Quinolines: Microwave-assisted synthesis and their antifungal, anticancer and radical scavenger properties

Design and Evaluation of Synthesized Pyrrole Derivatives as Dual COX-1 and COX-2 Inhibitors Using FB-QSAR Approach

This study delves into the intricate dynamics of the inflammatory response, unraveling the pivotal role played by cyclooxygenase (COX) enzymes, particularly COX-1 and COX-2 subtypes. Motivated by the pursuit of advancing scientific knowledge, our contribution to this field is marked by the design and synthesis of novel pyrrole derivatives. Crafted as potential inhibitors of COX-1 and COX-2 enzymes, our goal was to unearth molecules with heightened efficacy in modulating enzyme activity. A meticulous exploration of a synthesis library, housing around 3000 compounds, expedited the identification of potent candidates. Employing advanced docking studies and field-based Quantitative Structure-Activity Relationship (FB-QSAR) analyses enriched our understanding of the complex interactions between synthesized compounds and COX enzymes. Guided by FB-QSAR insights, our synthesis path led to the identification of compounds 4g, 4h, 4l, and 4k as potent COX-2 inhibitors, surpassing COX-1 efficacy. Conversely, compounds 5b and 5e exhibited heightened inhibitory activity against COX-1 relative to COX-2. The utilization of pyrrole derivatives as COX enzyme inhibitors holds promise for groundbreaking advancements in the domain of anti-inflammatory therapeutics, presenting avenues for innovative pharmaceutical exploration.

Recent developments on microwave-assisted organic synthesis of nitrogen- and oxygen-containing preferred heterocyclic scaffolds

In recent decades, the utilization of microwave energy has experienced an extraordinary surge, leading to the introduction of innovative and revolutionary applications across various fields of chemistry such as medicinal chemistry, materials science, organic synthesis and heterocyclic chemistry. Herein, we provide a comprehensive literature review on the microwave-assisted organic synthesis of selected heterocycles. We highlight the use of microwave irradiation as an effective method for constructing a diverse range of molecules with high yield and selectivity. We also emphasize the impact of microwave irradiation on the efficient synthesis of N- and O-containing heterocycles that possess bioactive properties, such as anti-cancer, anti-proliferative, and anti-tumor activities. Specific attention is given to the efficient synthesis of pyrazolopyrimidines-, coumarin-, quinoline-, and isatin-based scaffolds, which have been extensively studied for their potential in drug discovery. The article provides valuable insights into the recent synthetic protocols and trends for the development of new drugs using heterocyclic molecules.

Recent Advances in the Green Synthesis of Active N-Heterocycles and Their Biological Activities

N-heterocyclic scaffolds represent a privileged architecture in the process of drug design and development. It has widespread occurrence in synthetic and natural products, either those that are established or progressing as potent drug candidates. Additionally, numerous novel N-heterocyclic analogues with remarkable physiological significance and extended pharmaceutical applications are escalating progressively. Hence, the classical synthetic protocols need to be improvised according to modern requirements for efficient and eco-friendly approaches. Numerous methodologies and technologies emerged to address the green and sustainable production of various pharmaceutically and medicinally important N-heterocyclic compounds in last few years. In this context, the current review unveils greener alternatives for direct access to categorically differentiated N-heterocyclic derivatives and its application in the establishment of biologically active potent molecules for drug design. The green and sustainable methods accentuated in this review includes microwave-assisted reactions, solvent-free approaches, heterogeneous catalysis, ultrasound reactions, and biocatalysis.

Conversion of Glucose to 5-Hydroxymethylfurfural Using Consortium Catalyst in a Biphasic System and Mechanistic Insights

We found an effective catalytic consortium capable of converting glucose to 5-hydroxymethylfurfural (HMF) in high yields (50%). The reaction consists of a consortium of a Lewis acid (NbCl5) and a Brønsted acid (p-sulfonic acid calix[4]arene (CX4SO3H)), in a microwave-assisted reactor and in a biphasic system. The best result for the conversion of glucose to HMF (yield of 50%) was obtained with CX4SO3H/NbCl5 (5 wt%/7.5 wt%), using water/NaCl and MIBK (1:3), at 150 °C, for 17.5 min. The consortium catalyst recycling was tested, allowing its reuse for up to seven times, while maintaining the HMF yield constant. Additionally, it proposed a catalytic cycle by converting glucose to HMF, highlighting the following two key points: the isomerization of glucose into fructose, in the presence of Lewis acid (NbCl5), and the conversion of fructose into HMF, in the presence of CX4SO3H/NbCl5. A mechanism for the conversion of glucose to HMF was proposed and validated.

