Developing novel classes of protein kinase CK1δ inhibitors by fusing [1,2,4]triazole with different bicyclic heteroaromatic systems

7-Amino-[1,2,4]triazolo[1,5-a][1,3,5]triazines as CK1δ inhibitors: Exploring substitutions at the 2 and 5-positions

CK1δ is a serine-threonine kinase involved in several pathological conditions including neuroinflammation and neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis. Specifically, it seems that an inhibition of CK1δ could have a neuroprotective effect in these conditions. Here, a series of [1,2,4]triazolo[1,5-a][1,3,5]triazines were developed as ATP-competitive CK1δ inhibitors. Both positions 2 and 5 have been explored leading to a total of ten compounds exhibiting IC50s comprised between 29.1 µM and 2.08 µM. Three of the four most potent compounds (IC50 < 3 µM) bear a thiophene ring at the 2 position. All compounds have been submitted to computational studies that identified the chain composed of at least 2 atoms (e.g., nitrogen and carbon atoms) at the 5 position as crucial to determine a key bidentate hydrogen bond with Leu85 of CK1δ. Most potent compounds have been tested in vitro, resulting passively permeable to the blood-brain barrier and, safe and slight neuroprotective on a neuronal cell model. These results encourage to further structural optimize the series to obtain more potent CK1δ inhibitors as possible neuroprotective agents to be tested on models of the above-mentioned neurodegenerative diseases.

5-Aza-adenine Derivatives for Crop-Protection: Multicomponent Synthesis, Experimental and Theoretical Structural Analysis

A microwave-assisted synthesis of 7-amino-1,2,4-triazolo[1,5-a][1,3,5]triazine-2-propanamides was developed using a three-component, catalyst-free reaction of cyanamide and trimethyl orthoformate with 3-(5-amino-1H-1,2,4-triazol-3-yl)propanamides (3). The reaction tolerated structurally diverse substrates and proceeded chemo- and regio-selectively, affording the target compounds in high purity in 5-10 minutes. The convenient chromatography-free isolation and purification of the products add practicality to this method. The structural features of the prepared compounds were investigated using dynamic NMR spectroscopy, X-ray crystallography and computational chemistry calculations. X-ray crystallography performed on a representative compound, 3-(7-amino-1,2,4-triazolo[1,5-a][1,3,5]triazin-2-yl)-N-(4-benzyl)propanamide (4 l), showed the overall molecular conformation to adopt the shape of the letter C. Notable localisation of π-electron density is found within the 1,2,4-triazolo[1,5-a][1,3,5]triazine system; a relatively short C-NH2 bond is consistent with restricted rotation about this bond. This study also presents a detailed analysis of the molecular interactions in 4 l using DFT and QTAIM methods with a focus on the hydrogen-bonding and π-stacking interactions that influence the molecular packing of 4 l. The findings reveal the significant roles of N-H⋅O, N-H⋅N and C-H⋅N interactions, along with electrostatically enhanced π⋅π contacts. A broad screening for insecticidal, fungicidal and herbicidal properties identified several compounds with potent herbicidal activity against Matricaria inodora.

Impact of GSK-3β and CK-1δ on Wnt signaling pathway in alzheimer disease: A dual target approach

Alzheimer's disease (AD) is an enigmatic neurological illness that offers few treatment options. Recent exploration has highlighted the crucial connection of the Wnt signaling pathway in AD pathogenesis, shedding light on potential therapeutic targets. The present study focuses on the dual targeting of glycogen synthase kinase-3β (GSK-3β) and casein kinase-1δ (CK-1δ) within the framework of the Wnt signaling pathway as a possible technique for AD intervention. GSK-3β and CK-1δ are multifunctional kinases known for their roles in tau hyperphosphorylation, amyloid processing, and synaptic dysfunction, all of which are major hallmarks of Alzheimer's disease. They are intricately linked to Wnt signaling, which plays a pivotal part in sustaining neuronal function and synaptic plasticity. Dysregulation of the Wnt pathway in AD contributes to cognitive decline and neurodegeneration. This review delves into the molecular mechanisms by which GSK-3β and CK-1δ impact the Wnt signaling pathway, elucidating their roles in AD pathogenesis. We discuss the potential of small-molecule inhibitors along with their SAR studies along with the multi-targetd approach targeting GSK-3β and CK-1δ to modulate Wnt signaling and mitigate AD-related pathology. In summary, the dual targeting of GSK-3β and CK-1δ within the framework of the Wnt signaling pathway presents an innovative and promising avenue for future AD therapies, offering new hope for patients and caregivers in the quest to combat this challenging condition.

