The synthesis and anticancer activity of 2-styrylquinoline derivatives. A p53 independent mechanism of action

Novel triazole bridged quinoline-anthracene derivatives: synthesis, characterization, molecular docking, evaluation of electronic and enzyme inhibitory properties

Two novel quinoline-anthracene conjugates comprising styrylquinoline and anthracene moieties linked by triazole bridges were designed and synthesized in good yields. These molecules were determined for some metabolic enzymes activities. Results indicated that the synthetic molecules exhibited powerful inhibitory actions against all aims as compared to the control molecules. Ki values of novel compound QA-1 for hCA I, hCA II, AChE, and α-glycosidase enzymes were obtained of 20.18 ± 2.46 µM, 14.63 ± 1.14 µM, 71.48 ± 7.76 nM, 401.35 ± 36.84 nM, respectively. Both compounds showed promising candidate complexes for drug development with considerable in vitro different enzymes inhibitory activities. The binding conformations patterns and interaction of QA-1 and QA-2 compounds with α-glucosidase, acetycholinesterase, carbonic anhydrase-I and carbonic anhydrase-II enzymes were investigated through molecular docking profiles. The docking outputs are consistent with the Ki and IC50 values of novel compounds. Three dimensional geometries and electronic properties of the title compounds were obtained by the applicational computational approach at B3LYP/6-31++G(d,p) level of theory.Communicated by Ramaswamy H. Sarma.

4-Furanylvinylquinoline derivative as a new scaffold for the design of oxidative stress initiator and glucose transporter inhibitor drugs

In the present study, a detailed analysis of the effect of a substitution at the C4 position of the quinoline ring by styryl or furanylvinyl substituents on the structure-antitumour activity relationship was conducted. After analysing a library of derivatives from the styrylquinoline and furanylvinylquinoline groups, we selected the most active (IC50 below 100 nM) derivative 13, which contained the strongly electron-withdrawing nitro group in the furan substituent. The mechanism of action of this compound was studied on cell lines that differed in their p53 protein status. For this derivative, both cell cycle arrest (in G2/M phase in both HCT 116 cell lines and S phase for U-251 cell line) and the induction of apoptosis (up to 66% for U-251 cell line) were revealed. These studies were then confirmed by other methods at the gene and protein levels. Interestingly, we observed differences in the mechanism of action depending on the presence and mutation of the p53 protein, thus confirming its key role in cellular processes. Incubation with derivative 13 resulted in the induction of oxidative stress and triggered a cascade of cellular defence proteins that failed in the face of such an active compound. In addition, the results showed an inhibition of the GLUT-1 glucose transporter, which is extremely important in the context of anti-cancer activity.

Imbalance of redox homeostasis and altered cellular signaling induced by the metal complexes of terpyridine

Compounds that can induce oxidative stress in cancer cells while remaining nontoxic to healthy cells are extremely promising for potential anticancer drugs. 2,2':6',2''-terpyridine-metal complexes possess these properties. The high level of activity (IC50 = 0.605 µM) of 2,2':6',2''-terpyridine-metal complexes on lung, breast, pancreatic, and glioblastoma multiforme cancer lines and their selectivity (SI > 41.32) on human normal fibroblasts were confirmed and presented in this paper. The mechanism of action of these compounds is associated with the generation of reactive oxygen species, which affects several cellular pathways and signals. The results demonstrate that 2,2':6',2''-terpyridine-metal complexes affect cell cycle inhibition in the G0/G1 phase as well as the activation of apoptosis and autophagy cell death. These results were confirmed in several independent studies, including experiments measuring the fluorescence levels of reactive oxygen species, flow cytometry, and gene and protein analysis.

New multifunctional hybrids as modulators of apoptosis markers and topoisomerase II in breast cancer therapy: synthesis, characterization, and in vitro and in silico studies

Recently, molecular hybrids of two or more active pharmacophores have shown promise for designing and synthesizing anticancer drugs. Herein, a new multifunctional hybrid (PAHMQ), combining azobenzene and quinoline pharmacophores, and its M(ii) complexes (MPAHMQ) have been successfully developed and structurally characterized. The MTT assay revealed CuBHTP as the most efficient and safe breast cancer treatment, with an IC50 of 11.18 ± 0.39 μg mL-1 and a high selectivity index (SI) of 5.63 for cancer MCF-7 cells over healthy MCF10A cells. Moreover, the CuPAHMQ-treated MCF-7 cells experience a dramatic impact with regard to key apoptotic markers, including an increase in P53 and Bax expression, with a decrease in Bcl-2 expression levels compared to the untreated MCF-7 cells. Additionally, CuPAHMQ effectively halted the growth and division of MCF-7 cells by inducing cell cycle arrest in the crucial G1 and S phases, ultimately inhibiting both Topo II activity and cell proliferation. Molecular docking investigations validated the CuPAHMQ complex's groove binding and topoisomerase II binding, establishing it as a potent anticancer drug.

