Synthesis and anti-inflammatory evaluation of 4-anilinofuro[2,3-b]quinoline and 4-phenoxyfuro[2,3-b]quinoline derivatives. Part 3

Pyrazole-promoted synthesis of pyrrolo[3,4-c] quinoline-1,3-diones in a novel diketene-based reaction

We describe the first classic example of green synthesis of pyrrolo[3,4-c]quinolones scaffolds by catalyst-free unusual reaction of diketene, isatin, and primary amines in ethanol in the presence of pyrazole as a promoter for 4 h. The whole structure of the new product was confirmed by X-ray analysis. The overall transformation involves the cleavage and generation of multiple carbon-nitrogen and carbon-carbon bonds. This report represents a simple and straightforward approach for the synthesis of pyrrolo[3,4-c]quinoline-1,3-diones, which has significant advantages like readily available precursors, non-use of toxic solvent, operational simplicity, mild conditions, good atom economy, and excellent yields; therefore it provides a green and sustainable strategy for access to a range of interesting N-containing heterocyclic compounds in medicinal and organic chemistry.

New antiparasitic derivatives of the furoquinoline alkaloids kokusaginine and flindersiamine

In this work is reported the synthesis of 16 new compounds obtained from kokusaginine and flindersiamine, the main alkaloids isolated from the bark of Balfourodendron riedelianum . The activity of the compounds against axenic cultures of Trypanosoma cruzi epimastigtotes and trypomastigotes, as well as intracellular amastigotes, is described, together with their cytotoxic activity against three different human cell lines. The synthetic strategy for the preparation of the new compounds was based on the reactivity at the position C-4 of the furoquinoline core towards nucleophiles. The new derivatives were synthesized by a Buchwald-Hartwig reaction, in most cases under green, solvent free conditions. Compounds 1c and 1e displayed better in-vitro activity against trypomastigotes than benznidazole and nifurtimox (positive controls) with IC 50 < 4 µM. In addition, both compounds were not cytotoxic activity against the three human cell lines K562 (erytroleukimia), LM2 (breast cancer) and HaCat (keratinocyte). Interestingly, when evaluated against intracellular amastigotes, compound 1c was able to significantly reduce the number of this parasite form, compared to the negative control.

Molecular modeling and nonlinear optical properties of new isostructural halogenated dihydroquinolinones

Two new isostructural halogenated dihydroquinolinones were synthesized and characterized by single crystal X-ray diffraction.

Oximes: Novel Therapeutics with Anticancer and Anti-Inflammatory Potential

Oximes have been studied for decades because of their significant roles as acetylcholinesterase reactivators. Over the last twenty years, a large number of oximes have been reported with useful pharmaceutical properties, including compounds with antibacterial, anticancer, anti-arthritis, and anti-stroke activities. Many oximes are kinase inhibitors and have been shown to inhibit over 40 different kinases, including AMP-activated protein kinase (AMPK), phosphatidylinositol 3-kinase (PI3K), cyclin-dependent kinase (CDK), serine/threonine kinases glycogen synthase kinase 3 α/β (GSK-3α/β), Aurora A, B-Raf, Chk1, death-associated protein-kinase-related 2 (DRAK2), phosphorylase kinase (PhK), serum and glucocorticoid-regulated kinase (SGK), Janus tyrosine kinase (JAK), and multiple receptor and non-receptor tyrosine kinases. Some oximes are inhibitors of lipoxygenase 5, human neutrophil elastase, and proteinase 3. The oxime group contains two H-bond acceptors (nitrogen and oxygen atoms) and one H-bond donor (OH group), versus only one H-bond acceptor present in carbonyl groups. This feature, together with the high polarity of oxime groups, may lead to a significantly different mode of interaction with receptor binding sites compared to corresponding carbonyl compounds, despite small changes in the total size and shape of the compound. In addition, oximes can generate nitric oxide. This review is focused on oximes as kinase inhibitors with anticancer and anti-inflammatory activities. Oximes with non-kinase targets or mechanisms of anti-inflammatory activity are also discussed.

