Investigation of Thiazolidine-2,4-Dione Derivatives as Acetylcholinesterase Inhibitors: Synthesis, In Vitro Biological Activities and In Silico Studies

The inhibition of acetylcholinesterase (AChE), an enzyme responsible for the inactivation and decrease in acetylcholine in the cholinergic pathway, has been considered an attractive target for small-molecule drug discovery in Alzheimer's disease (AD) therapy. In the present study, a series of TZD derivatives were designed, synthesized, and studied for drug likeness, blood-brain barrier (BBB) permeability, and adsorption, distribution, metabolism, excretion, and toxicity (ADMET). Additionally, docking studies of the designed compounds were performed on AChE. Additionally, all the TZD derivatives (CHT1-5) showed an acceptable affinity for AChE inhibition, and the results showed convincing binding modes in the active site of AChE. Among them, 5-(4-methoxybenzylidene) thiazolidine-2,4-dione (CHT1) was identified as the most potent AChE inhibitor (IC50 of 165.93 nM) with the highest antioxidant activity. Following the exposure of PC12 cells to Aβ1-42 (100 μM), a marked reduction in cell survival was observed. Pretreatment of PC12 cells with TZD derivatives had a neuroprotective effect and significantly enhanced cell survival in response to Aβ-induced toxicity. Western blotting analysis revealed that CHT1 (5 and 8 μM) downregulated p-Tau and HSP70 expression levels. The results indicate that CHT1 is a promising and effective AchE-I that could be utilized as a powerful candidate against AD.

Advances in the structures, mechanisms and targeting of molecular chaperones

Molecular chaperones, a class of complex client regulatory systems, play significant roles in the prevention of protein misfolding and abnormal aggregation, the modulation of protein homeostasis, and the protection of cells from damage under constantly changing environmental conditions. As the understanding of the biological mechanisms of molecular chaperones has increased, their link with the occurrence and progression of disease has suggested that these proteins are promising targets for therapeutic intervention, drawing intensive interest. Here, we review recent advances in determining the structures of molecular chaperones and heat shock protein 90 (HSP90) chaperone system complexes. We also describe the features of molecular chaperones and shed light on the complicated regulatory mechanism that operates through interactions with various co-chaperones in molecular chaperone cycles. In addition, how molecular chaperones affect diseases by regulating pathogenic proteins has been thoroughly analyzed. Furthermore, we focus on molecular chaperones to systematically discuss recent clinical advances and various drug design strategies in the preclinical stage. Recent studies have identified a variety of novel regulatory strategies targeting molecular chaperone systems with compounds that act through different mechanisms from those of traditional inhibitors. Therefore, as more novel design strategies are developed, targeting molecular chaperones will significantly contribute to the discovery of new potential drugs.

Luteolin-mediated phosphoproteomic changes in chicken splenic lymphocytes: Unraveling the detoxification mechanisms against ammonia-induced stress

Long-term exposure to high ammonia concentrations could severely impact chicken health. On the other hand, luteolin has been shown to protect against ammonia poisoning. Although phosphorylation is critically involved in toxicity induction, the specific role of phosphorylated proteins in ammonia poisoning remains unclear. Herein, we constructed an in vitro model to study chicken ammonia poisoning and also analyzed the protective effects of luteolin. Specifically, a combined series of organic techniques such as protein extraction, enzyme digestion, modified peptide enrichment, Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) analysis, and bioinformatics analysis were employed for a quantitative omics study of phosphorylation modification in three groups of samples. Our findings revealed thousands of Differentially Expressed Proteins (DEPs). The differentially expressed modified proteins were subjected to GO classification, KEGG pathway analysis, cluster analysis, and protein interaction analysis, revealing the detoxification mechanism encompassed mitochondrial maintenance, signal transduction, transcriptional regulation, and cytoskeleton regulation. In the process, mitochondria and Golgi apparatus were the key organelles. Furthermore, the AKT1/FOXO signaling pathway and Heat Shock Proteins (HSPs) were the key core modifiers of the proteins. We hope that our findings will provide a theoretical basis and experimental support for future research on luteolin's detoxification mechanism against ammonia poisoning.

Merocyanines: Electronic Structure and Spectroscopy in Solutions, Solid State, and Gas Phase

Merocyanines, owing to their readily tunable electronic structure, are arguably the most versatile functional dyes, with ample opportunities for tailored design via variations of both the donor/acceptor (D/A) end groups and π-conjugated polymethine chain. A plethora of spectral properties, such as strong solvatochromism, high polarizability and hyperpolarizabilities, and sensitizing capacity, motivates extensive studies for their applications in light-converting materials for optoelectronics, nonlinear optics, optical storage, fluorescent probes, etc. Evidently, an understanding of the intrinsic structure-property relationships is a prerequisite for the successful design of functional dyes. For merocyanines, these regularities have been explored for over 70 years, but only in the past three decades have these studies expanded beyond the theory of their color and solvatochromism toward their electronic structure in the ground and excited states. This Review outlines the fundamental principles, essential for comprehension of the variable nature of merocyanines, with the main emphasis on understanding the impact of internal (chemical structure) and external (intermolecular interactions) factors on the electronic symmetry of the D-π-A chromophore. The research on the structure and properties of merocyanines in different media is reviewed in the context of interplay of the three virtual states: nonpolar polyene, ideal polymethine, and zwitterionic polyene.

The protein phosphatase-2A subunit PR130 is involved in the formation of cytotoxic protein aggregates in pancreatic ductal adenocarcinoma cells

As a major source of cellular serine and threonine phosphatase activity, protein phosphatase-2A (PP2A) modulates signaling pathways in health and disease. PP2A complexes consist of catalytic, scaffolding, and B-type subunits. Seventeen PP2A B-type subunits direct PP2A complexes to selected substrates. It is ill-defined how PP2A B-type subunits determine the growth and drug responsiveness of tumor cells. Pancreatic ductal adenocarcinoma (PDAC) is a disease with poor prognosis. We analyzed the responses of murine and human mesenchymal and epithelial PDAC cells to the specific PP2A inhibitor phendione. We assessed protein levels by immunoblot and proteomics and cell fate by flow cytometry, confocal microscopy, and genetic manipulation. We show that murine mesenchymal PDAC cells express significantly higher levels of the PP2A B-type subunit PR130 than epithelial PDAC cells. This overexpression of PR130 is associated with a dependency of such metastasis-prone cells on the catalytic activity of PP2A. Phendione induces apoptosis and an accumulation of cytotoxic protein aggregates in murine mesenchymal and human PDAC cells. These processes occur independently of the frequently mutated tumor suppressor p53. Proteomic analyses reveal that phendione upregulates the chaperone HSP70 in mesenchymal PDAC cells. Inhibition of HSP70 promotes phendione-induced apoptosis and phendione promotes a proteasomal degradation of PR130. Genetic elimination of PR130 sensitizes murine and human PDAC cells to phendione-induced apoptosis and protein aggregate formation. These data suggest that the PP2A-PR130 complex dephosphorylates and thereby prevents the aggregation of proteins in tumor cells.