Discovery of 2-aryloxy-4-amino-quinazoline derivatives as novel protease-activated receptor 2 (PAR2) antagonists

Design, Synthesis, and Biological Evaluation of New Potential Unusual Modified Anticancer Immunomodulators for Possible Non-Teratogenic Quinazoline-Based Thalidomide Analogs

Sixteen new thalidomide analogs were synthesized. The new candidates showed potent in vitro antiproliferative activities against three human cancer cell lines, namely hepatocellular carcinoma (HepG-2), prostate cancer (PC3), and breast cancer (MCF-7). It was found that compounds XII, XIIIa, XIIIb, XIIIc, XIIId, XIVa, XIVb, and XIVc showed IC50 values ranging from 2.03 to 13.39 µg/mL, exhibiting higher activities than thalidomide against all tested cancer cell lines. Compound XIIIa was the most potent candidate, with an IC50 of 2.03 ± 0.11, 2.51 ± 0.2, and 0.82 ± 0.02 µg/mL compared to 11.26 ± 0.54, 14.58 ± 0.57, and 16.87 ± 0.7 µg/mL for thalidomide against HepG-2, PC3, and MCF-7 cells, respectively. Furthermore, compound XIVc reduced the expression of NFκB P65 levels in HepG-2 cells from 278.1 pg/mL to 63.1 pg/mL compared to 110.5 pg/mL for thalidomide. Moreover, compound XIVc induced an eightfold increase in caspase-8 levels with a simultaneous decrease in TNF-α and VEGF levels in HepG-2 cells. Additionally, compound XIVc induced apoptosis and cell cycle arrest. Our results reveal that the new candidates are potential anticancer candidates, particularly XIIIa and XIVc. Consequently, they should be considered for further evaluation for the development of new anticancer drugs.

Design, synthesis, and biological screening of a series of pyrazolo [1,5-a]quina-zoline derivatives as SIRT6 activators

SIRT6 has emerged as a novel therapeutic target for a variety of diseases. In this study, a total of 102 pyrazolo [1,5-a]quinazoline derivatives were designed and synthesized. The result revealed that 2-methyl-N-(4-phenoxy-phenyl)pyrazolo [1,5-a]quinazoline-5-amine (21q) was the most active compound by structure-activity relationship study, which significantly enhanced SIRT6 defatty-acylation activity with an EC_1.5 value of 1.85±0.41 μM and EC₅₀ value of 11.15±0.33 μM. The biological activity of 21q was further verified by differential scanning fluorimetry assay (DSF) and surface plasmon resonance assay (SPR). Molecular docking showed that the pyrazolo [1,5-a]quinazoline of 21q formed a hydrogen bond with Val115 and four π- π interactions with Phe64, Phe82 and Phe86. 21q can significantly improve the thermal stability of SIRT6 protein and inhibit the PI3K/Akt signaling pathway in mouse embryonic fibroblasts (MEFs), thereby inhibiting the proliferation of MEFs. Collectively, we discovered a new potent SIRT6 activator, which can be taken as a lead compound for later studies.

Synthesis, Cytotoxic Evaluation, and Structure-Activity Relationship of Substituted Quinazolinones as Cyclin-Dependent Kinase 9 Inhibitors

Cyclin-dependent kinase 9 (CDK9) plays a critical role in transcriptional elongation, through which short-lived antiapoptotic proteins are overexpressed and make cancer cells resistant to apoptosis. Therefore, CDK9 inhibition depletes antiapoptotic proteins, which in turn leads to the reinstatement of apoptosis in cancer cells. Twenty-seven compounds were synthesized, and their CDK9 inhibitory and cytotoxic activities were evaluated. Compounds 7, 9, and 25 were the most potent CDK9 inhibitors, with IC50 values of 0.115, 0.131, and 0.142 μM, respectively. The binding modes of these molecules were studied via molecular docking, which shows that they occupy the adenosine triphosphate binding site of CDK9. Of these three molecules, compound 25 shows good drug-like properties, as it does not violate Lipinski's rule of five. In addition, this molecule shows promising ligand and lipophilic efficiency values and is an ideal candidate for further optimization.

Design, synthesis, and biological evaluation of novel bioactive thalidomide analogs as anticancer immunomodulatory agents

Cancer is still a dangerous disease with a high mortality rate all over the world. In our attempt to develop potential anticancer candidates, new quinazoline and phthalazine based compounds were designed and synthesized. The new derivatives were built in line with the pharmacophoric features of thalidomide. The new derivatives as well as thalidomide were examined against three cancer cell lines, namely: hepatocellular carcinoma (HepG-2), breast cancer (MCF-7) and prostate cancer (PC3). Then the effects on the expression levels of caspase-8, VEGF, NF-κB P65, and TNF-α in HepG-2 cells were evaluated. The biological data revealed the high importance of phthalazine based compounds (24a-c), which were far better than thalidomide with regard to the antiproliferative activity. 24b showed IC₅₀ of 2.51, 5.80 and 4.11 μg mL^-1 compared to 11.26, 14.58, and 16.87 μg mL^-1 for thalidomide against the three cell lines respectively. 24b raised caspase-8 level by about 7 folds, compared to 8 folds reported for thalidomide. Also, VEGF level in HepG-2 cells treated with 24b was 185.3 pg mL^-1, compared to 432.5 pg mL^-1 in control cells. Furthermore, the immunomodulatory properties were proven to 24b, which reduced TNF-α level by approximately half. At the same time, NF-κB P65 level in HepG-2 cells treated with 24b was 76.5 pg mL^-1 compared to 278.1 and 110.5 pg mL^-1 measured for control cells and thalidomide treated HepG-2 cells respectively. Moreover, an in vitro viability study against Vero non-cancerous cell line was investigated and the results reflected a high safety profile of all tested compounds. This work suggests 24b as a promising lead compound for development of new immunomodulatory anticancer agents.

