RETRACTED: Design, synthesis, and biological evaluation of heterotetracyclic quinolinone derivatives as anticancer agents targeting topoisomerases

New Benzimidazole-Triazole Derivatives as Topoisomerase I Inhibitors: Design, Synthesis, Anticancer Screening, and Molecular Modeling Studies

In this study, we designed, synthesized, and evaluated a series of 1,2,4-triazole benzimidazoles for their cytotoxic effects against the A549, C6, and NIH3T3 cell lines. Additionally, these compounds were assessed for their inhibitory activity against DNA topoisomerase I, aiming to develop novel anticancer agents. The synthesized final compounds 4a-h were characterized using 1H NMR, 13C NMR, and HRMS. Among them, compounds 4b and 4h emerged as the most potent agents against the A549 cell line, exhibiting an IC50 value of 7.34 ± 0.21 μM and 4.56 ± 0.18 μM, respectively. These results were compared to standard drugs, doxorubicin (IC50 = 12.420 ± 0.5 μM) and Hoechst 33342 (IC50 = 0.422 ± 0.02 μM). Notably, all tested compounds displayed higher cytotoxicity toward A549 cells than C6 cells. Compounds 4b and 4h demonstrated significant inhibitory activity against topoisomerase I, highlighting their potential as lead compounds in anticancer therapy. Subsequent in silico molecular docking studies were conducted to elucidate the potential binding interactions of compounds 4b and 4h with the target enzyme topoisomerase I. Molecular dynamics studies also assessed and validated the binding affinity and stability. These studies confirmed the promising binding affinity of these compounds, reinforcing their status as lead candidates. According to DFT, compound 4b having the lower energy gap value (ΔE = 3.598 eV) is more chemically reactive than the others, which is consistent with significant inhibitory activity against topoisomerase I. Furthermore, in silico ADME profiles for compounds 4b and 4h were evaluated using SwissADME, providing insights into their pharmacokinetic properties.

The mechanisms of multidrug resistance of breast cancer and research progress on related reversal agents

Chemotherapy is the mainstay in the treatment of breast cancer. However, many drugs that are commonly used in clinical practice have a high incidence of side effects and multidrug resistance (MDR), which is mainly caused by overexpression of drug transporters and related enzymes in breast cancer cells. In recent years, researchers have been working hard to find newer and safer drugs to overcome MDR in breast cancer. In this review, we provide the molecule mechanism of MDR in breast cancer, categorize potential lead compounds that inhibit single or multiple drug transporter proteins, as well as related enzymes. Additionally, we have summarized the structure-activity relationship (SAR) based on potential breast cancer MDR modulators with lower side effects. The development of novel approaches to suppress MDR is also addressed. These lead compounds hold great promise for exploring effective chemotherapy agents to overcome MDR, providing opportunities for curing breast cancer in the future.

Unexpected Substituent Effects in Spiro-Compound Formation: Steering N-Aryl Propynamides and DMSO toward Site-Specific Sulfination in Quinolin-2-ones or Spiro[4,5]trienones

A highly substituent-dependent rearrangement allows for the novel and SOCl₂-induced divergent synthesis of 3-methylthioquinolin-2-ones and 3-methylthiospiro[4.5]trienones through intramolecular electrophilic cyclization of N-aryl propyamides. DMSO acts as both solvent and sulfur source, and use of DMSO-h₆/d₆ enables the incorporation of SCH₃ or SCD₃ moieties to the 3-position of the heterocyclic framework. Different para-substituents trigger divergent reaction pathways leading to the formation of quinolin-2-ones for mild substituents and spiro[4,5]trienones for both electron-withdrawing and -donating substituents, respectively. On the basis of both computational and experimental results, a new mechanism has been put forward that accounts for the exclusive spirolization/defluorination process and the surprising substituent effects.

Pyridine moiety: An insight into recent advances in treatment of cancer

The incidence of cancer is increasing worldwide, affecting a vast majority of the human population. As new different anticancer agents are being developed now, the requirement is to deal somehow with them and evaluate their safety. Among them, pyridine based drugs are contributing a lot, as it is one of the imperative pharmacophores occurring synthetically as well as naturally in heterocyclic compounds, and having a wide range of therapeutic applications in the area of drug discovery, thereby offering many chances for further improvement in antitumor agents via acting onto numerous receptors of extreme prominence. Many pyridine derivatives have been reported to inhibit enzymes, receptors and many other targets for controlling and curing the global health issue of cancer. Nowadays, in combination with other moieties, researchers are focusing on the development of pyridine-based new derivatives for cancer treatment. Therefore, this review sheds light on the recent therapeutic expansions of pyridine together with its molecular docking, structure-activity-relationship, availability in the market, and a summary of recently patented and published research works that shall jointly help the scientists to produce effective drugs with the desired pharmacological activity.

Novel urea linked ciprofloxacin-chalcone hybrids having antiproliferative topoisomerases I/II inhibitory activities and caspases-mediated apoptosis

A novel series of urea-linked ciprofloxacin (CP)-chalcone hybrids 3a-j were synthesized and screened by NCI-60 cancer cell lines as potential cytotoxic agents. Interestingly, compounds 3c and 3j showed remarkable antiproliferative activities against both colon HCT-116 and leukemia SR cancer cells compared to camptothecin, topotecan and staurosporine with IC₅₀ = 2.53, 2.01, 17.36, 12.23 and 3.1 μM for HCT-116 cells, respectively and IC₅₀ = 0.73, 0.64, 3.32, 13.72 and 1.17 μM for leukemia SR cells, respectively. Also, compounds 3c and 3j exhibited inhibitory activities against Topoisomerase (Topo) I with % inhibition = 51.19% and 56.72%, respectively, compared to camptothecin (% inhibition = 60.05%) and Topo IIβ with % inhibition = 60.81% and 60.06%, respectively, compared to topotecan (% inhibition = 71.09%). Furthermore, compound 3j arrested the cell cycle of leukemia SR cells at G2/M phase. It induced apoptosis both intrinsically and extrinsically via activation of proteolytic caspases cascade (caspases-3, -8, and -9), release of cytochrome C from mitochondria, upregulation of proapoptotic Bax and down-regulation of Bcl-2 protein level. Thus, the new ciprofloxacin derivative 3j could be considered as a potential lead for further optimization of antitumor agent against leukemia and colorectal carcinoma.

Synthesis, anticancer evaluation and molecular docking studies of new benzimidazole- 1,3,4-oxadiazole derivatives as human topoisomerase types I poison

In this study, some benzimidazole-oxadiazole derivatives were synthesised and tested for their in vitro anticancer activities on five cancer cell lines, including HeLa, MCF7, A549, HepG2 and C6. Their structures were elucidated by IR, ¹H-NMR, ¹³C-NMR, 2 D-NMR and HRMS spectroscopic methods. Among all screened compounds; 5a, 5b, 5d, 5e, 5k, 5l, 5n and 5o exhibited potent selective cytotoxic activities against various tested cancer cell lines. Especially, compounds 5l and 5n exhibited the most antiproliferative activity than Hoechst 33342 and doxorubicin against HeLa cell line, with IC₅₀ of 0.224 ± 0.011 µM and 0.205 ± 0.010 µM, respectively. Furthermore, these potent lead cytotoxic agents were evaluated in terms of their inhibition potency against Topoisomerase I and it was determined that selected compounds inhibited the Topoisomerase I. Docking studies were performed and probable interactions in the DNA-Topo I enzyme complex was determined.