Synthesis of novel analogs of 2-pyrazoline obtained from [(7-chloroquinolin-4-yl)amino]chalcones and hydrazine as potential antitumor and antimalarial agents

Synthesis and anti-proliferative activity of some new quinoline based 4,5-dihydropyrazoles and their thiazole hybrids as EGFR inhibitors

Quinoline derivatives 2, 3, quinolinyl based pyrazolines 4a,b, 5 and quinolinyl pyrazolinyl thiazole hybrids 6a-d, 7a-c and 8a-d were synthesized and screened for their anti-proliferative activity against MCF-7, HeLa and DLD1 cancer cell lines as well as normal fibroblast WI-38. Most of the tested compounds showed promising anticancer activity in addition to their safety towards the normal cell line. Eight compounds eliciting superior cytotoxicity against DLD1 and safe to the normal cell line 2, 3, 5, 6a, 6b, 7b, 7c and 8a were evaluated for their efficacy as EGFR inhibitors. They revealed inhibitory activity at nanomolar level especially compounds 6b, 2 and 7c with IC₅₀ (31.80, 37.07 and 42.52 nM) in comparison to Gefitinib (IC₅₀ = 29.16 nM).

3-Formylpyrazolo[1,5- a]pyrimidines as Key Intermediates for the Preparation of Functional Fluorophores

A one-pot route for the regioselective synthesis of 3-formylpyrazolo[1,5- a]pyrimidines 4a-k in good yields through a microwave-assisted process is provided. The synthesis proceeds via a cyclocondensation reaction between β-enaminones 1 with NH-3-aminopyrazoles 2, followed by formylation with an iminium salt moiety (Vilsmeyer-Haack reagent). These N-heteroaryl aldehydes 4 were successfully used as strategic intermediates for the preparation of novel functional fluorophores with yields up to 98%. The structures of the products obtained and regioselectivity of the reactions were determined on the basis of NMR measurements and X-ray diffraction analysis. Since pyrazolo[1,5- a]pyrimidines (PPs) 3 have shown an important fluorescence, photophysical properties of four 2-methylderivatives substituted at position 7 with different acceptor (A) or donor (D) groups were investigated. The compounds evaluated exhibited large Stokes shift in different solvents, but only the substituted p-methoxyphenyl (4-An) showed a strong fluorescence intensity with quantum yields up to 44% due to its greater ICT. Therefore, hybrid systems based on pyrazolo[1,5- a]pyrimidines could be used as fluorescent probes to detect biologically or environmentally relevant species.

A review on diverse heterocyclic compounds as the privileged scaffolds in antimalarial drug discovery

The upward extend of malaria collectively with the emergence of resistance against predictable drugs has put enormous pressure on public health systems to introduce new malaria treatments. Heterocycles play an important role in the design and discovery of new malaria active compounds. Heterocyclic compounds have attracted significant attention for malaria treatment because of simplicity of parallelization and the examining power with regard to chemical space. Introduction of a variety of heterocyclic compounds have enabled to maintain the high levels of antimalarial potency observed for other more lipophilic analogues whilst improving the solubility and the oral bioavailability in pre-clinical species. In this review, we present an overview of recent literature to provide imminent into the applications of different heterocyclic scaffolds in fighting against malaria.

Synthesis of New 1,3,5-Triazine-Based 2-Pyrazolines as Potential Anticancer Agents

A new series of 1,3,5-triazine-containing 2-pyrazoline derivatives (8⁻11)a⁻g was synthesized by cyclocondensation reactions of [(4,6-bis((2-hydroxyethyl)amino)-1,3,5-triazin-2-yl)amine]chalcones 7a⁻g with hydrazine hydrate and derivatives. Chalcones 7a⁻g were obtained by Claisen-Schmidt condensation between aromatic aldehydes and triazinic derivative 5, which was synthesized in high yield by a microwave-assisted reaction. Seventeen of the synthesized compounds were selected and tested by the US National Cancer Institute (NCI) for their anticancer activity against 58 different human tumor cell lines. Compounds 7g and 10d,e,g showed important GI50 values ranging from 0.569 to 16.6 µM and LC50 values ranging from 5.15 to >100 µM.

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.

