Anti-amnestic Effect of Curcumin in Combination with Donepezil, an Anticholinesterase Drug: Involvement of Cholinergic System

Effect of woohwangchungsimwon and donepezil co-treatment on cognitive function and serum metabolic profiles in a scopolamine-induced model of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Woohwangchungsimwon (WCW) is a traditional medicine used in East Asian countries to treat central nervous system disorders. Reported pharmacological properties include antioxidant effects, enhanced learning and memory, and protection against ischemic neuronal cell death, supporting its use in treating neurodegenerative diseases like Alzheimer's disease (AD).

AIM OF THE STUDY

The study aims to assess the effects of co-treatment with WCW and donepezil on cognitive functions and serum metabolic profiles in a scopolamine-induced AD model.

MATERIALS AND METHODS

Cell viability and reactive oxygen species (ROS) levels were measured in amyloid β-peptide25-35 (Aβ25-35)-induced SH-SY5Y cells. An AD model was established in ICR mice by intraperitoneal scopolamine administration. Animals underwent the step-through passive avoidance test (PAT) and Morris water maze (MWM) test. Hippocampal tissues were collected to examine specific protein expression. Serum metabolic profiles were analyzed using nuclear magnetic resonance (NMR) spectroscopy.

RESULTS

Co-treatment with WCW and donepezil increased cell viability and reduced ROS production in Aβ25-35-induced SH-SY5Y cells compared to that with donepezil treatment alone. Co-treatment improved cognitive functions and was comparable to donepezil treatment alone in the PAT and MWM tests. Pathways related to tyrosine, phenylalanine, and tryptophan biosynthesis, phenylalanine metabolism, and cysteine and methionine metabolism were altered by co-treatment. Levels of tyrosine and methionine, major serum metabolites in these pathways, were significantly reduced after co-treatment.

CONCLUSIONS

Co-treatment with WCW and donepezil shows promise as a therapeutic strategy for AD and is comparable to donepezil alone in improving cognitive function. Reduced tyrosine and methionine levels after co-treatment may enhance cognitive function by mitigating hypertyrosinemia and hyperhomocysteinemia, known risk factors for AD. The serum metabolic profiles obtained in this study can serve as a foundation for developing other bioactive compounds using a scopolamine-induced mouse model.

Modulatory effects of Cannabis sativa co-administration with tramadol and codeine on cognitive function in male rats

Most teenagers mix up various psychoactive cocktail substances in combinations to get intoxicated. The role of the mixture combination of codeine (CDE), tramadol (TMD), and Cannabis sativa (CNB) on brain cognition, purinergic, cholinergic, and antioxidant enzyme activities remains unknown. This study sought to assess the mechanism of action of combinations of CDE+ TMD+ CNB on the function and activities of the brain of male Wistar rats. Forty-eight male Wistar rats were divided into 8 groups, n = 6. Group 1 served as a control, groups 2, 3, and 4 were exposed to CDE (2 mg/kg bw), TMD (10 mg/kg bw), and CNB (200 mg/kg bw), while groups 5, 6, 7, and 8 were co-administered with CDE+TMD, CNB+ TMD, CNB+CDE, and CNB+TMD+CDE orally for 28 days. This study revealed the effect of prolonged administration of CNB, TMD, and CDE on the suppression of cognitive function, acetyl-cholinesterase (AChE), butyl-cholinesterase (BChE), monoamine oxidase (MAO) enzyme activities, and antioxidant enzyme activities in rats' brains when compared against control rats (P < 0.05). However, the activities of ectonucleosides (NTPdase), adenosine deaminase (ADA), and malondialdehyde levels produced in the brain of rats were significantly elevated (P < 0.05). This study reported the mechanism behind the neurotoxicity of CNB, TMD, and CDE on rats' cognitive, cholinergic, purinergic, and antioxidant enzymes as a consequence of the drastic reduction in cholinesterase enzyme activities leading to neurotransmitter poisoning.

