Ameliorative effects of amide derivatives of 1,3,4-thiadiazoles on scopolamine induced cognitive dysfunction

Emerging synthetic strategies and pharmacological insights of 1,3,4-thiadiazole derivatives: a comprehensive review

This review meticulously examines the synthesis techniques for 1,3,4-thiadiazole derivatives, focusing on cyclization, condensation reactions and functional group transformations. It enhances the understanding of these chemical methods that re crucial for tailoring derivative properties and functionalities. This study is considered to be vital for researchers, detailing established effects such as antioxidant, antimicrobial and anticancer activities, and revealing emerging pharmacological potentials such as neuroprotective, antiviral and antidiabetic properties. It also discusses the molecular mechanisms underlying these effects. In addition, this article covers structure-activity relationship studies and computational modelling that are essential for designing potent, selective 1,3,4-thiadiazole compounds. This work lays a foundation for future research and targeted therapeutic development.

Synthesis of 1,3,4-Thiadiazole Derivatives and Their Anticancer Evaluation

Thiadiazole derivatives have garnered significant attention in the field of medicinal chemistry due to their diverse pharmacological activities, including anticancer properties. This article presents the synthesis of a series of thiadiazole derivatives and investigates their chemical characterization and potential anticancer effects on various cell lines. The results of the nuclear magnetic resonance (NMR) analyses confirmed the successful formation of the target compounds. The anticancer potential was evaluated through in silico and in vitro cell-based assays using LoVo and MCF-7 cancer lines. The assays included cell viability, proliferation, apoptosis, and cell cycle analysis to assess the compounds' effects on cancer cell growth and survival. Daphnia magna was used as an invertebrate model for the toxicity evaluation of the compounds. The results revealed promising anticancer activity for several of the synthesized derivatives, suggesting their potential as lead compounds for further drug development. The novel compound 2g, 5-[2-(benzenesulfonylmethyl)phenyl]-1,3,4-thiadiazol-2-amine, demonstrated good anti-proliferative effects, exhibiting an IC50 value of 2.44 µM against LoVo and 23.29 µM against MCF-7 after a 48-h incubation and little toxic effects in the Daphnia test.

Thiadiazole – A promising structure in design and development of anti-Alzheimer agents

The design and development of effective multitargeted agents in treating Alzheimer disease (AD) has always been a hot topic in the field of drug discovery. Since AD is a multifactorial disorder, various key hidden players such as deficit of acetylcholine (ACh), tau-protein aggregation, and oxidative stress have been associated with the incidence and progress of AD. In pursuit of improving efficacy and expanding the range of pharmacological activities of current AD drugs, the molecular hybridization method is also used intensively. Five-membered heterocyclic systems such as thiadiazole scaffolds have previously been shown to have therapeutic activity. Thiadiazole analogs as an anti-oxidant compound have been known to include a wide range of biological activity from anti-cancer to anti-Alzheimer properties. The suitable pharmacokinetic and physicochemical properties of the thiadiazole scaffold have introduced it as a therapeutic target in medicinal chemistry. The current review portrays the critical role of the thiadiazole scaffold in the design of various compounds with potential effects in the treatment of Alzheimer's disease. Furthermore, the rationale used behind hybrid-based design strategies and the outcomes achieved through the hybridization of Thiadiazole analogs with various core structures have been discussed. In addition, the data in the present review may help researchers in the design of new multidrug combinations that may provide new options for the treatment of AD.

Antioxidant Compounds in the Treatment of Alzheimer's Disease: Natural, Hybrid, and Synthetic Products

Alzheimer's disease (AD) which is associated with cognitive dysfunction and memory lapse has become a health concern. Various targets and pathways have been involved in AD's progress, such as deficit of acetylcholine (ACh), oxidative stress, inflammation, β-amyloid (Aβ) deposits, and biometal dyshomeostasis. Multiple pieces of evidence indicate that stress oxidative participation in an early stage of AD and the generated ROS could enable neurodegenerative disease leading to neuronal cell death. Hence, antioxidant therapies are applied in treating AD as a beneficial strategy. This review refers to the development and use of antioxidant compounds based on natural products, hybrid designs, and synthetic compounds. The results of using these antioxidant compounds were discussed with the given examples, and future directions for the development of antioxidants were evaluated.

