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

New pyridine-based chalcones and pyrazolines with anticancer, antibacterial, and antiplasmodial activities

New pyridine-based chalcones 4a-h and pyrazolines 5a-h (N-acetyl), 6a-h (N-phenyl), and 7a-h (N-4-chlorophenyl) were synthesized and evaluated by the National Cancer Institute (NCI) against 60 different human cancer cell lines. Pyrazolines 6a, 6c-h, and 7a-h satisfied the pre-determined threshold inhibition criteria, obtaining that compounds 6c and 6f exhibited high antiproliferative activity, reaching submicromolar GI50 values from 0.38 to 0.45 μM, respectively. Moreover, compound 7g (4-CH3) exhibited the highest cytostatic activity of these series against different cancer cell lines from leukemia, nonsmall cell lung, colon, ovarian, renal, and prostate cancer, with LC50 values ranging from 5.41 to 8.35 μM, showing better cytotoxic activity than doxorubicin. Furthermore, the compounds were tested for antibacterial and antiplasmodial activities. Chalcone 4c was the most active with minimal inhibitory concentration (MIC) = 2 μg/mL against methicillin-resistant Staphylococcus aureus (MRSA), while the pyrazoline 6h showed a MIC = 8 μg/mL against Neisseria gonorrhoeae. For anti-Plasmodium falciparum activity, the chalcones display higher activity with EC50 values ranging from 10.26 to 10.94 μg/mL. Docking studies were conducted against relevant proteins from P. falciparum, exhibiting the minimum binding energy with plasmepsin II. In vivo toxicity assay in Galleria mellonella suggests that most compounds are low or nontoxic.

Exploring diverse frontiers: Advancements of bioactive 4-aminoquinoline-based molecular hybrids in targeted therapeutics and beyond

Amongst heterocyclic compounds, quinoline and its derivatives are advantaged scaffolds that appear as a significant assembly motif for developing new drug entities. Aminoquinoline moiety has gained significant attention among researchers in the 21stcentury. Considering the biological and pharmaceutical importance of aminoquinoline derivatives, herein, we review the recent developments (since 2019) in various biological activities of the 4-aminoquinoline scaffold hybridized with diverse heterocyclic moieties such as quinoline, pyridine, pyrimidine, triazine, dioxine, piperazine, pyrazoline, piperidine, imidazole, indole, oxadiazole, carbazole, dioxole, thiazole, benzothiazole, pyrazole, phthalimide, adamantane, benzochromene, and pyridinone. Moreover, by gaining knowledge about SARs, structural insights, and molecular targets, this review may help medicinal chemists design cost-effective, selective, safe, and more potent 4-aminoquinoline hybrids for diverse biological activities.

Quinoline-derivatives as privileged scaffolds for medicinal and pharmaceutical chemists: A comprehensive review

The quinoline scaffolds are privileged for their numerous biological activities in the pharmaceutical field. This moiety constitutes a well-known space in several marketed preparations. The quinoline scaffolds gained attention in modern days being an important chemical moiety in the identification, designing, and synthesis of novel potent derivatives. The current review is developed to shine the light on critical and significant insights on the quinoline derivatives possessing diverse biological activities such as analgesic, anti-inflammatory, antialzheimer, anti-convulsant, anti-oxidant, antimicrobial, anti-cancer activities and so on. A detailed summary of quinoline ring from its origin to the recent advancements regarding its synthesis, green chemistry approaches, patented methods, and its marketed drugs is presented in the review. We attempted to review the literature compiling the critical information that has potential to encourage fellow researchers and scientists for the design and development of quinoline scaffold based active molecules that have improved therapeutic performance along with profound pharmacological properties.

Current Status and Structure Activity Relationship of Privileged Azoles as Antifungal Agents (2016-2020)

Fungal infections have major contribution to the infectious related deaths in recent century. The issue has gotten worse with the advent of immunity impairing conditions such as HIV epidemic. Eukaryote nature of fungal pathogens leads to harder eradication than bacterial infections. Given the importance of the problem, considerable efforts have been put on the synthesis and biological assessment of azole-based chemical scaffolds and their bioisosteres. The emergence of validated macromolecular targets within different fungal species inspires structure-based drug design strategies toward diverse azole-based agents. Despite of advantageous features, emergence of drug-resistant fungal species restrict the applicability of current azoles as the first-line antifungal agents. Consequently, it appears advisable to elucidate SARs and chemical biodiversity within antifungal azoles. Current contribution was devoted to a brief look at clinically applied drugs, structure-based classification of azole antifungals and their structure activity relationships (SARs). Reviewed molecules belong to the antifungal structures that were reported throughout 2016-2020.

