Identification of a new bisindolinone arresting IGROV1 cells proliferation

In an initial screening, a series of novel Knoevenagel adducts were submitted to the National Cancer Institute for evaluation of antitumor activity in human cell lines. In particular, compound 5f showed remarkable selectivity against IGROV1, an ovarian cancer cell line, without affecting healthy human fibroblast cells. Analyses of cytotoxicity, cell proliferation, cell migration, epigenetic changes, gene expression, and DNA damage were performed to obtain detailed information about its antitumor properties. Our results show that 5f causes proliferation arrest, decrease in motility, histone hyperacetylation, downregulation of cyclin D1 and α5 subunit of integrin β1 gene transcription. In addition, 5f treatment reduces transcript and protein levels of cyclin D1, which increases sensitivity to ionizing radiation and results in DNA damage comparable to cyclin D1 gene silencing.

Balancing Affinity, Selectivity, and Cytotoxicity of Hydrazone-Based G-Quadruplex Ligands for Activation of Interferon β Genes in Cancer Cells

G-quadruplex (G4) ligands are investigated to discover new anticancer drugs with increased cell-killing potency. These ligands can induce genome instability and activate innate immune genes at non-cytotoxic doses, opening the discovery of cytostatic immune-stimulating ligands. However, the interplay of G4 affinity/selectivity with cytotoxicity and immune gene activation is not well-understood. We investigated a series of closely related hydrazone derivatives to define the molecular bases of immune-stimulation activity. Although they are closely related to each other, such derivatives differ in G4 affinity, cytotoxicity, genome instability, and immune gene activation. Our findings show that G4 affinity of ligands is a critical feature for immune gene activation, whereas a high cytotoxic potency interferes with it. The balance of G4 stabilization versus cytotoxicity can determine the level of immune gene activation in cancer cells. Thus, we propose a new rationale based on low cell-killing potency and high immune stimulation to discover effective anticancer G4 ligands.

Synthesis and biological evaluation of thiazole derivatives on basic defects underlying cystic fibrosis

Cystic fibrosis is a genetic disease caused by loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator gene, encoding for CFTR protein. The most frequent mutation is the deletion of phenylalanine at position 508 (F508del), which leads to distinct defects in channel gating and cellular processing. In last years, several thiazole containing small molecules, endowed with dual F508del-CFTR modulator activity, proved to be able to target these defects. In search of new chemical entities able to restore CFTR function, we designed and synthesized a small series of sixteen thiazole derivatives. The designed compounds were studied as correctors and potentiators of F508del-CFTR. Although none of the molecules showed significant corrector activity, compounds 10 and 11 exhibited potentiator effects, thus allowing to determine some basic structural features which enable to obtain F508del-CFTR potentiator activity. In silico ADME studies showed that these derivatives obey Lipinski's rule of five and are expected to be orally bioavailable. Therefore, these molecules may represent a good starting point for the design of analogues endowed with improved CFTR potentiator activity and a good pharmacokinetic profile.

Monohydrazone Based G-Quadruplex Selective Ligands Induce DNA Damage and Genome Instability in Human Cancer Cells

Targeting G-quadruplex structures is currently viewed as a promising anticancer strategy. Searching for potent and selective G-quadruplex binders, here we describe a small series of new monohydrazone derivatives designed as analogues of a lead which was proved to stabilize G-quadruplex structures and increase R loop levels in human cancer cells. To investigate the G-quadruplex binding properties of the new molecules, in vitro biophysical studies were performed employing both telomeric and oncogene promoter G-quadruplex-forming sequences. The obtained results allowed the identification of a highly selective G-quadruplex ligand that, when studied in human cancer cells, proved to be able to stabilize both G-quadruplexes and R loops and showed a potent cell killing activity associated with the formation of micronuclei, a clear sign of genome instability.