Design, Synthesis, and Evaluation of Novel 2H-Benzo[b][1,4]thiazin-3(4H)-one Derivatives as New Acetylcholinesterase Inhibitors

Alzheimer’s disease (AD) is a slowly progressive neurodegenerative disease that causes dementia in people aged 65 and over. In the present study, a series of thiadiazole hybrid compounds with benzothiazine derivatives as acetylcholinesterase inhibitors were developed and evaluated for their biological activity. The AChE and BChE inhibition potentials of all compounds were evaluated by using the in vitro Ellman method. The biological evaluation showed that compounds 3i and 3j displayed significant inhibitory activity against AChE. Compounds 3i and 3j showed IC₅₀ values of 0.027 µM and 0.025 µM against AChE, respectively. The reference drug donepezil (IC₅₀ = 0.021 µM) also showed significant inhibition against AChE. Further docking simulation also revealed that these compounds (3i and 3j) interacted with the active site of the enzyme similarly to donepezil. The antioxidant study revealed that compounds 3i and 3j exhibited greater antioxidant effects. An in vitro blood–brain barrier permeability study showed that compounds 3i and 3j are promising compounds against AD. The cytotoxicity study of compounds 3i and 3j showed non-cytotoxic with an IC₅₀ value of 98.29 ± 3.98 µM and 159.68 ± 5.53 µM against NIH/3T3 cells, respectively.

Discovery of N-(1,3,4-thiadiazol-2-yl)benzamide derivatives containing a 6,7-methoxyquinoline structure as novel EGFR/HER-2 dual-target inhibitors against cancer growth and angiogenesis

Targeting EGFR and HER-2 is an essential direction for cancer treatment. Here, a series of N-(1,3,4-thiadiazol-2-yl)benzamide derivatives containing a 6,7-methoxyquinoline structure was designed and synthesized to serve as EGFR/HER-2 dual-target inhibitors. The kinase assays verified that target compounds could inhibit the kinase activity of EGFR and HER-2 selectively. The results of CCK-8 and 3D cell viability assays confirmed that target compounds had excellent anti-proliferation ability against breast cancer cells (MCF-7 and SK-BR-3) and lung cancer cells (A549 and H1975), particularly against SK-BR-3 cells, while the inhibitory effect on healthy breast cells (MCF-10A) and lung cells (Beas-2B) was weak. Among them, the hit compound YH-9 binded to EGFR and HER-2 stably in molecular dynamics studies. Further studies found thatYH-9could induce the release of cytochrome c and inhibit proliferation by promoting ROS expression in SK-BR-3 cells. Moreover,YH-9could diminish the secretion of VEGF and bFGF factors in SK-BR-3 cells, then inhibited tube formation and angiogenesis. Notably,YH-9could effectively inhibit breast cancer growth and angiogenesis with little toxicity in the SK-BR-3 cell xenograft model. Taken together,in vitroandin vivoresults revealed that YH-9 had high drug potential as a dual-target inhibitor of EGFR/HER-2 to inhibit breast cancer growth and angiogenesis.

Computational Studies on Acetylcholinesterase Inhibitors: From Biochemistry to Chemistry

Acetylcholinesterase inhibitors are the most promising therapeutics for Alzheimer's disease treatment as these prevent the loss of acetylcholine and slows the progression of the disease. The drugs approved for the management of Alzheimer's disease by the FDA are acetylcholinesterase inhibitors but are associated with side effects. Consistent and stringent efforts by the researchers with the help of computational methods opened new ways of developing novel molecules with good acetylcholinesterase inhibitory activity. In this manuscript, we reviewed the studies that identified the essential structural features of acetylcholinesterase inhibitors at the molecular level as well as the techniques like molecular docking, molecular dynamics, quantitative structure-activity relationship, virtual screening, and pharmacophore modelling that were used in designing these inhibitors.

Design, synthesis and biological assessment of acridine derivatives containing 1,3,4-thiadiazole moiety as novel selective acetylcholinesterase inhibitors

A novel series of acridine derivatives containing substituted thiadiazol-2-amine moiety was synthesized via multi-component condensation reaction of dimedone, aromatic aldehyde and 5-aryl-1,3,4-thiadiazol-2-amines in the presence of LaCl₃ as a catalyst under solvent-free conditions. Anticholinesterase (AChE and BuChE) activity evaluation of the derivatives showed that all the derivatives are capable of inhibiting both enzymes and are highly selective towards AChE. Among them, the ability of 4i and 4d with respective IC₅₀ values of 0.002 and 0.006 µM to inhibit AChE was higher than the reference compound tacrine (IC₅₀ = 0.016 µM). The kinetics studies demonstrated that 4i and 4d inhibit AChE through a competitive/non-competitive mixed mechanism. The HEPG2 cell viability assay evidenced that 4i and 4d significantly exhibit lower hepatotoxicity compared with tacrine. Blind docking experiments performed on TcAChE (PDB ID: 2ACE) indicated that an unknown site is preferred for binding by all the derivatives over classic binding site of the enzyme, site 1 (CAS/PAS). Identification of the residues by protein structure alignment confirmed that this site is site 2 which was recently recognized as a new allosteric site of hAChE. The binding modes of 4i and 4d were also investigated using local docking studies on site 1 and site 2.

