Design, synthesis, and antitumor evaluation of 2,4,6-triaryl pyridines containing chlorophenyl and phenolic moiety

Exploring the binding properties of DNA/BSA and cytotoxicity studies with new terpyridine-ester-based metal complexes (M = Fe(III), Ni(II), Cu(II) and Ru(III)) - A comparative analysis

Many terpyridines and their metal complexes are known to exhibit remarkable potential for the interaction of biological targets. Notably, a subtle change in the structure of the ligand can influence these interactions significantly. In this regard, it would be very interesting to assess the binding affinity of functionalized molecules with DNA/BSA. In this work, a novel ester-based terpyridine (L) and the corresponding four metal complexes with Ni(II) (MC1), Cu(II) (MC2), Fe(III) (MC3) and Ru(III) (MC4) were prepared and structurally characterized using various spectroscopic and analytical techniques including the validation of molecular structures of ligand (L) and Ni(II)-Tpy complex (MC1). The EPR data demonstrate that MC1 is diamagnetic and other complexes (MC2-MC4) exhibit paramagnetic behavior. Additionally, the structures of ligands and metal complexes were determined using DFT studies and the same were utilized for the docking studies. Interestingly, MC3 and MC4 exhibit a predominant lowest binding energy of -9.62 Kcal/mol (with DNA) and -10.05 Kcal/mol (with BSA) respectively. The binding affinity of the ligand and its complexes with protein and DNA was evaluated by spectroscopic techniques. Notably, the cytotoxicity studies of L and MC1-MC4 were performed against the MCF-7 (human breast cancer) cell lines. The complex MC4 displayed great activity with an IC50 of 3.5 ± 1.75 μM among all synthesized compounds and comparable with cisplatin.

Copper catalysed oxidative cascade deamination/cyclization of vinyl azide and benzylamine for the synthesis of 2,4,6-triarylpyridines

A highly efficient one-pot method for the synthesis of 2,4,6-triaryl pyridines has been developed via cascade deamination and annulation. Copper triflate and molecular iodine easily promoted the oxidative cyclization reaction of vinyl azide and benzylamine to access a wide variety of substituted pyridine substrates under an oxygen atmosphere. The presence of benzyl amine enables the cyclization process by providing the aryl functionality and the nitrogen source. Moreover, a broad range of substrates with good functional group tolerance, avoidance of external oxidants, excellent product yields, operational simplicity and mild conditions are the notable advantages of the present protocol.

Dihydrotestosterone-based A-ring-fused pyridines: microwave-assisted synthesis and biological evaluation in prostate cancer cells compared to structurally related quinolines

Dysfunction of the androgen receptor (AR) signalling axis plays a pivotal role in the development and progression of prostate cancer (PCa). Steroidal and non-steroidal AR antagonists can significantly improve the survival of PCa patients by blocking the action of the endogenous ligand through binding to the hormone receptor and preventing its activation. Herein, we report two synthetic strategies, each utilizing the advantages of microwave irradiation, to modify the A-ring of natural androgen 5α-dihydrotestosterone (DHT) with pyridine scaffolds. Treatment of DHT with appropriate Mannich salts led to 1,5-diketones, which were then converted with hydroxylamine to A-ring-fused 6'-substituted pyridines. To extend the compound library with 4',6'-disubstituted analogues, 2-arylidene derivatives of DHT were subjected to ring closure reactions according to the Kröhnke's pyridine synthesis. The crystal structure of a monosubstituted pyridine product was determined by single crystal X-ray diffraction. AR transcriptional activity in a reporter cell line was investigated for all novel A-ring-fused pyridines and a number of previously synthesized DHT-based quinolines were included to the biological study to obtain information about the structure-activity relationship. It was shown that several A-ring-fused quinolines acted as AR antagonists, in comparison with the dual or agonist character of the majority of A-ring-fused pyridines. Derivative 1d (A-ring-fused 6'-methoxyquinoline) was studied in detail and showed to be a low-micromolar AR antagonist (IC₅₀ = 10.5µM), and it suppressed the viability and proliferation of AR-positive PCa cell lines. Moreover, the candidate compound blocked the AR downstream signalling, induced moderate cell-cycle arrest and showed to bind recombinant AR and to target AR in cells. The binding mode and crucial interactions were described using molecular modelling.