Memory Recovery Effect of a New Bioactive Innovative Combination in Rats with Experimental Dementia

Alzheimer's disease manifests as a complex pathological condition, with neuroinflammation, oxidative stress and cholinergic dysfunction being a few of the many pathological changes. Due to the complexity of the disease, current therapeutic strategies aim at a multitargeted approach, often relying on a combination of substances with versatile and complementary effects. In the present study, a unique combination of α-lipoic acid, citicoline, extracts of leaves from olive tree and green tea, vitamin D3, selenium and an immune-supporting complex was tested in scopolamine-induced dementia in rats. Using behavioral and biochemical methods, we assessed the effects of the combination on learning and memory, and elucidated the mechanisms of these effects. Our results showed that, compared to its components, the experimental combination was most efficient in improving short- and long-term memory as assessed by the step-through method as well as spatial memory as assessed by T-maze and Barnes maze underlined by decreases in AChE activity (p < 0.05) and LPO (p < 0.001), increases in SOD activity in the cortex (p < 0.05) and increases in catalase (p < 0.05) and GPx (p < 0.01) activities and BDNF (p < 0.001) and pCREB (p < 0.05) levels in the hippocampus. No significant histopathological changes or blood parameter changes were detected, making the experimental combination an effective and safe candidate in a multitargeted treatment of AD.

Curcumin improves the ability of donepezil to ameliorate memory impairment in Drosophila melanogaster: involvement of cholinergic and cnc/Nrf2-redox systems

One of the well-established models for examining neurodegeneration and neurotoxicity is the Drosophila melanogaster model of aluminum-induced toxicity. Anti-cholinesterase drugs have been combined with other neuroprotective agents to improve Alzheimer's disease management, but there is not much information on the combination of anti-cholinesterases with dietary polyphenols to combat memory impairment. Here, we assess how curcumin influences some of the critical therapeutic effects of donepezil (a cholinesterase inhibitor) in AlCl3-treated Drosophila melanogaster. Harwich strain flies were exposed to 40 mM AlCl3 - alone or in combination with curcumin (1 mg/g) and/or donepezil (12.5 µg/g and 25 µg/g) - for seven days. The flies' behavioral evaluations (memory index and locomotor performance) were analyzed. Thereafter, the flies were processed into homogenates for the quantification of acetylcholinesterase (AChE), catalase, total thiol, and rate of lipid peroxidation, as well as the mRNA levels of acetylcholinesterase (ACE1) and cnc/NRF2. Results showed that AlCl3-treated flies presented impaired memory and increased activities of acetylcholinesterase and lipid peroxidation, while there were decrease in total thiol levels and catalase activity when compared to the control. Also, the expression of ACE1 was significantly increased while that of cnc/NRF2 was significantly decreased. However, combinations of curcumin and donepezil, especially at lower dose of donepezil, significantly improved the memory index and biochemical parameters compared to donepezil alone. Thus, curcumin plus donepezil offers unique therapeutic effects during memory impairment in the D. melanogaster model of neurotoxicity.

Anti-inflammatory, anticholinesterase, antioxidant, and memory enhancement potential of Phyllanthus amarus in potassium-dichromate induced neurotoxicity of male Wistar rats

This study investigated the protective effect of aqueous Phyllanthus amarus leaf extract (APALE) in Potassium dichromate (PDc)-induced neurotoxicity. Seventy young adult male, Wistar rats with a weight of 130-150 g, were randomised into seven groups (n = 10): Group 1; distilled water; Group 2: 300 mg/kg APALE; Group 3: 17 mg/kg PDc; Group 4: 5 mg/kg Donepezil (DPZ); Group 5: 17 mg/kg PDc + 400 mg/kg APALE; Group 6:17 mg/kg PDc + 200 mg/kg APALE; Group 7: 17 mg/kg PDc + 5 mg/kg DPZ. All administrations were given once daily via an orogastric cannula for 28 consecutive days. Cognitive assessment tests were employed to ascertain the treatments' effects on the rats' cognitive function. At the end of the experiment, the rats were sacrificed, morphometric analysis was done, and the brains were dissected for histology, enzyme, and other biochemical analysis. Findings from this study showed that APALE significantly improved locomotive activity, recognition memory sensitivity, protection against fear and anxiety, enhanced decision-making, and improved memory function in a dose-dependent manner comparably to DPZ. In addition, APALE significantly increased antioxidants level, reducing oxidative stress in PDc-induced neurotoxic rats and significantly reducing brain acetylcholinesterase (AchE) activity by regulating gamma amino butyric acid (GABA) levels in PDc-induced neurotoxic rats compared to DPZ. Furthermore, APALE alleviated neuroinflammatory responses via maintaining histoarchitecture and down-regulation of IBA1 and Tau in PDc-induced rats. In conclusion, APALE protected against PDc-induced neurotoxicity via a combination of anti-inflammatory, anticholinergic, and antioxidant effects on the prefrontal cortex of rats.