Synthesis and DFT Calculations of Novel Vanillin-Chalcones and Their 3-Aryl-5-(4-(2-(dimethylamino)-ethoxy)-3-methoxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde Derivatives as Antifungal Agents

Novel (E)-1-(aryl)-3-(4-(2-(dimethylamino)ethoxy)-3-methoxyphenyl) prop-2-en-1-ones 4 were synthesized by a Claisen-Schmidt reaction of 4-(2-(dimethylamino)ethoxy)-3-methoxy-benzaldehyde (2) with several acetophenone derivatives 3. Subsequently, cyclocondensation reactions of chalcones 4 with hydrazine hydrate afforded the new racemic 3-aryl-5-(4-(2-(dimethylamino)ethoxy)-3-methoxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehydes 5 when the reaction was carried out in formic acid. The antifungal activity of both series of compounds against eight fungal species was determined. In general, chalcone derivatives 4 showed better activities than pyrazolines 5 against all tested fungi. None of the compounds 4a–g and 5a–g showed activity against the three Aspergillus spp. In contrast, most of the compounds 4 showed moderate to high activities against three dermatophytes (MICs 31.25–62.5 µg/mL), being 4a followed by 4c the most active structures. Interestingly, 4a and 4c possess fungicidal rather than fungistatic activities, with MFC values between 31.25 and 62.5 μg/mL. The comparison of the percentages of inhibition of C. neoformans by the most active compounds 4, allowed us to know the role played by the different substituents of the chalcones’ A-ring. Also the most anti-cryptococcal compounds 4a–c and 4g, were tested in a second panel of five clinical C. neoformans strains in order to have an overview of their inhibition capacity not only of standardized but also of clinical C. neoformans strains. DFT calculations showed that the electrophilicity is the main electronic property to explain the differences in antifungal activities for the synthesized chalcones and pyrazolines compounds. Furthermore, a quantitative reactivity analysis showed that electron-withdrawing substituted chalcones presented the higher electrophilic character and hence, the greater antifungal activities among compounds of series 4.

Effects of 1,3,5-triphenyl-4,5-dihydro-1H-pyrazole derivatives on cell-cycle and apoptosis in human acute leukemia cell lines

Pyrazoline is an important 5-membered nitrogen heterocycle that has been extensively researched. Ten derivatives were synthesized and tested for antileukemic effects on 2 human acute leukemia cell lines, K562 and Jurkat. The most cytotoxic of these derivatives, compound 21, was chosen for investigation of cytotoxicity mechanisms. The results obtained with selectivity calculations revealed that compound 21 is more selective for acute leukemia (K562 and Jurkat cell lines) than for other tumor cell lines. Moreover, compound 21 was not cytotoxic to normal cell lines, indicating a potential use in clinical tests. Compound 21 caused a significant cell cycle arrest in the S-phase in Jurkat cells and increased the proportion of cells in the sub G0/G1 phase in both cell lines. Cells treated with compound 21 demonstrated morphological changes characteristic of apoptosis in the EB/AO assay, confirmed by externalization of phosphatidylserine by the annexin V – fluorescein isothiocyanate method and by DNA fragmentation. An investigation of cytotoxicity mechanisms suggests the involvement of an intrinsic apoptosis pathway due to mitochondrial damage and an increase in the ratio of mitochondrial Bax/Bcl2. Pyrazoline 21 obeyed Lipinski’s “rule of five” for drug-likeness. Based on these preliminary results, the antileukemic activity of compound 21 makes it a potential anticancer agent.

Tertiary amine derivatives of chlorochalcone as acetylcholinesterase (AChE) and buthylcholinesterase (BuChE) inhibitors: the influence of chlorine, alkyl amine side chain and α,β-unsaturated ketone group

A new series of tertiary amine derivatives of chlorochalcone (4a∼4l) were designed, synthesized and evaluated for the effect on acetylcholinesterase (AChE) and buthylcholinesterase (BuChE). The results indicated that all compounds revealed moderate or potent inhibitory activity against AChE, and some possessed high selectivity for AChE over BuChE. The structure–activity investigation showed that the substituted position of chlorine significantly influenced the activity and selectivity. The alteration of tertiary amine group also leads to obvious change in bioactivity. Among them, IC₅₀ of compound 4l against AChE was 0.17 ± 0.06 µmol/L, and the selectivity was 667.2 fold for AChE over BuChE. Molecular docking and enzyme kinetic study on compound 4l suggested that it simultaneously binds to the catalytic active site (CAS) and peripheral anionic site (PAS) of AChE. Further study showed that the pyrazoline derivatives synthesized from chlorochalcones had weaker activity and lower selectivity in inhibiting AChE compared to that of chlorochalcone derivatives.