Nickel-Catalyzed Cascade Reaction of 2-Vinylanilines with gem-Dichloroalkenes

An efficient nickel-catalyzed cascade reaction of 2-vinylanilines with gem-dichloroalkenes has been developed to deliver diversely substituted quinolines in good to high yields. This protocol enables effective access to quinolines bearing various functional groups in the cascade process from readily available feedstock chemicals. Mechanistic studies suggest that two plausible pathways are involved in the IPr-nickel catalytic system.

2-(4-Chlorophenyl)-4-(3,4-dimethoxy-phenyl)-6-methoxy-3-methylquinoline

A 2,4-diarylquinoline derivative, 2-(4-chlorophenyl)-4-(3,4-dimethoxyphenyl)-6-methoxy-3-methylquinoline, was synthesized in a conventional two-step procedure from p-anisidine, p-chlorobenzaldehyde and methyl isoeugenol as available starting reagents through a sequence of BF3·OEt2-catalyzed Povarov cycloaddition reaction/oxidative dehydrogenation aromatization processes under microwave irradiation conditions in the presence of a green oxidative I2-DMSO system. The structure of the compound was fully characterized by FT-IR, 1H and 13C-NMR, ESI-MS, and elemental analysis. Its physicochemical parameters (Lipinski’s descriptors) were also calculated using the Molinspiration Cheminformatics software. The diarylquinoline molecule obtained is an interesting model with increased lipophilicity and thus permeability, an important descriptor for quinoline-based drug design. Such types of derivatives are known for their anticancer, antitubercular, antifungal, and antiviral activities.

The Povarov Reaction: A Versatile Method to Synthesize Tetrahydroquinolines, Quinolines and Julolidines

The multicomponent Povarov reaction represents a powerful approach for the construction of substances containing N-heterocyclic frameworks. By using the Povarov reaction, in addition to accessing tetrahydroquinolines, quinolines and julolidines in a single step, it is possible to form the following new bonds: two Csp 3–Csp 3 and one Csp 3–Nsp 3, two Csp 2–Csp 2 and one Csp 2–Nsp 2, and four Csp 3–Csp 3 and two Csp 3–Nsp 1, respectively. This short review discusses the main features of the Povarov reaction, including its mechanism, the reaction scope by employing different catalysts and substrates, as well as stereoselective versions.

1 Introduction

2 Mechanism of the Povarov Reaction

3 Tetrahydroquinolines

4 Quinolines

5 Julolidines

6 Concluding Remarks

Recent advances in chemistry and therapeutic potential of functionalized quinoline motifs – a review

Quinoline, which consists of benzene fused with N-heterocyclic pyridine, has received considerable attention as a core template in drug design because of its broad spectrum of bioactivity. This review aims to present the recent advances in chemistry, medicinal potential and pharmacological applications of quinoline motifs to unveil their substantial efficacies for future drug development. Essential information in all the current and available literature used was accessed and retrieved using different search engines and databases, including Scopus, ISI Web of Knowledge, Google and PUBMED. Numerous derivatives of the bioactive quinolines have been harnessed via expeditious synthetic approaches, as highlighted herein. This review reveals that quinoline is an indisputable pharmacophore due to its tremendous benefits in medicinal chemistry research and other valuable areas of human endeavour. The recent in vivo and in vitro screening reported by scientists is highlighted herein, which may pave the way for novel drug development. Owing to the array of information available and highlighted herein on the medicinal potential of quinoline and its functionalized derivatives, a new window of opportunity may be opened to medicinal chemists to access more biomolecular quinolines for future drug development.

Quinoline, which consists of benzene fused with N-heterocyclic pyridine, has received considerable attention as a core template in drug design because of its broad spectrum of bioactivity.