Structural Investigations on 2-Amidobenzimidazole Derivatives as New Inhibitors of Protein Kinase CK1 Delta

Protein kinase CK1δ (CK1δ) is a serine-threonine/kinase that modulates different physiological processes, including the cell cycle, DNA repair, and apoptosis. CK1δ overexpression, and the consequent hyperphosphorylation of specific proteins, can lead to sleep disorders, cancer, and neurodegenerative diseases. CK1δ inhibitors showed anticancer properties as well as neuroprotective effects in cellular and animal models of Parkinson's and Alzheimer's diseases and amyotrophic lateral sclerosis. To obtain new ATP-competitive CK1δ inhibitors, three sets of benzimidazole-2-amino derivatives were synthesized (1-32), bearing different substituents on the fused benzo ring (R) and diverse pyrazole-containing acyl moieties on the 2-amino group. The best-performing derivatives were those featuring the (1H-pyrazol-3-yl)-acetyl moiety on the benzimidazol-2-amino scaffold (13-32), which showed CK1δ inhibitor activity in the low micromolar range. Among the R substituents, 5-cyano was the most advantageous, leading to a compound endowed with nanomolar potency (23, IC50 = 98.6 nM). Molecular docking and dynamics studies were performed to point out the inhibitor-kinase interactions.

[1,2,4]Triazolo[1,5-c]pyrimidines as Tools to Investigate A3 Adenosine Receptors in Cancer Cell Lines

The A3 adenosine receptor is an interesting target whose role in cancer is controversial. In this work, a structural investigation at the 2-position of the [1,2,4]triazolo[1,5-c]pyrimidine nucleus was performed, finding new potent and selective A3 adenosine receptor antagonists such as the ethyl 2-(4-methoxyphenyl)-5-(methylamino)-[1,2,4]triazolo[1,5-c]pyrimidine-8-carboxylate (20, DZ123) that showed a Ki value of 0.47 nM and an exceptional selectivity profile over the other adenosine receptor subtypes. Computational studies were performed to rationalize the affinity and the selectivity profile of the tested compounds at the A3 adenosine receptor and the A1 and A2A adenosine receptors. Compound 20 was tested on both A3 adenosine receptor positive cell lines (CHO-A3 AR transfected, THP1 and HCT16) and on A3 negative cancer cell lines, showing no effect in the latter and a pro-proliferative effect at a low concentration in the former. These interesting results pave the way to further investigation on both the mechanism involved and potential therapeutic applications.

PROTACs in the Management of Prostate Cancer

Cancer treatments with targeted therapy have gained immense interest due to their low levels of toxicity and high selectivity. Proteolysis-Targeting Chimeras (PROTACs) have drawn special attention in the development of cancer therapeutics owing to their unique mechanism of action, their ability to target undruggable proteins, and their focused target engagement. PROTACs selectively degrade the target protein through the ubiquitin-proteasome system, which describes a different mode of action compared to conventional small-molecule inhibitors or even antibodies. Among different cancer types, prostate cancer (PC) is the most prevalent non-cutaneous cancer in men. Genetic alterations and the overexpression of several genes, such as FOXA1, AR, PTEN, RB1, TP53, etc., suppress the immune response, resulting in drug resistance to conventional drugs in prostate cancer. Since the progression of ARV-110 (PROTAC for PC) into clinical phases, the focus of research has quickly shifted to protein degraders targeting prostate cancer. The present review highlights an overview of PROTACs in prostate cancer and their superiority over conventional inhibitors. We also delve into the underlying pathophysiology of the disease and explain the structural design and linkerology strategies for PROTAC molecules. Additionally, we touch on the various targets for PROTAC in prostate cancer, including the androgen receptor (AR) and other critical oncoproteins, and discuss the future prospects and challenges in this field.

Triazole-fused pyrimidines in target-based anticancer drug discovery

In recent decades, the development of targeted drugs has featured prominently in the treatment of cancer, which is among the major causes of mortality globally. Triazole-fused pyrimidines, a widely-used class of heterocycles in medicinal chemistry, have attracted considerable interest as potential anticancer agents that target various cancer-associated targets in recent years, demonstrating them as valuable templates for discovering novel anticancer candidates. The current review concentrates on the latest advancements of triazole-pyrimidines as target-based anticancer agents, including works published between 2007 and the present (2007-2022). The structure-activity relationships (SARs) and multiple pathways are also reviewed to shed light on the development of more effective and biotargeted anticancer candidates.