Green synthesis and antitumor activity of (E)-diethyl 2-styrylquinoline-3,4-dicarboxylates

In this work, a green, efficient and catalyst-free synthesis of a series of structurally novel (E)-diethyl 2-styrylquinoline-3,4-dicarboxylates via a direct olefination reaction between diethyl 2-methylquinoline-3,4-dicarboxylate and various aromatic aldehydes was successfully accomplished by employing eco-friendly 1,3-dimethylurea/l-(+)-tartaric acid (DMU/LTA) as an inexpensive, non-toxic and reusable reaction medium. This methodology has the attractive advantages of mild reaction conditions, simple experimental operation, and the absence of any dangerous catalysts or unsafe volatile organic solvents, with satisfactory to good yields. Subsequently, a primary in vitro evaluation for their anti-proliferative activity against human cancer cell lines A549, HT29 and T24 revealed that the compound with the 3,4,5-trimethoxystyryl moiety exhibited potent anti-tumor activity with IC50 values of 2.38, 4.52 and 9.86 μmol L-1, respectively, thereby being equipotent or even better than the reference cisplatin.

Synthesis, characterization, biological potency, and molecular docking of Co2+, Ni2+ and Cu2+ complexes of a benzoyl isothiocyanate based ligand

The primary objective of the present study was to produce metal complexes of H4DAP ligand (N,N'-((pyridine-2,6-diylbis(azanediyl))bis(carbonothioyl))dibenzamide) derived from 2,6-diaminopyridine and benzoyl isothiocyanate with either ML or M2L stoichiometry. There are three distinct coordination complexes obtained with the formulas [Co(H2DAP)]·H2O, [Ni2(H2DAP)Cl2(H2O)2]·H2O, and [Cu(H4DAP)Cl2]·3H2O. The confirmation of the structures of all derivatives was achieved through the utilization of several analytical techniques, including FT-IR, UV-Vis, NMR, GC-MS, PXRD, SEM, TEM analysis, and QM calculations. Aiming to analyze various noncovalent interactions, topological methods such as QTAIM, NCI, ELF, and LOL were performed. Furthermore, the capacity of metal-ligand binding was examined by fluorescence emission spectroscopy. An in vitro investigation showed that the viability of MDA-MB-231 and HepG-2 cells was lower when exposed to the manufactured Cu2+ complex, in comparison to the normal cis-platin medication. The compounds were further evaluated for their in vitro antibacterial activity. The Ni2+ complex has shown promising activity against all tested pathogens, comparable to the reference drugs Gentamycin and Ketoconazole. Furthermore, a computational docking investigation was conducted to further examine the orientation, interaction, and conformation of the recently created compounds on the active site of the Bcl-2 protein.

Styrylquinazoline derivatives as ABL inhibitors selective for different DFG orientations

Among tyrosine kinase inhibitors, quinazoline-based compounds represent a large and well-known group of multi-target agents. Our previous studies have shown interesting kinases inhibition activity for a series of 4-aminostyrylquinazolines based on the CP-31398 scaffold. Here, we synthesised a new series of styrylquinazolines with a thioaryl moiety in the C4 position and evaluated in detail their biological activity. Our results showed high inhibition potential against non-receptor tyrosine kinases for several compounds. Molecular docking studies showed differential binding to the DFG conformational states of ABL kinase for two derivatives. The compounds showed sub-micromolar activity against leukaemia. Finally, in-depth cellular studies revealed the full landscape of the mechanism of action of the most active compounds. We conclude that S4-substituted styrylquinazolines can be considered as a promising scaffold for the development of multi-kinase inhibitors targeting a desired binding mode to kinases as effective anticancer drugs.

Discovery of anti-colon cancer agents targeting wild-type and mutant p53 using computer-aided drug design

Mutations in the p53 gene are common and occur in over 50% of all cancers, as it is involved in DNA damage repair, cell cycle regulation and apoptosis. Moreover, the p53 gene is mutated in 70% of colon cancers. Therefore, the development of drugs to combat this mutation requires urgent attention. With this in mind, in silico drug design approaches were applied on quinoline derivatives with anticancer activity. In 3D-QSAR study, steric, electrostatic, hydrophobic and H-bond acceptor fields (SEHA) play an important role in prediction and design of new colon cancer compounds. Indeed, the two best CoMSIA/SEHA models with (Q2 = 0.737, R2 = 0.914, R pred 2 = 0.720) and (Q2 = 0.738, R2 = 0.919, R pred 2 = 0.739) show good prediction of human colon carcinoma HCT 116 (p53+/+) and (p53-/-) activities, respectively. Furthermore, the predictive ability and robustness of these models were tested by several validation methods. Molecular docking analyses reveal crucial interactions with the active sites of the p53 protein in both wild type and mutant. Based on these theoretical studies, we designed 10 new compounds with good anticancer activity potential, which were evaluated using ADMET properties. Molecular dynamics simulations were performed to confirm the detailed binding mode of the docking results. Finally, the MM-GBSA based on molecular dynamics simulation confirmed that the designed compounds were able to form stable hydrogen bonding interactions with the crucial residues, which are essential to overcome the p53 mutation in colon cancer.Communicated by Ramaswamy H. Sarma.

