Synthesis and antitumor activity of model cyclopentene-[g]annelated isoindigos

A set of cyclopenten-[g]annelated isoindigos (5a-g) has been prepared and tested for their in vitro antiproliferative activities against MCF-7 and HL60 cells. Among, the N-1-methyl-5'-nitro derivative (5g) displayed the highest activity against HL60 cells (IC50 = 67 nM) and acted as the most potent Flt3 inhibitor. Compounds 5d-g exhibited moderate activity against MCF-7 (IC50 = 50-80 μM).

Thermodynamic control synthesis of spiro[oxindole-3,3'-pyrrolines] via 1,4-dipolar cycloaddition utilizing imidazo[1,5-a]quinoline

A series of novel 2-(quinolin-2-yl)-spiro[oxindole-3,3'-pyrrolines] were synthesized by one-pot three-component reaction involving dimethyl acetylenedicarboxylate, 1-phenylimidazo[1,5-a]quinoline and N-alkylisatins in chloroform at ∼60 °C for 24 h. Structures of these new spiro derivatives were deduced from HRMS and NMR spectral data. A plausible mechanism for the observed thermodynamic control pathway is presented herewith. Interestingly, the spiro adduct, derived from 5-chloro-1-methylisatin, exhibited excellent antiproliferative activity on MCF7, A549 and Hela human cell lines (IC₅₀ ≃ 7 μM).

Thiophene ring-opening reactions VI. Attempted cyclization towards [fused]-tricyclic system involving a thiolate anion and suitably located electrophilic carbon

Model α-chloro-β-nitrothieno[2,3-c]pyridazines incorporating N1-(aryl) entity appended with ortho-methoxycarbonyl or trifluoromethyl group were prepared via intramolecular cyclization of their respective N-arylhydrazone precursors. Interaction of these substrates with N'-(p-fluorophenyl)benzothiohydrazide, in the presence of NEt₃, furnished the respective 1,3,4-thiadiazoline-pyridazine thiolate hybrids that were S-methylated to produce the corresponding "sulfanyl" derivatives. Their structures were deduced from spectral data, and confirmed by single-crystal X-ray diffraction.

New Trends in 1,4-Dipolar Cycloaddition Reactions. Thermodynamic Control Synthesis of Model 2'-(isoquinolin-1-yl)-spiro[oxindole-3,3'-pyrrolines]

Background:

A direct synthesis of functionalized spiro[oxindole-3,3'-pyrrolines] is achieved via thermodynamic control (~60 oC), three-component 1,4-dipolar cycloaddition reaction involving 3-phenylimidazo[5,1-a]isoquinoline, dimethyl acetylenedicarboxylate and N-alkylisatins. Methods: Conversely, this one-pot reaction furnished, upon conduction at 25–38 oC, the expected 1,3-oxazepino[7,6-b]indoles as the main kinetic control products. The calculated energy of the optimized molecular structures of model spiro-oxindole and its isomeric oxazepino-indole indicate that spiro-oxindole is more stable by 76.1 kJ/mol.

Results:

The structures of the synthesized spiro adducts were evidenced from NMR and MS spectral data and further confirmed by single-crystal X-ray diffraction. Characteristic features of the spiro-oxindoles are displaced in their 13C-spectra as diagnostic signals at ~53 and ~70 ppm assigned, respectively, to the spiro carbon-3 and sp3 CH-2' of the pyrroline ring.

Conclusion:

This unprecedented thermally induced pathway in 1,4-dipolar cycloaddition, utilizing imidazo[5,1-a]isoquinoline and related congeners would serve as a new route towards the synthesis of spiro[oxindole-3,3'-pyrrolines] that is a class of diverse biological activities. An insight into the thermodynamic control pathway is presented.

