A novel inhibitor of the mitochondrial respiratory complex I with uncoupling properties exerts potent antitumor activity.

Cancer cells are highly dependent on bioenergetic processes to support their growth and survival. Disruption of metabolic pathways, particularly by targeting the mitochondrial electron transport chain complexes (ETC-I to V) has become an attractive therapeutic strategy. As a result, the search for clinically effective new respiratory chain inhibitors with minimized adverse effects is a major goal. Here, we characterize a new OXPHOS inhibitor compound called MS-L6, which behaves as an inhibitor of ETC-I, combining inhibition of NADH oxidation and uncoupling effect. MS-L6 is effective on both intact and sub-mitochondrial particles, indicating that its efficacy does not depend on its accumulation within the mitochondria. MS-L6 reduces ATP synthesis and induces a metabolic shift with increased glucose consumption and lactate production in cancer cell lines. MS-L6 either dose-dependently inhibits cell proliferation or induces cell death in a variety of cancer cell lines, including B-cell and T-cell lymphomas as well as pediatric sarcoma. Ectopic expression of Saccharomyces cerevisiae NADH dehydrogenase (NDI-1) partially restores the viability of B-lymphoma cells treated with MS-L6, demonstrating that the inhibition of NADH oxidation is functionally linked to its cytotoxic effect. Furthermore, MS-L6 administration induces robust inhibition of lymphoma tumor growth in two murine xenograft models without toxicity. Thus, our data present MS-L6 as an inhibitor of OXPHOS, with a dual mechanism of action on the respiratory chain and with potent antitumor properties in preclinical models, positioning it as the pioneering member of a promising drug class to be evaluated for cancer therapy. MS-L6 exerts dual mitochondrial effects: ETC-I inhibition and uncoupling of OXPHOS. In cancer cells, MS-L6 inhibited ETC-I at least 5 times more than in isolated rat hepatocytes. These mitochondrial effects lead to energy collapse in cancer cells, resulting in proliferation arrest and cell death. In contrast, hepatocytes which completely and rapidly inactivated this molecule, restored their energy status and survived exposure to MS-L6 without apparent toxicity.

Advances in prodrug design for Alzheimer's disease: the state of the art.

INTRODUCTION: Alzheimer's disease (AD) is a complex and multifactorial neurodegenerative disease that remains today a challenge for drug discovery. Like many pathologies of the central nervous system, one of the first hurdle is the development of a compound with a sufficient brain exposure to ensure a potential therapeutic benefit. In this direction, the development of prodrugs has been an intense field of research in the last years. AREAS COVERED: Two main strategies of prodrugs development are analyzed in this review. First, the application of the classical modulation of an active compound to incorporate a promoiety has been exemplified in the field of AD. In a second chapter, a series of innovative prodrugs based on a polypharmacological approach is described to take into account the complexity of AD. EXPERT OPINION: In the past 10 years, prodrugs have been approved by the FDA for the treatment of CNS pathologies. Most of them have been developed in order to improve membrane permeability of the parent drugs. Facing the limitation of AD drug discovery, the development of prodrugs will likely play a central role in the next years with the rise of innovative pleiotropic prodrugs.

Desirable drug-drug interactions or when a matter of concern becomes a renewed therapeutic strategy.

Drug-drug interactions are sometimes considered to be detrimental and responsible for adverse effects. In some cases, however, some are stakeholders of the efficiency of the treatment and this combinatorial strategy is exploited by some drug associations, including levodopa (L-Dopa) and dopadecarboxylase inhibitors, ß-lactam antibiotics and clavulanic acid, 5-fluorouracil (5-FU) and folinic acid, and penicillin and probenecid. More recently, some drug-drug combinations have been integrated in modern drug design strategies, aiming to enhance the efficiency of already marketed drugs with new compounds acting not only as synergistic associations, but also as real boosters of activity. In this review, we provide an update of examples of such strategies, with a special focus on microbiology and oncology.

Two Antagonistic Microtubule Targeting Drugs Act Synergistically to Kill Cancer Cells.