Modulation of Transcription Profile Induced by Antiproliferative Thiosemicarbazone Metal Complexes in U937 Cancer Cells

Since the discovery of cisplatin, the search for metal-based compounds with therapeutic potential has been a challenge for the scientific community. In this landscape, thiosemicarbazones and their metal derivatives represent a good starting point for the development of anticancer agents with high selectivity and low toxicity. Here, we focused on the action mechanism of three metal thiosemicarbazones [Ni(tcitr)₂], [Pt(tcitr)₂], and [Cu(tcitr)₂], derived from citronellal. The complexes were already synthesized, characterized, and screened for their antiproliferative activity against different cancer cells and for genotoxic/mutagenic potential. In this work, we deepened the understanding of their molecular action mechanism using an in vitro model of a leukemia cell line (U937) and an approach of transcriptional expression profile analysis. U937 cells showed a significant sensitivity to the tested molecules. To better understand DNA damage induced by our complexes, the modulation of a panel of genes involved in the DNA damage response pathway was evaluated. We analyzed whether our compounds affected cell cycle progression to determine a possible correlation between proliferation inhibition and cell cycle arrest. Our results demonstrate that metal complexes target different cellular processes and could be promising candidates in the design of antiproliferative thiosemicarbazones, although their overall molecular mechanism is still to be understood.

Microwave and Cs+-assisted chemo selective reaction protocol for synthesizing 2-styryl quinoline biorelevant molecules

The reaction protocols and their continuous development to achieve the desired selectivity remain a primary target of organic chemistry, which is addressed here with the specific role of the cesium ion. The pharmacophore “2-styryl quinoline” was taken as a reference here because of the continuation of our work, where it was found fit as fusion inhibitors and anti-viral agents. The present protocol defines its importance for the synthesis of O-alkylated products. However, in most cases, N-alkylation proceeds because of nitrogen atoms’ more nucleophilic nature and electronic density. The cesium effect makes this possible because of the large cationic size and its affection for the oxygen atom. The plausible mechanism and its progression were demonstrated here with the help of density function theory calculation by analyzing the energy of intermediates. The protocol is also found suitable with microwave irradiation. Moreover, it gives the product a better yield in less reaction time. The present reaction protocol and its importance will address some of the crucial issues related to the synthesis of the complex molecule, and the present protocol will open up hope, where the selectivity and product yield would be a concern.

Conversion of 2-methyl-4-styrylquinolines into 2,4-distyrylquinolines: synthesis, and spectroscopic and structural characterization of five examples

Four new 2,4-distyrylquinolines and one 2-styryl-4-[2-(thiophen-2-yl)vinyl]quinoline have been synthesized using indium trichloride condensation reactions between aromatic aldehydes and the corresponding 2-methylquinolines, which were themselves prepared using Friedländer annulation reactions between mono- or diketones and (2-aminophenyl)chalcones: the products have all been fully characterized by spectroscopic and crystallographic methods. 2,4-Bis[(E)-styryl]quinoline, C25H19N, (IIa), and its dichloro analogue, 2-[(E)-2,4-dichlorostyryl]-4-[(E)-styryl]quinoline, C25H17Cl2N, (IIb), exhibit different orientations of the 2-styryl unit relative to the quinoline nucleus. In each of the 3-benzoyl analogues {2-[(E)-4-bromostyryl]-4-[(E)-styryl]quinolin-3-yl}(phenyl)methanone, C32H22BrNO, (IIc), {2-[(E)-4-bromostyryl]-4-[(E)-4-chlorostyryl]quinolin-3-yl}(phenyl)methanone, C32H21BrClNO, (IId), and {2-[(E)-4-bromostyryl]-4-[(E)-2-(thiophen-2-yl)vinyl]quinolin-3-yl}(phenyl)methanone, C30H20BrNOS, (IIe), the orientation of the 2-styryl unit is similar to that in (IIa), but the orientation of the 4-arylvinyl units show considerable variation. The thiophene unit in (IIe) is disordered over two sets of atomic sites having occupancies of 0.926 (3) and 0.074 (3). There are no hydrogen bonds of any kind in the structure of (IIa), but in (IId), a single C-H...O hydrogen bond links the molecules into cyclic centrosymmetric R22(20) dimers. A combination of C-H...N and C-H...π hydrogen bonds links the molecules of (IIb) into a three-dimensional framework structure. A combination of three C-H...π hydrogen bonds links the molecules of (IIc) into sheets, and a combination of C-H...O and C-H...π hydrogen bonds forms sheets in (IIe). Comparisons are made with the structures of some related compounds.

