Synthesis and SAR study of new hydroxy and chloro-substituted 2,4-diphenyl 5H-chromeno[4,3-b]pyridines as selective topoisomerase IIα-targeting anticancer agents

The Chromenopyridine Scaffold: A Privileged Platform in Drug Design

The chromenopyridine scaffold represents an important class of heterocyclic compounds exhibiting a broad spectrum of biological properties. This review describes novel and efficient procedures for the synthesis of this scaffold. Herein, several methods were detailed and grouped according to their starting material (e.g., salicylaldehydes, chromones, chromanones and coumarins) and respective biological activity, when reported. This review highlights the potential of the reported synthetic strategies for preparing chromenopyridine derivatives with promising biological activity, paving the way for further developments in drug discovery.

Overview of the New Bioactive Heterocycles as Targeting Topoisomerase Inhibitors Useful Against Colon Cancer

Colorectal cancer (CRC) is the third most common cancer globally, with high mortality. Metastatic CRC is incurable in most cases, and multiple drug therapy can increase patients' life expectancy by 2 to 3 years. Efforts are being made to understand the relationship between topoisomerase enzymes and colorectal cancer. Some studies have shown that higher expression of these enzymes is correlated to a poor prognosis for this type of cancer. One of the primary drugs used in the treatment of CRC is Irinotecan, which can be used in monotherapy or, more commonly, in therapeutic schemes such as FOLFIRI (Fluorouracil, Leucovorin, and Irinotecan) and CAPIRI (Capecitabine and Irinotecan). Like Camptothecin, Irinotecan and other compounds have a mechanism of action based on the formation of a ternary complex with topoisomerase I and DNA providing damage to it, therefore leading to cell death. Thus, this review focused on the principal works published in the last ten years that demonstrate a correlation between the inhibition of different isoforms of topoisomerase and in vitro cytotoxic activity against CRC by natural products, semisynthetic and synthetic compounds of pyridine, quinoline, acridine, imidazoles, indoles, and metal complexes. The results revealed that natural compounds, semisynthetic and synthetic derivatives showed potential in vitro cytotoxicity against several colon cancer cell lines, and this activity was often accompanied by the ability to inhibit both isoforms of topoisomerase (I and II), highlighting that these enzymes can be promising targets for the development of new chemotherapy against CRC. Pyridine analogs were considered the most promising for this study, while the evaluation of the real potential of natural products was limited by the lack of information in their work. Moreover, the complexes, although promising, presented as the main limitation the lack of selectivity.

Structure-Activity Relationship Studies of Chalcones and Diarylpentanoids with Antitumor Activity: Potency and Selectivity Optimization

We previously reported that chalcone CM-M345 (1) and diarylpentanoid BP-C4 (2) induced p53-dependent growth inhibitory activity in human cancer cells. Herein, CM-M345 (1) and BP-C4 (2) analogues were designed and synthesized in order to obtain more potent and selective compounds. Compounds 16, 17, 19, 20, and 22-24 caused pronounced in vitro growth inhibitory activity in HCT116 cells (0.09 < GI50 < 3.10 μM). Chemical optimization of CM-M345 (1) led to the identification of compound 36 with increased selectivity for HCT116 cells expressing wild-type p53 compared to its p53-null isogenic derivative and low toxicity to non-tumor HFF-1 cells. The molecular modification of BP-C4 (2) resulted in the discovery of compound 16 with more pronounced antiproliferative activity and being selective for HCT116 cells with p53, as well as 17 with enhanced antiproliferative activity against HCT116 cells and low toxicity to non-tumor cells. Compound 16 behaved as an inhibitor of p53-MDM2 interaction, and compound 17 was shown to induce apoptosis, associated with an increase in cleaved PARP and decreased levels of the anti-apoptotic protein Bcl-2. In silico studies allowed us to predict the druglikeness and ADMET properties for 16 and 17. Docking and molecular dynamics studies predicted that 16 could bind stably to the MDM2 binding pocket.

Green Protocol for the Novel Synthesis of Thiochromeno[4,3-b]pyridine and Chromeno[4,3-b]pyridine Derivatives Utilizing a High-Pressure System

A suitable and effective Q-tube-assisted strategy for the synthesis of novel, unrivalled thiochromeno[4,3-b]pyridine and chromeno[4,3-b]pyridine derivatives has been sophisticated, which includes ammonium acetate-mediated cyclocondensation reactions between 3-oxo-2-arylhydrazonopropanals and heterobenzocyclic ketones such as thiochroman-4-one and chroman-4-one, respectively. The high-pressure Q-tube reactor was shown to be superior to conventional heating. Furthermore, this Q-tube reactor-assisted protocol is safe owing to facile pressing and sealing, a broad substrate scope, and simple work-up and purification processes, as well as being scalable and having a high atom economy. The proposed mechanistic route includes two sequential dehydrative stages. In this investigation, X-ray crystallographic analysis was performed to authenticate the targeted products.

