Thieno[2,3-b]pyridine amines: Synthesis and evaluation of tacrine analogs against biological activities related to Alzheimer's disease

Fused thiophene as a privileged scaffold: A review on anti-Alzheimer's disease potentials via targeting cholinesterases, monoamine oxidases, glycogen synthase kinase-3, and Aβ aggregation

As a "silent threat," Alzheimer's disease (AD) is quickly rising to the top of the list of costly and troublesome diseases facing humanity. It is growing to be one of the most troublesome and expensive conditions, with annual health care costs higher than those of cancer and comparable to those of cardiovascular disorders. One of the main pathogenic characteristics of AD is the deficiency of the neurotransmitter acetylcholine (ACh) which plays a vital role in memory, learning, and attention. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) play a crucial role in hydrolyzing ACh. Consequently, a frequent therapy approach for AD is the suppression of AChE and BChE to improve cholinergic neurotransmission and reduce cognitive symptoms. The accumulation of amyloid plaques (Aβ) is a primary factor contributing to neurodegenerative diseases, particularly AD. Glycogen synthase kinase-3β (GSK3-β) is regarded as a pivotal player in the pathophysiology of AD since dysregulation of this kinase affects all major hallmarks of the disease, such as tau phosphorylation, Aβ aggregation, memory, neurogenesis, and synaptic function. One of the most challenging and risky issues in modern medicinal chemistry is the urgent and ongoing need for the study and development of effective therapeutic candidates for the treatment of AD. A significant class of heterocyclic molecules that can target the complex and multifactorial pathogenesis of AD are fused thiophene derivatives. The goal of the current review is to demonstrate the advancements made in fused thiophene derivatives' anti-AD activity. It also covers their mechanisms of action and studies of the structure-activity relationships in addition to the compilation of significant synthetic routes for fused thiophene derivatives with anti-AD potential. This review is intended to stimulate new ideas in the search for more rationale designs of derivatives based on fused thiophene, hoping to be more potent in treating AD.

Design, synthesis and biological evaluation of novel coumarin derivatives as multifunctional ligands for the treatment of Alzheimer's disease

Multi-targeted directed ligands (MTDLs) are emerging as promising Alzheimer's disease (AD) therapeutic possibilities. Coumarin is a multifunctional backbone with extensive bioactivity that has been utilized to develop innovative anti-neurodegenerative properties and is a desirable starting point for the construction of MTDLs. Herein, we explored and synthesized a series of novel coumarin derivatives and assessed their inhibitory effects on cholinesterase (AChE, BuChE), GSK-3β, and BACE1. Among these compounds, compound 30 displayed the multifunctional profile of targeting the AChE (IC₅₀ = 1.313 ± 0.099 μM) with a good selectivity over BuChE (SI = 24.623), GSK-3β (19.30% inhibition at 20 μM), BACE1 (IC₅₀ = 1.227 ± 0.112 μM), along with moderate HepG2 cytotoxicity, SH-SY5Y cytotoxicity, low HL-7702 cytotoxicity, as well as good blood-brain barrier (BBB) permeability. Kinetic and docking studies indicated that compound 30 was a competitive AChE inhibitor. Furthermore, acute toxicity experiments revealed that it was non-toxic at a dosage of 1000 mg/kg. The ADME prediction results indicate that 30 has acceptable physicochemical properties. Collectively, these findings demonstrated that compound 30 would be a potential multifunctional candidate for AD therapy.

In vitro cell-based models of drug-induced hepatotoxicity screening: progress and limitation

Drug-induced liver injury (DILI) is one of the major causes of post-approval withdrawal of therapeutics. As a result, there is an increasing need for accurate predictive in vitro assays that reliably detect hepatotoxic drug candidates while reducing drug discovery time, costs, and the number of animal experiments. In vitro hepatocyte-based research has led to an improved comprehension of the underlying mechanisms of chemical toxicity and can assist the prioritization of therapeutic choices with low hepatotoxicity risk. Therefore, several in vitro systems have been generated over the last few decades. This review aims to comprehensively present the development and validation of 2D (two-dimensional) and 3D (three-dimensional) culture approaches on hepatotoxicity screening of compounds and highlight the main factors affecting predictive power of experiments. To this end, we first summarize some of the recognized hepatotoxicity mechanisms and related assays used to appraise DILI mechanisms and then discuss the challenges and limitations of in vitro models.

Synthesis and evaluation of novel arylisoxazoles linked to tacrine moiety: in vitro and in vivo biological activities against Alzheimer's disease

Alzheimer's disease (AD) is now ranked as the third leading cause of death after heart disease and cancer. There is no definite cure for AD due to the multi-factorial nature of the disease, hence, multi-target-directed ligands (MTDLs) have attracted lots of attention. In this work, focusing on the efficient cholinesterase inhibitory activity of tacrine, design and synthesis of novel arylisoxazole-tacrine analogues was developed. In vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition assay confirmed high potency of the title compounds. Among them, compounds 7l and 7b demonstrated high activity toward AChE and BChE with IC₅₀ values of 0.050 and 0.039 μM, respectively. Both compounds showed very good self-induced Aβ aggregation and AChE-induced inhibitory activity (79.4 and 71.4% for compound 7l and 61.8 and 58.6% for compound 7b, respectively). Also, 7l showed good anti-BACE1 activity with IC₅₀ value of 1.65 µM. The metal chelation test indicated the ability of compounds 7l and 7b to chelate biometals (Zn²⁺, Cu²⁺, and Fe²⁺). However, they showed no significant neuroprotectivity against Aβ-induced damage in PC12 cells. Evaluation of in vitro hepatotoxicity revealed comparable toxicity of compounds 7l and 7b with tacrine. In vivo studies by Morris water maze (MWM) task demonstrated that compound 7l significantly reversed scopolamine-induced memory deficit in rats. Finally, molecular docking studies of compounds 7l and 7b confirmed establishment of desired interactions with the AChE, BChE, and BACE1 active sites.