Design and synthesis of 2-phenylnaphthalenoids and 2-phenylbenzofuranoids as DNA topoisomerase inhibitors and antitumor agents

Synthesis of 2-phenylnaphthalenoid amide derivatives and their topoisomerase IIα inhibitory and antiproliferative activities

Topoisomerases are highly associated with cell proliferation, becoming an important target for the development of antitumor drugs. 2-Phenylnaphthalenoids (2PNs) have been identified as human DNA topoisomerase IIα (TopoIIα) inhibitors. In this study, based on the 2PN scaffold, 20 amide derivatives (J1-J10, K1-K10) were synthesized. Among them, K10 showed high TopoIIα inhibitory activity and stronger antiproliferation activity against HepG-2 and MDA-MB-231 cells (IC50 0.33 and 0.63 μM, respectively) than the positive control VP-16 (IC50 9.19 and 10.86 μM) and the lead F2 (IC50 0.64 and 1.51 μM). Meanwhile, K10 could also inhibit migration and promote apoptosis of HepG-2 and MDA-MB-231 cells. Therefore, K10 can be developed into a potent TopoIIα inhibitor as an antitumor agent. The structure-activity relationship was also discussed.

Recent development of multi-targeted inhibitors of human topoisomerase II enzyme as potent cancer therapeutics

Multi-target therapies have been considered one of the viable options to overcome the challenges to eradicate intrinsic and acquired drug-resistant cancer cells. While to increase the efficacy of therapeutics, the use of a single drug against multiple structurally similar sites, which noncommittedly modulate several vital cellular pathways proposed as a potential alternative to a 'single drug single target'. Besides, it reduces the usage of a number of drugs and their side effects. Topoisomerase II enzyme plays a very significant role in DNA replication and thus served as an important target for numerous anti-cancer agents. However, in spite of promising clinical results, in several cases, it was found that cancer cells have developed resistance against the anti-cancer agents targeting this enzyme. Therefore, multi-target therapies have been proposed as an alternative to overcome different drug resistance mechanisms while topoisomerases II are a primary target site. In this review, we have tried to discuss the characteristics of the binding cavity available for interactions of drugs, and potent inhibitors concurrently modulate the functions of topoisomerases II as well as other structurally related target sites. Additionally, the mechanism of drug resistance by considering molecular and cellular insights by including various types of cancers.

Identification of novel topoisomerase II alpha inhibitors by virtual screening, molecular docking, and bioassay

Breast cancer is one of the most common tumors, and its treatment still leaves room for improvement. Topoisomerase II alpha is a potential target for the treatment of human diseases such as breast cancer. In this article, we attempted to discover a novel anticancer drug. We have used the topoisomerase II alpha protein-Homo sapiens (Human) to hierarchically screen the Maybridge database. Based on their docking score, the top hit compounds have been assayed for inhibition in a topoisomerase II pBR322 DNA relaxation assay in vitro. Candidate compound 6 (CP6) was found to have the best inhibitory effect for topoisomerase II among the 20 tested compounds. In addition, CP6 had potent cytotoxicity against eight tested tumor cell lines. At the same time, CP6 was shown to have potential anti-multidrug resistance capabilities. This study identifies CP6, which can contribute to the development of new topoisomerase II inhibitors as anticancer agents.

Identification of HN252 as a potent inhibitor of protein phosphatase PPM1B

Protein phosphatase 1B (PPM1B), a member of metal-dependent protein serine/threonine phosphatase family, is involved in the regulation of several signalling pathways. However, our understanding of its substrate interaction and physiological functions is still largely limited. There is no reported PPM1B inhibitor to date. In this study, we identified HN252, a p-terphenyl derivative, as a potent PPM1B inhibitor (K_i  = 0.52 ± 0.06 µM). HN252 binding to PPM1B displayed remarkable and specific inhibition of PPM1B in both in vitro and ex vivo. With the aid of this small molecular inhibitor, we identified 30 proteins' serine/threonine phosphorylation as potential substrates of PPM1B, 5 of which were demonstrated by immunoprecipitation, including one known (CDK2) and 4 novel ones (AKT1, HSP90B, β-catenin and BRCA1). Furthermore, GO and KEGG analysis of dramatically phosphorylated proteins by PPM1B inhibition indicated that PPM1B plays roles in the regulation of multiple cellular processes and signalling pathways, such as gene transcription, inflammatory regulation, ageing and tumorigenesis. Our work provides novel insights into further investigation of molecular mechanisms of PPM1B.

Benzofuran: A Key Heterocycle - Ring Closure And Beyond

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The benzofuranyl motif present in compounds exhibits various medicinal properties and non-drug applications. These derivatives are naturally occurring compounds or synthetic materials, which cover a broad spectrum of pharmacological activities like anti-inflammatory, anti-diabetic, anti- depressant, anti-HIV, anti-microbial, anti-proliferative, anti-convulsant, cytotoxic, analgesic, etc. Few of the commercially interesting compounds from this class are, ailanthoidol (anti-inflammatory), amiodarone, dronedarone, celivarone (anti-arrhythmic), bufuralol (muscular airways relaxant), morphine, 5-(2-aminopropyl)benzofuran; 5-APB, 6-(2-aminopropyl)benzofuran; 6-APB (CNS), rifampicin (antibiotic), etc., whereas, some of the non-drug applications are in perfumery industry (bergapten) and as tannin activators in sunscreen preparations (psoralen, 8-methoxypsoralen, and angelicin). Considering these interesting biological activities and commercial utilities, a review on the synthetic aspects of this privileged scaffold was attempted. For the benefit of natural product-based drug discovery, available sources of these derivatives, extraction process and reported biological activities have also been outlined in this review.

Chemoselective reduction of quinols as an alternative to Sonogashira coupling: synthesis of polysubstituted benzofurans

An efficient synthetic approach to polysubstituted benzofurans is described, using 2-methoxyquinone as a benzofuran backbone.

Avertoxins A-D, Prenyl Asteltoxin Derivatives from Aspergillus versicolor Y10, an Endophytic Fungus of Huperzia serrata

Aspergillus versicolor Y10 is an endophytic fungus isolated from Huperzia serrata, which showed inhibitory activity against acetylcholinesterase. An investigation of the chemical constituents of Y10 led to the isolation of four new prenylated asteltoxin derivatives, named avertoxins A-D (2-5), together with the known mycotoxin asteltoxin (1). In the present study, we report structure elucidation for 2-5 and the revised NMR assignments for asteltoxin and demonstrated that avertoxin B (3) is an active inhibitor against human acetylcholinesterase with the IC50 value of 14.9 μM (huperzine A as the positive control had an IC50 of 0.6 μM). In addition, the cytotoxicity of asteltoxin (1) and avertoxins A-D (2-5) against MDA-MB-231, HCT116, and HeLa cell lines was evaluated.