Paclitaxel is a microtubule stabilizing agent and a successful drug for cancer chemotherapy inducing, however, adverse effects. To reduce the effective dose of paclitaxel, we searched for pharmaceutics which could potentiate its therapeutic effect. We screened a chemical library and selected Carba1, a carbazole, which exerts synergistic cytotoxic effects on tumor cells grown in vitro, when co-administrated with a low dose of paclitaxel. Carba1 targets the colchicine binding-site of tubulin and is a microtubule-destabilizing agent. Catastrophe induction by Carba1 promotes paclitaxel binding to microtubule ends, providing a mechanistic explanation of the observed synergy. The synergistic effect of Carba1 with paclitaxel on tumor cell viability was also observed in vivo in xenografted mice. Thus, a new mechanism favoring paclitaxel binding to dynamic microtubules can be transposed to in vivo mouse cancer treatments, paving the way for new therapeutic strategies combining low doses of microtubule targeting agents with opposite mechanisms of action.

hERG toxicity assessment: Useful guidelines for drug design.

All along the drug development process, one of the most frequent adverse side effects, leading to the failure of drugs, is the cardiac arrhythmias. Such failure is mostly related to the capacity of the drug to inhibit the human ether-à-go-go-related gene (hERG) cardiac potassium channel. The early identification of hERG inhibition properties of biological active compounds has focused most of attention over the years. In order to prevent the cardiac side effects, a great number of in silico, in vitro and in vivo assays have been performed. The main goal of these studies is to understand the reasons of these effects, and then to give information or instructions to scientists involved in drug development to avoid the cardiac side effects. To evaluate anticipated cardiovascular effects, early evaluation of hERG toxicity has been strongly recommended for instance by the regulatory agencies such as U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA). Thus, following an initial screening of a collection of compounds to find hits, a great number of pharmacomodulation studies on the novel identified chemical series need to be performed including activity evaluation towards hERG. We provide in this concise review clear guidelines, based on described examples, illustrating successful optimization process to avoid hERG interactions as cases studies and to spur scientists to develop safe drugs.

Benzothienoquinazolinones as new multi-target scaffolds: Dual inhibition of human Topoisomerase I and tubulin polymerization.

3-(Alkyl(dialkyl)amino)benzothieno[2,3-f]quinazolin-1(2H)-ones (4-9) have been designed using Ellipticine structure as a model, replacing the carbazole core and the pyridine ring with a dibenzothiophene and a pyrimidine moiety, respectively. New benzothienoquinazolinones (4-9) have been synthesized by a simple one-pot reaction employing 3-aminodibenzothiophene as starting material. The benzothienoquinazolinones obtained (4-9), were evaluated for their anticancer activity against two breast cancer cell lines, MDA-MB-231 and MCF-7. The results revealed that compounds 4 and 7 presented a good antitumor activity toward the triple negative MDA-MB-231, without cytotoxicity against non-tumoral cells. Furthermore, the compounds 4 and 7 can be considered important molecular multi-target tools for their dual inhibition of different cellular proteins, i.e. Tubulin and human Topoisomerase I, involved in relevant cellular processes, as predicted by in silico studies and demonstrated by in vitro assays (for compound 4).

Novel multi target-directed ligands targeting 5-HT4 receptors with in cellulo antioxidant properties as promising leads in Alzheimer's disease.

Facing the complexity of Alzheimer's disease (AD), it is now currently admitted that a therapeutic pleiotropic intervention is needed to alter its progression. Among the major hallmarks of the disease, the amyloid pathology and the oxidative stress are closely related. We propose in this study to develop original Multi-Target Directed Ligands (MTDL) able to impact at the same time Aß protein accumulation and toxicity of Reactive Oxygen Species (ROS) in neuronal cells. Such MTDL were obtained by linking on a central piperidine two scaffolds of interest: a typical aminochlorobenzophenone present in numerous 5-HT4R agonists, and diverse antioxidant chemotypes. Interestingly, the most active compound 9g possesses a Ki of 12.7 nM towards 5-HT4R and an antioxidant activity in vitro and in cellulo.

A chemical screen identifies two novel small compounds that alter Arabidopsis thaliana pollen tube growth.