N-2-(Phenylamino) Benzamide Derivatives as Dual Inhibitors of COX-2 and Topo I Deter Gastrointestinal Cancers via Targeting Inflammation and Tumor Progression

Given the close association between inflammation and cancer, combining anti-inflammation therapy is prominent to improve the anticancer effect. Based on I-1, a series of agents targeting COX-2 and Topo I were designed by combining fenamates and phenols. The optimal compound 1H-30 displayed an enhanced inhibitory effect on COX-2 compared to tolfenamic acid and I-1 and showed better inhibition of Topo I than I-1. Importantly, 1H-30 showed potential anticancer effects and suppressed the activation of the NF-κB pathway in cancer cells. 1H-30 inhibited the nuclear translocation of NF-κB and suppressed the production of NO, COX-2, and IL-1β in RAW264.7. In vivo, 1H-30 showed acceptable pharmacokinetic parameters, decreased the tumor growth without affecting the body weight, down-regulated COX-2 and MMP-9, and induced apoptosis in the CT26.WT tumor-bearing mice. Accordingly, 1H-30 as a potential Topo I/COX-2 inhibitor which possessed anti-inflammatory and anticancer effects, with inhibition of the NF-κB pathway, is promising for gastrointestinal cancer therapy.

Applications of Choline Chlorine based Deep Eutectic Solvents as Sustainable Media and catalyst in the synthesis of Heterocyclic Scaffolds

Abstract:

Deep eutectic solvents (DESs), also referred to as low transition temperature mixtures (LTTMs), have emerged as sustainable and cheap alternatives to conventional organic solvents in organic synthesis. This is attributed to their exceptional characteristics viz. easy preparation with readily available cheap materials, water compatibility, non-flammability, non-toxicity, biocompatibility, biodegradability, etc. All these properties label them as versatile and cost-effective green solvents. The first reported DES, choline chloride urea mixture has appeared as an innocuous solvent and catalyst in many organic transformations. This prospective DES combination has been applied extensively to the synthesis of a wide range of heterocyclic compounds including quinolones, spirooxindoles, etc. The conditions employed are relatively mild and do not require additional acid catalysts or organic solvents. This eco-friendly blend for the synthesis of heterocycles reports excellent yields of products with shorter reaction times and a simple workup procedure. Evaluating these merits, this review focuses on the recent literature published on the use of choline chlorine-based DESs in the synthesis of a few important heterocyclic compounds.

Acidic tributyl phosphonium-based ionic liquid: an efficient catalyst for preparation of diverse pyridine systems via a cooperative vinylogous anomeric-based oxidation

Experimental procedure for the synthesis of triaryl pyridines, indolyl pyridines and nicotinonitriles.

Recent advances and future challenges in the synthesis of 2,4,6-triarylpyridines

2,4,6-Triarylpyridines are key building blocks to access functional molecules that are used in the design of advanced materials, metal-organic frameworks, supramolecules, reactive chemical intermediates and drugs. A number of synthetic protocols to construct this heterocyclic scaffold have been developed to date, the most recent of which (2015-present) are included and discussed in the present review. An emphasis has been placed on the utility of each synthetic approach in view of the scope of aryl/hetaryl substituents, limitations and an outlook of each method to be used in applied sciences.

Regiocontrolled synthesis of 2,4,6-triarylpyridines from methyl ketones, electron-deficient acetylenes and ammonium acetate

A novel one-pot two-step approach for the synthesis of 2,4,6-triarylpyridines via t-BuOK/DMSO-promoted C-vinylation of a variety of methyl ketones with electron-deficient acetylenes (alkynones) followed by a cyclization of the in situ generated unsaturated 1,5-dicarbonyl species with ammonium acetate has been developed. This approach possesses competitive advantages such as high regioselectivity, available starting materials and the absence of transition-metal catalysts, oxidants and undesirable byproducts. A wide synthetic utility of the developed approach was demonstrated by the synthesis of trisubstituted, tetrasubstituted and fused pyridines.

