Novel series of triazole containing coumarin and isatin based hybrid molecules as acetylcholinesterase inhibitors

Coumarin as an Elite Scaffold in Anti-Breast Cancer Drug Development: Design Strategies, Mechanistic Insights, and Structure-Activity Relationships

Breast cancer is the most common cancer among women. Currently, it poses a significant threat to the healthcare system due to the emerging resistance and toxicity of available drug candidates in clinical practice, thus generating an urgent need for the development of new potent and safer anti-breast cancer drug candidates. Coumarin (chromone-2-one) is an elite ring system widely distributed among natural products and possesses a broad range of pharmacological properties. The unique distribution and pharmacological efficacy of coumarins attract natural product hunters, resulting in the identification of numerous natural coumarins from different natural sources in the last three decades, especially those with anti-breast cancer properties. Inspired by this, numerous synthetic derivatives based on coumarins have been developed by medicinal chemists all around the globe, showing promising anti-breast cancer efficacy. This review is primarily focused on the development of coumarin-inspired anti-breast cancer agents in the last three decades, especially highlighting design strategies, mechanistic insights, and their structure-activity relationship. Natural coumarins having anti-breast cancer efficacy are also briefly highlighted. This review will act as a guideline for researchers and medicinal chemists in designing optimum coumarin-based potent and safer anti-breast cancer agents.

Novel isatin-triazole based thiosemicarbazones as potential anticancer agents: synthesis, DFT and molecular docking studies

Thiosemicarbazones of isatin have been found to exhibit versatile bioactivities. In this study, two distinct types of isatin-triazole hybrids 3a and 3b were accessed via copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC), together with their mono and bis-thiosemicarbazone derivatives 4a-h and 5a-h. In addition to the characterization by physical, spectral and analytical data, a DFT study was carried out to obtain the optimized geometries of all thiosemicarbazones. The global reactivity values showed that among the synthesized derivatives, 4c, 4g and 5c having nitro substituents are the most soft compounds, with compound 5c having the highest electronegativity and electrophilicity index values among the synthesized series, thus possessing strong binding ability with biomolecules. Molecular docking studies were performed to explore the inhibitory ability of the selected compounds against the active sites of the anticancer protein of phosphoinositide 3-kinase (PI3K). Among the synthesized derivatives, 4-nitro substituted bisthiosemicarbazone 5c showed the highest binding energy of -10.3 kcal mol-1. These findings demonstrated that compound 5c could be used as a favored anticancer scaffold via the mechanism of inhibition against the PI3K signaling pathways.

A Comprehensive Review of the Diverse Spectrum Activity of 1,2,3-Triazole-linked Isatin Hybrids

Heterocyclic compounds containing 1,2,3-triazole and isatin as core structures have emerged as promising drug candidates due to their diverse biological activities such as anti-cancer, antifungal, antimicrobial, antitumor, anti-epileptic, antiviral, and more. The presence of 1,2,3-triazoles and isatin heterocycles in these hybrids, both individually known for their medicinal significance, has increasingly piqued the interest of drug discovery researchers, as they seek to delve deeper into their extensive pharmacological potential for enhancing therapeutic efficacy. Moreover, these hybrid compounds are synthetically accessible using readily available materials. Therefore, there is a pressing need to provide a comprehensive overview of the existing knowledge in this field, offering valuable insights to readers and paving the way for the discovery of novel 1,2,3-triazole-linked isatin hybrids with therapeutic potential.

1,2,3-Triazole Hybrids Containing Isatins and Phenolic Moieties: Regioselective Synthesis and Molecular Docking Studies

The synthesis of hybrid molecules is one of the current strategies of drug discovery for the development of new lead compounds. The 1,2,3-triazole moiety represents an important building block in Medicinal Chemistry, extensively present in recent years. In this paper, we presented the design and the synthesis of new 1,2,3-triazole hybrids, containing both an isatine and a phenolic core. Firstly, the non-commercial azide and the alkyne synthons were prepared by different isatines and phenolic acids, respectively. Then, the highly regioselective synthesis of 1,4-disubstituted triazoles was obtained in excellent yields by a click chemistry approach, catalyzed by Cu(I). Finally, a molecular docking study was performed on the hybrid library, finding four different therapeutic targets. Among them, the most promising results were obtained on 5-lipoxygenase, an enzyme involved in the inflammatory processes.