Synthesis of 3-(Imidazo[2,1-b]thiazol-6-yl)-2H-chromen-2-one Derivatives and Study of Their Antiviral Activity against Parvovirus B19

Parvovirus B19 (B19V) is a human pathogenic virus associated with a wide range of clinical conditions. Currently, there are no recognized antiviral drugs for B19V treatment; therefore, efforts in the search for compounds inhibiting B19V replication are now being pursued. Coumarins (chromen-2-ones) are considered a privileged structure for designing novel orally bioavailable and non-peptidic antiviral agents. To further contribute to the development of new drugs against B19V, our research was focused on the synthesis, characterization and evaluation of antiviral activity of some new 3-(imidazo[2,1-b]thiazol-6-yl)-2H-chromen-2-one derivatives. The effects of the synthesized compounds on cell viability and viral replication were investigated by employing two relevant cellular systems, the myeloblastoid cell line UT7/EpoS1 and primary erythroid progenitor cells (EPCs). Some of the tested compounds showed inhibitory activity both on cell viability and on viral replication, depending on the cellular system. These results suggest that the mechanism involved in biological activity is sensitive to small structural changes and that it is possible to direct the activity of the 3-(imidazo[2,1-b]thiazol-6-yl)-2H-chromen-2-one core.

Abstract 4838: R loop-driven genome instability by G-quadruplex binders in BRCA2-silenced human cancer cells

G-quadruplexes (G4s) and R-loops are non-B DNA structures that can regulate basic processes such as transcription and replication. Unscheduled formation of R-loops is regarded as highly deleterious to cells, as R loops can induce replicative stress and DNA damage leading to genome instability. G4s are formed by four guanine residues held together by Hoogsteen hydrogen bonds and stabilized by monovalent cations. R loops are triple-stranded structures that contain an RNA-DNA hybrid duplex and a displaced single-stranded DNA. We have recently shown that Topoisomerase I (Top1) can affect genome-wide levels of R loops in human cancer cells consistently with the knowledge that DNA superhelical tension is a main driving force allowing non-B DNA structure formation. As G4 ligands were suggested to synergize with Top1 inhibitors, we asked the question of whether G4 ligands can affect R loops. We have thus investigated by immunofluorescence microscopy the effects of two different G4 binders, Pyridostatin (PDS) and FG (compound 1 in Amato et al J Med Chem 2016), on R-loops in human cancer cells. These G4 binders can increase both G4s and R loops while an inactive derivative of FG cannot induce them. Interestingly, the induction of G4s and R loops well correlate to each other in time and intensity with PDS being more effective than FG. After 24 hours, G4 binders induce a cell cycle arrest at the G2/M phase associated to double-stranded DNA cleavage as detected by γH2AX and 53BP1 foci formation and to activation of checkpoint response as shown by ATM phosphorylation. Interestingly, overexpression of RNaseH1 reduces both R loops and γH2AX foci induced by G4 binders showing that the ligands induce DNA cleavage via an R loop-mediated mechanism. Then, we silenced the BRCA2 gene by RNAi in U2OS cells and the results show that BRCA2 depletion increased γH2AX foci induced by PDS while overexpression of RNaseH1 rescue DNA cleavage induction. We also determined genomic R loop maps by DRIP-seq, and bioinformatic analyses of the specific location of G4-stabilized R loops provided information consistent with a model in which a G4 opposite to a DNA:RNA hybrid can stabilize R loops. Our study establishes for the first time that G4 binders stabilize either G4s and R loops in human cancer cells, and that they induce genome instability with a mechanism dependent on R loop formation. Partially supported by AIRC, Milan.

Citation Format: Alessio De Magis, Stefano Giustino Manzo, Marco Russo, Olivier Sordet, Rita Morigi, Giovanni Capranico. R loop-driven genome instability by G-quadruplex binders in BRCA2-silenced human cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4838.

Investigation on the Effects of Antimicrobial imidazo[2,1-b]thiazole Derivatives on the Genitourinary Microflora

BACKGROUND

Fused five-membered heterocyclic rings containing bridgehead nitrogen atom are particularly versatile in the field of medicinal chemistry because of their different biological activities. Among them, the imidazo[2,1-b]thiazole is an attractive fused heterocyclic core that has been extensively studied.