A three-step pathway from (2-aminophenyl)chalcones to novel styrylquinoline-chalcone hybrids: synthesis and spectroscopic and structural characterization of three examples

Three new styrylquinoline-chalcone hybrids have been synthesized using a three-step pathway starting with Friedländer cyclocondensation between (2-aminophenyl)chalcones and acetone to give 2-methyl-4-styrylquinolines, followed by selective oxidation to the 2-formyl analogues, and finally Claisen-Schmidt condensation between the formyl intermediates and 1-acetylnaphthalene. All intermediates and the final products have been fully characterized by IR and 1H/13C NMR spectroscopy, and by high-resolution mass spectrometry, and the three products have been characterized by single-crystal X-ray diffraction. The molecular conformations of (E)-3-{4-[(E)-2-phenylethenyl]quinolin-2-yl}-1-(naphthalen-1-yl)prop-2-en-1-one, C30H21NO, (IVa), and (E)-3-{4-[(E)-2-(4-fluorophenyl)ethenyl]quinolin-2-yl}-1-(naphthalen-1-yl)prop-2-en-1-one, C30H20FNO, (IVb), are very similar. In each compound, the molecules are linked into a three-dimensional array by hydrogen bonds, of the C-H...O and C-H...N types in (IVa), and of the C-H...O and C-H...π types in (IVb), and by two independent π-π stacking interactions. By contrast, the conformation of the chalcone unit in (E)-3-{4-[(E)-2-(2-chlorophenyl)ethenyl]quinolin-2-yl}-1-(naphthalen-1-yl)prop-2-en-1-one, C30H20ClNO, (IVc), differs from those in (IVa) and (IVb). There are only weak hydrogen bonds in the structure of (IVc), but a single rather weak π-π stacking interaction links the molecules into chains. Comparisons are made with some related structures.

Insights of metal 8-hydroxylquinolinol complexes as the potential anticancer drugs

8-Hydroxyquinoline and its derivatives, which belong to a well-known class of quinoline based drugs with varied biological activities, have been extensively explored for the treatments of cancer, Alzheimer's disease, neurodegenerative diseases and other life-threatening diseases. In virtue of the existence of bicyclic heterocyclic scaffold, their bidentate chelators can further bind to metal ions via O- and N-donors from 8-hydroxylquinolinol skeletons to yield a variety of metal 8-hydroxylquinolinol complexes appealing as the anticancer drugs with low toxicity, due to their better biological effects and higher anticancer activities than free 8-hydroxylquinolinol ligands and cis-diammine-dichloro-platinum. The present review summarizes the recent developments in the syntheses, crystal structures, and anticancer activities of metal 8-hydroxylquinolinol complexes, attempting to discover a correlation between their structures and anticancer activities, and to provide an evidence for their potential application perspectives. It means to offer the helpful and meaningful guidance for the researchers in the future syntheses of new and highly efficient anticancer metal 8-hydroxylquinolinol complexes based drugs.

Chemopreventive Effect on Human Colon Adenocarcinoma Cells of Styrylquinolines: Synthesis, Cytotoxicity, Proapoptotic Effect and Molecular Docking Analysis

Seven styrylquinolines were synthesized in this study. Two of these styrylquinolines are new and were elucidated by spectroscopic analysis. The chemopreventive potential of these compounds was evaluated against SW480 human colon adenocarcinoma cells, its metastatic derivative SW620, and normal cells (HaCaT). According to the results, compounds 3a and 3d showed antiproliferative activity in SW480 and SW620 cells, but their effect seemed to be caused by different mechanisms of action. Compound 3a induced apoptosis independent of ROS production, as evidenced by increased levels of caspase 3, and had an immunomodulatory effect, positively regulating the production of different immunological markers in malignant cell lines. In contrast, compound 3d generated a pro-oxidant response and inhibited the growth of cancer cells, probably by another type of cell death other than apoptosis. Molecular docking studies indicated that the most active compound, 3a, could efficiently bind to the proapoptotic human caspases-3 protein, a result that could provide valuable information on the biochemical mechanism for the in vitro cytotoxic response of this compound in SW620 colon carcinoma cell lines. The obtained results suggest that these compounds have chemopreventive potential against CRC, but more studies should be carried out to elucidate the molecular mechanisms of action of each of them in depth.

Synthesis and spectroscopic and structural characterization of three new 2-methyl-4-styrylquinolines formed using Friedländer reactions between (2-aminophenyl)chalcones and acetone

Three new 2-methyl-4-styrylquinoline derivatives have been synthesized in high yields using Friedländer reactions between chalcones [1-(2-aminophenyl)-3-arylprop-2-en-1-ones] and acetone, and characterized using IR, 1H and 13C NMR spectroscopy, and mass spectrometry, and by crystal structure analysis. In (E)-4-(4-fluorostyryl)-2-methylquinoline, C18H14FN, (I), the molecules are joined into cyclic centrosymmetric dimers by C-H...N hydrogen bonds and these dimers are linked into sheets by π-π stacking interactions. The molecules of (E)-2-methyl-4-[4-(trifluoromethyl)styryl]quinoline, C19H14F3N, (II), are linked into cyclic centrosymmetric dimers by C-H...π hydrogen bonds and these dimers are linked into chains by a single π-π stacking interaction. There are no significant hydrogen bonds in the structure of (E)-4-(2,6-dichlorostyryl)-2-methylquinoline, C18H13Cl2N, (III), but molecules related by translation along [010] form stacks with an intermolecular spacing of only 3.8628 (2) Å. Comparisons are made with the structures of some related compounds.