Pyridine and Pyrimidine Derivatives as Privileged Scaffolds in Biologically Active Agents

Pyridine and pyrimidine derivatives have received great interest in recent pharmacological research, being effective in the treatment of various malignancies, such as myeloid leukemia, breast cancer and idiopathic pulmonary fibrosis. Most of the FDA approved drugs show a pyridine or pyrimidine core bearing different substituents. The aim of this review is to describe the most recent reports in this field, with reference to the newly discovered pyridineor pyrimidine-based drugs, to their synthesis and to the evaluation of the most biologically active derivatives. The corresponding benzo-fused heterocyclic compounds, i.e. quinolines and quinazolines, are also reported.

Tuning the interpenetration of metal–organic frameworks through changing ligand functionality: effect on gas adsorption properties

Two interpenetrated MOFs are constructed with a 2-connected ligand, whereas one non-interpenetrated MOF is constructed by using a 3-connected ligand.

Discovery and Biological Evaluations of Halogenated 2,4-Diphenyl Indeno[1,2-b]pyridinol Derivatives as Potent Topoisomerase IIα-Targeted Chemotherapeutic Agents for Breast Cancer

With the aim of developing new effective topoisomerase IIα-targeted anticancer agents, we synthesized a series of hydroxy- and halogenated 2,4-diphenyl indeno[1,2-b]pyridinols using a microwave-assisted single step synthetic method and investigated structure-activity relationships. The majority of compounds with chlorophenyl group at 2-position and phenol group at the 4-position of indeno[1,2-b]pyridinols exhibited potent antiproliferative activity and topoisomerase IIα-selective inhibition. Of the 172 compounds tested, 89 showed highly potent and selective topoisomerase IIα inhibition and antiproliferative activity in the nanomolar range against human T47D breast (2.6 nM) cancer cell lines. In addition, mechanistic studies revealed compound 89 is a nonintercalative topoisomerase II poison, and in vitro studies showed it had promising cytotoxic effects in diverse breast cancer cell lines and was particularly effective at inducing apoptosis in T47D cells. Furthermore, in vivo administration of compound 89 had significant antitumor effects in orthotopic mouse model of breast cancer.

A comprehensive review of topoisomerase inhibitors as anticancer agents in the past decade

The topoisomerase enzymes play an important role in DNA metabolism, and searching for enzyme inhibitors is an important target in the search for new anticancer drugs. Discovery of new anticancer chemotherapeutical capable of inhibiting topoisomerase enzymes is highlighted in anticancer research. Therefore, biologists, organic chemists and medicinal chemists all around the world have been identifying, designing, synthesizing and evaluating a variety of novel bioactive molecules targeting topoisomerase. This review summarizes types of topoisomerase inhibitors in the past decade, and divides them into nine classes by structural characteristics, including N-heterocycles compounds, quinone derivatives, flavonoids derivatives, coumarin derivatives, lignan derivatives, polyphenol derivatives, diterpenes derivatives, fatty acids derivatives, and metal complexes. Then we discussed the application prospect and development of these anticancer compounds, as well as concluded parts of their structural-activity relationships. We believe this review would be invaluable in helping to further search potential topoisomerase inhibition as antitumor agent in clinical usage.

Facile Synthesis and Fluorescent Properties of Two Novel 4-Aryl-2,6-Dicoumarinylpyridines

Two novel 4-aryl-2,6-dicoumarinylpyridines were synthesised in the presence of tetrabutylammonium hydrogen sulphate via a one-pot reaction. In addition, the absorption and fluorescence spectra of the synthesised compounds in chloroform were measured for the first time.

Synthesis, Characterization and Photophysical Studies of Tricoumarin-Pyridines

A series of novel tricoumarin-pyridines have been synthesized by the reaction of 4-formyl coumarins and substituted 3-acetylcoumarin with ammonium acetate for the application in organic electronics as well as fluorescent dyes. The structures of all new compounds were confirmed and characterized by IR, ¹H NMR and ESI-Mass analysis. All the important photo physical prerequisites for organic electronic application such as strong and broad optical absorption, thermal stability were determined for the synthesized molecules. Optical properties were studied by UV-Vis absorption and fluorescence spectroscopy. Optical band gaps of the tricoumarin-pyridines were found to be 2.72-3.10 eV as calculated from their onset absorption edge. The tricoumarin-pyridines were thermally stable up to 290-370 °C as determined by thermogravimetric analysis (TGA). Photophysical studies indicate the synthesized materials are promising candidates for organic electronic applications.