Thiophene ring-opening reactions IV. Facile generation of novel ethyl 4-hydroxy-6-thioxonicotinate─1,3,4- thiadiazoline hybrids

:

A set of triethylammonium 4-oxo-6-pyridinethiolate–1,3,4-thiadiazoline hybrids (3a-e) were prepared via the reaction of ethyl 2-chloro-6-cyclopropyl-3- nitro-4-oxothieno[2,3-b]pyridine- 5-carboxylate (2) with the appropriate thiobenzoyl- hydrazide (1a-e) in acetonitrile and triethylamine. These hybrids were readily converted, under neutral mild conditions, into the corresponding 4-hydroxy-6-thioxopyridine –thiadiazoline hybrids (5a-e). The structures of the latter set are supported by HRMS, 1H NMR and 13C NMR spectral data and further confirmed by single-crystal X-ray diffraction studies. Alkylation of these hybrids in the presence of triethylamine occurred exclusively at the 6-thioxosulfur, yielding the respective 6-sulfanyl derivatives (6a-c).

Design, Synthesis and Characterization of Novel Isoxazole Tagged Indole Hybrid Compounds

Sixteen new isoxazole tagged indole compounds have been synthesized via copper (I) catalyzed click chemistry of the aryl hydroxamoyl chloride and an indole containing alkyne moiety. The chemical structure of the synthesized compounds has been established using various physicochemical techniques. X-ray single crystal analysis of Ethyl 1-((3-phenylisoxazol-5-yl) methyl)-1H-indole-2-carboxylate (8a) has been analyzed. All compounds were tested for their antibacterial and anticancer activities. The activities for the new compounds were weak against both bacterial strains and the cancer cell lines.

Utilization of 1-phenylimidazo[1,5-a]quinoline as partner in 1,4-dipolar cycloaddition reactions

A Selected set of 2-(quinolin-2-yl)-1,3-oxazepino[7,6-b]indoles 4a–d and dihydroacenaphtho[1,2-f][1,3]oxazepine 5 have been prepared via 1,4-dipolar cycloaddition reaction involving 1-phenylimidazo[1,5-a]quinoline, dimethyl acetylenedicarboxylate, and N-(substituted)isatins or acenaphthoquinone. Structures of the new heterocycles 4a–d and 5 are supported by NMR and HRMS spectral data, and confirmed by single-crystal X-ray crystallography for 4c and 5.

Bis-heterocycles. Part I: tetrahydro-5,5′- bi(1,2,4-triazin-6-ones)

Selected sets of tetrahydro-5,5′-bi(1,2,4-triazines) (1–3) appended with acetyl, benzoyl, and ester moieties at C-3 position and N-1 (p-substituted)phenyl ring have been prepared and characterized by spectral (IR, NMR, MS) data and X-ray diffraction for compound 3a. Their synthesis was achieved in high yield via the reaction of diethyl aminomalonate with various N-(aryl)hydrazonoyl chlorides in the presence of triethylamine.

Fused thia-heterocycles via isothiocyanates. Part II. A convenient synthesis of some new thieno[2,3-b]thiopyran-4-one derivatives

A facile synthesis of some methyl 5-(arylamino)-4-oxothieno[2,3-b]thiopyran-6-carboxylates 6a–g is achieved via direct reaction of deprotonated methyl 3-(2,5-dichlorothien-3-yl)-3-oxopropanoate with aryl isothiocyanates in anhydrous tetrahydrofuran (THF) under reflux. Upon saponification of 6a,b, the ester group is eliminated, most logically via decarboxylation of the presumably-formed carboxyl group. Structures of the new compounds 6a–g and 7a,b are supported by microanalytical and spectral [NMR, MS electron impact (EI) and HRMS] data.

