Ameliorative effect of deoxyvasicine on scopolamine-induced cognitive dysfunction by restoration of cholinergic function in mice

Zexieyin formula alleviates Alzheimer's disease via post-synaptic CaMKII modulating AMPA receptor: Involved in promoting neurogenesis to strengthen synaptic plasticity in mice hippocampus

BACKGROUND

Alzheimer's disease (AD) is a serious neurodegenerative disease and brings a serious burden to society and families. Due to lack of effective drugs for the treatment of AD, it's urgent to develop new and effective drug for the treatment of AD.

PURPOSE

The study aimed to investigate the potential of Zexieyin formula (ZXYF), a Chinese medicine formula, for the treatment of AD and its potential mechanism of action.

METHODS

We used chronic scopolamine (SCOP) induction mice model and APP/PS1 mice to reveal and confirm ZXYF for the treatment of AD with donepezil (DON) as a positive reference. The learning and memory function were detected by morris water maze test (MWM) and y-maze test. Moreover, western blot and immunofluorescence were used to detect the molecular mechanism of ZXYF for the alleviation of AD in hippocampus. Lastly, pharmacological technology was applied to evaluate AMPA receptor involved in the role of ZXYF in the treatment of AD.

RESULTS

The results showed that ZXYF could improve memory and learning deficits both in two AD models including scopolamine (SCOP)-induced mice model and APP/PS1mice. Moreover, ZXYF or not DON increased expressions of BrdU/DCX and Ki67 positive cells in dentate gyrus (DG), up-regulated the levels of AMPA subunit type (GluA1) and PKA in hippocampus in SCOP-induced mice model, although ZXYF and DON activated CaMKII, CaMKII-phosphorylation, CREB, CREB-phosphorylation and PSD95 in hippocampus in SCOP-induced mice model. ZXYF also activated CaMKII, CaMKII-phosphorylation and GluA1 in HT22 cells. Furthermore, transient inhibiting AMPA receptor was capable of blocking the effects of ZXYF to treat AD in MWM and suppressing the number of BrdU/DCX positive cells increased by ZXYF in DG in SCOP-induced mice model, but had no effect on the alteration of Ki67 positive cells.

CONCLUSION

ZXYF had the therapeutic effects on AD-treatment, which activated CaMKII to promote AMPA receptor (GluA1) and subsequently up-regulated PKA/CREB signaling to facilitate neurogenesis to achieve enhanced postsynaptic protein.

Lancao decoction alleviates cognitive dysfunction: A new therapeutic drug and its therapeutic mechanism

BACKGROUND

Cognitive dysfunction (CD) is a neurodegenerative disease characterized primarily by the decline of learning and memory abilities. The physiological and pathological mechanisms of CD are very complex, which is mainly related to normal function of the hippocampus. Lancao decoction (LC) is a Chinese medicine formula, which has been used to treat neurodegenerative disorders. However, the potential of LC for the treatment of CD, as well as its underlying mechanisms, is unclear.

PURPOSE

In the study, we aimed to reveal the functional and neuronal mechanisms of LC's treatments for CD in scopolamine-induced mice.

METHODS

Gas chromatography (GC) was used to determine the stability of LC's extraction. CD model was established by the chronic induction of scopolamine (Scop, 1 mg/kg/day) for 1 week. Behavioral tests including morris water maze (MWM) and y-maze were used to evaluate learning and memory abilities of mice after LC's treatments. Immunofluorescence was used to detected the expressions of cFOS, Brdu and Ki67 after LC's treatments. Pharmacological blockade experiments explored the role of α-Amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) in LC's treatments for CD and its relationships with regeneration, activities and differentiation of neurons.

RESULTS

The results showed that LC was capable of improving spatial learning and memory and spontaneous alternating abilities in Scop-induced mice, which was similar to donepezil. LC could increase the number of cFOS positive cells, which was used as a marker of neuronal activity to upregulate by neuronal activities in hippocampus, but donepezil did not. Moreover, LC could strengthen neurogenesis and neuro-differentiation by increasing the number of Brdu and Ki67 positive cells in hippocampal dentate gyrus (DG), meanwhile, donepezil could only enhance the number of Ki67 positive cells. Transient inhibition of AMPAR by NBQX blunted the function of LC's treatment for CD and inhibited the enhanced effect of LC on Scop-induced hippocampal neuronal excitability and neurogenesis in mice.