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

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

Design, synthesis, topoisomerase I & II inhibitory activity, antiproliferative activity, and structure-activity relationship study of pyrazoline derivatives: An ATP-competitive human topoisomerase IIα catalytic inhibitor

A series of pyrazoline derivatives (5) were synthesized in 92-96% yields from chalcones (3) and hydrazides (4). Subsequently, topo-I and IIα-mediated relaxation and antiproliferative activity assays were evaluated for 5. Among the tested compounds, 5h had a very strong topo-I activity of 97% (Camptothecin, 74%) at concentration of 100 μM. Nevertheless, all the compounds 5a-5i showed significant topo II inhibitory activity in the range of 90-94% (Etoposide, 96%) at the same concentration. Cytotoxic potential of these compounds was tested in a panel of three human tumor cell lines, HCT15, BT474 and T47D. All the compounds showed strong activity against HCT15 cell line with IC50 at the range of 1.9-10.4 μM (Adriamycin, 23.0; Etoposide, 6.9; and Camptothecin, 7.1 μM). Moreover, compounds 5c, 5f and 5i were observed to have strong antiproliferative activity against BT474 cell lines. Since, compound 5d showed antiproliferative activity at a very low IC50 thus 5d was then selected to study on their mode of action with diverse methods of ATP competition assay, ATPase assay and DNA-topo IIα cleavable complex assay and the results revealed that it functioned as a ATP-competitive human topoisomerase IIα catalytic inhibitor. Further evaluation of endogenous topo-mediated DNA relaxation in cells has been conducted to find that, 5d inhibited endogenous topo-mediated pBR322 plasmid relaxation is more efficient (78.0 ± 4.7% at 50 μM) than Etoposide (36.0 ± 1.7% at 50 μM).

A water-soluble Pd(ii) complex with a terpyridine ligand: experimental and molecular modeling studies of the interaction with DNA and BSA; and in vitro cytotoxicity investigations against five human cancer cell lines

[Pd(4-OHPh-tpy)Cl]Cl was prepared. The complex interacts with DNA via a combination of covalent, intercalation, and hydrogen bonding interactions.

Synthesis, characterization and pharmacological screening of some novel 5-imidazopyrazole incorporated polyhydroquinoline derivatives

A new category of polyhydroquinoline derivatives 8a-t were synthesized in moderate to good yield (64-85%) by one-pot three-component cyclocondensation reaction of 5-(1H-imidazol-1-yl)-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde 3 with various enaminones 6a-h and different active methylene compounds (malononitrile 7a, ethylcaynoacetate 7b and caynoacetamide 7c) in absolute ethanol. The newly synthesized compounds were evaluated for their in vitro antimalarial activity against Plasmodium falciparum, in vitro antibacterial activity against a panel of pathogenic strains of bacteria and fungi and also for their antitubercular activity against Mycobacterium tuberculosis H37Rv strain. Two of them (8n, 8t) exhibited excellent antimalarial activity. Some of them exhibited excellent antibacterial activity and moderate antituberculosis activity compared with the first line drugs.

1,1,2,2-Tetra-kis[2,4-dichloro-6-(dieth-oxy-meth-yl)phen-oxy-meth-yl]ethene

In the title compound, C(50)H(60)Cl(8)O(12), the mol-ecules are disordered about an inversion center located at the mid-point of the central C=C bond. These atoms show disorder and were modelled with two different orientations with site occupancies of 0.828 (3) and 0.172 (3). The dihedral angle between the two benzene rings in the asymmetric unit is 52.80 (6)°. Intramolecular C-H⋯O and C-H⋯Cl interactions occur and the crystal packing features inversion dimers linked by pairs of C-H⋯O bonds, generating R(2) (2)(10) loops.