Design, synthesis and biological evaluation of novel 4,5-dihydro-[1,2,4]triazolo[4,3-f]pteridine derivatives as potential BRD4 inhibitors

Non-kinase off-target inhibitory activities of clinically-relevant kinase inhibitors

Protein kinases are responsible for a myriad of cellular functions, such as cell cycle, apoptosis, and proliferation. Because of this, kinases make excellent targets for therapeutics. During the process to identify clinical kinase inhibitor candidates, kinase selectivity profiles of lead inhibitors are typically obtained. Such kinome selectivity screening could identify crucial kinase anti-targets that might contribute to drug toxicity and/or reveal additional kinase targets that potentially contribute to the efficacy of the compound via kinase polypharmacology. In addition to kinome panel screening, practitioners also obtain the inhibition profiles of a few non-kinase targets, such as ion-channels and select GPCR targets to identify compounds that might possess potential liabilities. Often ignored is the possibility that identified kinase inhibitors might also inhibit or bind to the other proteins (greater than 20,000) in the cell that are not kinases, which may be relevant to toxicity or even additional mode of drug action. This review highlights various inhibitors, which have been approved by the FDA or are currently undergoing clinical trials, that also inhibit other non-kinase targets. The binding poses of the drugs in the binding sites of the target kinases and off-targets are analyzed to understand if the same features of the compounds are critical for the polypharmacology.

Design, Synthesis and Biological Evaluation of Novel Phenyl-Substituted Naphthoic Acid Ethyl Ester Derivatives as Strigolactone Receptor Inhibitor

Strigolactones (SLs) are plant hormones that regulate several key agronomic traits, including shoot branching, leaf senescence, and stress tolerance. The artificial regulation of SL biosynthesis and signaling has been considered as a potent strategy in regulating plant architecture and combatting the infection of parasitic weeds to help improve crop yield. DL1b is a previously reported SL receptor inhibitor molecule that significantly promotes shoot branching. Here, we synthesized 18 novel compounds based on the structure of DL1b. We performed rice tillering activity assay and selected a novel small molecule, C6, as a candidate SL receptor inhibitor. In vitro bioassays demonstrated that C6 possesses various regulatory functions as an SL inhibitor, including inhibiting germination of the root parasitic seeds Phelipanche aegyptiaca, delaying leaf senescence and promoting hypocotyl elongation of Arabidopsis. ITC analysis and molecular docking experiments further confirmed that C6 can interact with SL receptor proteins, thereby interfering with the binding of SL to its receptor. Therefore, C6 is considered a novel SL receptor inhibitor with potential applications in plant architecture control and prevention of root parasitic weed infestation.

Cytosporone E analogues as BRD4 inhibitors for cancer treatment: molecular docking and molecular dynamic investigations

Cancer is considered one of the worldwide life-threatening and leading causes of human mortality. In 2020, 19,292,789 cancer cases and 9,958,133 cancer deaths have been estimated worldwide. Therefore, efforts have been devoted to discover novel anticancer agents. Bromodomains have a vital role in the regulation of transcription. Many reports have shown that bromodomain-containing protein 4 (BRD4) is an important target for cancer therapeutics. In this study, several in silico approaches were utilized to discover new inhibitors against the BRD4 protein using the Schrodinger suite. A library of 27 cytosporone E derivatives was docked into the active site of the BRD4 protein. Docked ligands showed docking scores ranging between -11.289 to -3.992 Kcal/mol. Ligands 1-4 showed better binding affinities with docking scores ranging from -11.289 to -8.917 Kcal/mol compared to the reference ligand BI-2536 (-8.426 Kcal/mol). These ligands displayed favorable MM-GBSA free binding energy. Also, ligands 1-4 were subjected to molecular dynamics simulations for 100 ns to get insight into the ligand-binding stability. These compounds exhibited an average RMSD below 2.8 Å, indicating the stability of the compounds with BRD4 protein. Further, Moreover, ligands 1-3 displayed favorable AMDET properties (absorption, distribution, metabolism, excretion, and toxicity). These new compounds might be potential leads to combat cancer.Communicated by Ramaswamy H. Sarma.

Design, synthesis, and biological evaluation of novel 4,4-difluoro-1-methyl-N, 6-diphenyl-5, 6-dihydro-4H-pyrimido [4, 5-b] [1, 2, 4] triazolo [4, 3-d] [1, 4] diazepin-8-amine derivatives as potential BRD4 inhibitors

Bromodomain-containing protein 4 (BRD4) plays an extremely important physiological role in cancer, and the BRD4 inhibitors can effectively inhibit the proliferation of tumor cells. By taking BI-2536 (PLK1 and BRD4 inhibitor) as the lead compound, sixteen novel BRD4 inhibitors with the 4,4-difluoro-1-methyl-N,6-diphenyl-5,6-dihydro-4H-pyrimido[4,5-b] [1,2,4] triazolo[4,3-d] [1,4] diazepine-8-amine structure were designed and synthetized. Among the target compounds, compound 15h exhibited outstanding inhibition for BRD4-BD1 (IC₅₀ value of 0.42 μM) in the BRD4-BD1 inhibitory activity assay. Additionally, cell growth inhibition assay demonstrated that compound 15h potently suppressed the proliferation of MV4-11 cells (IC₅₀ value of 0.51 μM). Besides, compound 15h induced apoptosis and G0/G1 cycle arrest in MV4-11 leukemia cells effectively, and downregulated the expression of c-Myc in a dose-dependent manner. In summary, the optimal compound 15h is expected to become the clinical therapeutic drug for further research.