Structure-activity relationship (SAR) study and design strategies of nitrogen-containing heterocyclic moieties for their anticancer activities

The present review article offers a detailed account of the design strategies employed for the synthesis of nitrogen-containing anticancer agents. The results of different studies describe the N-heterocyclic ring system is a core structure in many synthetic compounds exhibiting a broad range of biological activities. Benzimidazole, benzothiazole, indole, acridine, oxadiazole, imidazole, isoxazole, pyrazole, triazoles, quinolines and quinazolines including others drugs containing pyridazine, pyridine and pyrimidines are covered. The following studies of these compounds suggested that these compounds showed their antitumor activities through multiple mechanisms including inhibiting protein kinase (CDK, MK-2, PLK1, kinesin-like protein Eg5 and IKK), topoisomerase I and II, microtubule inhibition, and many others. Our concise representation exploits the design and anticancer potency of these compounds. The direct comparison of anticancer activities with the standard enables a systematic analysis of the structure-activity relationship among the series.

Hybrid molecules: The privileged scaffolds for various pharmaceuticals

The practice of polypharmacology is not a new concept but the approaches which are being adopted for administering the two or more drugs together are varied from time to time. Taking two or more drugs simultaneously, co-formulation of two or more active agents in a single tablet and development of hybrid molecular entities capable to modulate multiple targets are the three popular approaches for multidrug therapy. The simultaneous use of more than one drug for the chemotherapy of a single disease demands a lot of patient compliance. Hence the present form of polypharmacology is gaining popularity in the form of hybrid molecules (multiple ligand approach). From the last 1-2 decades, the synthesis of hybrid molecules by the combination of different biologically relevant moieties has been under constant escalation along with their evaluation as diverse range of pharmacological agents and as potent drugs. This review is focused on the biological potential of hybrid molecules with particular mention of those exhibiting anti-fungal, anti-tuberculosis, anti-malarial, anti-inflammatory and anti-cancer activities. A comparison of the drug potency of the hybrid molecules with their individual counterparts is discussed for quantifying the significance of the concept of molecular hybridisation.

Microwave-assisted stereoselective approach to novel steroidal ring D-fused 2-pyrazolines and an evaluation of their cell-growth inhibitory effects in vitro

Novel ring D-condensed 2-pyrazolines in the Δ(5)-androstene series were efficiently synthesized from 16-dehydropregnenolone or its acetate with different arylhydrazines or methylhydrazine, respectively, under microwave irradiation. The reactions are assumed to occur via hydrazone intermediates, followed by intramolecular 1,4-addition leading to the fused heteroring stereoselectively with a 16α,17α-cis ring junction. The synthesized compounds were subjected to in vitro pharmacological studies of their antiproliferative activities against four human breast (MCF7, T47D, MDA-MB-231 and MDA-MB-361) and three cervical (HeLa, C33A and SiHA) malignant cell lines. Flow cytometry revealed that the most potent agent elicited a cell cycle disturbance.

Hybrid Molecules Containing a 7-Chloro-4-aminoquinoline Nucleus and a Substituted 2-Pyrazoline with Antiproliferative and Antifungal Activity

Twenty-four new hybrid analogues (15–38) containing 7-chloro-4-aminoquinoline and 2-pyrazoline N-heterocyclic fragments were synthesized. Twelve of the new compounds were evaluated against 58 human cancer cell lines by the U.S. National Cancer Institute (NCI). Compounds 25, 30, 31, 36, and 37 showed significant cytostatic activity, with the most outstanding GI₅₀ values ranging from 0.05 to 0.95 µM. The hybrid compounds (15–38) were also evaluated for antifungal activity against Candida albicans and Cryptococcus neoformans. From the obtained results some structure–activity relationships were outlined.

Synthesis and Evaluation of New Pyrazoline Derivatives as Potential Anticancer Agents

New pyrazoline derivatives were synthesized and evaluated for their cytotoxic effects on AsPC-1 human pancreatic adenocarcinoma, U87 and U251 human glioblastoma cell lines. 1-[((5-(4-Methylphenyl)-1,3,4-oxadiazol-2-yl)thio)acetyl]-3-(2-thienyl)-5-(4-chlorophenyl)-2-pyrazoline (11) was found to be the most effective anticancer agent against AsPC-1 and U251 cell lines, with IC50 values of 16.8 µM and 11.9 µM, respectively. Tumor selectivity of compound 11 was clearly seen between Jurkat human leukemic T-cell line and human peripheral blood mononuclear cells (PBMC). Due to its promising anticancer activity, compound 11 was chosen for apoptosis/necrosis evaluation and DNA-cleavage analysis in U251 cells. Compound 11-treated U251 cells exhibited apoptotic phenotype at low concentration (1.5 µM). DNA-cleaving efficiency of this ligand was more significant than cisplatin and was clearly enhanced by Fe(II)-H₂O₂-ascorbic acid systems. This result pointed out the relationship between the DNA cleavage and the cell death.

