Chemistry and pharmacological diversity of quinoxaline motifs as anticancer agents

Inhibition of protein misfolding and aggregation by steroidal quinoxalin-2(1H)-one and their molecular docking studies

A series of D-ring fused 16-substituted steroidal quinoxalin-2(1H)-one attached to an electron-releasing (ER) or electron-withdrawing (EW) groups via steroidal oxoacetate intermediate were synthesized to investigate their protein aggregation inhibition potential using human lysozyme (HLZ). The influence of the type of substituent at the C-6 positions of the quinoxalin-2(1H)-one ring on the protein aggregation inhibition potential was observed, showing that the EW moiety improved the protein aggregation inhibition potency. Of all the evaluated compounds, NO2-substituted quinoxalin-2(1H)-one derivative 13 was the most active compound and had a maximum protein aggregation inhibition effect. Significant stabilization effects strongly support the binding of the most biologically active steroidal quinoxalin-2(1H)-one with docking studies. The predicted physicochemical and ADME properties lie within a drug-like space which shows no violation of Lipinski's rule of five except compounds 12 and 13. Combined, our results suggest that D-ring fused 16-substituted steroidal quinoxalin-2(1H)-one has the potential to modulate the protein aggregation inhibition effect.

Highly Efficient Photoinitiation Systems Based on Dibenzo[a,c]phenazine Sensitivity to Visible Light for Dentistry

In this work, photoinitiation systems based on dibenzo[a,c]phenazine sensitivity to visible light were designed for their potential application in dentistry. Modification of the structure of dibenzo[a,c]phenazine consisted of introducing electron-donating and electron-withdrawing substituents and heavy atoms into position 11. The synthesized compounds are able to absorb radiation emitted by dental lamps during photoinitiation of the polymerization process. In the presence of acrylates, dibenzo[a,c]phenazines show excellent photoinitiating abilities in systems containing an electron donor or a hydrogen-atom donor as a second component. The developed systems initiate the polymerization process comparable to a commercial photoinitiator, i.e., camphorquinone. Moreover, the performed studies showed a significant shortening of the polymerization time and a reduction in the amount of light absorber. This indicates that polymeric materials are obtained at a similar rate despite a significant reduction in the concentration of the newly developed two-component photoinitiating systems.

Quinoxaline derivatives: Recent discoveries and development strategies towards anticancer agents

Cancer is a leading cause of death and a major health problem worldwide. While many effective anticancer agents are available, most drugs currently on the market are not specific, raising issues like the common side effects of chemotherapy. However, recent research hold promises for the development of more efficient and safer anticancer drugs. Quinoxaline and its derivatives are becoming recognized as a novel class of chemotherapeutic agents with activity against different tumors. The present review compiles and discusses studies concerning the therapeutic potential of the anticancer activity of quinoxaline derivatives, covering articles published between January 2018 and January 2023.

In Silico Design of Potential Small-Molecule Antibiotic Adjuvants against Salmonella typhimurium Ortho Acetyl Sulphydrylase Synthase to Address Antimicrobial Resistance

The inhibition of O-acetyl sulphydrylase synthase isoforms has been reported to represent a promising approach for the development of antibiotic adjuvants. This occurs via the organism developing an unpaired oxidative stress response, causing a reduction in antibiotic resistance in vegetative and swarm cell populations. This consequently increases the effectiveness of conventional antibiotics at lower doses. This study aimed to predict potential inhibitors of Salmonella typhimurium ortho acetyl sulphydrylase synthase (StOASS), which has lower binding energy than the cocrystalized ligand pyridoxal 5 phosphate (PLP), using a computer-aided drug design approach including pharmacophore modeling, virtual screening, and in silico ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) evaluation. The screening and molecular docking of 4254 compounds obtained from the PubChem database were carried out using AutoDock vina, while a post-screening analysis was carried out using Discovery Studio. The best three hits were compounds with the PubChem IDs 118614633, 135715279, and 155773276, possessing binding affinities of -9.1, -8.9, and -8.8 kcal/mol, respectively. The in silico ADMET prediction showed that the pharmacokinetic properties of the best hits were relatively good. The optimization of the best three hits via scaffold hopping gave rise to 187 compounds, and they were docked against StOASS; this revealed that lead compound 1 had the lowest binding energy (-9.3 kcal/mol) and performed better than its parent compound 155773276. Lead compound 1, with the best binding affinity, has a hydroxyl group in its structure and a change in the core heterocycle of its parent compound to benzimidazole, and pyrimidine introduces a synergistic effect and consequently increases the binding energy. The stability of the best hit and optimized compound at the StOASS active site was determined using RMSD, RMSF, radius of gyration, and SASA plots generated from a molecular dynamics simulation. The MD simulation results were also used to monitor how the introduction of new functional groups of optimized compounds contributes to the stability of ligands at the target active site. The improved binding affinity of these compounds compared to PLP and their toxicity profile, which is predicted to be mild, highlights them as good inhibitors of StOASS, and hence, possible antimicrobial adjuvants.