OBJECTIVE

The aim of the current study was to study the therapeutic applications of imidazo[2,1- b]thiazole derivatives as antimicrobial agents for the treatment of genitourinary infections.

METHOD

A traditional synthetic methodology was involved to obtain a small series of imidazothiazole derivatives.

RESULTS

Herein, we report the antimicrobial activity of the imidazo[2,1-b]thiazole or imidazo[2,1- b]thiazolidine derivatives against selected fungi, Gram-positive and Gram-negative bacteria. Moreover, experiments were carried out to investigate the interference towards the endogenous microbiota.

CONCLUSION

The most interesting of the series are the thiocyano derivatives (19, 23) showing a good profile for the treatment of genitourinary infections: a spectrum of activity covering both bacteria and fungi together with a reduced impact versus critical lines of Lactobacillus exerting defense against pathogens.

Recent Patents on Thiazole Derivatives Endowed with Antitumor Activity

Cancer is a disease of remarkable importance in the world today and is projected to become the primary cause of death within the coming years, therefore the design and development of new antitumor agents is one of the most pressing research areas in medicinal chemistry. Considering the importance of thiazole ring as scaffold present in a wide range of therapeutic agents, the medicinal chemists have been encouraged to synthesize a large number of novel antitumors bearing this heterocycle, which furnish extensive synthetic possibilities due to the presence of several reaction sites. The present review describes the patents from 2008 to present concerning new thiazole compounds useful for the development of new drug molecules. It has been divided according to the molecular target and describes the pathways involved in the biological activities and the structure of the most potent compounds, together with the screening results.

Toward the Development of Specific G-Quadruplex Binders: Synthesis, Biophysical, and Biological Studies of New Hydrazone Derivatives

G-Quadruplex-binding compounds are currently perceived as possible anticancer therapeutics. Here, starting from a promising lead, a small series of novel hydrazone-based compounds were synthesized and evaluated as G-quadruplex binders. The in vitro G-quadruplex-binding properties of the synthesized compounds were investigated employing both human telomeric and oncogene promoter G-quadruplexes with different folding topologies as targets. The present investigation led to the identification of potent G-quadruplex stabilizers with high selectivity over duplex DNA and preference for one G-quadruplex topology over others. Among them, selected derivatives have been shown to trap G-quadruplex structures in the nucleus of cancer cells. Interestingly, this behavior correlates with efficient cytotoxic activity in human osteosarcoma and colon carcinoma cells.

2-Indolinone a versatile scaffold for treatment of cancer: a patent review (2008-2014)

INTRODUCTION

2-Indolinone is a well-known aromatic heterocyclic organic compound. A lot of work has been done on this bicyclic structure by academic and company researchers to synthesize compounds directed to a plethora of molecular targets in order to discover new drug leads. This review presents up-to-date information in the field of cancer therapy research based on this small building block.

AREAS COVERED

The present review gives an account of the recent patent literature (2008-2014) describing the discovery of 2-indolinone derivatives with selected therapeutic activities. In this period, a large amount of patents were published on this topic. We have limited the analysis to 37 patents on 2-indolinone derivatives having potential clinical application as chemotherapeutic agents. In this review, the therapeutic applications of 2-indolinone derivatives for the treatment of cancer reported in international patents have been discussed.

EXPERT OPINION

2-Indolinone is the scaffold of the compounds considered from a medicinal chemistry perspective. Many of them have been developed and marketed for therapeutic use. In cancer chemotherapy, progress has been made in designing selective 2-indolinone derivatives. Some of them show preclinical efficacy. However, 2-indolinone has not exhausted all of its potential in the development of new compounds for clinical applications and remains a great tool for future research.