Synthesis of 4-Hydroxyquinolines as Potential Cytotoxic Agents

The synthesis of alkyl 2-(4-hydroxyquinolin-2-yl) acetates and 1-phenyl-4-(phenylamino)pyridine-2,6(1H,3H)-dione was optimised. Starting from 4-hydroxyquinolines (4HQs), aminomethylation was carried out via the modified Mannich reaction (mMr) applying formaldehyde and piperidine, but a second paraformaldehyde molecule was incorporated into the Mannich product. The reaction also afforded the formation of bisquinoline derivatives. A new 1H-azeto [1,2-a]quinoline derivative was synthesised in two different ways; namely starting from the aminomethylated product or from the ester-hydrolysed 4HQ. When the aldehyde component was replaced with aromatic aldehydes, Knoevenagel condensation took place affording the formation of the corresponding benzylidene derivatives, with the concomitant generation of bisquinolines. The reactivity of salicylaldehyde and hydroxynaphthaldehydes was tested; under these conditions, partially saturated lactones were formed through spontaneous ring closure. The activity of the derivatives was assessed using doxorubicin-sensitive and -resistant colon adenocarcinoma cell lines and normal human fibroblasts. Some derivatives possessed selective toxicity towards resistant cancer cells compared to doxorubicin-sensitive cancer cells and normal fibroblasts. Cytotoxic activity of the benzylidene derivatives and the corresponding Hammett–Brown substituent were correlated.

Substituent-Controlled Structural, Supramolecular, and Cytotoxic Properties of a Series of 2-Styryl-8-nitro and 2-Styryl-8-hydroxy Quinolines

Styryl quinolines are biologically active compounds with properties largely depending on the substituents on the styryl and quinoline rings. The supramolecular aspects of this class of compounds are rarely explored. In this study, two new series of styryl quinoline derivatives, bearing -OH and -NO₂ groups at the eighthposition of the quinoline ring and -SCH₃, -OCH₃, and -Br groups on the styryl ring, have been developed, and their structural, supramolecular, and cytotoxic properties have been analyzed. Crystallographic analyses revealed the exciting substituent-dependent structural and supramolecular features of these compounds. In general, the 8 -OH substituted derivatives (SA series) exhibited a non-planar molecular geometry having larger dihedral angles (5.75-59.3°) between the planes of the aromatic rings. At the same time, the 8 -NO₂ substituted derivatives (SB series) exhibited a more or less planar molecular geometry, as revealed by the smaller dihedral angles (1.32-3.45°) between the aromatic rings. Multiple O-H···O, C-H···O, O-H···N, and π-π stacking interactions among the molecules lead to fascinating supramolecular architectures such as hydrogen-bonded triple helices, zig-zag 1D chains, π-π stacked infinite chains, and so forth in their crystal lattice. Hirshfeld surface analyses confirmed the existence of strong π-π stacking and other weak bonding interactions in these compounds. The preliminary cytotoxic properties of SA and SB series compounds were evaluated against the human cervical cancer cell lines (HeLa cells), which further highlighted the roles of functional substituents on the aromatic rings. The SA series compounds with the -OH substituent on the quinoline ring exhibited better cytotoxicity than the SB series compounds with a -NO₂ substituent. Similarly, the electron-withdrawing group -Br on the styryl ring enhanced the cytotoxicity in both series. The IC₅₀ values were 2.52-4.69 and 2.897-10.37 μM, respectively, for the SA and SB series compounds. Compound S3A having -OH and -Br groups on the quinoline and styryl ring, respectively, exhibited the best IC₅₀ value of 2.52 μM among all the compounds tested. These findings confirm the relevance of the hydroxyl group in the eighth position of quinoline. In short, the present study attempts to provide a systematic analysis of the effects of aromatic ring substituents on the structural, supramolecular, and cytotoxic properties of styryl quinolines for the first time.

Anticancer potential and through study of the cytotoxicity mechanism of ionic liquids that are based on the trifluoromethanesulfonate and bis(trifluoromethylsulfonyl)imide anions

Ionic liquids (ILs) are known for their unique physicochemical properties. However, despite the great number of published papers, still little attention has been paid to their biological activity. Anticancer potential and the molecular mechanisms underlying the toxicity of these compounds are especially interesting and still unexplored. In the current work, a broad analysis of the cytotoxicity towards colon and breast cancers as well as glioblastoma of the ILs with pyridinium, piperidinium, pyrrolidinium, and imidazolium cations and trifluoromethanesulfonate or bis(trifluoromethylsulfonyl)imide anions indicated previously as the most toxic for normal human dermal fibroblasts were presented. In the case of MCF-7 cells, the activity of 1-decyl-3-methylimidazolium trifluoromethanesulfonate was more than twice as high as cisplatin. It was found that the inhibition of the cell cycle of colon cancer and glioblastoma cells occurs in different phases. More importantly, the different types of cell death were detected for both selected ILs, namely 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium trifluoromethane-sulfonate, on colon cancer and glioblastoma, respectively, apoptosis and autophagy, confirmed at the gene and protein levels. Additionally, kinetic studies of the reactive oxygen species indicated that the tested ILs disturbed the cellular redox homeostasis.