Heterocycles [h]-fused onto 4-oxoquinoline-3-carboxylic acid. Part XII: synthesis of 5-fluoro-7-oxodihydo[1,3,4]thiadiazino [5,6-h]quinoline-8-carboxylic acid and ester

Direct interaction of dithizone with 7-chloro-6- fluoro-8-nitro-4-oxoquinoline-3-carboxylic acid or with its ester delivered the corresponding novel 1,3,4-thiadiazino [5,6-h]quinoline 3-carboxylic acid, or its ester which was then hydrolyzed to the respective acid. Structures of the latter tricyclic hybrids were deduced from analytical and spectral data and confirmed by single crystal X-ray structure determination of the ester derivative. The free acid showed moderate activity against Staphylococcus aureus with a MIC value of 25 μg mL−1.

Synthesis and antibacterial activity of N1-(carbazol-3-yl)amidrazones incorporating piperazines and related congeners

A selected set of N1-(4-chloro-9-ethylcarbazol-3-yl)amidrazones (7a–n) has been synthesized by reacting the respective hydrazonoyl chloride 5 derived from 3-amino-9-ethylcarbazole (3), with an appropriate sec-cyclic amine (6a–n) in ethanol in the presence of triethylamine. Unexpectedly, aromatic ring chlorination occurred at C-4 of 3 during its conversion to 6 as evidenced by analytical and spectral data and further confirmed by single crystal X-ray structure determination of the amidrazone 7n. Compounds 7a–n were tested for their in vitro antibacterial activity. Among the tested bacterial strains, methicillin-resistant Staphylococcus aureus was the most susceptible to 7f and Bacillus cereus to 7b both with a minimum inhibitory concentration value of 1.56 µg mL−1. Compounds 7c, 7f, and 7h could be useful as lead structures for further development of new antibacterial agents against Gram-positive and Gram-negative pathogens.

The Pyridone-Annelated Isoindigo (5‘-Cl) Induces Apoptosis, Dysregulation of Mitochondria and Formation of ROS in Leukemic HL-60 Cells

Background/Aims: In our quest to develop an isoindigo with improved efficacy and bioavailability, we recently synthesized a series of novel substituted pyridone-annelated isoindigo and evaluated their antiproliferative effects. We identified the compound [(E)-1-(5'-Chloro-2'-oxoindolin-3'-ylidene)-6-ethyl-2,3,6,9-tetrahydro-2,9-dioxo-1H-pyrrolo[3,2-f] quinoline-8-carboxylic acid], abbreviated as 5'-Cl, which shows selective antiproliferative activities against various cancer cell lines mediated through apoptosis. Here we have investigated the molecular mechanisms underlying the apoptotic activity of 5'-Cl in the human promyelocytic leukemia HL-60 cells. Methods: We employed different methods to determine the apoptotic pathways triggered by 5'-Cl in HL-60 cells, using flow cytometry, nuclear staining, caspases activation, mitochondria functioning, generation of reactive oxygen species (ROS) and Western blotting techniques. Results: Low concentrations (1-8 µM) of 5'-Cl inhibited the growth of HL-60 cells in a dose and time-dependent manner. Cytotoxicity of this compound is found to be mediated by a caspase-dependent apoptosis. Also, there were indications of caspase independent apoptosis as z-VAD-FMK failed to fully rescue the cells from 5‘-Cl-induced apoptosis. In addition, the compound triggered generation of Reactive Oxygen Species (ROS), caused depolarization of the mitochondrial inner membrane, decreased the level of cellular ATP, modulated the expression and phosphorylation of Bcl-2 leading to loss of its association with Bax and increased the release of cytochrome c to the cytosol of treated cells. The effects of 5‘-Cl on mitochondria and apoptosis were substantially blocked in the presence of a combination between z-VAD-FMK and either of the ROS scavenger N-acetyl-L-cysteine (NAC) or pyrrolidine dithiocarbamate (PDTC). Conclusion: We demonstrated that the growth inhibitory effects of 5'-Cl in HL-60 cells involve multiple pathways of apoptosis and dysregulation of mitochondrial functions.