CONCLUSION

To sum up, our study demonstrated that LC had the function of treating CD by enhancing content of acetylcholine (ACh) to activate AMPAR, which further up-regulated neurogenesis and neuronal differentiation to strengthen neuroactivities in hippocampus.

Influence of Neostigmine on Early Postoperative Cognitive Dysfunction in Older Adult Patients Undergoing Noncardiac Surgery: A Double-Blind, Placebo-Controlled, Randomized Controlled Trial

BACKGROUND

The goal of this study was to investigate the efficacy of neostigmine on postoperative cognitive dysfunction (POCD) and determine its effect on systematic markers of oxidative stress in older patients.

METHODS

This double-blind placebo-controlled trial enrolled 118 elderly patients (≥65 years) undergoing noncardiac surgeries who were allocated to a neostigmine treatment group (0.04 mg/kg) or a placebo control group (normal saline) postoperatively. POCD was diagnosed if the Z -scores for the mini-mental state examination and the Montreal Cognitive Assessment were both ≤-1.96. Postoperative serum levels of malondialdehyde (MDA), superoxide dismutase (SOD), and brain-derived neurotrophic factor (BDNF) were also compared. Multivariable regression analysis with dose adjustment of atropine was used to demonstrate the influence of neostigmine on the incidence of POCD.

RESULTS

Patients receiving neostigmine had a significantly reduced incidence of POCD compared to patients who were treated with placebo on the first day after surgery (-22%, 95% confidence interval [CI], -37 to -7), but not on the third (8%, 95% CI, -4 to 20) or seventh day after surgery (3%, 95% CI, -7 to 13). Postoperative plasma MDA levels were significantly lower ( P = .016), but SOD and BDNF levels were increased ( P = .036 and .013, respectively) in the neostigmine group compared to the control group on the first day after surgery.

CONCLUSIONS

Neostigmine reduced POCD on the first day after noncardiac surgery in older patients. Neostigmine treatment inhibited oxidative stress and increased serum BDNF levels. There was no significant influence of neostigmine on POCD on the third or seventh day after surgery. The clinical influence of neostigmine on POCD should be further investigated.

Constituents, pharmacological activities, pharmacokinetic studies, clinical applications, and safety profile on the classical prescription Kaixinsan

Kaixinsan (KXS) is a noteworthy classical prescription, which consists of four Chinese medicinal herbs, namely Polygalae Radix, Ginseng Radix et Rhizoma, Poria, and Acori Tatarinowii Rhizoma. KXS was initially documented in the Chinese ancient book Beiji Qianjin Yaofang written by Sun Simiao of the Tang Dynasty in 652 A.D. As a traditional Chinese medicine (TCM) prescription, it functions to nourish the heart and replenish Qi, calm the heart tranquilize the mind, and excrete dampness. Originally used to treat amnesia, it is now also effective in memory decline and applied to depression. Although there remains an abundance of literature investigating KXS from multiple aspects, few reviews summarize the features and research, which impedes better exploration and exploitation of KXS. This article intends to comprehensively analyze and summarize up-to-date information concerning the chemical constituents, pharmacology, pharmacokinetics, clinical applications, and safety of KXS based on the scientific literature, as well as to examine possible scientific gaps in current research and tackle issues in the next step. The chemical constituents of KXS primarily consist of saponins, xanthones, oligosaccharide esters, triterpenoids, volatile oils, and flavonoids. Of these, saponins are the predominant active ingredients, and increasing evidence has indicated that they exert therapeutic properties against mental disease. Pharmacokinetic research has illustrated that the crucial exposed substances in rat plasma after KXS administration are ginsenoside Re (GRe), ginsenoside Rb1 (GRb1), and polygalaxanthone III (POL). This article provides additional descriptions of the safety. In this review, current issues are highlighted to guide further comprehensive research of KXS and other classical prescriptions.