Stereochemistry of the methyl-idene-bridged quinazoline-iso-quinoline alkaloid 3-{[6,7-dimeth-oxy-1-(4-nitro-phen-yl)-1,2,3,4-tetra-hydro-isoquinolin-2-yl]methyl-idene}-1,2,3,9-tetra-hydro-pyrrolo-[2,1-b]quinazolin-9-one methanol monosolvate

Two potentially bioactive fragments, namely a tricyclic quinazoline derivative with an exocyclic alkene moiety and a substituted iso-quinoline, are coupled to give 3-{[6,7-dimeth-oxy-1-(4-nitro-phen-yl)-1,2,3,4-tetra-hydro-isoquinolin-2-yl]methyl-idene}-1,2,3,9-tetra-hydro-pyrrolo-[2,1-b]quinazolin-9-one. The target product crystallizes as a methanol solvate, C29H26N4O5·CH4O, and is E configured. The alternative Z isomer would necessarily imply either considerable twist about the central double bond or very unfavourable intra-molecular contacts between sterically more demanding substituents. The main residue and the co-crystallized solvent mol-ecule aggregate to discrete pairs via a classical O-H⋯O hydrogen bond with a distance of 2.8581 (7) Å between the methanol OH donor and the quinazolinone O=C acceptor.

Novel quinoline derivatives carrying nitrones/oximes nitric oxide donors: Design, synthesis, antiproliferative and caspase-3 activation activities

Novel quinoline derivatives carrying nitrones and oxime as nitric oxide donors were prepared and characterized using different spectroscopic techniques. Nitrones can release nitric oxide in larger amounts compared to corresponding oximes. Antiproliferative screening results showed that the 2-benzylthioquinoline nitrones 6e and 6f and the 2-methylthio analogues 6g and 6h exhibited promising antiproliferative activity especially against leukemia and colon cancer cell lines. Compounds 6c, 6e, and 6f exhibited higher potency as anticancer agents compared to doxorubicin, with IC₅₀ ranging from 0.45 to 0.91 μM. A remarkable overexpression of caspase-3 protein levels was observed in cells treated with the tested compounds. Compound 6e exhibited more pre-G1 apoptosis and cell cycle arrest at the G2/M phase than in other phases. These results revealed that the tested compounds can cause programmed cell death through overexpression of caspase 3, which may be attributed to the release of nitric oxide.

Preparation and Antibacterial Activity of Some New 4-(2-Heterylidenehydrazinyl)-7-chloroquinoline Derivatives

N-(4-Substituted phenyl)acetamides, which were prepared from acetic anhydride and p-substituted anilines, were utilized as precursors for reactions to Vilsmeier-Haack reagent to form 6-substituted-2-chloroquinoline-3-carbaldehydes 3a–c. Meanwhile, a similar reagent was applied to 1-[1-(4-substituted phenyl)ethylidene]-2-phenylhydrazines as substrates, which were synthesized from phenylhydrazine hydrochloride and p-substituted acetophenones, and 1,3-diarylpyrazole-4-carbaldehydes 3d–f were observed as a result. Reactions between the aldehydes 3a–f and 7-chloro-4-hydrazinylquinoline 2, obtained from reaction of 4,7-dichloroquinoline 1 and hydrazine hydrate, formed six new hydrazone compounds, namely, 4-{2-[(6-substituted-2-chloroquinolin-3-yl)methylidene]hydrazinyl}-7-chloroquinolines 4a–c and 4-(2-{[3-(4-substituted phenyl)-1-phenyl-1H-pyrazol-4-yl]methylene}hydrazinyl)-7-chloroquinolines 4d–f. The chemical structures of all synthesized compounds were elucidated by the analysis of IR, 1H, 13C-NMR, and HRMS spectral data. Additionally, all of the synthesized hydrazones were evaluated in terms of cytotoxic activity against four strains of bacteria and four strains of fungus at several concentrations of substrates. As a result, three of them, 4a–c, possess the good ability as growth inhibitor of Bacillus subtilis and Aspergillus niger at the concentration of 25 μg/mL and 50 μg/mL, respectively, while compound 4e only shows a cytotoxic activity against Aspergillus niger at the concentration of 25 μg/mL.