Synthesis, Antibacterial, Antioxidant, and Molecular Modeling Studies of Novel [2,3′-Biquinoline]-4-Carboxylic Acid and Quinoline-3-Carbaldehyde Analogs

Currently, it has been common to see people being affected and dying from untreatable infections caused by multidrug-resistant (MDR) germs. To tackle this problem, developing new effective chemotropic agents is urgently needed. Hence, this project aims to design, synthesize, and evaluate their antibacterial and antioxidant activities of new series of [2,3′-biquinoline]-4-carboxylic acid and quinoline-3-carbaldehyde analogs. The molecular docking analysis of the compounds against E. coli DNA gyrase was computed to investigate the binding mode of the compounds within the active site of the enzyme. In this regard, a new series of [2,3′-biquinoline]-4-carboxylic acid and quinoline-3-carbaldehyde analogs were synthesized by utilization of Vilsmeier–Haack, Doebner, nucleophilic substitution, and hydrolysis reactions. The structures of the synthesized compounds were determined using UV-Vis, FT-IR, and NMR. The synthesized compounds were screened for their antibacterial activity against four bacterial strains using disc diffusion methods. The findings of the study revealed that seven of synthetic compounds possess good antibacterial activity compared to ciprofloxacin which was used as a positive control in the experiment. Among them, compounds 4, 9, and 10 displayed the highest mean inhibition zone of 13.7 ± 0.58, 16.0 ± 1.7, and 20.7 ± 1.5 mm, respectively, at 0.1 μg/μL. The radical scavenging property of these compounds was evaluated using DPPH radical assay where compounds 9 and 20 showed the strongest activity with IC50 values of 1.25 and 1.75 μg/mL, respectively. At the same concentration, the IC50 value of ascorbic acid was 4.5 μg/mL. The synthesized compounds were also assessed for their in silico molecular docking analysis. Compounds 4 (−6.9 kcal/mol), 9 (−6.9 kcal/mol), and 10 (−7.9 kcal/mol) showed the maximum binding affinity close to ciprofloxacin (−7.2 kcal/mol) used as a positive control. Thus, compounds 4, 9, and 10 showed the best antibacterial activities in both in vitro and molecular docking analyses among the synthetic compounds. The results of in silico molecular docking evaluation of the synthetic compounds against E. coli DNA gyrase B were in good agreement with the in vitro antibacterial analysis. Therefore, the antibacterial activity displayed by these compounds is encouraging for further investigation to improve the activities of [2,3′-biquinoline]-4-carboxylic acid by incorporating various bioisosteric groups in either of the quinoline rings.

Tailored Quinolines Demonstrate Flexibility to Exert Antitumor Effects through Varied Mechanisms-A Medicinal Perspective

BACKGROUND

Quinoline is considered to be a privileged heterocyclic ring owing to its presence in diverse scaffolds endowed with promising activity profiles. In particular, quinoline containing compounds have exhibited substantial antiproliferative effects through the diverse mechanism of actions, which indicates that the heteroaryl unit is flexible as well as accessible to subtle structural changes that enable its inclusion in chemically distinct anti-tumor constructs.

METHODS

Herein, we describe a medicinal chemistry perspective on quinolines as anticancer agents by digging into the peer-reviewed literature as well as patents published in the past few years.

RESULTS

This review will serve as a guiding tool for medicinal chemists and chemical biologists to gain insights about the benefits of quinoline ring installation to tune the chemical architectures for inducing potent anticancer effects.

CONCLUSION

Quinoline ring containing anticancer agents presents enough optimism and promise in the field of drug discovery to motivate the researchers towards the continued explorations on such scaffolds. It is highly likely that adequate efforts in this direction might yield some potential cancer therapeutics in the future.

Ex vivo potential of a quinoline-derivative nail lacquer as a new alternative for dermatophytic onychomycosis treatment

Introduction. Onychomycosis infections currently show a significant increase, affecting about 10 % of the world population. Trichophyton rubrum is the main agent responsible for about 80 % of the reported infections. The clinical cure for onychomycosis is extremely difficult and effective new antifungal therapy is needed.Hypothesis/Gap Statement. Ex vivo onychomycosis models using porcine hooves can be an excellent alternative for evaluating the efficacy of new anti-dermatophytic agents in a nail lacquer.Aim. Evaluation of the effectiveness of a nail lacquer containing a quinoline derivative on an ex vivo onychomycosis model using porcine hooves, as well as the proposal of a plausible antifungal mechanism of this derivative against dermatophytic strains.Methodology. The action mechanism of a quinoline derivative was evaluated through the sorbitol protection assay, exogenous ergosterol binding, and the determination of the dose-response curves by time-kill assay. Scanning electron microscopy evaluated the effect of the derivative in the fungal cells. The efficacy of a quinoline-derivative nail lacquer on an ex vivo onychomycosis model using porcine hooves was evaluated as well.Results. The quinoline derivative showed a time-dependent fungicidal effect, demonstrating reduction and damage in the morphology of dermatophytic hyphae. In addition, the ex vivo onychomycosis model was effective in the establishment of infection by T. rubrum.Conclusion. Treatment with the quinoline-derivative lacquer showed a significant inhibitory effect on T. rubrum strain in this infection model. Finally, the compound presents high potential for application in a formulation such as nail lacquer as a possible treatment for dermatophytic onychomycosis.