Bis-indole derivatives with antitumor activity turn out to be specific ligands of human telomeric G-quadruplex

Bis-indolinone derivatives having either 2,6-disubstituted pyridine core (1a and 1b) or 1,10-disubstituted phenanthroline core (2a and 2b), already known to have antitumor activity, have been tested as potential G-quadruplex binders. Compounds 2a and 2b are able to selectively stabilize G-quadruplex over duplex DNA, and also to discriminate among different G-quadruplex structures, having a particular affinity for the parallel form of the human telomeric G-quadruplex. Both compounds are also able to induce telomeric DNA damage that may explain the activity of these compounds.

Substituted E-3-(3-indolylmethylene)1,3-dihydroindol-2-ones with antiproliferative activity. Study of the effects on HL-60 leukemia cells

The synthesis of new substituted E-3-(3-indolylmethylene)1,3-dihydroindol-2-ones is reported. The antiproliferative activity was evaluated according to protocols available at the National Cancer Institute (NCI), Bethesda, MD. The action of the most active compound 10 was further investigated in HL-60 leukemia cells. Results obtained show that it causes a block in cell cycle progression, with cell arrest in the G2/M phase, associated with activation of apoptosis accompanied with increased oxidative stress and deregulation of the homeostasis of divalent cations, with significant increase in the cellular concentrations of free Ca(2+) and Mg(2+).

Cytotoxic activities of substituted 3-(3,4,5-trimethoxybenzylidene)-1,3-dihydroindol-2-ones and studies on their mechanisms of action

The synthesis of new trimethoxybenzylidene-indolinones is reported. Their cytotoxic activity was evaluated according to Developmental Therapeutics Program, National Cancer Institute, Bethesda, MD, drug screen protocols. The study of the mechanism of action suggests that inhibition of Nox4 in B1647 cells (acute myeloid leukemia) could contribute to the antiproliferative effect of some compounds. Moreover, inhibition of tubulin assembly was observed for the most cytotoxic compound, and the structural basis for this activity was delineated by binding models.

Substituted 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones and analogues: synthesis, cytotoxic activity, and study of the mechanism of action

The synthesis of substituted 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones and analogues is reported. Their cytotoxic activity was evaluated according to protocols available at the National Cancer Institute (NCI), Bethesda, MD. The action of selected compounds was examined for potential inhibition of tubulin assembly in comparison with the potent colchicine site agent combretastatin A-4. The most potent compounds also strongly and selectively inhibited the phosphorylation of the oncoprotein kinase Akt in cancer cells. The effect of the most interesting compounds was examined on the growth of HT-29 colon cancer cells. These compounds caused the cells to arrest in the G2/M phase of the cell cycle, as would be expected for inhibitors of tubulin assembly.

Diclofenac salts, part 7: are the pharmaceutical salts with aliphatic amines stable?

Eight cyclic aliphatic amines, pyrrolidine (Py), piperidine (Pp), morpholine (M), piperazine (Pz), and the N-hydroxyethyl (HE) analogues, were employed to prepare a salt with acidic diclofenac (D). These salts were examined by thermal [differential scanning calorimetry (DSC), thermogravimetric analysis, and hot-stage microscopy (HSM)] and spectroscopic [Fourier transform infrared (FTIR), Raman, (1) H NMR, and ultraviolet] analysis. The results show the thermal instability of these salts: the thermal dissociation leaves the starting acidic D, evidenced by the FTIR and Raman spectra inside the molten mass of the salts with M and HEM. The nature of the salt with Pz (1:1 or 1:2) and HEPy (anhydrous or hydrate polymorph), but not for the salt with HEPz and Py, depends on the polarity of the solvent used for the preparation of the salt. Incomplete dehydration of the hydrate Py and Pz salts progressively modifies the thermogram profiles and originates false information. Melting of the salts with Pp, M, and HEM could be demonstrated by HSM, but not with DSC. The difficulty of providing a description of these salts in a simple way originates doubts on the utility of a wide application of aliphatic amines to prepare pharmaceutical salts with D, whose solubility in water does not significantly differ from that of the common sodium D.