Synthesis, Crystal Structure, Spectral Characterization and Antifungal Activity of Novel Phenolic Acid Triazole Derivatives

At present, phenolic acid derivatives and triazole derivatives have a good antifungal effect, which has attracted widespread attention. A series of novel phenolic acid triazole derivatives were synthesized, and their structures were characterized by IR, MS, NMR, and X-ray crystal diffraction. Compound methyl 4-(2-bromoethoxy)benzoate, methyl 4-(2-(1H-1,2,4-triazol-1-yl) ethoxy)benzoate, 4-(2-(1H-1,2,4-triazol-1-yl)ethoxy)benzoic acid and 4-(2-(1H-1,2,4-triazol-1-yl) ethoxy)-3-methoxybenzoic acid crystallize in the monoclinic system with space group P21/n, the monoclinic system with space group P21, the monoclinic system with space group P21 and the orthorhombic system with space group Pca21, respectively. At a concentration of 100 μg/mL and 200 μg/mL, the antifungal activity against seven plant pathogen fungi was determined. Compound methyl 4-(2-bromoethoxy)benzoate has the best inhibitory effect on Rhizoctonia solani AG1, and the inhibitory rate reached 88.6% at 200 μg/mL. The inhibitory rates of compound methyl 4-(2-(1H-1,2,4-triazol-1-yl) ethoxy)benzoate against Fusarium moniliforme and Sphaeropsis sapinea at a concentration of 200 μg/mL were 76.1% and 75.4%, respectively, which were better than that of carbendazim.

Review of triazole scaffolds for treatment and diagnosis of Alzheimer's disease

Triazole scaffolds, a series of 5-membered heterocycles, are well known for their high efficacy, low toxicity, and superior pharmacokinetics. Alzheimer's disease (AD) is the first neurodegenerative disorder with complex pathological mechanisms. Triazole, as an aromatic group with three nitrogen atoms, forms polar and non-polar interactions with diverse key residues in the receptor-ligand binding procedure, and has been widely used in the molecular design in the development of anti-AD agents. Moreover, considering the simple synthesis approaches, triazole scaffolds are commonly used to link two pharmacodynamic groups in one chemical molecule, forming multi-target directed ligands (MTDLs). Furthermore, the click reaction between azide- and cyano-modified enzyme and ligand provides feasibility for the new modulator discovery, compound tissue distribution evaluation, enzyme localization, and pharmacological mechanism study, promoting the diagnosis of AD course.

Theophylline-based hybrids as acetylcholinesterase inhibitors endowed with anti-inflammatory activity: synthesis, bioevaluation, in silico and preliminary kinetic studies

In this study, we investigated the conjugation of theophylline with different compounds of natural origin hoping to construct new hybrids with dual activity against cholinergic and inflammatory pathways as potential agents for the treatment of Alzheimer's disease (AD). Out of 28 tested hybrids, two hybrids, acefylline-eugenol 6d and acefylline-isatin 19, were able to inhibit acetylcholinesterase (AChE) at low micromolar concentration displaying IC50 values of 1.8 and 3.3 μM, respectively, when compared to the galantamine standard AChE inhibitor. Moreover, the prepared hybrids exhibited a significant anti-inflammatory effect against lipopolysaccharide induced inflammation in RAW 264.7 and reduced nitric oxide (NO), tumor necrosis alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) levels in a dose dependent manner. These hybrids demonstrated significant reductions in nitric oxide (NO), tumor necrosis alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) levels in RAW 264.7 cells induced by lipopolysaccharide (LPS). The findings of this study were further explained in light of network pharmacology analysis which suggested that AChE and nitric oxide synthase were the main targets of the most active compounds. Molecular docking studies revealed their ability to bind to the heme binding site of nitric oxide synthase 3 (NOS-3) and effectively occupy the active site of AChE, interacting with both the peripheral aromatic subsite and catalytic triad. Finally, the compounds demonstrated stability in simulated gastric and intestinal environments, suggesting potential absorption into the bloodstream without significant hydrolysis. These findings highlight the possible therapeutic potential of acefylline-eugenol 6d and acefylline-isatin 19 hybrids in targeting multiple pathological mechanisms involved in AD, offering promising avenues for further development as potential treatments for this devastating disease.

