Microwave prompted multigram synthesis, structural determination, and photo-antiproliferative activity of fluorinated 4-hydroxyquinolinones

Novel Multi-Target Agents Based on the Privileged Structure of 4-Hydroxy-2-quinolinone

In this work, the privileged scaffold of 4-hydroxy-2quinolinone is investigated through the synthesis of carboxamides and hybrid derivatives, as well as through their bioactivity evaluation, focusing on the ability of the molecules to inhibit the soybean LOX, as an indication of their anti-inflammatory activity. Twenty-one quinolinone carboxamides, seven novel hybrid compounds consisting of the quinolinone moiety and selected cinnamic or benzoic acid derivatives, as well as three reverse amides are synthesized and classified as multi-target agents according to their LOX inhibitory and antioxidant activity. Among all the synthesized analogues, quinolinone-carboxamide compounds 3h and 3s, which are introduced for the first time in the literature, exhibited the best LOX inhibitory activity (IC50 = 10 μM). Furthermore, carboxamide 3g and quinolinone hybrid with acetylated ferulic acid 11e emerged as multi-target agents, revealing combined antioxidant and LOX inhibitory activity (3g: IC50 = 27.5 μM for LOX inhibition, 100% inhibition of lipid peroxidation, 67.7% ability to scavenge hydroxyl radicals and 72.4% in the ABTS radical cation decolorization assay; 11e: IC50 = 52 μM for LOX inhibition and 97% inhibition of lipid peroxidation). The in silico docking results revealed that the synthetic carboxamide analogues 3h and 3s and NDGA (the reference compound) bind at the same alternative binding site in a similar binding mode.

BiCl3-catalyzed green synthesis of 4-hydroxy-2-quinolone analogues under microwave irradiation

Traditional chemical synthesis, which involves the use of dangerous protocols, hazardous solvents, and toxic products and catalysts, is considered environmentally inappropriate and harmful to human health. Bearing in mind its numerous drawbacks, it has become crucial to substitute conventional chemistry with green chemistry which is safer, more ecofriendly and more effective in terms of time and selectivity. Elaborating synthetic protocols producing interesting new compounds using both microwave heating and heterogeneous non-toxic catalysts is acknowledged as a green approach that avoids many classical chemistry-related problems. In the current study, β-enaminones were used as precursors to the synthesis of modified 4-hydroxy-2-quinolone analogues. The synthesis was monitored in a benign way under microwave irradiation and was catalyzed by bismuth chloride III in an amount of 20 mol%. This method is privileged by using a non-corrosive, non-toxic, low-cost and available bismuth Lewis acid catalyst that has made it more respectful to the demands of green chemistry. The synthesized compounds were obtained in moderate to good yields (51-71%) and were characterized by 1H, 13C NMR, and IR spectroscopy as well as elemental analysis. Compound 5i was subjected to a complete structural elucidation using the X-ray diffraction method, and the results show the obtention of the enolic tautomeric form.

Sequential Oxidative Fragmentation and Skeletal Rearrangement of Peroxides for the Synthesis of Quinazolinone Derivatives

For the first time, the sequential reaction of peroxyoxindole that involves base-promoted oxidative fragmentation to isocyanate formation and primary amine or amino alcohol accelerated skeletal rearrangement to synthesize exo-olefinic-substituted quinazolinone or oxazoloquinazolinone is reported. The advantages of this new reaction include a broad substrate scope and transition-metal-free and room-temperature conditions. The formation of the isocyanate as a key intermediate that accelerates oxidative skeletal rearrangement has been confirmed by trapping experiments and spectroscopic evidence.

Novel Amino Acid Derivatives of Quinolines as Potential Antibacterial and Fluorophore Agents

A new series of amino acid derivatives of quinolines was synthesized through the hydrolysis of amino acid methyl esters of quinoline carboxamides with alkali hydroxide. The compounds were purified on silica gel by column chromatography and further characterized by TLC, NMR and ESI-TOF mass spectrometry. All compounds were screened for in vitro antimicrobial activity against different bacterial strains using the microdilution method. Most of the synthesized amino acid-quinolines show more potent or equipotent inhibitory action against the tested bacteria than their correspond esters. In addition, many of them exhibit fluorescent properties and could possibly be utilized as fluorophores. Molecular docking and simulation studies of the compounds at putative bacterial target enzymes suggest that the antimicrobial potency of these synthesized analogues could be due to enzyme inhibition via their favorable binding at the fluoroquinolone binding site at the GyrA subunit of DNA gyrase and/or the ParC subunit of topoisomerase-IV.

Greening Solid-Phase Organic Synthesis: Environmentally Conscious Synthesis of Pharmaceutically Relevant Privileged Structures 5,6-Dihydropyridin-2(1H)-ones and Quinolin-2(1H)-ones

Solid-phase organic synthesis (SPOS) is a very efficient methodology for the synthesis of diverse organic molecules, particularly exploited in drug discovery. Here, we present the transformation of the traditional SPOS to an eco-friendlier methodology on examples of pharmacologically relevant privileged structures 5,6-dihydropyridin-2(1H)-ones and quinolin-2(1H)-ones. The green approach is primarily based on the utilization of environmentally friendly solvent 2-MeTHF in all steps of the synthesis. Target heterocycles were synthesized by extending our previously published synthesis of five-membered tetramic acid analogues to six-membered cycles. The crucial step of the synthesis is cyclization via nonclassical Wittig olefination of resin-bound esters. Traditional and green protocols provided comparable results with respect to purity and yield of products, thus opening the way for greener access to a variety of diverse heterocycles.