Structural modification of 4, 5-dihydro-[1, 2, 4] triazolo [4, 3-f] pteridine derivatives as BRD4 inhibitors using 2D/3D-QSAR and molecular docking analysis

Cancer treatment continues to be one of the most serious public health issues in the world. The overexpression of BRD4 protein has led to a series of malignant tumors, hence the development of small molecule BRD4 protease inhibitors has always been a hot spot in the field of medical research. In this study, a series of 4,5-dihydro-[1, 2, 4] triazolo [4, 3-f] pteridine derivatives were used to establish 3D/2D-QSAR models and to discuss the relationship between inhibitor structure and activity. Four ideal models were established, including the comparative molecular field analysis (CoMFA: [Formula: see text] = 0.574, [Formula: see text] = 0.947) model, comparative molecular similarity index analysis (CoMSIA: [Formula: see text]= 0.622, [Formula: see text] = 0.916) model, topomer CoMFA ([Formula: see text] = 0.691, [Formula: see text]= 0.912) model and hologram quantitative structure-activity relationship (HQSAR: [Formula: see text]= 0.759, [Formula: see text] = 0.963) model. They show quite good external predictive power for the test set, with [Formula: see text] values of 0.602, 0.624, 0.671 and 0.750, respectively. In addition, the contour and color code map given by the 2D/3D-QSAR model with the results of molecular docking analyzed to chalk up modification methods for improving inhibitory activity, which was verified by designing novel compounds. The analysis results are helpful to promote the modification of the inhibitor framework and to provide a reference for the construction of new and promising BRD4 inhibitor compounds.

An insight on medicinal attributes of 1,2,4-triazoles

The present review aims to summarize the pharmacological profile of 1,2,4-triazole, one of the emerging privileged scaffold, as antifungal, antibacterial, anticancer, anticonvulsant, antituberculosis, antiviral, antiparasitic, analgesic and anti-inflammatory agents, etc. along with structure-activity relationship. The comprehensive compilation of work carried out in the last decade on 1,2,4-triazole nucleus will provide inevitable scope for researchers for the advancement of novel potential drug candidates having better efficacy and selectivity.

A New Family of Fused Azolo[1,5-a]pteridines and Azolo[5,1-b]purines

The nitration of azolo[1,5-a]pyrimidin-7-amines with several nitration agents (such as acetic nitric anhydride, nitronium tetrafluoroborate, and a mixture of concentrated nitric acid and sulfuric acid) has been investigated. It has been shown that, depending on the conditions, the nitration of pyrazolopyrimidin-7-amines bearing electron-withdrawing groups in the pyrazole ring leads to nitration products in the pyrimidine and/or pyrazole ring. The nitration of triazolo[1,5-a]pyrimidin-7-amines with "nitrating mixture" has been optimized, thus allowing us to obtain a series of 6-nitro[1,2,4]triazolo[1,5-a]pyrimidin-7-amines, followed by their reduction into the corresponding [1,2,4]triazolo[1,5-a]pyrimidin-6,7-diamines (yields 86-89%). The latter have been subjected to heterocyclization by a variety of electrophilic compounds (such as CS₂, glyoxal, triethyl orthoformate) with the formation of five- or six-membered annulated cycles.

Design, synthesis, and biological evaluation of 4,5-dihydro-[1,2,4]triazolo[4,3-f]pteridine derivatives as novel dual-PLK1/BRD4 inhibitors

Protein kinase inhibitors and epigenetic regulatory molecules are two main kinds of anticancer drugs developed in recent years. Both kinds of drugs harbor their own advantages and disadvantages in the treatment of cancer, and the development of small molecules which could target at kinases and epigenetic targets simultaneously can avoid the defects of drugs which only targets at kinases or epigenetic proteins. In this study, a series of 4,5-dihydro-[1,2,4]triazolo [4,3-f]pteridine derivatives were designed and synthesized based on the structure of PLK1 inhibitor BI-2536. Subsequent targets affinity screen and antiproliferative activity test led to the discovery of the most potent dual PLK1/BRD4 inhibitor 9b with good potency for both PLK1 (IC50 = 22 nM) and BRD4 (IC50 = 109 nM) as well as favorable antiproliferative activity against a panel of cancer cell lines. 9b could induce cell cycle arrest and apoptosis in acute myeloid leukemia cell line MV 4-11 in a concentration dependent manner. It could also downregulate the transcription of several proliferation-related oncogenes, including c-MYC, MYCN and BCL-2. Finally, in a MV4-11 mouse xenograft model, 9b exhibited favorable in vivo antitumor activity with 66% tumor growth inhibition (TGI) at a dose of 60 mg/kg while without obvious toxicity. This study thus provided us a start point for the development of new dual PLK1/BRD4 inhibitors as anticancer agents.