The anticancer activity of the substituted pyridone-annelated isoindigo (5'-Cl) involves G0/G1 cell cycle arrest and inactivation of CDKs in the promyelocytic leukemia cell line HL-60

BACKGROUND/AIMS

The antileukemic potential of isoindigos make them desired candidates for understanding their mechanism of action. We have recently synthesized a novel group of pyridone-annelated isoindigos and identified the derivative 5'-Cl that is cytotoxic to various cancer cell lines. In the present study, we analyzed the effect of this compound on cell cycle of the promyelocytic leukemia cell line HL-60.

METHODS

HL-60 cells were treated with 5'-Cl and its effect on cell cycle stages were determined by flow cytometry. Expression of cyclins, cyclin dependent kinases (CDKs) and cyclin kinase inhibitors (CKIs) were determined by Western blotting, and activation of CDKs was studied using kinase assays.

RESULTS

5'-Cl remarkably arrested cell cycle in HL-60 cells at the G0/G1 phase in a dose and time-dependent manner. Furthermore, 5'-Cl treatment significantly inhibited expression of D-cyclins, CDK2 and CDK4 and suppressed phosphorylation of the retinoblastoma protein Rb, whereas it increased the level of CKI p21. Molecular modelling experiments show that 5'-Cl may compete with ATP for binding to the catalytic subunit of CDK2 and CDK4 that could lead to inhibition of these enzymes. Indeed, 5'-Cl inhibited the kinase activity of CDK2 and CDK4 both in cell free systems and in treated cells. 5'-Cl also inhibited cell cycle progression in several other tumor cell lines.

CONCLUSION

We demonstrate the potent inhibitory effects of 5'-Cl on HL-60 cells could be mediated by arresting cells in the G0/G1 phase.

Synthesis and biological evaluation of new pyridone-annelated isoindigos as anti-proliferative agents

A selected set of substituted pyridone-annelated isoindigos 3a-f has been synthesized via interaction of 5- and 6-substituted oxindoles 2a-f with 6-ethyl-1,2,9-trioxopyrrolo[3,2-f]quinoline-8-carboxylic acid (1) in acetic acid at reflux. Among these isoindigos, the 5'-chloro and 5'-bromo derivatives 3b and 3d show strong and selective antiproliferative activities against a panel of human hematological and solid tumor cell-lines, but not against noncancerous cells, suggesting their potential use as anticancer agents. In all the tested cell lines, compound 3b was a 25%-50% more potent inhibitor of cell growth than 3d, suggesting the critical role of the substitution at 5'-position of the benzo-ring E. The IC50 values after 48 hours incubation with the 5'-chloro compound 3b were 6.60 µM in K562, 8.21 µM in THP-1, 8.97 µM in HepG2, 11.94 µM in MCF-7 and 14.59 µM in Caco-2 cancer cells, while the IC50 values in noncancerous HEK-293 and L-929 were 30.65 µM and 40.40 µM, respectively. In addition, compound 3b induced higher levels apoptosis in K562 cells than 3d, as determined by annexin V/7-AAD flowcytometry analysis. Therefore, further characterization of the antitproliferative mechanisms of compounds 3b and 3d may provide a novel chemotherapeutic agents.

Synthesis of 6-Ethyl-1,2,9-trioxopyrrolo[3,2-f ]quinoline-8-carboxylic Acid

Interaction of 6-amino-1-ethyl-4-oxoquinoline-3-carboxylic ester (7) with chloral hydrate and hydroxylamine hydrochloride gave the corresponding isonitroso-acetamido derivative 8 which, upon treatment with concentrated sulfuric acid, was converted regioselectively into 1,2,9-trioxopyrrolo[ 3,2- f ]quinoline-8-carboxylic acid (3). This novel tricyclic system was isolated in good yield as a stable hydrate 3H. Structural assignments of the new compounds are based on microanalytical and spectral (MS and NMR) data

Synthesis and Properties of Some New 1,4-Dihydrothieno[3,2-e][1,2,4]triazepin-5-ones

Methyl 3-aminothiophene-2-carboxylate reacts readily, in the presence of triethylamine, with hydrazonoyl chlorides (7a - c) to afford good yields of the corresponding N-arylamidrazones (8a - c). The latter acyclic adducts undergo, in the presence of t-BuOK/t-BuOH, cyclocondensation accompanied by elimination of the acetyl group present in 8, to deliver the respective thieno-1,3,4-triazepin- 5-ones 10a - c.