"2-Amino glucose" as a substrate for synthesis of magnetically recoverable nanocatalyst NiFe2O4@SiO2@amino glucose for the green synthesis of novel bis (1,2-dihydro-4-hydroxy-2-oxoquinolin-3-yl)methanes

2-Amino glucose ((2S,3R,4S,5S,6R)-2-amino-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol) as a substrate for the synthesis of NiFe₂O₄@SiO₂@amino glucose supply an environmentally friendly procedure for the synthesis of bis(1,2-dihydro-4-hydroxy-2-oxoquinolin-3-yl)methanes through one-pot condensation of aldehyde or pyrazolo carbaldehyde and two equivalents of 4-hydroxyquinolin-2(1H)-ones in aqueous media. Eco-friendliness, high purity of the desired products, short reaction time and easy workup procedure can be mentioned as the other advantages of this method. The structures of the synthesized 4-hydroxy-2(1H)-quinolone compounds were confirmed by ¹H, ¹³C NMR and FTIR spectral data and elemental analyses.

Synthesis of new triazole linked carbohybrids with ROS-mediated toxicity in breast cancer

Carbohybrids are an important class of molecules which exhibit diverse biological activities. New coumarins and quinolones linked carbohybrids are synthesised which are showing selective anticancer activity.

Use of Nanocrystalline ZnO as an Efficient and Reusable Catalyst for a One-Pot, Three-Component Synthesis of 6-Chloro- and 5,7-Dichloro-4-Hydroxy-3-[Aryl (Piperidin-1-yl)Methyl]Quinolin-2(1H)-Ones in Water

A one-pot, green, efficient and facile procedure was applied for the preparation of a series of 4-hydroxy-3-[aryl(piperidin-1-yl)methyl] quinolin-2(1 H)-ones via the reaction of 6-chloro-4- hydroxyquinoline-2(1 H)-one 1 and/or 5,7-dichloro-4-hydroxyquinoline-2(1 H)-one 2, piperidine and aromatic aldehydes in water in the presence of nanocrystalline ZnO under reflux conditions. The desired products were obtained in satisfactory yields. The nanocrystalline ZnO can be separated and reused at least up to three times with almost the same catalytic activity.

Stereoselective synthesis of natural product inspired carbohydrate fused pyrano[3,2-c]quinolones as antiproliferative agents

Design and efficient synthesis of new carbohydrate fused pyrano[3,2-c]quinolone derivatives and their submicromolar anticancer activity.

Design, synthesis and antitubercular potency of 4-hydroxyquinolin-2(1H)-ones

In this study, a 50-membered library of substituted 4-hydroxyquinolin-2(1H)-ones and two closely related analogues was designed, scored in-silico for drug likeness and subsequently synthesized. Thirteen derivatives, all sharing a common 3-phenyl substituent showed minimal inhibitory concentrations against Mycobacterium tuberculosis H37Ra below 10 μM and against Mycobacterium bovis AN5A below 15 μM but were inactive against faster growing mycobacterial species. None of these selected derivatives showed significant acute toxicity against MRC-5 cells or early signs of genotoxicity in the Vitotox™ assay at the active concentration range. The structure activity study relation provided some insight in the further favourable substitution pattern at the 4-hydroxyquinolin-2(1H)-one scaffold and finally 6-fluoro-4-hydroxy-3-phenylquinolin-2(1H)-one (38) was selected as the most promising member of the library with a MIC of 3.2 μM and a CC₅₀ against MRC-5 of 67.4 μM.

Synthesis and SAR studies of novel 6,7,8-substituted 4-substituted benzyloxyquinolin-2(1H)-one derivatives for anticancer activity

BACKGROUND AND PURPOSE

4-Phenylquinolin-2(1H)-one (4-PQ) derivatives can induce cancer cell apoptosis. Additional new 4-PQ analogs were investigated as more effective, less toxic antitumour agents.

EXPERIMENTAL APPROACH

Forty-five 6,7,8-substituted 4-substituted benzyloxyquinolin-2(1H)-one derivatives were synthesized. Antiproliferative activities were evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliun bromide assay and structure-activity relationship correlations were established. Compounds 9b, 9c, 9e and 11e were also evaluated against the National Cancer Institute-60 human cancer cell line panel. Hoechst 33258 and Annexin V-FITC/PI staining assays were used to detect apoptosis, while inhibition of microtubule polymerization was assayed by fluorescence microscopy. Effects on the cell cycle were assessed by flow cytometry and on apoptosis-related proteins (active caspase-3, -8 and -9, procaspase-3, -8, -9, PARP, Bid, Bcl-xL and Bcl-2) by Western blotting.