Effects and mechanism of extracts rich in phenylpropanoids-polyacetylenes and polysaccharides from Codonopsis Radix on improving scopolamine-induced memory impairment of mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) is a progressive developmental neurodegenerative disease that primarily develops in old age. Memory impairment is an important manifestation of AD. It has been demonstrated that inflammation and oxidative stress are important mediators in the development and progression of AD. Codonopsis Radix (CR) has a long history of consumption, exhibiting lots of beneficial health effects, including anti-ageing, antioxidant, and anti-inflammatory properties. However, studies on the effects of CR on scopolamine-induced amnesia have rarely been reported.

AIM OF THE STUDY

The aim of this study was to investigate the ameliorative effect of macromolecular portion (polysaccharides, POL) and small molecule portion (fine extract rich in phenylpropanoids-polyacetylenes, EPP) from CR on improving scopolamine-induced memory impairment and to elucidate the potential mechanism of action.

MATERIALS AND METHODS

C57BL/6 mice were pretreated with EPP (0.2, 0.4, and 0.6 g/kg), POL (0.3, 0.6, and 0.9 g/kg), and donepezil (5 mg/kg) by gavage for 7 days, followed by intraperitoneal injection of scopolamine (1 mg/kg) to induce memory impairment. The 16S rRNA gene sequencing, histopathological, western blotting, and biochemical analysis (various biochemical markers and protein expressions related to cholinergic system, oxidative stress, and neuroinflammation) were performed to further elucidate the mechanism of action. Moreover, the acetylcholinesterase (AChE) inhibitory activities of POL, EPP, and its main compounds tangshenoside I, lobetyol, lobetyolin, and lobetyolinin were evaluated.

RESULTS

Experiments have confirmed that both POL and EPP from CR could improve scopolamine-induced spatial learning memory deficits. Both of them could regulate cholinergic function by inhibiting AChE and activating choline acetyltransferase (ChAT) activities. They also could enhance antioxidant defense via increasing the activities of superoxide dismutase and glutathione peroxidase, and anti-inflammatory function through suppressing inflammatory factors (nitric oxide, TNF-α, and IL-6) and regulating gut flora. Besides, in vitro experiments demonstrated that four monomeric compounds and EPP, except POL, exhibited inhibition of AChE activity.

CONCLUSION

EPP and POL from CR exert a beneficial effect on learning and memory processes in mice with scopolamine-induced memory impairment. CR may be a promising medicine for preventing and improving learning memory.

Ameliorative effect of scopolamine-induced cognitive dysfunction by Fufangmuniziqi formula: The roles of alkaloids, saponins, and flavonoids

ETHNOPHARMACOLOGICAL RELEVANCE

Fufangmuniziqi formula (FFMN), a traditional Uyghur medicine used in China, is derived from an ancient Uyghur medical book and consists of 13 herbs. The herbs of FFMN, such as Peganum harmala L., Glycyrrhiza uralensis Fisch., and Nigella glandulifera, have been demonstrated to have acetylcholinesterase (AChE) inhibitory, anti-neuroinflammatory, or antioxidant effects. Therefore, FFMN may have a good anti-Alzheimer's disease (AD) effect, but its specific action and mechanism need to be further proven.

AIM OF THE STUDY

This study aims to investigate the anti-AD effects of FFMN and the role played by alkaloids, flavonoids, and saponins in anti-AD.

MATERIALS AND METHODS

The alkaloids, flavonoids, and saponins fractions of FFMN were prepared by macroporous resin chromatography. The absorbed ingredients in the drug-containing serum were identified by UPLC⁃Q⁃TOF⁃MS. An AD mouse model was established by intraperitoneal injection of scopolamine (SCO). The role of different fractions of FFMN in the anti-AD process was examined by Morris water maze (MWM), in-vitro cell, and AChE inhibition assay.