X-Ray Structure Analysis of Substituted 5-(2,3-Dihydro-7-benzofuryl)- 1-methylpyrazolo[4,3-d]pyrimidin-7-one (Biagra)

X-ray crystal structure data for the title compound dihydrobenzofuryl-pyrazolo[4,3-d]pyrimidin- 7-one (2) reveal that the two bicyclic heteroaryl systems are virtually coplanar along their joint C (5)-C(11) axis with an interplanar angle of 1.13°. This planar conformation is held by an intramolecular hydrogen bond between the pyrimidinone N(6)-H and the O(17) lone pair of the dihydrobenzofuryl moiety. The spatial interatomic distance for O(17)-N(6), determined as 2.04 Å, favours this H-bridge.

Synthesis and Chiroptical Properties of Some N-(2-Chloro-7-cyclopropyl-4,7-dihydro-4-oxo-thieno[2,3-b]pyridine-5-carbonyl) L-α-Amino Esters

A series of N-(2-chloro-7-cyclopropyl-4,7-dihydro-4-oxothieno[2,3-b]pyridine-5-carbonyl)-L-α-amino esters (5 ) have been prepared via the respective thieno[2,3-b]pyridinyl-5-carbonyl chloride (4). The CD spectra of the L-aliphatic (5a -d ) and L-aromatic (5e-g) a-amino acid derivatives display, in organic solvents, sign inversion of the measured Cotton effect (CE) bands. This chiroptical behaviour is probably associated with differences in conformational isomerism of either set. MS and NMR spectral data of the title compounds are presented.

Notizen: New Colchicine and Homoaporphine- N-Oxide Alkaloids from Colchicum Ritchii: The First Homoaporphine TV-Oxide Found in Nature

From Colchicum ritchii R.Br (Liliaceae) of Jordanian origin, the new colchicine-type alkaloid (-)-O -methylspeciosine (1), the known alkaloid (-)-speciosine (2) and two new homoaporphine- N-oxides are isolated and characterized: (+)-kreysigine-N-oxide (5) and (+)-szovitsamine-N-oxide (6). Additinally, two photoisomers of the cholchicine alkaloids are identified after their isolation and their 1H and 13C NMR data reinvistigated: β-lumicornigerine (3) and β-lumidemecolcine (4).

Bischler-Napieralski Synthesis of Some New Pyrazole-Fused β-Carbolines

3-(4-Acylaminopyrazol-5-yl)-4-methylindoles (13a,b), under Bischler-Napieralski reaction conditions, undergo cyclization at the pyrrolic carbon-2 with ultimate formation of the corresponding pyrazolo[3,4:5′,6′]pyrido[3,4-b]indoles (14a,b) as evidenced by crystal structure analysis of 14a.

Synthesis and Antitumor Activity of Some N2-(Thien-3-yl)amidrazones

A set of new N2-(thien-3-yl)amidrazones (-h) incorporating N-piperazines and related congeners has been synthesized by reacting the hydrazonoyl chloride 4(derived from 3-aminothiophene- 2-carboxylate) with the appropriate sec-cyclic amine. The antitumor activity of these compounds was evaluated on breast cancer (MCF-7) and leukemic (K562) cell lines by a cell viability assay utilizing the tetrazolium dye (MTT). The amidrazone 6d encompassing the N-piperazine moiety, was the most active against MCF-7 and K562 with IC50 of 7.28 and 9:91 μM, respectively.