Styrylquinolines Derivatives: SAR study and Synthetic Approaches

Abstract:

In the present-day scenario, heterocyclic derivatives have revealed the primary function of various medicinal agents precious for humanity. Out of a diverse range of heterocycles, Styrylquinolines scaffolds have been proved to play an essential role in a broad range of biological activities, includinganti-HIV-1, antimicrobial, anti-inflammatory, anti-Alzheimer activity with antiproliferative effects on tumor cell lines. Due to the immense pharmacological importance, distinct synthetic methods have been executed to attain new drug entities from Styrylquinolines. Various schemes for synthesizing Styrylquinolines derivatives like one-pot, ultrasound-promoted heterogeneous acid-catalysed, microwave-assisted, solvent-free, and green synthesis were discussed in the present review. Some products of Styrylquinolines are in clinical trials, and patents are also granted for the novel synthesis of Styrylquinolines. According to the structure-activity relationship, replacement at the R-7 and R-8 positions is required for various activities. In this review, recent synthetic approaches in the medicinal chemistry of Styrylquinolines and potent Styrylquinolines derivatives based on structural activity relationships (SAR) are outlined. Moreover, their primary methods and modifications are also discussed.

Synthesis of 2-styryl-quinazoline and 3-styryl-quinoxaline based sulfonate esters via sp3 C-H activation and their evaluation for α-glucosidase inhibition

Synthesis of 2-styryl-quinazolines and 3-styryl-quinoxaline based sulfonates is reported via sp3 C-H functionalization in the presence of triethylamine (10 mol%). The resulting compounds were tested for the α-glucosidase enzyme inhibition...

Recent contributions of quinolines to antimalarial and anticancer drug discovery research

Quinoline, a privileged scaffold in medicinal chemistry, has always been associated with a multitude of biological activities. Especially in antimalarial and anticancer research, quinoline played (and still plays) a central role, giving rise to the development of an array of quinoline-containing pharmaceuticals in these therapeutic areas. However, both diseases still affect millions of people every year, pointing to the necessity of new therapies. Quinolines have a long-standing history as antimalarial agents, but established quinoline-containing antimalarial drugs are now facing widespread resistance of the Plasmodium parasite. Nevertheless, as evidenced by a massive number of recent literature contributions, they are still of great value for future developments in this field. On the other hand, the number of currently approved anticancer drugs containing a quinoline scaffold are limited, but a strong increase and interest in quinoline compounds as potential anticancer agents can be seen in the last few years. In this review, a literature overview of recent contributions made by quinoline-containing compounds as potent antimalarial or anticancer agents is provided, covering publications between 2018 and 2020.

Synthesis and cytotoxicity against tumor cells of pincer N-heterocyclic ligands and their transition metal complexes

The complexes: [CoL₂](ClO₄)₂ (1), [FeL₂](ClO₄)₂ (2), [NiL₂](ClO₄)₂ (3) and [MnLCl₂] (4), with L = diethyl-1,1′-(pyridine-2,6-diyl)bis(5-methyl-1H-pyrazole-3-carboxylate), were synthesized and fully characterized. Structural analysis revealed two distinct patterns influenced by the counter ions where L acts as a tridentate chelating ligand. The in vitro antitumor activity of L and L′ (diethyl 2,2′-(pyridine-2,6-diylbis(5-methyl-1H-pyrazole-3,1-diyl)) diacetate) as well as their metal complexes, was tested by the measurement of their cytostatic and cytotoxic properties towards the blood cancer mastocytoma cell line P815. We have also investigated their interactions with the antioxidant enzyme system. As a result, [MnL′Cl₂] (1′) exhibited the strongest activity compared to reference cis-platin with no cytotoxicity towards normal cells PBMCs (Peripheral Blood Mononuclear Cells). On the other hand, the antioxidant enzyme activity showed that the efficiency of metal complex 1′ against P815 tumor cells was via the rise in the SOD activity and inhibition of CAT enzyme activity. This proof of concept study allows disclosure of a new class of molecules in cancer therapeutics.

The complexes: [CoL₂](ClO₄)₂ (1), [FeL₂](ClO₄)₂ (2), [NiL₂](ClO₄)₂ (3) and [MnLCl₂] (4), with L = diethyl-1,1′-(pyridine-2,6-diyl)bis(5-methyl-1H-pyrazole-3-carboxylate), were synthesized and fully characterized.

Synthesis and evaluation of the in vitro and in vivo antitrypanosomal activity of 2-styrylquinolines

In this study, we report the synthesis and evaluation of in vitro and in vivo antitrypanosomal activity of styrylquinoline-like compounds (SQ) 3a-h. Synthesis was carried out by using quinaldine and 8- hydroxyquinaldine with a variety of aromatic aldehydes. The structure of SQs was corroborated by one and two-dimension NMR spectroscopy. In vitro antitrypanosomal activity on T. cruzi Talahuen strain was evaluated using β-galactosidase enzymatic method; cytotoxicity on U-937 cells was assessed by using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] method. On the other hand, in vivo therapeutical response to 3a-f compounds was evaluated in BALB/c mice (Mus musculus) experimentally infected with T. cruzi blood trypomastigotes and then orally administered with 100 mg/kg weight day for 20 days. All of the compounds showed in vitro activity with EC₅₀ values ranging between 4.6 ± 0.1 μg/mL (14.4 μM) and 36.6 ± 6.1 μg/mL (91 μM). Furthermore, treatment with 3a-f compounds for 20 days resulted in improvement in all of the mice, with a 83–96% decrease in parasitic load at day 90 post-treatment. Treatment with benznidazol (BZ) managed to cure 100% of the mice at the end of treatment. None of the treatments affected the weight of the animals or alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine levels in serum. These results suggest a therapeutic potential of 3a-f compounds as treatment for the infection.