Synthesis of 5H-chromeno[3,4-b]pyridines via DABCO-catalyzed [3 + 3] annulation of 3-nitro-2H-chromenes and allenoates

The DABCO-catalyzed [3 + 3] annulation between 3-nitro-2H-chromenes and benzyl 2,3-butadienoate has been developed as a route to 5H-chromeno[3,4-b]pyridine derivatives. Under optimal reaction conditions, 5H-chromeno[3,4-b]pyridines incorporating two allenoate units were obtained in moderate to good yields (30-76%). The same type of transformation could be carried out using butynoates as allene surrogates. Mechanistic studies by mass spectrometry allowed the identification of the key intermediates involved in the reaction mechanism. The reported synthetic methodology represents an entirely new approach for the synthesis of the 5H-chromeno[3,4-b]pyridine core structure based on allene chemistry.

Synthesis and structure-activity relationships of hydroxylated and halogenated 2,4-diaryl benzofuro[3,2-b]pyridin-7-ols as selective topoisomerase IIα inhibitors

The objective of this study was to discover potential topoisomerase (topo) targeting anticancer agents. Novel series of hydroxylated and halogenated(-F, -Cl, and -CF₃) 2,4-diaryl benzofuro[3,2-b]pyridin-7-ols were systematically designed and synthesized by faster, economic, and environmentally friendly _l-proline catalyzed and microwave-assisted one pot reaction method. The synthesized compounds were assessed for topo I and IIα inhibitory and anti-proliferative activities. The in vitroevaluation displayed that most of the compounds have selective topo IIα inhibitoryactivity as well as selectivity towards T47D human cancer cell line. Structure-activity relationship study suggested that the introduction of additional hydroxyl functionality at 7-positon of benzofuro[3,2-b]pyridine skeleton is crucial for selective topo IIα inhibitory activity. Placement of phenolic moiety on the 4-position of the tricyclic system imparts better topo IIα inhibitory and anti-proliferative activity.

Medicinal attributes of pyridine scaffold as anticancer targeting agents

Background

The heterocyclic compounds particularly pyridine displayed clinical and biological implementation. Pyridine scaffolds have been detected in most relevant drug molecules that included pyridine provided a great possibility for treatment.

Main text

Pyridine-containing compounds have increasing importance for medicinal application as antiviral, anticholinesterase activities, antimalarial, antimicrobial, antidiabetic and anticancer. This has generated concern among researchers in synthesising a variety of pyridine derivatives.

Conclusion

This review focuses on different pyridine targets as anticancer and their pharmacophoric elements controlling its activity.

A proficient microwave synthesis with structure elucidation and the exploitation of the biological behavior of the newly halogenated 3-amino-1H-benzo[f]chromene molecules, targeting dual inhibition of topoisomerase II and microtubules

In our endeavors to develop novel and powerful agents with antiproliferative activities, a series of β-enamionitriles, linked to the 8-bromo-1H-benzo[f]chromene moieties (4a-m), was designed and synthesized under microwave irradiation conditions. The structures of the target compounds were established on the basis of their spectral data: IR, ¹H NMR, ¹³C NMR, ¹³C NMR-DEPT/APT, ¹⁹F NMR and MS. Furthermore, the antiproliferative properties were evaluated against the human cancer cell lines MCF-7, HCT-116, and HepG-2 in comparison to the positive controls Vinblastine and Doxorubicin, employing the viability assay. The obtained results confirmed that most of the tested molecules revealed strong and selective cytotoxic activities against the three cancer cell lines. The most potent cytotoxic compounds 4b, 4d, 4e, 4i, and 4k were elected for further examination, such as the cell cycle analysis, the apoptosis assay, the Caspase production, and the DNA fragmentation. This study also revealed that the desired compounds stimulate cell cycle arrest at the G2/M phases, increase the production of Caspases 3, 8, and 9, and finally cause intrinsic and extrinsic apoptotic cell death. Moreover, these compounds suppress the action of the topoisomerase II enzyme and also disrupt the microtubule functions. The SAR study of the synthesized compounds verified that the substitution on the phenyl ring of the 1H-benzo[f]chromene nucleus, accompanied with the presence of the bromine atom at the 8-position, increases the ability of these molecules against different cell lines.

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.