Combined Donepezil with Astaxanthin via Nanostructured Lipid Carriers Effective Delivery to Brain for Alzheimer's Disease in Rat Model

Introduction

Donepezil (DPL), a specific acetylcholinesterase inhibitor, is used as a first-line treatment to improve cognitive deficits in Alzheimer's disease (AD) and it might have a disease modifying effect. Astaxanthin (AST) is a natural potent antioxidant with neuroprotective, anti-amyloidogenic, anti-apoptotic, and anti-inflammatory effects. This study aimed to prepare nanostructured lipid carriers (NLCs) co-loaded with donepezil and astaxanthin (DPL/AST-NLCs) and evaluate their in vivo efficacy in an AD-like rat model 30 days after daily intranasal administration.

Methods

DPL/AST-NLCs were prepared using a hot high-shear homogenization technique, in vitro examined for their physicochemical parameters and in vivo evaluated. AD induction in rats was performed by aluminum chloride. The cortex and hippocampus were isolated from the brain of rats for biochemical testing and histopathological examination.

Results

DPL/AST-NLCs showed z-average diameter 149.9 ± 3.21 nm, polydispersity index 0.224 ± 0.017, zeta potential -33.7 ± 4.71 mV, entrapment efficiency 81.25 ±1.98% (donepezil) and 93.85 ±1.75% (astaxanthin), in vitro sustained release of both donepezil and astaxanthin for 24 h, spherical morphology by transmission electron microscopy, and they were stable at 4-8 ± 2°C for six months. Differential scanning calorimetry revealed that donepezil and astaxanthin were molecularly dispersed in the NLC matrix in an amorphous state. The DPL/AST-NLC-treated rats showed significantly lower levels of nuclear factor-kappa B, malondialdehyde, β-site amyloid precursor protein cleaving enzyme-1, caspase-3, amyloid beta (Aβ1‑42), and acetylcholinesterase, and significantly higher levels of glutathione and acetylcholine in the cortex and hippocampus than the AD-like untreated rats and that treated with donepezil-NLCs. DPL/AST-NLCs showed significantly higher anti-amyloidogenic, antioxidant, anti-acetylcholinesterase, anti-inflammatory, and anti-apoptotic effects, resulting in significant improvement in the cortical and hippocampal histopathology.

Conclusion

Nose-to-brain delivery of DPL/AST-NLCs is a promising strategy for the management of AD.