KEY RESULTS

Nine 6,7,8-substituted 4-substituted benzyloxyquinolin-2(1H)-one derivatives (7e, 8e, 9b, 9c, 9e, 10c, 10e, 11c and 11e) displayed high potency against HL-60, Hep3B, H460, and COLO 205 cancer cells (IC₅₀ < 1 μM) without affecting Detroit 551 normal human cells (IC₅₀ > 50 μM). Particularly, compound 11e exhibited nanomolar potency against COLO 205 cancer cells. Mechanistic studies indicated that compound 11e disrupted microtubule assembly and induced G2/M arrest, polyploidy and apoptosis via the intrinsic and extrinsic signalling pathways. Activation of JNK could play a role in TRAIL-induced COLO 205 apoptosis.

CONCLUSION AND IMPLICATIONS

New quinolone derivatives were identified as potential pro-apoptotic agents. Compound 11e could be a promising lead compound for future antitumour agent development.

Recent advances in the synthesis of quinolines: a review

This review article gives information about the recent advances in the synthesis of quinoline derivatives by various eco-friendly, green and clean protocols.

Efficient synthesis of 4-oxo-4,5-dihydrothieno[3,2-c]quinoline-2-carboxylic acid derivatives from aniline

The first reported synthesis of potential kinase inhibitors, 4-oxo-4,5-dihydrothieno[3,2-c]quinoline-2-carboxylic acid derivatives starting from aniline is described. This efficient high yielding sequence was carried out in six steps without any chromatographic purification. A tandem nucleophilic aromatic substitution/cyclization reaction was used as a key step in the sequence. The versatile intermediate 2-carboxylic acid was used as a suitable precursor to access the functionalization of the C-ring, by convergent analog synthesis of several novel derivatives.

Recent advances in the design and synthesis of heterocycles as anti-tubercular agents

Due to the unusual structure and chemical composition of the mycobacterial cell wall, effective tuberculosis (TB) treatment is difficult, making many antibiotics ineffective and hindering the entry of drugs. With approximately 33% of infection, TB is still the second most deadly infectious disease worldwide. The reasons for this are drug-resistant TB (multidrug resistant and extensively drug resistant), persistent infection (latent TB) and synergism of TB with HIV; furthermore no new chemical entity has emerged in last 40 years. New data available from the recently sequenced genome of the mycobacterium and the application of methods of modern drug design promise much for the fight against this disease. In this review, we present an introduction to TB, followed by an overview of new heterocyclic anti-tubercular moieties published during the last decade.

Novel lipophilic 7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid derivatives as potential antitumor agents: improved synthesis and in vitro evaluation

A convenient route for the synthesis of some acyloxymethyl esters and carboxamides of levofloxacin (LV) with modulated lipophilicity is described. The synthesized compounds were evaluated in vitro for their growth inhibitory effect in five human cancer cell lines. The most efficient LV derivatives (ester 2e and amide 4d) displayed IC(50) values in the 0.2-2.2 μM range, while IC(50) values for parent LV ranged between 70 and 622 μM depending on the cell line. The esters displayed no in vivo toxicity up to 80 mg/kg when administered intraperitoneally. This study thus shows that LV analogs displayed antitumor efficacy, at least in vitro, a feature that appeared to be independent from the lipophilicity of the grafted substituent.

Synthesis and anti-HIV activity of alkylated quinoline 2,4-diols

Naturally occurring quinolone alkaloids, buchapine (1) and compound 2 were synthesized as reported in literature and evaluated for anti-HIV potential in human CD4+ T cell line CEM-GFP, infected with HIV-1(NL4.3) virus by p24 antigen capture ELISA assay. The compounds 1 and 2 showed potent inhibitory activity with IC(50) value of 2.99 and 3.80microM, respectively. Further, 45 alkylated derivatives of quinoline 2,4-diol were synthesized and tested for anti-HIV potential in human CD4+ T cell line CEM-GFP. Among these, 13 derivatives have shown more than 60% inhibition. We have identified three most potent inhibitors 6, 9 and 23; compound 6 was found to be more potent than lead molecule 1 with IC(50) value of 2.35microM and had better therapeutic index (26.64) as compared to AZT (23.07). Five derivatives 7, 19a, 19d, 21 and 24 have displayed good noticeable anti-HIV activity. All active compounds showed higher CC(50) values which indicate that they have better therapeutic indices.

Synthesis and cytotoxic activity of trisubstituted-1,3,5-triazines

1,3,5-Triazine derivatives were screened for phototoxicity as well as the cytotoxic activities against leukemia and adenocarcinoma derived cell lines in comparison to the normal human keratinocytes. A simple and environmentally friendly procedure has been developed for the synthesis of 1,3,5-triazine derivatives under microwave irradiation in the presence of a HY zeolite. The catalyst can be recovered and reused. Thus, the procedure provides a simple and green synthetic methodology under environmentally friendly conditions. Structure-activity relationships between the chemical structures and antimycobacterial and photosynthesis-inhibiting activity of the evaluated compounds are also discussed.