Discovery of Anticancer Agents from 2-Pyrazoline-Based Compounds

As nitrogen-containing five-membered heterocyclic structural units, the substituted pyrazole derivatives have a broad spectrum of pharmacological activities, especially 4,5-dihydro-1H-pyrazoles that also commonly known as 2-pyrazolines. Since 2010, considerable studies have been found that the 2-pyrazoline derivatives possess potent anticancer activities. In the present review, it covers the pyrazoline derivatives reported by literature from 2010 till date (2010-2019). This review aims to establish the relationship between the anticancer activities variation and different substituents introduced into a 2-pyrazoline core, which could provide important pharmacophore clues for the discovery of new anticancer agents containing 2-pyrazoline scaffold.

Recent advancements in the development of bioactive pyrazoline derivatives

Pyrazolines remain privileged heterocycles in drug discovery. 2-Pyrazoline scaffold has been proven as a ubiquitous motif which is present in a number of pharmacologically important drug molecules such as antipyrine, ramifenazone, ibipinabant, axitinib etc. They have been widely explored by the scientific community and are reported to possess wide spectrum of biological activities. For combating unprecedented diseases and worldwide increasing drug resistance, 2-pyrazoline has been tackled as a fascinating pharmacophore to generate new molecules with improved potency and lesser toxicity along with desired pharmacokinetic profile. This review aims to summarizes various recent advancements in the medicinal chemistry of pyrazoline based compounds with the following objectives: (1) To represent inclusive data on pyrazoline based marketed drugs as well as therapeutic candidates undergoing preclinical and clinical developments; (2) To discuss recent advances in the medicinal chemistry of pyrazoline derivatives with their numerous biological significances for the eradication of various diseases; (3) Summarizes structure-activity relationships (SAR) including in silico and mechanistic studies to afford ideas for the design and development of novel compounds with desired therapeutic implications.

Design, Facile Synthesis and Characterization of Dichloro Substituted Chalcones and Dihydropyrazole Derivatives for Their Antifungal, Antitubercular and Antiproliferative Activities

Infectious diseases caused by fungi and mycobacteria pose an important problem for humankind. Similarly, cancer is one of the leading causes of death globally. Therefore, there is an urgent need for the development of novel agents to combat the deadly problems of cancer, tuberculosis, and also fungal infections. Hence, in the present study, we designed, synthesized, and characterized 30 compounds including 15 chalcones (2–16) and 15 dihydropyrazoles (17–31) containing dichlorophenyl moiety and also screened these compounds for their antifungal, antitubercular, and antiproliferative activities. Among these compounds, the dihydropyrazoles showed excellent antifungal and antitubercular activities whereas the chalcones exhibited promising antiproliferative activity. Among the dihydropyrazoles, compound 31 containing 2-thienyl moiety showed promising antifungal activity (MIC 5.35 µM), whereas compounds 22 and 24 containing 2,4-difluorophenyl and 4-trifluoromethyl scaffolds revealed significant antitubercular activity with the MICs of 3.96 and 3.67 µM, respectively. Compound 16 containing 2-thienyl moiety in the chalcone series showed the highest anti-proliferative activity with an IC₅₀ value of 17 ± 1 µM. The most active compounds identified through this study could be considered as starting points in the development of drugs with potential antifungal, antitubercular, and antiproliferative activities.

Synthesis of New Oxindoles and Determination of Their Antibacterial Properties

A versatile method for the synthesis of new oxindoles was developed by the reaction between substituted isatins and 5-aminopyrazoles. The reaction was carried out at room temperature in ethanol using p-toluenesulfonic acid as the catalyst. The products were obtained with acceptable to excellent yields (44–96%). Structures of the new compounds were unambiguously established by spectroscopic and analytical techniques. The antibacterial activity was determined by microdilution assays. Compounds 3b, 3e, and 3g showed antistaphylococcal activity, particularly compound 3e displayed a potent activity against the vancomycin intermediate Staphylococcus aureus (VISA). Compounds 3i, 3j, and 3o inhibited Neisseria gonorrhoeae growth.

Synthesis and biological evaluation of 2-phenyl-4-aminoquinolines as potential antifungal agents

A series of 2-phenyl-4-aminoquinolines were designed, synthesized and evaluated for their antifungal activities against three phytopathogenic fungi in vitro. All of the target compounds were fully elucidated by ¹H NMR, ¹³C NMR and HRMS spectra. The results indicated that most of the target compounds demonstrated significant activities against the tested fungi. Among them, compound 6e exhibited more promising inhibitory activities against C. lunata (EC₅₀ = 13.3 μg/mL), P. grisea (EC₅₀ = 14.4 μg/mL) and A. alternate (EC₅₀ = 15.6 μg/mL), superior to azoxystrobin, a commercial agricultural fungicide. The structure-activity relationship (SAR) revealed that the aniline moiety at position 4 of the quinoline scaffold played a key role in the potency of a compound. And the substitution positions of the aniline moiety significantly influenced the activities. These encouraging results yielded a variety of 2-phenylquinolines bearing an aniline moiety acting as promising antifungal agents.