Quinolines, a perpetual, multipurpose scaffold in medicinal chemistry

Quinoline is a versatile pharmacophore, a privileged scaffold and an outstanding fused heterocyclic compound with a wide range of pharmacological prospective such as anticancer, anti-inflammatory, antibacterial, antiviral drug and superlative moiety in drug discovery. The quinoline hybrids have already been shown excellent results with new targets with a different mode of actions as an inhibitor of cell proliferation by cell cycle arrest, apoptosis, angiogenesis, disruption of cell migration and modulation. This review emphasized the mode of action, structure activity relationship and molecular docking to reveal the various active pharmacophores of quinoline hybrids accountable for novel anticancer, anti-inflammatory, antibacterial and miscellaneous activities. Therefore, several quinoline candidates are under clinical trials for the treatment of certain diseases, for example ferroquine (antimalarial), dactolisib (antitumor) and pelitinib (EGFR TK inhibitors) etc. Plenty of research has been summarized the recent advances of quinoline derivatives and explore the various therapeutic prospects of this moiety. This review would help the researchers to strategically design diverse novel quinoline derivatives for the development of clinically viable drug candidates for the treatment of incurable diseases.

Engineered N-doped graphene quantum dots/CoFe2O4 spherical composites as a robust and retrievable catalyst: fabrication, characterization, and catalytic performance investigation in microwave-assisted synthesis of quinoline-3-carbonitrile derivatives

Nitrogen-doped graphene quantum dots (N-GQDs), which are less than 10 nm in size, are an interesting member of the nanocarbon materials family. N-GQDs nanostructures have been broadly applied in various fields, such as drug-gene delivery systems, photocatalytic reactions, and catalysts, owing to their unique properties. However, N-GQDs have rarely been introduced as a catalyst in organic synthesis. Herein, CoFe₂O₄ nanocomposites with diverse morphologies are fabricated in various conditions (e.g. green routes, various pH adjusters, temperatures). Due to further active sites on the surface of the nanocomposites, morphology engineering can be effective in catalytic activities. Following the synthesis, the catalytic activity of the engineered CoFe₂O₄ nanocomposites was screened, and it presented the order of spherical > rod > prism > cubic. The uniform spherical morphology provides more accessible active sites. Then, the novel nano-sized N-GQDs/CoFe₂O₄ magnetic spherical composite was readily fabricated by a green, low-cost, and easy hydrothermal route. The engineered composite was applied as an efficient magnetic nanocatalyst for the MW-assisted one-pot synthesis of new and known quinoline-3-carbonitrile derivatives (83–96%) in the shortest reaction time (60–90 s). Furthermore, the green route, easy separation of the nanocatalyst, and reusability (7 runs) without noticeable loss of catalytic efficiency are other advantages.

Sustainable fabrication of spherical N-GQDs/CoFe₂O₄ nanocomposites as a novel magnetically retrievable catalyst for the synthesis of quinoline-3-carbonitrile derivatives has been developed.

Anise Essential Oil as a Sustainable Substrate in the Multicomponent Double Povarov Reaction for Julolidine Synthesis

The use of star anise oil from a natural source as a dienophile in the multicomponent double Povarov reaction (MCPRs) to produce highly substituted julolidines with diverse technological applications is described. Within the framework of green chemistry, these MCPRs have many advantages such as (i) use of water in the reaction, (ii) creation of up to six bonds in one sequence, (iii) water as a sole waste, (iv) 100% of carbon economy, (v) a metal-free process, and (vi) nontoxic and reusable organocatalysts. These advantages, along with a simple workup procedure, make this protocol greener for the synthesis of julolidines.