Substituted E-3-(3-indolylmethylene)-1,3-dihydroindol-2-ones with antitumor activity. In depth study of the effect on growth of breast cancer cells

The synthesis of new substituted E-3-(3-indolylmethylene)-1,3-dihydroindol-2-ones is reported. The antitumor activity was evaluated according to protocols available at the National Cancer Institute (NCI), Bethesda, MD. Structure-activity relationships are discussed. The action of selected compounds was investigated in MCF-7 breast cancer cells. The ability of these derivatives to inhibit cellular proliferation was accompanied by increased level of p53 and its transcriptional targets p21 and Bax, interference in the cell cycle progression with cell accumulation in the G2/M phase, and activation of apoptosis.

Antitumor activity of new substituted 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones and 3-(5-imidazo[2,1-b]thiadiazolylmethylene)-2-indolinones: selectivity against colon tumor cells and effect on cell cycle-related events

The synthesis of new 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones and 3-(5-imidazo[2,1-b]thiadiazolylmethylene)-2-indolinones is reported. The antitumor activity was evaluated according to the protocols available at the National Cancer Institute (NCI), Bethesda, MD. To investigate the mechanism of action of the most potent antitumor agent of this series, its effect on growth of HT-29 colon carcinoma cells was studied. Its ability to inhibit cellular proliferation was mediated by cell cycle arrest at the G2/M phase, accompanied by inhibition of ornithine decarboxylase (ODC), the limiting enzyme of polyamine synthesis, and followed by induction of apoptosis.

Antitumor activity of bis-indole derivatives

This paper reports the synthesis of compounds formed by two indole systems separated by a heterocycle (pyridine or piperazine). As a primary screening, the new compounds were submitted to the National Cancer Institute for evaluation of antitumor activity in the human cell line screen. The pyridine derivatives were far more active than the piperazine derivatives. For the study of the mechanism of action, the most active compounds were subjected to COMPARE analysis and to further biological tests including proteasome inhibition and inhibition of plasma membrane electron transport. The compound bearing the 5-methoxy-2-indolinone moiety was subjected to the first in vivo experiment (hollow fiber assay) and was active. It was therefore selected for the second in vivo experiment (human tumor xenograft in mice). In conclusion we demonstrated that this approach was successful, since some of the compounds described are much more active than the numerous, so far prepared and tested 3-indolylmethylene-2-indolinones.

Diphenidol-related diamines as novel muscarinic M4 receptor antagonists

A series of hydrochloride derivatives 2a-9a and quaternary ammonium derivatives 3b-9b of diphenidol have been synthesized and characterized in receptor binding and cellular functional assays versus human muscarinic M(1)-M(5) receptors expressed in CHO cells. Compound 8b, a methiodide derivative with a bipiperidinyl moiety and a second diphenidol framework, showed a potent and selective M(4) activity as competitive antagonist. Moreover 8b, acting as an allosteric modulator, was able to retard the dissociation rate of [(3)H]-N-methylscopolamine from CHO-M(4) cell membranes exposed to atropine. Taken together, these data suggest that 8b might open new avenues to the discovery of novel multivalent antagonists for the muscarinic receptors.

Chemiluminescent high-throughput microassay applied to imidazo[2,1-b]thiazole derivatives as potential acetylcholinesterase and butyrylcholinesterase inhibitors

The synthesis of a new series of imidazo[2,1-b]thiazole derivatives is described. They were tested as potential acetylcholinesterase and butyrylcholinesterase inhibitors by means of a chemiluminescent microassay. Although most of the new compounds did not show significant cholinesterase inhibition potency, three of them displayed selective antiacetylcholinesterase activity in the micromolar range.