Insights of 8-hydroxyquinolines: A novel target in medicinal chemistry

8-Hydroxyquinoline (8-HQ) is a significant heterocyclic scaffold in organic and analytical chemistry because of the properties of chromophore and is used to detect various metal ions and anions. But from the last 2 decades, this moiety has been drawn great attention of medicinal chemists due to its significant biological activities. Synthetic modification of 8-hydroxyquinoline is under exploration on large scale to develop more potent target-based broad spectrum drug molecules for the treatment of several life-threatening diseases such as anti-cancer, HIV, neurodegenerative disorders, etc. Metal chelation properties of 8-hydroxyquinoline and its derivatives also make these potent drug candidates for the treatment of various diseases. This review comprises 8-hydroxyquinoline derivatives reported in the literature in last five years (2016-2020) and we anticipate that it will assist medicinal chemists in the synthesis of novel and pharmacologically potent agents for various therapeutic targets, mainly anti-proliferative, anti-microbial, anti-fungal and anti-viral as well as for the treatment of neurodegenerative disorders.

Hypervalent iodine(iii) induced oxidative olefination of benzylamines using Wittig reagents

We have developed hypervalent iodine mediated oxidative olefination of 1° and 2° amines using 2C-Wittig reagents for the synthesis of α,β-unsaturated esters.

New derivatives of 4'-phenyl-2,2':6',2″-terpyridine as promising anticancer agents

Terpyridine derivatives are known from their broad application including anticancer properties. In this work we present the newly synthesized 4'-phenyl-2,2':6',2″-terpyridine group with high antiproliferative activity. We suggest that these compounds influence cellular redox homeostasis. Cancer cells are particularly susceptible to any changes in the redox balance because of their handicapped and inefficient antioxidant cellular systems. The antiproliferative activity of the studied compounds was tested on five different cell lines that represent several types of tumours; glioblastoma, leukemia, breast, pancreatic and colon. Additionally, we also tested their selectivity towards normal cells. We performed molecular biology studies in order to detect the response of a cell to its treatment with the compounds that were tested. We looked at the in-depth changes in the proteins and cellular pathways that lead to cell cycle inhibition (G0/G1 and S), and consequently, death on the apoptosis and autophagy pathways. We proved that the studied compounds targeted DNA as well. Special attention was paid to the targets connected with ROS generation.

Synthesis, Structure-Activity Relationship, and Antimalarial Efficacy of 6-Chloro-2-arylvinylquinolines

There is an urgent need to develop new efficacious antimalarials to address the emerging drug-resistant clinical cases. Our previous phenotypic screening identified styrylquinoline UCF501 as a promising antimalarial compound. To optimize UCF501, we herein report a detailed structure-activity relationship study of 2-arylvinylquinolines, leading to the discovery of potent, low nanomolar antiplasmodial compounds against a Plasmodium falciparum CQ-resistant Dd2 strain, with excellent selectivity profiles (resistance index < 1 and selectivity index > 200). Several metabolically stable 2-arylvinylquinolines are identified as fast-acting agents that kill asexual blood-stage parasites at the trophozoite phase, and the most promising compound 24 also demonstrates transmission blocking potential. Additionally, the monophosphate salt of 24 exhibits excellent in vivo antimalarial efficacy in the murine model without noticeable toxicity. Thus, the 2-arylvinylquinolines represent a promising class of antimalarial drug leads.

Recent Advances in the Synthesis and Biological Activity of 8-Hydroxyquinolines

Compounds containing the 8-hydroxyquinoline (8-HQ) 1 nucleus exhibit a wide range of biological activities, including antimicrobial, anticancer, and antifungal effects. The chemistry and biology of this group have attracted the attention of chemists, medicinal chemists, and professionals in health sciences. A number of prescribed drugs incorporate this group, and numerous 8-HQ- based molecules can be used to develop potent lead compounds with good efficacy and low toxicity. This review focusses on the recent advances in the synthesis of 8-HQ derivatives with different pharmacological properties, including anticancer, antiviral, and antibacterial activities. For this purpose, recent relevant references were searched in different known databases and search engines, such as MEDLINE (PubMed), Google Scholar, Science Direct, Scopus, Cochrane, Scientific Information Database (SID), SciFinder, and Institute for Scientific Information (ISI) Web of Knowledge. This review article provides a literature overview of the various synthetic strategies and biological activities of 8-HQ derivatives and covers the recent related literature. Taken together, compounds containing the 8-HQ moiety have huge therapeutic value and can act as potential building blocks for various pharmacologically active scaffolds. In addition, several described compounds in this review could act leads for the development of drugs against numerous diseases including cancer.