Multicomponent Reactions for Integrating Multiple Functional Groups into an Antioxidant

A large number of convincing evidences has revealed the correlation of the pathogeny of diseases with the oxidative damages of DNA, protein, biomembrane, and other biological species, while supplementation of antioxidants is demonstrated to be a promising way to avoid, at least, rectify the unbalance redox status in vivo. Although many endeavors have focused on synthesis of antioxidants, a main hurdle still hinders the wide usages of synthetic antioxidants because of low bioavailability and potential cytotoxicity. The search for antioxidants with multiple functional groups being recognized by different receptors becomes a much sought by researchers, and multicomponent reactions (MCRs) provide with powerful tools for the construction of multifunctional antioxidants. Presented herein is a personal account on the application of MCRs for the synthesis of multifunctional antioxidants, while radical-induced oxidation of DNA acts as the experimental system for evaluating antioxidative effect. Concretely, the Biginelli three-component reaction (3CR) affords such a dihydropyrimidine scaffold that the tautomerization between C=S and C-SH leads to antioxidative effect. The Povarov 3CR is able to integrate multiple antioxidative groups, i. e., ferrocenyl and -N(CH₃ )₂ , into a quinoline scaffold, while the Groebke 3CR provides with imidazo[1,2-a]pyridine skeleton for inhibiting DNA oxidation. Additionally, the Knoevenagel-related MCRs also become efficient strategies for achieving radical-scavengers. On the other hand, the Ugi 4CR and Passerini 3CR result in the dipeptide and α-acyloxycarboxamide, respectively, with the benefit for the integration of antioxidative features by aliphatic chains. Therefore, MCRs have emerged as efficient tools for integrating multiple antioxidative features into one molecule in order to meet with complicated requirements from various biological surroundings.

Quinolines derivatives as promising new antifungal candidates for the treatment of candidiasis and dermatophytosis

Fungal infections have emerged as a current serious global public health problem. The main problem involving these infections is the expansion of multidrug resistance. Therefore, the prospection of new compounds with efficacy antifungal becomes necessary. Thus, this study evaluated the antifungal profile and toxicological parameters of quinolines derivatives against Candida spp. and dermatophyte strains. As a result, a selective anti-dermatophytic action was demonstrated by compound 5 (geometric means (GM = 19.14 μg ml⁻¹)). However, compounds 2 (GM = 50 μg ml⁻¹) and 3 (GM = 47.19 μg ml⁻¹) have presented only anti-Candida action. Compounds 3 and 5 did not present cytotoxic action. Compound 5 did not produce dermal and mucosal toxicity. In addition, this compound showed the absence of genotoxic potential, suggesting safety for topical and systemic use. Quinolines demonstrated a potent anti-dermatophytic and anti-yeast action. Moreover, compound 5 presented an excellent toxicological profile, acting as a strong candidate for the development of a new effective and safe compound against dermatophytosis of difficult treatment.

Tetrazolo[1,5-a]quinoline moiety-based Os(IV) complexes: DNA binding/cleavage, bacteriostatic and photocytotoxicity assay

Biological applications of platinum group metal-based complexes have been widely explored in synthetic and inorganic chemistry. The compounds have been subjected to DNA binding, DNA cleavage, In-vivo and In-vitro photocytotoxicity (HCT-116 cell line) and bacteriostatic activities. Binding constant of complexes are 1.42-5.62 × 10⁴ M^-1, whereas that of ligands are 1.12-4.72 × 10⁴ M^-1. K_sv of complexes are about 1.32-5.21 × 10³ M^-1, whereas K_f is about 1.24-6.83 × 10³ M^-1. IC₅₀ of compounds screened using HCT-116 cell line in dark are found to be 121-342 μg/mL. Whereas photocytotoxicity is found in the range of 48-316 μg/mL. Docking energy of molecules have been evaluated to evaluate efficacy of binding. Molecular docking energy of complexes are in the range of -286.00 to -303.11 kJ/mol. Whereas that of ligands are -254.03 to -282.96 kJ/mol. MIC of complexes are 47 ± 2.5 to 77.50 ± 7.5 μM. LC₅₀ values of ligands fall in the range of 4.05-19.72 μg/mL and that of Os(IV) complexes fall in the range of 3.99-15.99 μg/mL. The Os(IV) complexes dominate in proving its potentiality compared to N, N-donor ligands in biological activities. [Formula: see text]Communicated by Ramaswamy H. Sarma.