Substituted E-3-(2-chloro-3-indolylmethylene)1,3-dihydroindol-2-ones with antitumor activity. Effect on the cell cycle and apoptosis

The synthesis and antitumor activity of new E-3-(2-chloro-3-indolylmethylene)1,3-dihydroindol-2-ones is described. They were studied at the National Cancer Institute, taking into consideration the 50% growth inhibitory power (pGI50), the cytostatic effect (pTGI = total growth inhibition), and the cytotoxic effect (pLC50). All the compounds were potent growth inhibitors, with mean pGI50 ranging from 5.26 to 7.72. They were also analyzed with NCI COMPARE algorithm. Further studies were dedicated to the effects on the cell cycle and apoptosis.

Synthesis and Antitumor Activity of Guanylhydrazones from 6-(2,4-Dichloro-5-nitrophenyl)imidazo[2,1-b]thiazoles and 6-Pyridylimidazo[2,1-b]thiazoles

The design and synthesis of antitumor imidazothiazole guanylhydrazones are reported. The compounds were submitted to NCI for testing. All but one were more active than methyl-GAG. A few compounds were selected for further studies in search of a possible mechanism of action. The results from these studies and a final search with the NCI COMPARE algorithm suggest that the guanylhydrazones described in this paper are acting through a novel mechanism of action.

Antitumor Activity of Substituted E-3-(3,4,5-Trimethoxybenzylidene)-1,3-dihydroindol-2-ones

The design and synthesis of anticancer E-3-(3,4,5-trimethoxybenzylidene)-1,3-dihydroindol-2-ones is reported. Strong COMPARE correlations among the cell line responses suggest that these compounds may be acting similarly through a combination of different mechanisms of action. The 5-methoxy derivative (2h) was the most active compound with a mean pGI50 of 6.34, and it is now under review by Biological Evaluation Committee of the National Cancer Institute for possible further studies.

Synthesis and chemiluminescent high throughput screening for inhibition of acetylcholinesterase activity by imidazo[2,1-b]thiazole derivatives

The synthesis of a new series of imidazo[2,1-b]thiazole derivatives is described. They were tested as acetylcholinesterase inhibitors by means of a chemiluminescent method suitable for high throughput screening. The compounds without quaternization had no appreciable inhibitory potency probably because they are poorly soluble in water. The corresponding quaternized compounds were good inhibitors with activity related to the spacer employed.

Antitumor Activity of New Substituted 3-(5-Imidazo[2,1-b]thiazolylmethylene)-2-indolinones and Study of Their Effect on the Cell Cycle

This paper reports the synthesis of a new series of 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones which were tested as potential antitumor agents at the National Cancer Institute. Two derivatives are now under review by BEC (Biological Evaluation Committee of NCI). To investigate the mechanism of action, the effect on cell cycle progression was studied by monitoring them in colon adenocarcinoma HT-29: both were able to block HT-29 in mitosis. 3-[(2,6-Dimethylimidazo[2,1-b]thiazol-5-yl)methylene]-5-chloro-2-indolinone was the most active compound.

Potential Antitumor Agents. 37. Synthesis and Antitumor Activity of Guanylhydrazones from Imidazo[2,1-b]thiazoles and from the New Heterocyclic System Thiazolo[2‘,3‘:2,3]imidazo[4,5-c]quinoline

This paper reports synthesis and antitumor activity of new guanylhydrazones from imidazo[2,1-b]thiazoles and from the new heterocyclic system thiazolo[2',3':2,3]imidazo[4,5-c]quinoline. The compounds were tested as potential antitumor agents at the National Cancer Institute. The effect of the guanylhydrazone of 2-chloro-6-(2,5-dimethoxy-4-nitrophenyl)imidazo[2,1-b]thiazole-5-carbaldehyde (41) was investigated, and it was found to be an inhibitor of Complex III of the mitochondrial respiratory chain and is able to induce apoptosis in the cell lines HT29 and HL60.