Vitamin E therapy prevents the accumulation of congophilic amyloid plaques and neurofibrillary tangles in the hippocampus in a rat model of Alzheimer's disease

OBJECTIVES

Vitamin E may have beneficial effects on oxidative stress and Aβ-associated reactive oxygen species production in Alzheimer's disease. But, the exact role of vitamin E as a treatment for Alzheimer's disease pathogenesis still needs to be studied. Hence, we examined the therapeutic effects of vitamin E on the density of congophilic amyloid plaques and neurofibrillary tangles in rats' hippocampi.

MATERIALS AND METHODS

Wistar rats were randomly assigned to control (no drug treatment), sham scopolamine (3 mg/kg)+saline and Sham scopolamine+sesame oil groups, and three experimental groups that received scopolamine+vitamin E (25, 50, and 100 mg/kg/day) daily for 14 days after scopolamine injection. The rats' brains were collected immediately following transcardial perfusion and fixed in 4% paraformaldehyde. Pathological brain alterations were monitored through Congo red and bielschowsky silver staining.

RESULTS

Scopolamine treatment led to a significant increase in the density of congophilic amyloid plaques and neurofibrillary tangles in the hippocampus. IP injection of vitamin E in three doses (25, 50, and 100 mg/kg/day) significantly reversed the scopolamine-induced increase of the congophilic amyloid plaque density and density of neurofibrillary tangles in the hippocampus. Although vitamin E (25 and 50 mg/kg/day) doses were also effective, but a 100 mg/kg/day dose of vitamin E was more effective in the reduction of congophilic amyloid plaque and neurofibrillary tangle density.

CONCLUSION

Vitamin E could exert a therapeutic effect in the reduction of congophilic amyloid plaque and neurofibrillary tangle density in the hippocampus of scopolamine-treated rats and it is useful for Alzheimer's disease.

The basolateral amygdala regulation of complex cognitive behaviours in the five-choice serial reaction time task

RATIONALE

The basolateral amygdala (BLA) plays important roles in the cognitive control in human and non-human animals. However, inconsistent findings between species have been observed and there have been relatively few detailed investigations of the cognitive properties of BLA, especially in mice.

OBJECTIVE

Our aim was to determine the role of BLA in cognition by using optogenetic manipulations.

METHODS

Male C57BL/six mice were trained and tested on the five-choice serial reaction time task (5-CSRTT), open-field test (OFT), elevated plus maze (EPM), Y-maze, and novel object recognition (NOR) test during optogenetic stimulation and inhibition of the BLA.

RESULTS

Optogenetic activation of the BLA decreased the impulsivity and increased the compulsivity of mice, whereas optogenetic inhibition of BLA had the opposite effect. Similarly, anxiety-like behaviours and spatial working memory were increased in BLA activation mice, whereas BLA inhibition decreased these behaviours. However, both BLA activation and inhibition decreased the motivation of the mice.

CONCLUSIONS

These data demonstrate that the BLA regulates impulsive action and spatial working memory, and plays a critical role in anxiety-like behaviours.

Design, synthesis, and evaluation of novel N-(4-phenoxybenzyl)aniline derivatives targeting acetylcholinesterase, β-amyloid aggregation and oxidative stress to treat Alzheimer's disease

Novel hybrids N-(4-phenoxybenzyl)aniline were designed, synthesized, and evaluated for their potential AChE inhibitory activity along with antioxidant potential. The inhibitory potential (IC₅₀) of synthesized analogs was evaluated against human cholinesterases (hAChE and hBChE) using Ellman's method. Among all the tested compounds, 42 with trimethoxybenzene substituent showed maximum hAChE inhibition with the competitive type of enzyme inhibition (IC₅₀ = 1.32 µM; Ki = 0.879 µM). Further, parallel artificial membrane permeation assay (PAMPA-BBB) showed favorable BBB permeability by most of the synthesized compounds. Meanwhile, compound 42 also inhibited AChE-induced Aβ aggregation (39.5-66.9%) in thioflavin T assay. The in vivo behavioral studies showed dose-dependent improvement in learning and memory by compound 42. The ex vivo studies also affirmed the significant AChE inhibition and antioxidant potential of compound 42 in brain homogenates.