BACKGROUND: During sexual reproduction, pollen grains land on the stigma, rehydrate and produce pollen tubes that grow through the female transmitting-tract tissue allowing the delivery of the two sperm cells to the ovule and the production of healthy seeds. Because pollen tubes are single cells that expand by tip-polarized growth, they represent a good model to study the growth dynamics, cell wall deposition and intracellular machineries. Aiming to understand this complex machinery, we used a low throughput chemical screen approach in order to isolate new tip-growth disruptors. The effect of a chemical inhibitor of monogalactosyldiacylglycerol synthases, galvestine-1, was also investigated. The present work further characterizes their effects on the tip-growth and intracellular dynamics of pollen tubes. RESULTS: Two small compounds among 258 were isolated based on their abilities to perturb pollen tube growth. They were found to disrupt in vitro pollen tube growth of tobacco, tomato and Arabidopsis thaliana. We show that these 3 compounds induced abnormal phenotypes (bulging and/or enlarged pollen tubes) and reduced pollen tube length in a dose dependent manner. Pollen germination was significantly reduced after treatment with the two compounds isolated from the screen. They also affected cell wall material deposition in pollen tubes. The compounds decreased anion superoxide accumulation, disorganized actin filaments and RIC4 dynamics suggesting that they may affect vesicular trafficking at the pollen tube tip. CONCLUSION: These molecules may alter directly or indirectly ROP1 activity, a key regulator of pollen tube growth and vesicular trafficking and therefore represent good tools to further study cellular dynamics during polarized-cell growth.

Multifaceted properties of 1,4-dimethylcarbazoles: Focus on trimethoxybenzamide and trimethoxyphenylurea derivatives as novel human topoisomerase II inhibitors.

Natural or synthetic carbazole derivatives have recently attracted the attention of the scientific world because of their multiple biological activity, leading to an increase of designed, synthesized and studied analogues. In this paper, four 1,4-dimethylcarbazole derivatives, analogues of Ellipticine, have been investigated for their ability to block cancer cells growth, with low effects on the proliferation of normal cells. DNA topoisomerases inhibition assays, docking simulations, stability studies and effects on a membrane model are reported. Particularly, compounds 2 and 3 have been found thermally stable and able to inhibit, strongly and selectively, the human DNA topoisomerase II. These properties confer a good and broad antitumoral activity in vitro, with very low cytotoxic effect on the proliferation of normal cell lines and without damaging, in contrast with Ellipticine, the cell membrane model. The presented outcomes set the most active compounds as good candidates for pre-clinical studies useful in cancer treatment.

Novel benzylidenephenylpyrrolizinones with pleiotropic activities potentially useful in Alzheimer's disease treatment.

This work describes the synthesis and the biological evaluation of novel benzylidenephenylpyrrolizinones as potential antioxidant, metal chelating or amyloid ß (ßA) aggregation inhibitors. Some derivatives exhibited interesting results in regard to several of the performed evaluations and appear as valuable Multi-Target Directed Ligands with potential therapeutic interest in Alzheimer's disease. Among them, compound 29 particularly appears as a valuable radical and NO scavenger, a Cu(II) and Fe(II) chelating agent and exhibits moderate ßA aggregation inhibition properties. These activities, associated to a good predictive bioavailability and a lack of cytotoxicity, design it as a promising hit for further in vivo investigation.

3-(Dipropylamino)-5-hydroxybenzofuro[2,3-f]quinazolin-1(2H)-one (DPA-HBFQ-1) plays an inhibitory role on breast cancer cell growth and progression.

A series of unknown 3-(alkyl(dialkyl)amino)benzofuro[2,3-f]quinazolin-1(2H)-ones 4-17 has been synthesized as new ellipticine analogs, in which the carbazole moiety and the pyridine ring were replaced by a dibenzofuran residue and a pyrimidine ring, respectively. The synthesis of these benzofuroquinazolinones 4-17 was performed in a simple one-pot reaction using 3-aminodibenzofuran or its 2-methoxy derivative, as starting materials. From 3-(dipropylamino)-5-methoxybenzofuro[2,3-f] quinazolin-1(2H)-one (13), we prepared 3-(dipropylamino)-5-hydroxybenzofuro[2,3-f]quinazolin-1(2H)-one (18), referred to as DPA-HBFQ-1. The cytotoxic activities of all the synthesized compounds, tested in different human breast cancer cell lines, revealed that DPA-HBFQ-1 was the most active compound. In particular, the latter was able to inhibit anchorage-dependent and -independent cell growth and to induce apoptosis in estrogen receptor alpha (ERα)-positive and -negative breast cancer cells. It did not affect proliferation and apoptotic responses in MCF-10A normal breast epithelial cells. The observed effects have been ascribed to an enhanced p21(Cip1/WAF1) expression in a p53-dependent manner of tumor suppressor and to a selective inhibition of human topoisomerase II. In addition, DPA-HBFQ-1 exerted growth inhibitory effects also in other cancer cell lines, even though with a lower cytotoxic activity. Our results indicate DPA-HBFQ-1 as a good candidate to be useful as cancer therapeutic agent, particularly for breast cancer.