Effects of new ubiquinone-imidazo[2,1-b]thiazoles on mitochondrial complex I (NADH-ubiquinone reductase) and on mitochondrial permeability transition pore

In this work we describe the synthesis of a series of imidazo[2,1-b]thiazoles and 2,3-dihydroimidazo[2,1-b]thiazoles connected by means of a methylene bridge to CoQ(0). These compounds were tested as specific inhibitors of the NADH:ubiquinone reductase activity in mitochondrial membranes. The imidazothiazole system when bound to the quinone ring in place of the isoprenoid lateral side chain, may increase the inhibitory effect (with an IC(50) for NADH-Q(1) activity ranging between 0.25 and 0.96 microM) whereas the benzoquinone moiety seems to lose the capability to accept electrons from complex I as indicated by very low maximal velocity elicited by the compounds tested. Moreover the low rotenone sensitivity for almost all of these compounds suggests that they are only partially able to interact with the physiological ubiquinone-reduction site. The compounds were investigated for the capability of increasing the permeability transition of the inner mitochondrial membrane in isolated mitochondria. Unlike CoQ(0), which is considered a mitochondrial membrane permeability transition inhibitor, the new compounds were inducers.

N-Benzyl-2-chloroindole-3-carboxylic acids as potential anti-inflammatory agents. Synthesis and screening for the effects on human neutrophil functions and on COX1/COX2 activity

The synthesis of N-benzyl-2-chloroindole-3-carboxylic acids related to indomethacin is reported. These compounds were tested on in vitro human neutrophil activation. Some of them, more soluble in water, were tested to define the influence on prostaglandin biosynthesis via inhibition of cyclooxygenases (COX1 and COX2) by a chemiluminescent method suitable for fast screening. Several derivatives showed inhibitory effects and in some cases were more active than the parent compound.

Substituted E -3-(2-Chloro-3-indolylmethylene)1,3-dihydroindol-2-ones with antitumor activity

The synthesis and antitumor activity of a new series of E-3-(2-chloro-3-indolylmethylene)1,3-dihydroindol-2-ones is described. Several compounds were active on the primary test (three human cell lines) and entered the second level (60 human cell lines). All of them were potent growth inhibitors with GI(50) ranging from -5.32 to -7.27. Four are now under review by BEC (Biological Evaluation Committee of the NCI). The most potent antitumor derivatives were also evaluated as cardiotonic agents (in view of a possible coanthracyclinic activity). In order to find a possible mechanism of action their effects on cell cycle progression in an adenocarcinoma cell line (HT29) were tested, evidencing that these molecules are able to block HT29 in mitosis. The introduction of new substituents in the indolinone moiety while maintaining the same chloroindole portion generated interesting derivatives. 3-(2-Chloro-5-methoxy-6-methyl-3-indolylmethylene)5-hydroxy-1,3-dihydroindol-2-one was the most active of the whole series. It was more potent than vincristine against seven of the nine tumors considered. Moreover it was selective towards some cell lines such as MDA-MB-435 (breast), OVCAR-3 (ovarian) and SK-MEL-28 (melanoma). Even the introduction of a benzyl ring at the nitrogen of the chloroindole portion, gave rise to potent compounds.

Potential antitumor agents. 34.(1) Synthesis and antitumor activity of guanylhydrazones from imidazo[2,1-b]thiazoles and from diimidazo[1,2-a: 1,2-c] pyrimidine

We report the synthesis of new guanylhydrazones from imidazo[2,1-b]thiazoles and of a bis-guanylhydrazone from diimidazo[1,2-a:1,2-c]pyrimidine. The compounds were tested as potential antitumor agents at the National Cancer Institute. Two derivatives are now under review by BEC: one of these was also subjected to a test for positive inotropic activity in view of a possible coanthracyclinic activity. Tyrosine kinase receptors may be involved as molecular targets in the mechanism of action of the guanylhydrazones described.

Synthesis and antitumor activity of 1,5,6-substituted E-3-(2-chloro-3-indolylmethylene)-1,3-dihydroindol-2-ones

Synthesis and antitumor activity of new E-3-(2-chloro-3-indolylmethylene)-1,3-dihydroindol-2-ones are described. All compounds prepared were active in the primary test (three human cell lines) and entered the second level (60 human cell lines). The most active antitumor derivatives bear the same substituents in the chloroindole ring and are not CDK1 inhibitors. A COMPARE analysis showed that they could act as tubulin binders. In most cell lines, E-3-(2-chloro-5-methoxy-6-methyl-3-indolylmethylene)-1,3-dihydroindol-2-one was a growth inhibitor more potent than vincristine.