RESULTS

A total of 20 ingredients were identified in the serum samples collected after oral administration of FFMN, and seven compounds were selected as candidate active compounds. MWM experiments showed that different fractions of FFMN could significantly improve SCO-induced learning memory impairment in mice. The alkaloids fraction (ALK) regulated cholinergic function by inhibiting AChE activity, activating choline acetyltransferase activity, and protein expression. Flavonoids and saponins were more potent than the ALK in downregulating pro-inflammatory factors or inflammatory mediators, such as TNF-α, MPO, and nitric oxide. Western blot results further confirmed that flavonoids and saponins attenuated neuroinflammation by inhibiting the phosphorylation of IκB and NF-κB p65. This result was also verified by in-vitro cellular assays. FFMN enhanced antioxidant defense by increasing the activity of superoxide dismutase and reducing the production of MDA. Combined with cellular experiments, flavonoids and saponins were proven more protective against oxidative damage.

CONCLUSION

FFMN improved cognitive and memory impairment in the SCO-induced AD mouse model. ALK mainly enhanced the function of the cholinergic system. Flavonoid and saponin fractions mainly attenuated neuroinflammation and oxidative stress by modulating the NF-κB pathway. All these findings strongly suggested that the combination of alkaloid, flavonoid, and saponin fractions derived from FFMN is a promising anti-AD agent that deserves further development.

A Comparative Study of the Impact of NO-Related Agents on MK-801- or Scopolamine-Induced Cognitive Impairments in the Morris Water Maze

Learning and memory deficits accompany numerous brain dysfunctions, including schizophrenia and Alzheimer’s disease (AD), and many studies point to the role of nitric oxide (NO) in these processes. The present investigations constitute the follow-up of our previous research, in which we investigated the activity of NO releasers and a selective inhibitor of neuronal NO synthase (nNOS) to prevent short-term memory deficits in novel object recognition and T-maze. Here, the ability of the compounds to prevent the induction of long-term memory deficits by MK-801 or scopolamine administration was investigated. The Morris Water Maze test, a reliable and valid test of spatial learning and memory, was used, in which escape latency in the acquisition phase and nine different parameters in the retention phase were measured. A fast NO releaser (spermine NONOate), a slow NO releaser (DETA NONOate), and a nNOS inhibitor, N(ω)-propyl-L-arginine (NPLA), were used. The compounds were administered i.p. at a dose range of 0.05–0.5 mg/kg. All compounds prevented learning deficits in the acquisition phase and reversed reference memory deficits in the retention phase of the scopolamine-treated mice. Spermine NONOate was the least effective. In contrast, the drugs poorly antagonised MK-801-induced deficits, and only the administration of DETA NONOate induced some improvements in the retention trial.

Thymol in Trachyspermum ammi seed extract exhibits neuroprotection, learning, and memory enhancement in scopolamine-induced Alzheimer's disease mouse model

Several reports have stated the neuroprotective and learning/memory effects of Tachyspermum ammi seed extract (TASE) and its principal component thymol; however, little is known about its underlying molecular mechanisms and neurogenesis potential. This study aimed to provide insights into TASE and a thymol-mediated multifactorial therapeutic approach in a scopolamine-induced Alzheimer's disease (AD) mouse model. TASE and thymol supplementation significantly reduced oxidative stress markers such as brain glutathione, hydrogen peroxide, and malondialdehyde in mouse whole brain homogenates. Tumor necrosis factor-alpha was significantly downregulated, whereas the elevation of brain-derived neurotrophic factor and phospho-glycogen synthase kinase-3 beta (serine 9) enhanced learning and memory in the TASE- and thymol-treated groups. A significant reduction in the accumulation of Aβ 1-42 peptides was observed in the brains of TASE- and thymol-treated mice. Furthermore, TASE and thymol significantly promoted adult neurogenesis, with increased doublecortin positive neurons in the subgranular and polymorphic zones of the dentate gyrus in treated-mice. Collectively, TASE and thymol could  potentially act as natural therapeutic agents for the treatment of  neurodegenerative disorders, such as  AD.

Trimethoxyflavones from Ocimum basilicum L. leaves improve long term memory in mice by modulating multiple pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Traditionally, Ocimum basilicum L. leaves (OB) are recommended for various brain disorders.

