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

Biologically active quinoline and quinazoline alkaloids part II

To follow-up on our prior Part I review, this Part II review summarizes and provides updated literature on novel quinoline and quinazoline alkaloids isolated during the period of 2009-2016, together with the biological activity and the mechanisms of action of these classes of natural products. Over 200 molecules with a broad range of biological activities, including antitumor, antiparasitic and insecticidal, antibacterial and antifungal, cardioprotective, antiviral, anti-inflammatory, hepatoprotective, antioxidant, anti-asthma, antitussive, and other activities, are discussed. This survey should provide new clues or possibilities for the discovery of new and better drugs from the original naturally occurring quinoline and quinazoline alkaloids.

Recent advances in the chemistry of 2-chloroquinoline-3-carbaldehyde and related analogs

This review highlights the recently cited research data in the literature on the chemistry of 2-chloroquinoline-3-carbaldehyde and related analogs and their applications over the period from 2013 to 2017. It covers: synthesis of quinoline ring systems and reactions adopted to construct fused or binary quinoline-cord heterocyclic systems. The biological evaluation and the synthetic applications of the target compounds were illustrated.

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.

Recent advances of pyrazole-containing derivatives as anti-tubercular agents

One-third of the world's population infected tuberculosis (TB), and more than 1 million deaths annually. The co-infection between the mainly pathogen Mycobacterium tuberculosis (MTB) and HIV, and the incidence of drug-resistant TB, multi-drug resistant TB, extensively drug-resistant TB as well as totally drug-resistant TB have further aggravated the mortality and spread of this disease. Thus, there is an urgent need to develop novel anti-TB agents against both drug-susceptible and drug-resistant TB. The wide spectrum of biological activities and successful utilization of pyrazole-containing drugs in clinic have inspired more and more attention towards this kind of heterocycles. Numerous of pyrazole-containing derivatives have been synthesized for searching new anti-TB agents, and some of them showed promising potency and may have novel mechanism of action. This review aims to outline the recent achievements in pyrazole-containing derivatives as anti-TB agents and their structure-activity relationship.

DABCO as a green catalyst for the synthesis of pyranoquinoline derivatives

In this study, a rapid and convenient synthesis of quinolines was developed. The reaction involves a one-pot synthesis of pyranoquinoline derivatives from aldehyde, malonitrile, and 8-hydroxyquinoline using DABCO as a catalyst at 80 °C in H2O/EtOH as the solvent in good to high yields.

α,β-Functionalization of saturated ketones with anthranils via Cu-catalyzed sequential dehydrogenation/aza-Michael addition/annulation cascade reactions in one-pot

An efficient method to access functionalized quinolines from the readily available saturated ketones and anthranils have been explored.

Silver-catalyzed cyclization of nitrones with 2-azetine: a radical approach to 2,3-disubstituted quinolines

A silver-catalyzed intermolecular cyclization of nitrones with 2-azetine has been developed for the synthesis of 2,3-disubstituted quinolines under mild conditions.

Synthesis and biological screening of novel 2-morpholinoquinoline nucleus clubbed with 1,2,4-oxadiazole motifs

Novel series of 2-morpholinoquinoline scaffolds (6a-n), containing the 1,2,4-oxadiazole and moiety, was designed and synthesized in good yield (76-86%). The synthesized compounds were screened for their preliminary in vitro antimicrobial activity against a panel of pathogenic strains of bacteria and fungi. Molecular docking and pharmacokinetic study were carried out for the prepared compounds. The cytotoxicity of the synthesized compounds was tested at different concentrations using bioassay of S. pombe cells at the cellular level. The effect of synthesized compounds on the DNA integrity of S. pombe was observed on agarose gel. Compounds 6d, 6e, 6g, 6h, 6j and 6n exhibited excellent antimicrobial potency as compared to the standard drugs (i.e Ampicillin, Norfloxacin, Chloramphenicol, Ciprofloxacin). Compounds 6d, 6e, 6g, 6k and 6n were found to have significant antifungal activity as compared to griseofulvin. Compounds 6f, 6i, 6k, 6l were found very less cytotoxic, while compounds 6d, 6e, 6g, 6h were found to exhibit maximum toxicity. The rest of the synthesized compounds were found to be moderately toxic.

Recent advances in research of natural and synthetic bioactive quinolines

Many natural products that consist of quinoline core are found to be bioactive and the versatility of quinoline and its derivatives have attracted great attention in the field of drug development. As a result, in recent years, many green and sustainable synthetic approaches for the synthesis of structurally diverse quinolines have been developed. This review covers four main aspects, namely bioactive quinoline alkaloids, the biological activity and mechanism of action of quinoline-based compounds as well as various quinoline syntheses.

Iron-catalyzed addition/cyclization cascade of activated alkenes with alcohols: access to carbonyl substituted quinoline-2,4-diones

Iron-catalyzed radical addition/cyclization cascade of o-cyanoarylacrylamides with alcohols has been developed for the synthesis of carbonyl substituted quinoline-2,4(1H,3H)-diones.