Recent Advances in Phenanthroindolizidine and Phenanthroquinolizidine Derivatives with Anticancer Activities.

Phenanthroindolizidine and phenanthroquinolizidine derivatives constitute a series of compounds that are being intensively studied as potential anticancer agents. Related natural products such as antofine and tylophorine alkaloids are well known for their high cytotoxic activity; however, their clinical application has been limited because of their side effects. In this review we report, in detail, on the main structural modifications applied to the phenanthroindolizidine and phenanthroquinolizidine skeletons, and we also describe their associated anticancer activities. New derivatives with promising antitumoral activities have emerged. Simplified analogues were prepared using rapid synthetic routes, and a certain number of these analogues displayed increased anticancer activity and selectivity towards tumor cell lines. It is hoped that a better understanding of the mechanisms of action associated with structure-activity relationships (SAR) will enable us to rationalize the development of new anticancer drugs.

Discovery of new thienopyrimidinone derivatives displaying antimalarial properties toward both erythrocytic and hepatic stages of Plasmodium.

A preliminary in vitro screening of compounds belonging to various chemical families from our library revealed the thieno[3,2-d]pyrimidin-4(3H)-one scaffold displayed a promising profile against Plasmodium falciparum. Then, 120 new derivatives were synthesized and evaluated in vitro; compared to drug references, 40 showed good activity toward chloroquine sensitive (IC50 35-344 nM) and resistant (IC50 45-800 nM) P. falciparum strains. They were neither cytotoxic (CC50 15-50 µM) toward HepG2 and CHO cells, nor mutagenic. Structure-activity relationships were defined. The lead-compound also appeared active against the Plasmodium liver stages (Plasmodium yoelii IC50 = 35 nM) and a preliminary in vivo evaluation indicated the in vitro activity was preserved (45% reduction in parasitemia compared to untreated infected mice). A mechanistic study demonstrated these molecules do not involve any of the pathways described for commercial drugs and exert a specific activity on the ring and trophozoite stages.

6-Sulfonylbenzothiazolones as potential scaffolds for the design of 5-HT6 ligands.

5-HT6 Receptors are relatively recently discovered receptors that interact with cholinergic, glutamatergic, GABAergic and dopaminergic transmission systems. These receptors have been implicated in the CNS system as therapeutic targets in applications such as psychosis, reduction of body weight or Alzheimer's disease. As part of our efforts to develop 5-HT6 antagonists, we explored the benzothiazolone scaffold substituted in position 3 or 6 respectively with ethylamino chains and an aromatic ring connected through a sulfonyl linker. Final compounds were evaluated in radioligand binding assays for their ability to interact with 5-HT6 receptors. Their potential cytotoxic effects were determined on the human neuroblastoma cell line SY5Y. They showed very low cytotoxicity, and one of them has submicromolar affinity for 5-HT6 receptors.

Design of donecopride, a dual serotonin subtype 4 receptor agonist/acetylcholinesterase inhibitor with potential interest for Alzheimer's disease treatment.

RS67333 is a partial serotonin subtype 4 receptor (5-HT4R) agonist that has been widely studied for its procognitive effect. More recently, it has been shown that its ability to promote the nonamyloidogenic cleavage of the precursor of the neurotoxic amyloid-ß peptide leads to the secretion of the neurotrophic protein sAPPα. This effect has generated great interest in RS67333 as a potential treatment for Alzheimer's disease (AD). We show herein that RS67333 is also a submicromolar acetylcholinesterase (AChE) inhibitor and therefore, could contribute, through this effect, to the restoration of the cholinergic neurotransmission that becomes altered in AD. We planned to pharmacomodulate RS67333 to enhance its AChE inhibitory activity to take advantage of this pleiotropic pharmacological profile in the design of a novel multitarget-directed ligand that is able to exert not only a symptomatic but also, a disease-modifying effect against AD. These efforts allowed us to select donecopride as a valuable dual (h)5-HT4R partial agonist (Ki = 10.4 nM; 48.3% of control agonist response)/(h)AChEI (IC50 = 16 nM) that further promotes sAPPα release (EC50 = 11.3 nM). Donecopride, as a druggable lead, was assessed for its in vivo procognitive effects (0.1, 0.3, 1, and 3 mg/kg) with an improvement of memory performances observed at 0.3 and 1 mg/kg on the object recognition test. On the basis of these in vitro and in vivo activities, donecopride seems to be a promising drug candidate for AD treatment.