AIM OF THE STUDY

Scientific evidence highlights the cognition improvement capacity of Ocimum basilicum L. leave extract (OBE), however, the compound(s) responsible for this effect and the associated mechanism was not reported. The present study was, thus, designed to isolate and identify the compound responsible for memory improvement effects of OB and to delineate the associated mechanism of action.

MATERIALS AND METHODS

In-vitro acetylcholinesterase (AChE) inhibitory (Ellman method) and antioxidant (DPPH scavenging) assays guided fractionation was employed to isolate the bioactive compounds from OBE. The isolated compounds were characterised using spectroscopic techniques (FTIR, NMR and MS). In-silico and in-vivo [mouse model of scopolamine (SCOP) induced amnesia] investigations were used to substantiate the memory improvement effects of isolated compounds and to understand their mechanism of action.

RESULTS

AChE and DPPH assays guided fractionation of OBE lead to isolation of two pure compounds namely, 5,7-dihydroxy-3',4',5'-trimethoxyflavone (S1) and 3-hydroxy-3',4',5'-trimethoxyflavone (S2). Both S1 and S2 mitigated the cognitive impairment due to SCOP in mice by reducing brain AChE activity, TBARS, TNF-α, IL-1β, IL-6 and caspase-3 concentrations and elevating reduced glutathione and IL-10 levels; together with amelioration of brain hippocampus histopathological aberration (H and E staining). Moreover, the molecular docking of S1 and S2 at the active pockets of AChE and caspase-3 has shown good interactions with vital amino acid residues.

CONCLUSIONS

Our findings show that trimethoxy flavones are responsible for the memory improvement effect of OBE due to their anticholinergic, antioxidant, anti-inflammatory and anti-apoptotic properties. These maybe developed as valuable alternatives for management of cognitive disorders.

A multi-parameter evaluation of the neuroprotective and cognitive-enhancing effects of Origanum onites L. (Turkish Oregano) essential oil on scopolamine-induced amnestic rats

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive deterioration of cognitive functions (dementia) and represents a growing public health concern since the population in the age groups at risk is increasing. The latter raises an urgent need to translate research findings in the basic brain and behavioral sciences into anti-AD drugs and disease-modifying therapies. Origanum onites (L.), also called Turkish oregano, is a perennial and herbaceous plant species grown for centuries for medicinal, cosmetic and culinary purposes. This is the first study to investigate the putative neuroprotective and pro-cognitive activities of O. onites essential oil (OOEO) against scopolamine-induced amnesia of AD-type in Wistar albino rats. The results of behavioral tests revealed that OOEO administration was able to significantly alleviate learning and memory impairments induced by scopolamine in vivo. The observed effects could be attributed to inhibition of acetylcholinesterase activity, attenuation of oxidative stress and prevention of neuronal apoptosis in the hippocampus and frontal cortex of AD rats. Modulation of pro-inflammatory enzymes, including cyclooxygenase-2, inducible nitric oxide synthase and myeloperoxidase, might further contribute to the neuroprotective properties of OEOO, as predicted by our in silico models. These findings offer novel insights into the therapeutic potential of OEOO in patients with AD.

Attenuation of spatial memory in 5xFAD mice by targeting cholinesterases, oxidative stress and inflammatory signaling using 2-(hydroxyl-(2-nitrophenyl)methyl)cyclopentanone