Comprehensive strategies of machine-learning-based quantitative structure-activity relationship models

Early quantitative structure-activity relationship (QSAR) technologies have unsatisfactory versatility and accuracy in fields such as drug discovery because they are based on traditional machine learning and interpretive expert features. The development of Big Data and deep learning technologies significantly improve the processing of unstructured data and unleash the great potential of QSAR. Here we discuss the integration of wet experiments (which provide experimental data and reliable verification), molecular dynamics simulation (which provides mechanistic interpretation at the atomic/molecular levels), and machine learning (including deep learning) techniques to improve QSAR models. We first review the history of traditional QSAR and point out its problems. We then propose a better QSAR model characterized by a new iterative framework to integrate machine learning with disparate data input. Finally, we discuss the application of QSAR and machine learning to many practical research fields, including drug development and clinical trials.

Drug repositioning as an effective therapy for protease-activated receptor 2 inhibition

Proteinase-activated receptor 2 (PAR-2) is a G protein-coupled receptor activated by both trypsin and a specific agonist peptide, SLIGKV-NH2. It has been linked to various pathologies, including pain and inflammation. Several peptide and peptidomimetic agonizts for PAR-2 have been developed exhibiting high potency and efficacy. However, the number of PAR-2 antagonists is smaller. We screened the Food and Drug Administration library of approved compounds to retrieve novel antagonists for repositioning in the PAR-2 structure. The most efficacious compound bicalutamide bound to the PAR-2 binding groove near the extracellular domain as observed in the in silico studies. Further, it showed reduced Ca²⁺ release in trypsin activated cells in a dose-dependent manner. Hence, bicalutamide is a novel and potent PAR-2 antagonist which could be therapeutically useful in blocking multiple pathways diverging from PAR-2 signaling. Further, the novel scaffold of bicalutamide represents a new molecular structure for PAR-2 antagonism and can serve as a basis for further drug development.

Discovery of 2-(4-Substituted-piperidin/piperazine-1-yl)-N-(5-cyclopropyl-1H-pyrazol-3-yl)-quinazoline-2,4-diamines as PAK4 Inhibitors with Potent A549 Cell Proliferation, Migration, and Invasion Inhibition Activity

A series of novel 2,4-diaminoquinazoline derivatives were designed, synthesized, and evaluated as p21-activated kinase 4 (PAK4) inhibitors. All compounds showed significant inhibitory activity against PAK4 (half-maximal inhibitory concentration IC₅₀ < 1 μM). Among them, compounds 8d and 9c demonstrated the most potent inhibitory activity against PAK4 (IC₅₀ = 0.060 μM and 0.068 μM, respectively). Furthermore, we observed that compounds 8d and 9c displayed potent antiproliferative activity against the A549 cell line and inhibited cell cycle distribution, migration, and invasion of this cell line. In addition, molecular docking analysis was performed to predict the possible binding mode of compound 8d. This series of compounds has the potential for further development as PAK4 inhibitors for anticancer activity.

Protease activated receptor 2 (PAR2) modulators: a patent review (2010-2015)

INTRODUCTION

Protease activated receptor 2 (PAR2) is a self-activated G protein-coupled receptor that has been implicated in several diseases, including inflammatory, gastrointestinal, respiratory, metabolic diseases, cancers and others, making it an important prospective drug target. No known endogenous ligands are available for PAR2, so having potent exogenous agonists and antagonists can be helpful for studying physiological functions of PAR2.

AREAS COVERED

This review covers agonist-, antagonist-, antibody- and pepducin-based modulators of PAR2 reported in patent applications between 2010-2015, along with their available structure-activity relationships, biological activities and potential uses for studying PAR2.

EXPERT OPINION

In the last six years, substantial efforts were made towards developing PAR2 modulators, but most lack potency or selectivity or have poor pharmacokinetic profiles. Many PAR2 modulators were assessed by measuring Gαq protein-mediated calcium release in cells. This may be insufficient to fully characterize ligand function, since different ligands signal through PAR2 via multiple signaling pathways. It may be feasible to develop biased ligands as drugs that can selectively modulate one or more specific signaling pathways linking PAR2 to a specific diseased state. Accordingly, potent, orally bioavailable, pathway- and receptor-selective PAR2 modulators may be an achievable goal to realizing effective drugs that can treat PAR2-mediated diseases.