Synthesis of thieno[2,3-c]acridine and furo[2,3-c]acridine derivatives via an iodocyclization reaction and their fluorescence properties and DFT mechanistic studies

In this paper, we report the novel synthesis of thieno[2,3-c]acridine and furo[2,3-c]acridine derivatives via intramolecular iodocyclization reaction. The thieno[2,3-c]acridine derivatives exhibited blue fluorescence in hexane.

Synthesis of pyrrolo[3,4-c]quinoline-1,3-diones: a sequential oxidative annulation followed by dehydrogenation and N-demethylation strategy

A synthetic strategy for pyrrolo[3,4-c]quinoline-1,3-diones via oxidative annulation followed by DDQ mediated dehydrogenation and N-demethylation.

Discovery of Indeno[1,2-c]quinoline Derivatives as Potent Dual Antituberculosis and Anti-Inflammatory Agents

A series of indeno[1,2-c]quinoline derivatives were designed, synthesized and evaluated for their anti-tuberculosis (anti-TB) and anti-inflammatory activities. The minimum inhibitory concentration (MIC) of the newly synthesized compound was tested against Mycobacterium tuberculosis H₃₇R_V. Among the tested compounds, (E)-N′-[6-(4-hydroxypiperidin-1-yl)-11H-indeno[1,2-c]quinolin-11-ylidene]isonicotino-hydrazide (12), exhibited significant activities against the growth of M. tuberculosis (MIC values of 0.96 μg/mL) with a potency approximately equal to that of isoniazid (INH), an anti-TB drug. Important structure features were analyzed by quantitative structure–activity relationship (QSAR) analysis to give better insights into the structure determinants for predicting the anti-TB activity. The anti-inflammatory activity was induced by superoxide anion generation and neutrophil elastase (NE) release using the formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLF)-activated human neutrophils method. Results indicated that compound 12 demonstrated a potent dual inhibitory effect on NE release and superoxide anion generation with IC₅₀ values of 1.76 and 1.72 μM, respectively. Our results indicated that compound 12 is a potential lead compound for the discovery of dual anti-TB and anti-inflammatory drug candidates. In addition, 6-[3-(hydroxymethyl)piperidin-1-yl]-9-methoxy-11H-indeno[1,2-c]quinolin-11-one (4g) showed a potent dual inhibitory effect on NE release and superoxide anion generation with IC₅₀ values of 0.46 and 0.68 μM, respectively, and is a potential lead compound for the discovery of anti-inflammatory drug candidates.

Convenient one-step synthesis of pyrrolo[3,4-c]quinolin-1-ones via TMSCl-catalyzed cascade reactions of isatins and β-enamino ketones

A series of pyrrolo[3,4-c]quinolin-1-ones were afforded by TMSCl-catalyzed isatins and β-enamino ketones in high yields under mild conditions.

A direct synthetic route to fused tricyclic quinolones from 2,3-diaminoquinolin-4(1H)one

Fused tricyclic heterocycles are useful compounds in many areas of chemistry. In this study, 2,3-diaminoquinolin-4(1

Quinoline-Based Compound BPIQ Exerts Anti-Proliferative Effects on Human Retinoblastoma Cells via Modulating Intracellular Reactive Oxygen Species

Retinoblastoma (Rb) is the most common primary intraocular malignant tumor of childhood. It is important to develop the strategy for Rb treatment. We have tested a quinolone derivative 2,9-bis[2-(pyrrolidin-1-yl)ethoxy]-6-{4-[2-(pyrrolidin-1-yl)ethoxy]phenyl}-11H-indeno[1,2-c]quinolin-11-one (BPIQ) for its anti-cancer effects against Rb via cultured human Rb cell line Y79. Our results showed that BPIQ significantly inhibits cell growth of Y79. Furthermore, the flow cytometer-based assays and Western blotting showed that BPIQ induces the apoptosis of Y79 via increasing the level of reactive oxygen species (ROS). Besides, the activation of γH2AX, a DNA damage sensor in human Y79 cells was also observed, indicating the potential of BPIQ for causing DNA damage of Rb cells. On the contrary, BPIQ-induced apoptosis of Y79 cells was attenuated significantly by N-acetyl-L-cysteine (NAC), an ROS scavenger. The results of Western blot showed that BPIQ down-regulates the levels of anti-apoptotic proteins Bcl-2, survivin and XIAP while up-regulates the pro-apoptotic proteins Bad, Bax and Bid. Our present study demonstrated the anti-proliferative effect of BPIQ in human Y79 cells. The inhibitory effect of BPIQ on the proliferation of Y79 cells is, at least, partly mediated by the regulation of ROS and DNA damage pathway. In conclusion, BPIQ may provide an alternative option in the chemotherapeutics or chemoprevention on the Rb therapy in the future.