An Overview of 1,2,3-triazole-Containing Hybrids and Their Potential Anticholinesterase Activities

Acetylcholine (ACh) neurotransmitter of the cholinergic system in the brain is involved in learning, memory, stress responses, and cognitive functioning. It is hydrolyzed into choline and acetic acid by two key cholinesterase enzymes, viz., acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). A loss or degeneration of cholinergic neurons that leads to a reduction in ACh levels is considered a significant contributing factor in the development of neurodegenerative diseases (NDs) such as Alzheimer's disease (AD). Numerous studies have shown that cholinesterase inhibitors can raise the level of ACh and, therefore, enhance people's quality of life, and, at the very least, it can temporarily lessen the symptoms of NDs. 1,2,3-triazole, a five-membered heterocyclic ring, is a privileged moiety, that is, a central scaffold, and is capable of interacting with a variety of receptors and enzymes to exhibit a broad range of important biological activities. Recently, it has been clubbed with other pharmacophoric fragments/molecules in hope of obtaining potent and selective AChE and/or BuChE inhibitors. The present updated review succinctly summarizes the different synthetic strategies used to synthesize the 1,2,3-triazole moiety. It also highlights the anticholinesterase potential of various 1,2,3-triazole di/trihybrids reported in the past seven years (2015-2022), including a rationale for hybridization and with an emphasis on their structural features for the development and optimization of cholinesterase inhibitors to treat NDs.

Recent advances in the development of active hybrid molecules in the treatment of cardiovascular diseases

Multifactorial nature of the underlying pathophysiology of chronic disorders hinders in the effective treatment and management of many complex diseases. The conventional targeted therapies have limited applications due to highly complicated disease etiology. Cardiovascular diseases (CVDs) are the group of disorders of the heart and blood vessels. Currently, there is limited knowledge on the underlying cellular and molecular mechanisms of many of the CVDs due to their complex pathophysiology and co-morbidities. Their management with conventional medications results in failure due to adverse drug reactions and clinical specificity of solo-targeting drug therapy. Therefore, it is critical to introduce an alternative strategy to treat multi-factorial diseases. In the past few years, discovery and use of multi-targeted drug therapy with hybrid molecules have shown promising results with minimal side effects, and thus considered a most effective approach. In this review article, prominent hybrid molecules combining with different active moieties are reported to synergistically and simultaneously block different pathways involved in CVDs. Here, we provide a critical evaluation and discussion on their pharmacology with mechanistic insights and the structure activity relationship. The timely information provided in this article reveals the recent trends of molecular hybridization to the scientific community interested in CVDs and help them in designing the next generation of multi-targeting drug therapeutics.

Donepezil-Inspired Multitargeting Indanone Derivatives as Effective Anti-Alzheimer's Agents

In continuous efforts to develop anti-Alzheimer's agents, we rationally designed and synthesized a series of multitargeting molecules by incorporating the essential molecular features of the standard drug donepezil. Among the series, compound 4b showed multitargeting properties to act as an anti-Alzheimer's agent, which is better tolerable in vivo than donepezil. Acetylcholinesterase (AChE) inhibition data showed that compound 4b inhibits the enzyme with a half-maximal inhibitory concentration (IC₅₀) value of 0.78 μM and also showed DNA protection, which was confirmed through the DNA nicking assay, suggesting the protective effect of 4b against oxidative DNA damage. Compound 4b also showed 53.04% inhibition against Aβ_1-42 aggregations, which was found comparable to that of the standard compound curcumin. Molecular dynamics simulations were performed to check the stability of compound 4b with the enzyme AChE, which showed that the enzyme-ligand complex is stable enough to block the hydrolysis of acetylcholine in the brain. Its higher LD₅₀ cutoff value (50 mg/kg) in comparison to donepezil (LD₅₀: 25 mg/kg) made it safer, suggesting that it can be used in further clinical experiments. To evaluate its anti-Alzheimer property, a mice model with melamine-induced cognitive dysfunction was used, and Morris water maze and Rotarod tests were performed. A significant improvement in memory was observed after the treatment with compound 4b and donepezil. The study postulated that the introduction of important structural features of donepezil (dimethoxyindanone moiety as ring-A) embarked with terminal aromatic ether (ring-B and ring-C) made 4b a multitargeting molecule that offers a way for developing alternative therapeutics in the future against Alzheimer's disease (AD).