NaCl as Catalyst and Water as Solvent: Highly E-Selective Olefination of Methyl Substituted N-Heteroarenes with Benzyl Amines and Alcohols

Oxidative coupling of benzylamines and alcohols with methyl substituted N-heteroarenes such as quinolines and quinoxalines has been achieved using chloride, a sea abundant anion as the catalyst for practical synthesis of a wide range of E-disubstituted olefins in aqueous medium. Detailed mechanistic studies and control experiments were carried out to deduce the reaction mechanism which indicated that in situ formed ClO₂^- is the active form of the catalyst. We have successfully carried out a 1 g scale reaction using this methodology, and five pharmaceutically relevant conjugated olefins were also synthesized by this method in moderate to good yields.

Design, Synthesis, and Dual Evaluation of Quinoline and Quinolinium Iodide Salt Derivatives as Potential Anticancer and Antibacterial Agents

A series of novel quinoline and quinolinium iodide derivatives were designed and synthesized to discover potential anticancer and antibacterial agents. With regard to anticancer properties, in vitro cytotoxicities against three human cancer cell lines (A-549, HeLa and SGC-7901) were evaluated. The antibacterial properties against two strains, Escherichia coli (ATCC 29213) and Staphylococcus aureus (ATCC 8739), along with minimum inhibitory concentration (MIC) values were evaluated. The target alkyliodine substituted compounds exhibited significant antitumor and antibacterial activity, of which compound 8-((4-(benzyloxy)phenyl)amino)-7-(ethoxycarbonyl)-5-propyl-[1,3]dioxolo[4,5-g]quinolin-5-ium (12) was found to be the most potent derivative with IC₅₀ values of 4.45±0.88, 4.74±0.42, 14.54±1.96, and 32.12±3.66 against A-549, HeLa, SGC-7901, and L-02 cells, respectively, stronger than the positive controls 5-FU and MTX. Furthermore, compound 12 had the most potent bacterial inhibitory activity. The MIC of this compound against both E. coli and S. aureus was 3.125 nmol ⋅ mL^-1 , which was smaller than that against the reference agents amoxicillin and ciprofloxacin.

The combination of artesunate and carboplatin exerts a synergistic anti-tumour effect on non-small cell lung cancer

Carboplatin (CBP) is a widely used targeted anticancer therapeutic drug; however, multi-drug resistance induced by the accumulation of CBP eventually causes diseases progression. The anti-malarial drug artesunate (ART) also exerts anticancer effects in various cancers; however, the combined effect of ART and CBP on non-small cell lung cancer (NSCLC) remains unclear. In the present study, the NSCLC cell line A549 was pretreated with various concentrations of CBP, ART and gemcitabine (GEM). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were conducted to detect cell viability. Cell apoptosis was evaluated by both flow cytometry and TUNEL apoptotic assay. The expression profiles of cell cycle-related proteins and apoptotic proteins were determined by western blot. Cell clone numbers were visualized using crystal violet staining. Here, we found that both CBP and ART suppressed cell viability, and promoted cell apoptosis, and the combined application of ART and CBP at a lower concentration exhibited synergistic effects. Specifically, the combination of ART and CBP at a lower concentration suppressed cell clone numbers, promoted cell cycle arrest at the G₂ /M phase, and induced the expression of the cell cycle and apoptosis-related proteins BAX, p21, p53, and Caspase-3, while decreasing Bcl-2 and Cyclin B1 expression. Based on these results, we concluded that combined application of ART and CBP exerts synergistic anti-tumour effects on NSCLC by enhancing cell apoptosis in a mitochondria-dependent manner.

Antifungal Styryloquinolines as Candida albicans Efflux Pump Inhibitors: Styryloquinolines are ABC Transporter Inhibitors

Styrylquinolines are heterocyclic compounds that are known for their antifungal and antimicrobial activity. Metal complexation through hydroxyl groups has been claimed to be a plausible mechanism of action for these types of compounds. A series of novel structures with protected hydroxyl groups have been designed and synthesized to verify the literature data. Their antifungal activity against wild-type Candida albicans strain and mutants with silenced efflux pumps activity has been determined. Combinations with fluconazole revealed synergistic interactions that were dependent on the substitution pattern. These results open a new route for designing active antifungal agents on a styrylquinoline scaffold.

Acid selective pro-dye for cellular compartments

A novel pro-dye approach for the acid-selective staining of the subcellular compartments for better permeability and selectivity was applied. The designed sensor has suitable physicochemical properties such as a large Stokes shift and a long-lived intracellular fluorescence. The Schiff base fragment was used for the acid-sensitive release of a fluorophore without affecting the overall stability of the biological systems. Due to the presence of an imine bond in its structure and its unique fluorescent properties, it can be presented as a “pro-dye” for acidic structures such as lysosomes. As a result of an imine bond cleavage, a new fluorescent compound is released, whose substantially shifted excitation and emission wavelengths enable a more selective and effective imaging of lysosomes and endosomes. The presented report provides the chemical, physicochemical and optical profiles as well as biological assays and theoretical calculations.