Quantum Hall effect in hydrogenated graphene

The quantum Hall effect is observed in a two-dimensional electron gas formed in millimeter-scale hydrogenated graphene, with a mobility less than 10  cm2/V·s and corresponding Ioffe-Regel disorder parameter (k(F)λ)(-1) ≫ 1. In a zero magnetic field and low temperatures, the hydrogenated graphene is insulating with a two-point resistance of the order of 250h/e2. The application of a strong magnetic field generates a negative colossal magnetoresistance, with the two-point resistance saturating within 0.5% of h/2e2 at 45 T. Our observations are consistent with the opening of an impurity-induced gap in the density of states of graphene. The interplay between electron localization by defect scattering and magnetic confinement in two-dimensional atomic crystals is discussed.

Endovascular therapy for patients with renal angiomyolipoma presenting with retroperitoneal haemorrhage

We report our experience treating four patients with acutely bleeding angiomyolipoma (AML) of sizes between 4 and 12 cm who were managed with endovascular embolisation with a mean follow-up of 10 months. In our case series, we demonstrate that endovascular embolisation in the acute setting for bleeding AMLs is a viable treatment option. AML should be in the differential diagnosis of acutely bleeding renal masses, even when there is no fat assessed by computed tomography (CT) imaging in the renal mass.

Differential use of anhydropyranosides for enantiopure routes to bis-gamma-butyrolactones: a new approach to the frameworks of antibiotic and anticancer agents isoavenaciolide and ethisolide

Regio- and chemoselective syntheses of enantiopure bis-furanoids are described. These compounds are chirons for several families of bioactive natural products, including isoavenaciolide and ethisolide. Reaction of a 3,4-epoxy pyran with beta-ketoester dianions delivers substituted pyranosides in high yield. Cyclization then yields fused furan-pyran intermediates. Oxidation, deprotection, and rearrangement lead to bis-furanoids that bear the essential framework and stereochemistry of ethisolide and isoavenaciolide.

Facile synthesis of some novel pyrido[3',2':4,5]thieno[2,3-b][1,4]thiazine-8-carboxylic acids

Model tetrahydropyrido[3',2':4,5]thieno[2,3-b][1,4]thiazines 9a-c were synthesized via reductive lactamization, using sodium dithionite, of the respective 2-[(carboxyalkyl)thio]-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acids 7a-c. The latter derivatives were made via interaction of 2-chloro-7-cyclopropyl-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acid (6) with each of alpha-mercaptoacetic, alpha-mercaptopropionic, and alpha-mercaptosuccinic acids and triethylamine in aqueous acetone at room temperature. The structures of 7a-7c and 9a-9c are supported by microanalytical and spectral (IR, MS, NMR) data. Compounds 9a and 9c showed potent inhibitory activity against the IGROV1 (Ovarian Cancer) cell line.

A new eudesmane type sesquiterpene from Inula viscosa

Investigation of Inula viscosa of Jordanian origin afforded the new sesquiterpene 1beta-hydroxyilicic acid in addition to the known 2beta-hydroxyilicic acid.

The chemical constituents of Capparis spinosa of Jordanian origin

Investigation of Capparis spinosa of Jordanian origin lead to isolation of two new compounds beta-sitosterylglucoside-6'-octadecanoate (1) and 3-methyl-2-butenyl-beta-glucoside (2). Linked Scan MS measurements were used to propose a mass fragmentation pattern for the alkaloid Cadabicine isolated here for the second time from nature.

New sesquiterpenoids from the jordanian medicinal plant inula viscosa

Four new and 14 known compounds have been isolated from Inula viscosa of Jordanian origin. The new isolates are 11(13)-eudesmen-12-oic acids, 3beta-hydroxyilicic acid (1), 3alpha-hydroxy-epi-ilicic acid (2), 2alpha-hydroxyilicic acid (3) and 9beta-hydroxy-2-oxoisocostic acid (4).