Chemistry of Phosphorus Ylides: Part 41 Synthesis of Antimicrobial Agents from the Reaction of Aminoantipyrine, Coumarin- and Quinoline-carbaldehyde with Phosphacumulene and Phosphaallene Ylides

Pyrrolo-pyrazoles were obtained from the reaction between phosphacumulenes and aminoantipyrine, while the reaction with the phosphaallene (hexaphenylcarbodiphosphorane ylide) afforded the azaphosphole and pyrazolo-phosphanylidene. The aminocoumarin carbaldehyde gave the chromeno-phosphanylidene and the chromeno-pyridinone, when it was allowed to react with phosphacumulenes. The reaction of chloroquinoline carbaldehyde with the phosphacumulenes, gave chloroquinoline phosphanylidenecyclobutane, while the reaction with phosphaallene resulted in the formation of oxaphosphetane, phosphanylidene ethenyl- and oxaphosphetyl-quinoline. The structure of cyclobutanedione was confirmed by X-ray crystallography. The antimicrobial activity of the new compounds is also reported.

An efficient access to the synthesis of novel 12-phenylbenzo[6,7]oxepino[3,4-b]quinolin-13(6H)-one derivatives

An efficient access to the tetracyclic-fused quinoline systems, 12-phenylbenzo[6,7]oxepino[3,4-b]quinolin-13(6H)-one derivatives 4a–l, is described, involving the intramolecular Friedel–Crafts acylation reaction of 2-(phenoxymethyl)-4-phenylquinoline-3-carboxylic acid derivatives 3a–l aided by the treatment with PPA (polyphosphoric acid) or Eaton’s reagent. The required starting compound (2) was obtained by Friedländer reaction of 2-aminobenzophenone (1) with 4-chloroethylacetoacetate by using CAN (cerium ammonium nitrate, 10 mol %) as catalyst at room temperature. The substrates 3a–l were prepared through one-pot reaction of ethyl 2-(chloromethyl)-4-phenylquinoline-3-carboxylate (2) and substituted phenols. Our developed strategy, involving a three-step route, offers easy access to tetracyclic-fused quinoline systems in short reaction times, and the products are obtained in moderate to good yields.

Identification of benzofuro[2,3-b]quinoline derivatives as a new class of antituberculosis agents

A series of 11-alkoxylated and 11-aminated benzofuro[2,3-b]quinoline derivatives were designed, synthesized, and evaluated for their anti-TB and cytotoxic activities. The known 11-chlorobenzofuro[2,3-b]quinoline (3) was synthesized in a single step from anthranilic acid and 2-coumaranone in phosphorus oxychloride in 51% yield for the first time. Treatment of 3 with alcohols and amines gave 11-alkoxylated and 11-aminated benzofuro[2,3-b]quinoline derivatives respectively, which were evaluated for their anti-TB and cytotoxic activities. Our results indicated that 11-arylaminated derivatives were more active than their respective 11-aryloxylated isosteric isomers against Mycobacterium tuberculosis. Among the tested compounds, 11-methoxybenzofuro[2,3-b]quinoline (4), 11-methylamino- benzofuro[2,3-b]quinoline (9), and 11-dimethylaminobenzofuro[2,3-b]quinoline (14) exhibited significant activities against the growth of M. tuberculosis (MIC values of <0.20 microg/mL) and low cytotoxicities against VERO cell with IC(50) values of 11.77, 5.55, and >30.00 microg/mL respectively. The selectivity index (SI=IC(50)/MIC) for 4, 9, and 14 was greater than 58.85, 27.75, and 150 respectively.