Anti-malarials are anti-cancers and vice versa - one arrow two sparrows

Repurposing is the novel means of drug discovery in modern science due to its affordability, safety and availability. Here, we systematically discussed the efficacy and mode of action of multiple bioactive, synthetic compounds and their potential derivatives which are used to treat/prevent malaria and cancer. We have also discussed the detailed molecular pathway involved in anti-cancer potentiality of an anti-malarial drug and vice versa. Although the causative agents, pathophysiology and manifestation of both the diseases are different but special emphasis has been given on similar pathways governing disease manifestation and the drugs which act through deregulating those pathways. Finally, a future direction has been speculated to combat these two diseases by a single agent developed using nanotechnology. Extended combination and new formulation of existing drugs for one disease may lead to the discovery of drug for other diseases like an arrow for two sparrows.

An efficient synthesis of new caffeine-based chalcones, pyrazolines and pyrazolo[3,4-b][1,4]diazepines as potential antimalarial, antitrypanosomal and antileishmanial agents

A new series of chalcones 5a-f were synthesized from caffeine-based aldehyde 3 and substituted acetophenones 4a-f. Treatment of compounds 5a-f with hydrazine hydrate led to pyrazolines 6a-f, and their subsequent reaction with acetic anhydride or formic acid afforded the corresponding N-substituted pyrazolines 7a-f and 8a-f respectively. Additionally, the regioselective cyclocondensation reaction of chalcones 5a-f with 4,5-diaminopyrazole 9 afforded the diazepine derivatives 10a-f. Synthesis of the above novel compounds was carried out through a simple procedure involving an easy work-up and mild reaction conditions. In vitro antimalarial activity against Plasmodium falciparum was evaluated for the obtained compounds. Among of them, just pirazoline 6a showed an outstanding growth inhibition percentage 85.2 ± 5.4%, while diazepines 10a-f showed remarkable growth inhibitions in the range of 80.3 ± 13.5 to 94.2 ± 0.2% when were tested at 20 μg/mL. Compounds 5b, 5e, 7c and 7f showed remarkable activities against Leishmania panamensis with growth inhibition of 88.3 ± 1.5, 82.6 ± 2.2, 82.8 ± 1.7 and 87.6 ± 0.5% respectively, at 20 μg/mL. In vitro assays against Trypanozoma cruzi showed that pyrazoline 6d displayed a growth inhibition of 61.9 ± 7.8% at 20 μg/mL while chalcone 5f was considered especially active with a growth inhibition of 9.7 ± 1.5% for a very low concentration of 1.0 μg/mL.

Reaction of isatins with 6-amino uracils and isoxazoles: isatin ring-opening vs. annulations and regioselective synthesis of isoxazole fused quinoline scaffolds in water

A straightforward approach for the one-pot synthesis of isoxazoloquinoline and spiroxindole derivatives in water has been established using p-toluene sulphonic acid as a catalyst.

4-Aminoquinoline-hybridization en route towards the development of rationally designed antimalarial agents

Recent developments in 4-aminoquinoline-hybridization, as an attractive strategy for averting and delaying the drug resistance along with improvement in efficacy of new antimalarials, are described.

Preparation of rotenone derivatives and in vitro analysis of their antimalarial, antileishmanial and selective cytotoxic activities

Six derivatives of the known biopesticide rotenone were prepared by several chemical transformations. Rotenone and its derivatives showed differential in vitro antiparasitic activity and selective cytotoxicity. In general, compounds were more active against Plasmodium falciparum than Leishmania panamensis. Rotenone had an EC₅₀ of 19.0 µM against P. falciparum, and 127.2 µM against L. panamensis. Although chemical transformation does not improve its biological profile against P. falciparum, three of its derivatives showed a significant level of action within an adequate range of activity with EC₅₀ values < 50.0 µM. This antiplasmodial activity was not due to red blood cell hemolysis, since LC₅₀ was >>400 µM. On the other hand, all derivatives displayed a non-specific cytotoxicity on several cell lines and primary human cell cultures.