Synthesis of quinoline acetohydrazide-hydrazone derivatives evaluated as DNA gyrase inhibitors and potent antimicrobial agents

(E)-N′-(Substituted-benzylidene)-2-(7-fluoro-2-methoxyquinolin-8-yl)acetohydrazide-hydrazone derivatives9a–nrepresent a new series of antibacterial agents and DNA gyrase inhibitors.

An efficient synthesis of sulfonated quinoline diones by copper catalyzed sulfonylation of activated alkenes with sulfonylhydrazides

A novel and highly efficient cascade synthesis of sulfonated quinoline dione derivatives from N-(2-cyanoaryl) methylacrylamides and sulfonylhydrazides in good yields is described.

Testing anti-HIV activity of antiretroviral agents in vitro using flow cytometry analysis of CEM-GFP cells infected with transfection-derived HIV-1 NL4-3

An assay, specifically optimized to evaluate the anti-HIV activity of antiretrovirals by flow cytometry analysis, is described. As widely used anti-HIV agents, zidovudine (AZT), abacavir (ABC), 2',3'-dideoxyinosine (DDI), lamivudine (3TC), nevirapine (NVP), and efavirenz (EFV), and as drugs of recent approval raltegravir (RAL), etravirine (ETR), and rilpivirine (RPV), were utilized as reference drugs. HIV-1 NL4-3 virus was prepared by transfection of HEK293T cells with purified plasmid DNA and quantified by p24 antigen-capture assay. For infection, CEM-GFP cells were exposed to vehicle or to several concentrations of the drugs for 2 hr at 37 °C before HIV-1 NL4-3 was added to each sample. The adsorption was prolonged for 3 hr at 37 °C. After 72 hr of incubation, HIV-induced GFP expression in infected CEM-GFP cells was assessed by flow cytometry analysis and expressed as % positive cells. For comparison, p24 production in supernatants was assessed by a commercial ELISA kit. On the basis of IC50 values, the anti-HIV activity, as assayed by this method, was EFV > 3TC > AZT > NVP > DDI > ABC and ETR > RPV > RAL. The comparison between the IC50 values calculated through flow cytometry and p24 production revealed overlapping results, showing that the optimized protocol of CEM-GFP infection with HIV NL4-3 is a suitable method to perform quantitative, rapid and low-expensive screening tests to evaluate the in vitro effect of new candidate anti-HIV drugs.

Compounds from Geijera parviflora with prostaglandin E2 inhibitory activity may explain its traditional use for pain relief

ETHNOPHARMACOLOGICAL RELEVANCE

Australian Aboriginal people used crushed leaves of Geijera parviflora Lindl. both internally and externally for pain relief, including for toothache (Cribb and Cribb, 1981). This study tested the hypothesis that this traditional use might be at least in part explained by the presence of compounds with anti-inflammatory activity.

MATERIALS AND METHODS

A crude extract (95% EtOH) was prepared from powdered dried leaves. From the CH3Cl fraction of this extract compounds were isolated by bioassay-guided fractionation and tested for: (1) cytotoxicity in RAW 264.7 murine leukemic monocyte-macrophages, (2) prostaglandin E2 (PGE2) inhibitory activity in 3T3 Swiss albino mouse embryonic fibroblast cells, as well as (3) nitric oxide (NO) and (4) tumour necrosis factor alpha (TNFα) inhibitory activity in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Isolated compounds were also tested for (5) antibacterial activity against a panel of Gram-positive (Staphylococcus aureus ATCC 29213 and ATCC 25923, Staphylococcus epidermidis ATCC 35984, biofilm-forming) and Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) strains by broth microdilution.

RESULTS

Eleven compounds were isolated, including one new flavone and one new natural product, with a further four compounds reported from this species for the first time. Some of the compounds showed good anti-inflammatory activity in vitro. In particular, flindersine (1) and N-(acetoxymethyl) flindersine (3) inhibited PGE2 release with IC50 values of 5.0μM and 4.9μM, respectively, without any significant cytotoxicity. Several other compounds showed moderate inhibition of NO (5, 6, 7) and TNF-α (6), with IC50 in the low micromolar range; however much of this apparent activity could be accounted for by the cytotoxicity of these compounds. None of the compounds showed anti-bacterial activity.

CONCLUSIONS

The inhibition of PGE2, an important mediator of inflammation and pain, by flindersine and a derivative thereof, along with the moderate anti-inflammatory activity shown by several other compounds isolated from Geijera parviflora leaf extract, support the traditional use of this plant for pain relief by Australian Aboriginal people.

Synthesis of polysubstituted quinolines via transition-metal-free oxidative cycloisomerization of o-cinnamylanilines

An efficient synthesis of 2-aryl 4-substituted quinolines from stable and readily available o-cinnamylanilines, prepared from anilines and cinnamylalcohols, has been developed. The reaction occurred via a regioselective 6-endo-trig intramolecular oxidative cyclization using KO(t)Bu as a mediator and DMSO as an oxidant at rt. The reaction showed a broad substrate scope with good to excellent yields.

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.

Investigation of quinoline-4-carboxylic acid as a highly potent scaffold for the development of alkaline phosphatase inhibitors: synthesis, SAR analysis and molecular modelling studies

The present study is directed towards the development of quinoline-4-carboxylic acid derivatives as potential alkaline phosphatase inhibitors.