective 3-chloro derivatives 6a-k showing similar toxicities under both aerobic and hypoxic conditions. These compounds were used as intermediates for the synthesis of a new series of water-soluble compounds derived from 3-[[(N,N- dialkylamino)alkyl[amino]-2-quinoxalinecarbonitrile 1,4-di-N-oxides 10a-i and 11a-i. The 7-chloro and the 7-trifluoromethyl derivatives 10b,f have demonstrated high potency (0.4 and 0.3 microM) and excellent selectivity (HCR = 250 and 340). Several 7-chloro analogues, 12b, 13b.1,b.2, and 14b, and the dimer 16b have been prepared and evaluated in order to determine the optimum lateral chain in position 3, which appears to be the [(N,N-dimethylamino)propyl]amino moiety.

Hypoxia-selective agents derived from quinoxaline 1,4-di-N-oxides.

Hypoxic cells, which are a common feature of solid tumors, but not normal tissues, are resistant to both anticancer drugs and radiation therapy. Thus the identification of drugs with selective toxicity toward hypoxic cells is an important objective in anticancer chemotherapy. The benzotriazine di-N-oxide (SR 4233, Tirapazamine) has been shown to be an efficient and selective cytotoxin for hypoxic cells. Since the bioreductive activation of Tirapazamine is thought to be due to the presence of the 1,4-di-N-oxide moiety, a series of 3-aminoquinoxaline-2-carbonitrile 1,4-di-N-oxides with a range of electron-donating and -withdrawing substitutents in the 6- and/or 7- positions has been synthesized and evaluated for toxicity to hypoxic cells. Electrochemical studies of the quinoxaline di-N-oxides and Tirapazamine showed that as the electron-withdrawing nature of the 6(7)-substituent increases, the reduction potential becomes more positive and the compound is more readily reduced. Apart from the unsubstituted 6a and the 6,7-dimethyl derivative 6c, the quinoxaline di-N-oxides have reduction potentials significantly more positive than Tirapazamine (Epc -0.90 V). The most potent cytotoxins to cells in culture were the 6,7-dichloro and 6,7-difluoro derivatives 6i and 6l, which were 30-fold more potent than Tirapazamine. The 6(7)-fluoro and 6(7)-chloro compounds, 6e and 6h, showed the greatest hypoxia selectivity. Four of the compounds, 63, 6f, 6h and 6i, killed the inner cells of multicellular tumor spheroids in vitro. In vivo Balb/c mice tolerated a dose of these four compounds twice the size of that of Tirapazamine. This study demonstrates that quinoxaline 1,4-di-N-oxides could provide useful hypoxia-selective therapeutic agents.

Synthesis of 2-piperazinylbenzothiazole and 2-piperazinylbenzoxazole derivatives with 5-HT3 antagonist and 5-HT4 agonist properties.

New 2-piperazinylbenzothiazole and 2-piperazinylbenzoxazole derivatives were prepared and tested as 5-HT3 receptor antagonists. Some of the new compounds antagonized the effect of 5-HT at the longitudinal muscle myenteric plexus (LMMP) preparation of the guinea pig ileum, and two benzothiazole derivatives, compounds 2e and 2f, were more potent than ondansetron in this regard. However, these two compounds were much weaker than the typical 5-HT3 receptor antagonist as displacers of [3H]BRL-43694 binding to rat cerebral cortex homogenates or as antagonists of the bradycardia response to 5-HT in the anaesthetized rat. Like the prokinetic agent cisapride, some of the new compounds enhanced gastric emptying in rats. Compound 2f not only markedly enhanced gastric emptying but was also a potent agonist at the isolated rat oesophageal tunica muscularis mucosae, a preparation sensitive to 5-HT4 receptor stimulation, and enhanced the twitch response in the LMMP preparation. The latter effect was blocked by a high concentration of tropisetron or by previous desensitization with 5-methoxytryptamine. Compound 2f appears to show a promising pharmacological profile as a potential gastrokinetic agent.

Novel antagonists of 5-HT3 receptors. Synthesis and biological evaluation of piperazinylquinoxaline derivatives.

A series of piperazinylquinoxalines has been synthesized and studied as 5-HT3 receptor antagonists in different preparations. Antagonism to 5-HT in the longitudinal muscle of the guinea pig ileum was particularly prominent in cyanoquinoxaline derivatives with an alkyl substitutuent on the piperazine moiety. The pA2 of some selected compounds against the 5-HT3 agonist 2-methyl-5HT in the guinea pig ileum was in the range of tropisetron or ondansetron, and one of them, 7e, was more potent than these reference compounds by approximately 2 or 3 orders of magnitude. However, these compounds were markedly less potent than either tropisetron or ondansetron as displacers of 3H-BRL 43694 binding to rat cortical membranes or as antagonists of the Bezold-Jarisch reflex in rats. Piperazinylcyanoquinoxalines represent a new class of 5-HT3 antagonists with a selective effect on guinea pig peripheral receptors.

New 5-hydroxy-2-indolecarbohydrazides as platelet aggregation inhibitors in ethylene glycol.

The effect of ethylene glycol on blood platelet aggregation was examined using a previously described method. This method also was used to investigate several derivatives of 2-indolecarbohydrazide in vitro. All compounds inhibited platelet aggregation induced by collagen, epinephrine, or adenosine diphosphate at concentrations below 5 x 10(-4) M.