Alzheimer's disease (AD) is classified pathologically as a progressive neurological disorder associated with memory decline. The study was designed to assess the underlying molecular signaling involved in the neuroprotective effect of the 2-(hydroxyl-(2-nitrophenyl)methyl)cyclopentanone (2NCP) as a novel therapeutic agent for AD. In this connection, in vitro cholinesterases inhibitory and antioxidant activities were investigated. In vivo studies were carried out on a well-known 5xFAD mice model in different behavioural models such as light/dark box,balance beam, rotarod, elevated plus maze (EPM),novel object recognition (NOR), paddling Y-maze, and Morris water maze (MWM) tests. Hippocampus (HC) and frontal cortex (FC) homogenates were examined for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, glutathione S-transferase (GST), glutathione (GSH), and catalase. Further, we examined the expression of inflammatory cytokines and Nrf2 in the HC and FC through RT-PCR. Computational studies were conducted to predict the binding mode of the 2NCP with target sites of nuclear factor-κB (NF-κB) and cholinesterases. The findings of in vitro assays revealed that the IC₅₀ values of the 2NCP against AChE and BChE were 17 and 23 µg/ml respectively. DPPH antioxidant assay displayed an IC₅₀ value for the 2NCP was 62 µg/ml. Whereas, theex vivo study depicted that the activities of AChE and BChEwere significantly reduced. Moreover, free radicals load, GSH level, catalase and GST activities were significantly declined. Furthermore, in vivostudies showed that the 2NCP treated animals exhibited gradual memory improvement and improved motor functions. RT-PCR study revealed that mRNA levels of the inflammatory mediators (IL-1β, IL-6, TNF-α) were significantly reduced, while the expression of antioxidant Nrf2 was significantly increased.The molecular docking studies further confirmed that the 2NCP showed excellent binding affinities for NF-κB and cholinesterases. Taken together, the 2NCP improves spatial memory and learning, short- and long-term memory,markedly inhibits cholinesterases, reduced neuroinflammation, and mitigated oxidative stress in the 5xFAD mice; hence the 2NCP may be a potential candidate for the management of AD.

Bay Leaf (Laurus Nobilis L.) Incense Improved Scopolamine-Induced Amnesic Rats by Restoring Cholinergic Dysfunction and Brain Antioxidant Status

Bay leaf (Laurus nobilis L.) has been shown to possesses various biological activities such as wound healing activity, antioxidant activity, antibacterial activity, antiviral activity, immunostimulant activity, anticholinergic activity, antifungal activity, insect repellant activity, anticonvulsant activity, antimutagenic activity, and analgesic and anti-inflammatory activity. The present study aimed to investigate whether the bay leaf incense (BL) elicits the memory formation via the action on the cholinergic system using a scopolamine (Sco)-induced rat model. Rats were exposed to BL over 5 min in a smoking chamber apparatus once daily for 22 days, whereas memory impairment was induced by Sco (0.7 mg/kg), a muscarinic receptor antagonist, delivered 30 min before each behavioral test. The phytochemical composition of BL was achieved by gas chromatograph–mass spectrometry (GCMS). Behavioral effects in rats were assessed by Y-maze, radial arm maze (RAM), and novel object recognition (NOR) paradigms. Additionally, the acetylcholinesterase (AChE) activity and the oxidative stress markers in the rat hippocampus were also evaluated. Exposure to BL significantly ameliorated Sco-induced cognitive impairment and oxidative stress in the rat hippocampus. The obtained results suggested that BL-induced ameliorative cognitive effects are mediated by enhancement of the cholinergic system and antioxidant activities.

Potential of Naturally Derived Alkaloids as Multi-Targeted Therapeutic Agents for Neurodegenerative Diseases

Alkaloids are a class of secondary metabolites that can be derived from plants, fungi and marine sponges. They are widely known as a continuous source of medicine for the management of chronic disease including cancer, diabetes and neurodegenerative diseases. For example, galanthamine and huperzine A are alkaloid derivatives currently being used for the symptomatic management of neurodegenerative disease. The etiology of neurodegenerative diseases is polygenic and multifactorial including but not limited to inflammation, oxidative stress and protein aggregation. Therefore, natural-product-based alkaloids with polypharmacology modulation properties are potentially useful for further drug development or, to a lesser extent, as nutraceuticals to manage neurodegeneration. This review aims to discuss and summarise recent developments in relation to naturally derived alkaloids for neurodegenerative diseases.