Synthesis and in vitro evaluation of 4-trichloromethylpyrrolo[1,2-a]quinoxalines as new antiplasmodial agents.

Thanks to a preliminary in vitro screening of several CCl3-substituted-nitrogen containing heterocycles belonging to our chemical library, the 2-trichloromethylquinoxaline scaffold appeared to be of potential interest for developing new antiplasmodial agents. Then, combining these experimental results to the antimalarial properties reported for various pyrrolo[1,2-a]quinoxaline derivatives, an original series of fifteen 7-substituted-4-trichoromethylpyrrolo[1,2-a]quinoxalines was synthesized in a 4 to 5 reaction steps pathway. All molecules were evaluated in vitro toward both their antiplasmodial activity on the K1 multi-resistant Plasmodium falciparum strain and their cytotoxicity on the HepG2 human cell line. Thus, 3 hit molecules were identified, displaying IC50 values in the micromolar range and low cytotoxicity values, reaching good selectivity indexes, in comparison with the reference drugs chloroquine and doxycycline. Structure-activity relationship studies showed that the pyrrolo[1,2-a]quinoxaline scaffold can support selective antiplasmodial activity when substituted at position 4 by a CCl3 group. However, substitution at position 7 of the same scaffold is neither beneficial for cytotoxicity nor favourable for the solubility in the biological media.

Synthesis and evaluation of cytotoxic activities of new guanidines derived from carbazoles.

Several new alkylguanidines derived from carbazole have been synthesized in a simple one-pot reaction starting from 3-aminocarbazole derivatives. The aminocarbazoles were reacted with ethoxycarbonylisothiocyanate, to give thiourea intermediates, followed by the addition of an alkylamine and HgCl2 to give ethoxycarbonylguanidine intermediates. The reaction mixture was then heated at 160 °C to give the N-(1,4-dimethyl-9H-carbazol-3-yl)-N'-alkylguanidines. The cytotoxic activity of all the synthesized guanidines was evaluated against different cell lines.

N-substituted piperazinopyridylsteroid derivatives as abiraterone analogues inhibit growth and induce pro-apoptosis in human hormone-independent prostate cancer cell lines.

Nine new 17-(piperazin-1-yl)pyridin-5-yl)steroids as abiraterone analogues were synthesized. Compounds 5d and 5g showed selective activities against 17α-hydroxylase/C17,20-lyase (CYP17A1) and aromatase (CYP19), respectively. IC50 values of 5d were 5.09 and >50 µm, whereas these values for 5g were >50 µm and 7.40 µm, respectively, for CYP17A1 and CYP19. Molecular modelling highlighted that the inhibitor designed to bind cytochrome P450 haem iron is a necessary condition but not the only rationale to explain inhibitory activity. These abiraterone analogues were then evaluated on hormone-independent prostate cancer cell lines DU-145 and PC-3 and on hormone-dependent breast and prostate cancer cell lines MCF-7 and LNCaP, respectively. Compounds 5e, 5g and 5i have showed potent activities only on hormone-independent prostate cancer cell lines DU-145 and PC-3 with 60-85% inhibition of both cell viability and growth at 10 nm with pro-apoptotic mechanism as illustrated in PC-3 cells by DNA ladder assay and Western blotting of Bax, Casp-3 and its substrate, the poly (ADP-ribose) polymerase. We conclude that hybrid heterocycle steroids could be good lead compounds in the drug design especially against hormone-independent prostate cancer.

MR22388, a novel anti-cancer agent with a strong FLT-3 ITD kinase affinity.

This work describes the study of the mechanism of action and spectrum of activity of MR22388, a novel anti-cancer agent belonging to the tripentone series. MR22388 is highly cytotoxic (within the nanomolar range) against numerous cancer cell lines and studies of its cytotoxicity mechanisms show that it is a weak inhibitor of the polymerization of tubulin and that it induces apoptosis via the MAP kinase pathways. Further MR22388 is a very strong inhibitor of several kinases including the tyrosine kinase FLT3-ITD. FLT3-ITD is a mutated form of the tyrosine kinase receptor (RTK) FLT3, resulting in the constitutive activation of the kinase, occurring in about 25% of normal karyotypes' Acute Myeloid Leukemia (AML) and is linked to a bad prognosis. Consecutively, MR22388 appears as a novel promising anticancer lead agent especially for AML therapy.