AlCl3-Promoted Intramolecular Indolinone-Quinolone Rearrangement of Spiro[indoline-3,2'-quinoxaline]-2,3'-diones: Easy Access to Quinolino[3,4-b]quinoxalin-6-ones

A facile and direct intramolecular indolinone-quinolone rearrangement was developed for the synthesis of quinolino[3,4-b]quinoxalin-6-ones from spiro[indoline-3,2'-quinoxaline]-2,3'-diones, which are readily available with use of isatines, malononitrile, and 1,2-phenylenediamines under quite mild conditions. This efficient approach provides excellent yields and could potentially be used for the construction of a diverse library of quinolino[3,4-b]quinoxalin-6-ones for high-throughput screening in medicinal chemistry. The reaction mechanism is explored by extensive DFT calculations.

Design, Synthesis, and Biological Evaluation of quinoxaline bearing tetrahydropyridine derivatives as anticancer, antioxidant, and anti-tubercular agents

BACKGROUND

Quinoxaline and Tetrahydropyridine derivatives showed various biological properties. The combination of these two scaffolds may contribute to good biological activity and may give novel and efficacious bioactive candidates.

OBJECTIVE

The present study aimed to identify bioactive agents with quinoxaline bearing tetrahydropyridine derivatives possessing anticancer, antioxidant, and anti-tubercular agents.

METHOD

A series of novel quinoxaline bearing tetrahydropyridine derivatives have been designed and synthesized in good yields. The synthetic protocol involves three-component Povarov reactions of 6-amino quinoxaline, propenyl guaethol, and substituted aldehydes using BF3•OEt2 as catalyst. The newly synthesized molecules were evaluated for their anticancer activity against four cell lines, i.e. A-549, MCF-7, PC-3, and HepG2.

RESULTS

The results from in vitro assay indicated that compound 4a proved to be as potent as the standard drug adriamycin against all cell lines with GI50 values <10 μg/ml. Compounds 4b, 4f, and 4i exhibited good cytotoxicity against A-549 cell line. All synthesized molecules were evaluated for their antioxidant activity and the results revealed that the compounds 4a, 4b, and 4i showed promising antioxidant activities against DPPH and H2O2 scavenging. In addition, the anti-mycobacterial activity of the synthesized compounds against MTB H37Rv strain was determined using MABA method. The results indicate that the compounds 4a, 4b, 4g, and 4i showed better anti-mycobacterial activity than the standard drugs pyrazinamide, ciprofloxacin and streptomycin with MIC value 1.6 μg/ml. Furthermore, molecular docking studies and ADME properties showed good pharmacokinetic profile and drug-likeness properties.

CONCLUSION

These studies showed that a series of novel quinoxaline bearing tetrahydropyridine derivatives exhibit anticancer, anti-mycobacterial, and antioxidant activities.

Recent updates on the anticancer activity of quinoxaline hybrids (Jan. 2017-Jan. 2022)

Abstract:

Cancer as one of the leading causes of death among non-communicable diseases has already posed a heavy burden on the world health system. Chemotherapy is one of the most effective approaches for cancer treatment, but multidrug resistance, lack of efficacy, and toxic side effects hamper efficacious cancer chemotherapy, creating an urgent need to develop novel, more effective and less toxic anticancer therapeutics. Quinoxalines as fascinating structures constitute an important class of heterocycles in drug discovery. Quinoxaline hybrids could exert anticancer activity through diverse mechanisms and possess profound in vitro and in vivo efficacy against various cancers including multidrug-resistant forms. Thus, quinoxaline hybrids represent useful templates for the control and eradication of cancer. The purpose of the present review article is to provide an emphasis on the recent developments (Jan. 2017-Jan. 2022) in quinoxaline hybrids with insights into their in vitro and in vivo anticancer potential as well as structure-activity relationships (SARs) to facilitate further rational design of more effective candidates.

Quinoxaline Derivatives as a Promising Scaffold for Breast Cancer Treatment

According to Global Cancer Statistics 2021, female breast cancer has exceeded lung cancer as the most frequently diagnosed cancer. As a result of this widespread breast cancer, it was necessary...

Brønsted Acid-Catalyzed Minisci-Type Cross-Dehydrogenative Coupling of N-Heteroaromatics and Cyclic Ethers

Brønsted acid-catalyzed direct C(sp²)-H alkylation of N-heteroaromatics with cyclic ethers via a cross-dehydrogenative coupling reaction in the presence of benzoyl peroxide was developed. This methodology successfully provided an easy access to a variety of alkyl-substituted quinoxaline, benzoimidazole, pyrazine, pyrimidine, quinoline, isoquinoline, and pyridine derivatives in up to 94% yield under metal-free conditions.