Role of protein phosphorylation in cell signaling, disease, and the intervention therapy

Protein phosphorylation is an important post-transcriptional modification involving an extremely wide range of intracellular signaling transduction pathways, making it an important therapeutic target for disease intervention. At present, numerous drugs targeting protein phosphorylation have been developed for the treatment of various diseases including malignant tumors, neurological diseases, infectious diseases, and immune diseases. In this review article, we analyzed 303 small-molecule protein phosphorylation kinase inhibitors (PKIs) registered and participated in clinical research obtained in a database named Protein Kinase Inhibitor Database (PKIDB), including 68 drugs approved by the Food and Drug Administration of the United States. Based on previous classifications of kinases, we divided these human protein phosphorylation kinases into eight groups and nearly 50 families, and delineated their main regulatory pathways, upstream and downstream targets. These groups include: protein kinase A, G, and C (AGC) and receptor guanylate cyclase (RGC) group, calmodulin-dependent protein kinase (CaMK) group, CMGC [Cyclin-dependent kinases (CDKs), Mitogen-activated protein kinases (MAPKs), Glycogen synthase kinases (GSKs), and Cdc2-like kinases (CLKs)] group, sterile (STE)-MAPKs group, tyrosine kinases (TK) group, tyrosine kinase-like (TKL) group, atypical group, and other groups. Different groups and families of inhibitors stimulate or inhibit others, forming an intricate molecular signaling regulatory network. This review takes newly developed new PKIs as breakthrough point, aiming to clarify the regulatory network and relationship of each pathway, as well as their roles in disease intervention, and provide a direction for future drug development.

Synthesis and Biological Investigation of 1,2,4-Triazolo[4,3-a]azines as Potential HSF1 Inductors

Derivatives of fused 1,2,4-triazines containing heterocyclic and metallocene fragments were obtained by one-pot oxidative cyclization of heterocyclic hydrazones in the presence of hypervalent iodine(III) reagents. For 1,2,4-triazolo[4,3-a]azines, the ability to activate HSF1 was investigated. The obtained compounds were shown to increase the degree of HSF1 activation. It was shown that the 1,2,4-triazines can be used to induce Hsp70 expression and decrease the extent of mutant HTT aggregate formation.

Casein Kinase 1δ Inhibitors as Promising Therapeutic Agents for Neurodegenerative Disorders

Casein kinase 1 (CK1) belongs to the serine-threonine kinase family and is expressed in all eukaryotic organisms. At least six human isoforms of CK1 (termed α, γ1-3, δ and ε) have been cloned and characterized. CK1 isoform modulates several physiological processes, including DNA damage repair, circadian rhythm, cellular proliferation and apoptosis. Therefore, CK1 dysfunction may trigger diverse pathologies, such as cancer, inflammation and central nervous system disorders. Overexpression and aberrant activity of CK1 has been connected to hyperphosphorylation of key proteins implicated in the development of neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases and Amyotrophic Lateral Sclerosis. Thus, CK1 inhibitors have attracted attention as potential drugs for these pathologies and several compounds have been synthesized or isolated from natural sources to be evaluated for their CK1 inhibitory activity. Here we report a comprehensive review on the development of CK1 inhibitors, with a particular emphasis on structure-activity relationships and computational studies which provide useful insight for the design of novel inhibitors.

Structure-Activity Relationship of Cytotoxic Natural Products from Indonesian Marine Sponges

Indonesian marine natural products have been one of the most promising sources in the race to obtain potential drugs for cancer treatment. One of the primary producers of cytotoxic compounds is sponges. However, there are still limited sources of comprehensive reviews related to the relationship between the structure of isolated compounds and their cytotoxic activity. This review remarks the attempt to provide a preliminary guidance from the perspective of structure-activity relationship and its participation on marine natural products research. This guidance is segregated by the compound's classes and their cytotoxic targets to obtain and organized a reliable summary of inter-study of the isolated compounds and their cytotoxicity. Structure-activity relationship is well-known for its ability to tune the bioactivity of a specific compound, especially on synthetic organic chemistry and in silico study but rarely used on natural product chemistry. The present review is intended to narrow down the endless possibilities of cytotoxicity by giving a predictable structure-activity relationship for active compounds. In addition, bioactive framework leads were selected by uncovering a noticeable structure-activity relationship with the intervention of cytotoxic agents from natural sources, especially Indonesian marine sponge.

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