Synthesis and screening for antiacetylcholinesterase activity of (1-benzyl-4-oxopiperidin-3-ylidene)methylindoles and -pyrroles related to donepezil

The design, synthesis, and rapid evaluation of a new class of acetylcholinesterase (AChE) inhibitors related to donepezil are reported. A molecular dynamics simulation of the complex between AChE and one representative compound of the series showed a possible inhibitor binding mode in which favorable interactions are formed between the benzylpiperidinone moiety and some active-site residues. The biochemical evaluation of this newly synthesized series was performed using a chemiluminescent method suitable for high-throughput screening.

Synthesis and antitubercular activity of imidazo[2,1-b]thiazoles

A number of selected imidazo[2,1-b]thiazoles entered the screening at the Tuberculosis Antimicrobial Acquisition and Coordinating Facility (TAACF) and one of these compounds, 2-chloro-6-phenylimidazo[2,1-b]thiazole, showed antitubercular activity. On this basis we planned the synthesis of new analogues bearing a substituted ring at the 6 position. For one compound only (2-chloro-6-p-chlorophenylimidazo[2,1-b]thiazole) the 5-nitroso derivative was also prepared. The antitubercular activity of these compounds was compared with the known analogues lacking the chlorine at the 2 position. 5-Nitroso-6-p-chlorophenylimidazo[2,1-b]thiazole showed potent antitubercular activity.

Synthesis and antitumor activity of substituted 3-(5-imidazo[2,1-b]thiazolylmethylene)-2-indolinones

The synthesis of 3-(5-imidazo]2,1-blthiazolylmethylene)-2-indolinones, analogs of compounds recently published, is described. The EIZ isomerism was studied by means of nuclear Overhauser effect experiments and X-ray crystallography. All the compounds were tested as potential antitumor agents. They were also tested as potential inhibitors of cyclin-dependent kinase 1 (CDK1), in order to determine if the antitumor activity was related to this mechanism of action. The results showed that under certain substitution conditions (5-methoxy group for the indole benzene ring and 2-methyl group for the imidazothiazole system), an interesting antitumor activity was found for some compounds. From the analysis of the antitumor data, 3-1(2,6-dimethylimidazo[2,1-bJ-thiazol-5-yl)methylenel-5-methoxy-2-indolinone was the most active of the whole series.

Imidazo[2,1 -b]thiazolylmethylene- and indolylmethylene-2-indolinones: a new class of cyclin-dependent kinase inhibitors. Design, synthesis, and CDK1/cyclin B inhibition

Compounds containing a 2-indolinone moiety linked to imidazothiazole and indole fragments were studied as cyclin-dependent kinase inhibitors. The activity of all the new derivatives was tested in vitro against CDK1/cyclinB and the selectivity towards two other kinases was determined for the most promising compounds. The binding mode of one representative compound was investigated by means of a three-dimensional model of the inhibitor-CDK1 complex. The work allowed us to identify (2-chloroindolyl)methylene-2-indolinone as a new lead of a class of CDK1/cyclinB inhibitors, whose potency can be improved by the introduction of suitable variations on the basic molecular skeleton.

Potential antitumor agents. Part 29(1): synthesis and potential coanthracyclinic activity of imidazo[2,1-b]thiazole guanylhydrazones

This paper reports the synthesis of new imidazo[2,1-b]thiazole guanylhydrazones which were tested as potential antitumor agents. Three of these derivatives (those bearing a 3- or 4-nitrophenyl group) were the most potent and one of these showed a mild effect as CDK1 inhibitor. These same three derivatives were also tested as positive inotropic agents and two of them were more potent than amrinone at 10(-5) M. These two guanylhydrazones could be useful coanthracyclinic agents.