Synthesis and in vitro antitumor activity of a novel series of 2-pyrazoline derivatives bearing the 4-aryloxy-7-chloroquinoline fragment

A new series of NH-pyrazoline derivatives 6 was synthesized by cyclocondensation reaction of novel [(7-chloroquinolin-4-yl)oxy]chalcones 5 with hydrazine hydrate. The treatment of pyrazolines 6 with acetic anhydride or formic acid yielded the N-acetyl- or N-formylpyrazoline derivatives 7–8, respectively. These novel 2-pyrazoline derivatives 6–8 were evaluated by the U.S. National Cancer Institute (NCI). Compounds 7b,d,f and 8c,f showed remarkable antitumor activity against 58 cancer cell lines, with the most important GI₅₀ values from in vitro assays ranging from 0.48 to 1.66 μM. The 2-pyrazoline derivatives bearing the 4-aryloxy-7-chloroquinoline fragment are thus considered to be useful leads for the rational design of new antitumor agents.

A new series of diarylamides possessing quinoline nucleus: Synthesis, in vitro anticancer activities, and kinase inhibitory effect

Synthesis of a new series of diarylamides possessing 6,7-dimethoxy(dihydroxy)quinoline scaffold is described. Their in vitro antiproliferative activities against NCI-58 human cancer cell lines of nine different cancer types were tested. Compounds 1a and 1d-g showed the highest mean %inhibition values over the 58 cell line panel at 10 μM, and they were further tested in 5-dose testing mode to determine their IC50 values. The five compounds were more potent than Imatinib against all the cell lines of nine different cancer types. Compound 1g showed the highest potencies. It showed inhibitory effect against C-RAF kinase (76.65% at 10 μM concentration).

(2E)-1-(4-Chloro-phen-yl)-3-[4-(propan-2-yl)phen-yl]prop-2-en-1-one

In the title compound, C18H17ClO, the dihedral angle between the benzene rings is 53.5 (1)°. The mean plane of the prop-2-en-1-one group is twisted by 24.5 (8) and 33.5 (3)° from the chloro- and propanyl-substituted rings, respectively.

Microwave-assisted synthesis of diverse pyrrolo[3,4-c]quinoline-1,3-diones and their antibacterial activities

With the aim of developing a general and practical method for library production, a novel and efficient two-phase microwave-assisted cascade reaction between isatins and β-ketoamides in [Bmim]BF4/toluene was developed for the synthesis of pyrrolo[3,4-c]quinoline-1,3-diones. The features of this methodology are, the use of microwave-assisted rapid synthesis, mild reaction conditions, high yields, operational simplicity, facile product separation, and recyclability. Furthermore, the antibacterial activities of the pyrrolo[3,4-c]quinoline-1,3-dione derivatives produced were evaluated against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus). These derivatives showed antibacterial activities against Gram-positive strains that were at least equivalent to that against Gram-negative strains. Compound 7{3,5} displayed the most potent antibacterial activity against P. aeruginosa (MIC = 0.5 μg/mL) and greater activity than standard ampicillin (MIC = 1 μg/mL). Compound 7{4,7} exhibited the best inhibitory activity against E. coli and E. aerogenes (MIC = 1 and 0.5 μg/mL), compared with the standard ampicillin (both MICs = 1 μg/mL). The synthesized pyrrolo[3,4-c]quinoline-1,3-diones are expected to be widely used as lead compounds for the development of new antibacterial agents.

(E)-3-{4-[(7-chloroquinolin-4-yl)oxy]-3-methoxyphenyl}-1-(4-methylphenyl)prop-2-en-1-one: a ladder-like structure resulting solely from π-π stacking interactions

In the title compound, C26H20ClNO3, the quinoline fragment is nearly orthogonal to the adjacent aryl ring, while the rest of the molecular skeleton is close to being planar. The crystal structure contains no hydrogen bonds of any sort, but there are two π-π stacking interactions present. One, involving the quinoline ring, links molecules related by inversion, while the other, involving the two nonfused aryl rings, links molecules related by translation, so together forming a ladder-type arrangement.

Discovery of a novel fluorescent HSP90 inhibitor and its anti-lung cancer effect

A novel fluorescent HSP90 inhibitor with strong growth inhibitory effects on lung cancer cells was developed.