A comprehensive overview of the medicinal chemistry of antifungal drugs: perspectives and promise

The emergence of new fungal pathogens makes the development of new antifungal drugs a medical imperative that in recent years motivates the talents of numerous investigators across the world. Understanding not only the structural families of these drugs but also their biological targets provides a rational means for evaluating the merits and selectivity of new agents for fungal pathogens and normal cells. An equally important aspect of modern antifungal drug development takes a balanced look at the problems of drug potency and drug resistance. The future development of new antifungal agents will rest with those who employ synthetic and semisynthetic methodology as well as natural product isolation to tackle these problems and with those who possess a clear understanding of fungal cell architecture and drug resistance mechanisms. This review endeavors to provide an introduction to a growing and increasingly important literature, including coverage of the new developments in medicinal chemistry since 2015, and also endeavors to spark the curiosity of investigators who might enter this fascinatingly complex fungal landscape.

Recent Progress in the Synthesis of Quinolines

BACKGROUND

Quinoline-containing compounds present in both natural and synthetic products are an important class of heterocyclic compounds. Many of the substituted quinolines have been used in various areas including medicine as drugs. Compounds with quinoline skeleton possess a wide range of bioactivities such as antimalarial, anti-bacterial, anthelmintic, anticonvulsant, antiviral, anti-inflammatory, and analgesic activity. Due to such a wide range of applicability, the synthesis of quinoline derivatives has attracted a lot of attention of chemists to develop effective methods. Many known methods have been expanded and improved. Furthermore, various new methods for quinoline synthesis have been established. This review will focus on considerable studies on the synthesis of quinolines date which back to 2014.

OBJECTIVE

In this review, we discussed recent achievements on the synthesis of quinoline compounds. Some classical methods have been modified and improved, while other new methods have been developed. A vast variety of catalysts were used for these transformations. In some studies, quinoline synthesis reaction mechanisms were also displayed.

CONCLUSION

Many methods for the synthesis of substituted quinoline rings have been developed recently. Over the past five years, the majority of those reported have been based on cycloisomerization and cyclization processes. Undoubtedly, more imaginative approaches to quinoline synthesis will appear in the literature in the near future. The application of known methods to natural product synthesis is probably the next challenge in the field.

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.

Tetrahydroquinolines by the multicomponent Povarov reaction in water: calix[n]arene-catalysed cascade process and mechanistic insights

A new calixarene-catalyzed cascade process, via the Povarov reaction, for the synthesis of tetrahydroquinolines is described, and the proposed reaction mechanism was validated.

Green recipes to quinoline: A review

The quinoline core possesses a vast number of biological activities such as anticancer, antimalarial, antimicrobial, antifungal, antitubercular and antileishmanial. The conventional classical synthetic methods require the use of expensive and harsh conditions such as high temperature. Currently the scientific communities are searching new methodology to eliminate the use of chemicals, solvents and catalysts, which are hazardous to human health as well as to environment. This review provides a concise overview of new dimensions of green chemistry approaches in designing quinoline scaffold that would encourage the researchers towards green chemistry as well as future application of these greener, non-toxic, environment friendly methods in designing quinoline scaffold.

Design, synthesis and in vitro anticancer activity of novel quinoline and oxadiazole derivatives of ursolic acid

A series of new quinoline derivatives of ursolic acid were designed and synthesized in an attempt to develop potential anticancer agents. The structures of these compounds were identified by 1H NMR, 13C NMR, IR and ESI-MS spectra analysis. The target compounds were evaluated for their in vitro cytotoxicity against three human cancer cell lines (MDA-MB-231, Hela and SMMC-7721). From the results, compounds 3a-d displayed significant antitumor activity against three cancer cell lines. Especially, compound 3b was found to be the most potent derivative with IC50 values of 0.61±0.07, 0.36±0.05, 12.49±0.08μM against MDA-MB-231, HeLa and SMMC-7721 cells, respectively, stronger than positive control etoposide. Furthermore, the Annexin V-FITC/PI dual staining assay revealed that compound 3b could significantly induce the apoptosis of MDA-MB-231 cells in a dose-dependent manner. The cell cycle analysis also indicated that compound 3b could cause cell cycle arrest of MDA-MB-231 cells at G0/G1 phase.