Attenuation of Nrf2/Keap1/ARE in Alzheimer's Disease by Plant Secondary Metabolites: A Mechanistic Review

Alzheimer’s disease (AD) is a progressive neuronal/cognitional dysfunction, leading to disability and death. Despite advances in revealing the pathophysiological mechanisms behind AD, no effective treatment has yet been provided. It urges the need for finding novel multi-target agents in combating the complex dysregulated mechanisms in AD. Amongst the dysregulated pathophysiological pathways in AD, oxidative stress seems to play a critical role in the pathogenesis progression of AD, with a dominant role of nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein-1 (Keap1)/antioxidant responsive elements (ARE) pathway. In the present study, a comprehensive review was conducted using the existing electronic databases, including PubMed, Medline, Web of Science, and Scopus, as well as related articles in the field. Nrf2/Keap1/ARE has shown to be the upstream orchestrate of oxidative pathways, which also ameliorates various inflammatory and apoptotic pathways. So, developing multi-target agents with higher efficacy and lower side effects could pave the road in the prevention/management of AD. The plant kingdom is now a great source of natural secondary metabolites in targeting Nrf2/Keap1/ARE. Among natural entities, phenolic compounds, alkaloids, terpene/terpenoids, carotenoids, sulfur-compounds, as well as some other miscellaneous plant-derived compounds have shown promising future accordingly. Prevailing evidence has shown that activating Nrf2/ARE and downstream antioxidant enzymes, as well as inhibiting Keap1 could play hopeful roles in overcoming AD. The current review highlights the neuroprotective effects of plant secondary metabolites through targeting Nrf2/Keap1/ARE and downstream interconnected mediators in combating AD.

Attenuation of Spatial Memory in 5xFAD Mice by Halting Cholinesterases, Oxidative Stress and Neuroinflammation Using a Cyclopentanone Derivative

Alzheimer's disease (AD) is an irreversible and chronic neurological disorder that gradually destroys memory and thinking skills. The research study was designed to investigate the underlying molecular signaling involved in the neuroprotective effects of cyclopentanone derivative i.e., 2-(hydroxyl-(3-nitrophenyl)methyl)cyclopentanone (3NCP) as a therapeutic agent for AD. In this study, In vivo studies were carried out on a well-known 5xFAD mice model using different behavioural test models such as open field, rotarod, Morris water maze (MWM), and Y-maze tests. Furthermore, in vitro cholinesterase inhibition activity assays were carried out. The frontal cortex (FC) and hippocampus (HC) homogenates were tested for the levels/activities of cholinesterases, glutathione (GSH), glutathione S-transferase (GST), and catalase. Furthermore, the hippocampal expression of inflammatory cytokines was observed via RT-PCR and western blot. The results of in vivo studies show an enhancement in the learning behavior. The 3NCP treatment reduced latency time in MWM and Y-maze tests, also increase spontaneous alternation indicate significant effect of 3NCP on memory. Furthermore, open field and rotarod studies revealed that 3NCP does not cause motor coordination deficit. The results of the in vitro studies revealed that the IC50 values of the 3NCP against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were 16.17 and 20.51 µg/mL, respectively. This decline in AChE and BChE was further supported by ex vivo studies. Further, the 3NCP mitigates the GSH level, GST, and catalase activities in HC and FC. The mRNA and protein expression of inflammatory cytokines (IL-1β, IL-6, TNF-α) markedly declined in RT-PCR and western blotting. The results of the current study conclusively demonstrate that 3NCP reduces oxidative stress and mitigates neuroinflammation in 5xFAD mice, implying that 3NCP may be a potential therapeutic candidate for AD treatment in the future.

Bergapten Improves Scopolamine-Induced Memory Impairment in Mice via Cholinergic and Antioxidative Mechanisms

Bergapten is a furanocoumarin naturally occurring in the Apiaceae family and it is a well-known photosensitizing agent used in photochemotherapy. In this study, we investigated the influence of bergapten on cognitive function and mechanism underlying these effects in scopolamine-induced memory impairment in male Swiss mice. The passive avoidance test was used to evaluate the efficiency of memory acquisition and consolidation. The results demonstrated that both single and repeated administration of bergapten improved not only the acquisition but also consolidation of memory. The behavioral tests showed that bergapten prevented memory impairment induced by administration of scopolamine. Observed effects may result from the inhibition of acetylcholinesterase activity in the hippocampus and prefrontal cortex. Also, bergapten caused significant anti-oxidative effects. These new findings provide pharmacological and biochemical support for the development of the coumarin’s potential in cognitive deficits.