Kai Xin San ameliorates scopolamine-induced cognitive dysfunction

Kai Xin San (KXS, containing ginseng, hoelen, polygala, and acorus), a traditional Chinese herbal compound, has been found to regulate cognitive dysfunction; however, its mechanism of action is still unclear. In this study, 72 specific-pathogen-free male Kunming mice aged 8 weeks were randomly divided into a vehicle control group, scopolamine group, low-dose KXS group, moderate-dose KXS group, high-dose KXS group, and positive control group. Except for the vehicle control group and scopolamine groups (which received physiological saline), the doses of KXS (0.7, 1.4 and 2.8 g/kg per day) and donepezil (3 mg/kg per day) were gastrointestinally administered once daily for 2 weeks. On day 8 after intragastric treatment, the behavioral tests were carried out. Scopolamine group and intervention groups received scopolamine 3 mg/kg per day through intraperitoneal injection. The effects of KXS on spatial learning and memory, pathological changes of brain tissue, expression of apoptosis factors, oxidative stress injury factors, synapse-associated protein, and cholinergic neurotransmitter were measured. The results confirmed the following. (1) KXS shortened the escape latency and increased residence time in the target quadrant and the number of platform crossings in the Morris water maze. (2) KXS increased the percentage of alternations between the labyrinth arms in the mice of KXS groups in the Y-maze. (3) Nissl and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining revealed that KXS promoted the production of Nissl bodies and inhibited the formation of apoptotic bodies. (4) Western blot assay showed that KXS up-regulated the expression of anti-apoptotic protein Bcl-2 and inhibited the expression of pro-apoptotic protein Bax. KXS up-regulated the expression of postsynaptic density 95, synaptophysin, and brain-derived neurotrophic factor in the cerebral cortex and hippocampus. (5) KXS increased the level and activity of choline acetyltransferase, acetylcholine, superoxide dismutase, and glutathione peroxidase, and reduced the level and activity of acetyl cholinesterase, reactive oxygen species, and malondialdehyde through acting on the cholinergic system and reducing oxidative stress damage. These results indicate that KXS plays a neuroprotective role and improves cognitive function through reducing apoptosis and oxidative stress, and regulating synapse-associated protein and cholinergic neurotransmitters.

The phosphodiesterase 5 inhibitor, KJH-1002, reverses a mouse model of amnesia by activating a cGMP/cAMP response element binding protein pathway and decreasing oxidative damage

BACKGROUND AND PURPOSE

Inhibition of PDE5 improves synaptic plasticity and memory via enhancing cGMP expression, thus activating the cGMP/cAMP response element binding protein (CREB) signalling pathway. This study investigated the effects of a PDE5 inhibitor on scopolamine-induced cognitive dysfunction, using memory-related behavioural tests and biochemical assays.

EXPERIMENTAL APPROACH

In mice were pretreated with PDE5 inhibitor, amnesia was induced by scopolamine. The learning and memory abilities of mice were tested using the Morris water maze test, the Y-maze test, the passive avoidance test and the novel object recognition test in sequence. Expression of memory-related bio-molecules and oxidative stress parameters in brain tissue were measured using Western blot and spectrophotometry respectively.

KEY RESULTS

KJH-1002, a novel and potent inhibitor of PDE5 (IC₅₀ 0.059 ± 0.04 nmol·L^-1 ), was synthesized. In the behavioural tests, it markedly improved the memory performance impaired by scopolamine, indicating a restoration of cognitive function in the mice. Moreover, KJH-1002 increased cGMP levels in the cortex and the scopolamine-reduced expression of phosphorylated CREB, Levels of ERK 1/2, Akt and brain-derived neurotrophic factor in the cortex and hippocampus were restored by KJH-1002 treatment. In addition, KJH-1002 administration increased the activities of SOD, glutathione peroxidase and glutathione reductase, and decreased the level of malondialdehyde.

CONCLUSION AND IMPLICATIONS

KJH-1002 restored cognitive function in scopolamine-induced amnesia mice by activating the cGMP/CREB signalling pathway and attenuating oxidative stress. The beneficial effects of KJH-1002 on cognition indicate its potential as a therapeutic candidate for Alzheimer's disease.

Isosteroidal alkaloids as potent dual-binding site inhibitors of both acetylcholinesterase and butyrylcholinesterase from the bulbs of Fritillaria walujewii

Five new isosteroidal alkaloids, walujewine A (1), walujewine B (4), walujewine C (5), walujewine D (6), walujewine E (10) were isolated from the bulbs of Fritillaria walujewii together with seven known isosteroidal alkaloids (2, 3, 7-9, 11, 12). Their structures were elucidated on the basis of IR, ESI-MS, HR-ESI-MS, 1D and 2D NMR spectroscopic data analyses and single-crystal X-ray diffraction. All the isolates were tested for ChE inhibiting activity by the Ellman's method. Compounds 3-5 and 8-10 were potent dual AChE-BChE inhibitors, and compound 1 showed highly selective AChE inhibition. The structure-activity relationship of compounds 1-12 was discussed in details. And kinetic analysis showed that compounds 1, 3-5, and 8-10 were mixed-type reversible inhibitors of AChE, simultaneously binding to the catalytic and peripheral anionic sites, which was verified by in silico docking studies. The docking simulation also showed that active compound 3 and 8 created many interactions with the CAS and PAS gorges of BChE, revealing their mixed-type inhibition. ADMET analysis further confirmed the therapeutic potential of some isosteroidal alkaloids based on their high BBB-penetration.