Hybridized Quinoline Derivatives as Anticancer Agents: Design, Synthesis, Biological Evaluation and Molecular Docking

Objective:

Conjugating quinolones with different bioactive pharmacophores to obtain potent anticancer active agents.

Methods:

Fused pyrazolopyrimidoquinolines 3a-d, Schiff bases 5, 6a-e, two hybridized systems: pyrazolochromenquinoline 7 and pyrazolothiazolidinquinoline 8, different substituted thiazoloquinolines 13-15 and thiazolo[3,2-a]pyridine derivatives 16a-c were synthesized. Their chemical structures were characterized through spectral and elemental analysis, cytotoxic activity on five cancer cell lines, caspase-3 activation, tubulin polymerization inhibition and cell cycle analysis were evaluated.

Results:

Four compounds 3b, 3d, 8 and 13 showed potent activity than doxorubicin on HCT116 and three compounds 3b, 3d and 8 on HEPG2. These promising derivatives showed increase in the level of caspase-3. The trifloromethylphenyl derivatives of pyrazolopyrimidoquinolines 3b and 3d showed considerable tubulin polymerization inhibitory activity. Both compounds arrested cell cycle at G2/M phase and induced apoptosis.

Conclusion:

Compounds 3b and 3d can be considered as promising anticancer active agents with 70% of colchicine activity on tubulin polymerization inhibition and represent hopeful leads that deserve further investigation and optimization.

Hybrid Molecules Development: A Versatile Landscape for the Control of Antifungal Drug Resistance: A Review

Hybrid molecule approach of drug design has become popular due to advantages such as delayed resistance, reduced toxicity, ease of treatment of co-infection and lower cost of preclinical evaluation. Antifungal drugs currently available for the treatment of fungal diseases suffer a major side effect of drug resistance. Hybrid drugs development is one of the approaches that has been employed to control microbial resistance. Their antifungal activity is influenced by their design. This review is focused on hybrid molecules exhibiting antifungal properties to guide scientists in search of more efficient drugs for the treatment of fungal diseases.

Quinolines and Quinolones as Antibacterial, Antifungal, Anti-virulence, Antiviral and Anti-parasitic Agents

Infective diseases have become health threat of a global proportion due to appearance and spread of microorganisms resistant to majority of therapeutics currently used for their treatment. Therefore, there is a constant need for development of new antimicrobial agents, as well as novel therapeutic strategies. Quinolines and quinolones, isolated from plants, animals, and microorganisms, have demonstrated numerous biological activities such as antimicrobial, insecticidal, anti-inflammatory, antiplatelet, and antitumor. For more than two centuries quinoline/quinolone moiety has been used as a scaffold for drug development and even today it represents an inexhaustible inspiration for design and development of novel semi-synthetic or synthetic agents exhibiting broad spectrum of bioactivities. The structural diversity of synthetized compounds provides high and selective activity attained through different mechanisms of action, as well as low toxicity on human cells. This review describes quinoline and quinolone derivatives with antibacterial, antifungal, anti-virulent, antiviral, and anti-parasitic activities with the focus on the last 10 years literature.

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).

The status of cryptococcosis in Latin America

Cryptococcosis is a life-threatening fungal infection caused by the encapsulated yeasts Cryptococcus neoformans and C. gattii, acquired from the environment. In Latin America, as occurring worldwide, C. neoformans causes more than 90% of the cases of cryptococcosis, affecting predominantly patients with HIV, while C. gattii generally affects otherwise healthy individuals. In this region, cryptococcal meningitis is the most common presentation, with amphotericin B and fluconazole being the antifungal drugs of choice. Avian droppings are the predominant environmental reservoir of C. neoformans, while C. gattii is associated with several arboreal species. Importantly, C. gattii has a high prevalence in Latin America and has been proposed to be the likely origin of some C. gattii populations in North America. Thus, in the recent years, significant progress has been made with the study of the basic biology and laboratory identification of cryptococcal strains, in understanding their ecology, population genetics, host-pathogen interactions, and the clinical epidemiology of this important mycosis in Latin America.

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.

Microwave-Assisted Synthesis of Diversely Substituted Quinoline-Based Dihydropyridopyrimidine and Dihydropyrazolopyridine Hybrids

An efficient, catalyst-free, and one-pot three-component procedure for the synthesis of novel and nitrogen rich dihydropyrido[2,3-d]pyrimidines and dihydro-1H-pyrazolo[3,4-b]pyridines bearing a quinoline pharmacophore fragment is provided. Reactions proceeded in DMF under microwave irradiation of three-component mixtures of formyl-quinoline derivatives, primary heterocyclic amines and cyclic 1,3-diketones. Interestingly, when conventional heating at reflux was used for the starting 5-amino-1-phenylpyrazole, the corresponding aromatized pyrazolopyridines were obtained as the main products. Single crystal X-ray analysis confirmed unequivocally the structure of both the dihydro- and aromatized products.