Protective effects of curcumin and Ginkgo biloba extract combination on a new model of Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative illnesses, and yet, no workable treatments have been discovered to prevent or reverse AD. Curcumin (CUR), the major polyphenolic compound of turmeric (Curcuma longa) rhizomes, and Ginkgo biloba extract (GBE) are natural substances derived from conventional Chinese herbs that have long been shown to provide therapeutic advantages for AD. The uptake of curcumin into the brain is severely restricted by its low ability to cross the blood-brain barrier (BBB). Meanwhile, GBE has been shown to improve BBB permeability. The present study evaluated the neuroprotective effects and pharmacokinetic profile of curcumin and GBE combination to find out whether GBE can enhance curcumin's beneficial effects in AD by raising its brain concentration. Results revealed that CUR + GBE achieved significantly higher levels of curcumin in the brain and plasma after 30 min and 1 h of oral administration, compared to curcumin alone, and this was confirmed by reversed phase high-performance liquid chromatography (RP-HPLC). The effect of combined oral treatment, for 28 successive days, on cognitive function and other AD-like alterations was studied in scopolamine-heavy metal mixtures (SCO + HMM) AD model in rats. The combination reversed at least, partially on the learning and memory impairment induced by SCO + HMM. This was associated with a more pronounced inhibitory effect on acetylcholinesterase (AChE), caspase-3, hippocampal amyloid beta (Aβ1-42), and phosphorylated tau protein (p-tau) count, and pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukine-1beta (IL-1β), as compared to the curcumin alone-treated group. Additionally, the combined treatment significantly decreased lipid peroxidation (MDA) and increased levels of reduced glutathione (GSH), when compared with the curcumin alone. These findings support the concept that the combination strategy might be an alternative therapy in the management/prevention of neurological disorders. This study sheds light on a new approach for exploring new phyto-therapies for AD and emphasizes that more research should focus on the synergic effects of herbal drugs in future.

Aqueous extract of Ceratonia siliqua L. leaves elicits antioxidant, anti-inflammatory, and AChE inhibiting effects in amyloid-β42-induced cognitive deficit mice: Role of α7-nAChR in modulating Jak2/PI3K/Akt/GSK-3β/β-catenin cascade

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder attributed to several etiological factors including cholinergic dysregulation, neuroinflammation, oxidative stress, β-amyloidogenesis, and tauopathy. This demands the search for multitarget drugs, especially of natural sources owing to their pleiotropic activities and low adverse effects. The present study was conducted to investigate the cognitive-improving potential of Ceratonia siliqua L. (Cs) extract compared with donepezil, an acetylcholinesterase inhibitor, on AD-like pathological alterations induced by single intracerebroventricular amyloid-β42 (Aβ42) injection in mice. Aβ42-injected mice were treated with Cs (100 mg/kg/day, po) with or without methyllycaconitine (MLA; 1 mg/kg/day, ip), an α7-nAChR antagonist. Aβ42-injected animals demonstrated an elevation of hippocampal Aβ42, p-Tau, and acetylcholinesterase. They also showed a decline in phosphorylated levels of Jak2, PI3K, Akt, and GSK-3β, leading to induction of neuroinflammation and oxidative stress. Noteworthy, Cs improved the histopathological and behavioral variables in addition to mitigating AD hallmarks. It also exerted neuroprotection by reducing NF-κBp65 and TNF-α, while elevating Nrf2 and HO-1, along with stabilizing β-catenin under the impact of Jak2/PI3K/Akt/GSK-3β signaling. These beneficial effects of Cs were abrogated by MLA co-administration signifying the α7-nAChR involvement in Cs-mediated effects. Therefore, Cs can ameliorate Aβ42-induced neurodegeneration by modulating Jak2/PI3K/Akt/GSK-3β/β-catenin axis in an α7-nAChR-dependent manner.

Ex Vivo Antioxidant and Cholinesterase Inhibiting Effects of a Novel Galantamine-Curcumin Hybrid on Scopolamine-Induced Neurotoxicity in Mice

Oxidative stress is an essential factor in the development and progression of Alzheimer's disease (AD). An excessive amount of reactive oxygen species (ROS) induces the peroxidation of lipid membranes, reduces the activity of antioxidant enzymes and causes neurotoxicity. In this study, we investigated the antioxidant and cholinesterase inhibitory potential of a novel galantamine-curcumin hybrid, named 4b, administered orally in two doses (2.5 mg/kg and 5 mg/kg) in scopolamine (SC)-induced neurotoxicity in mice. To evaluate the effects of 4b, we used galantamine (GAL) (3 mg/kg) and curcumin (CCN) (25 mg/kg) as positive controls. Ex vivo experiments on mouse brains showed that the higher dose of 4b (5 mg/kg) increased reduced glutathione (GSH) levels by 46%, catalase (CAT) and superoxide dismutase (SOD) activity by 57%, and glutathione peroxidase (GPx) activity by 108%, compared with the SC-treated group. At the same time, 4b (5 mg/kg) significantly reduced the brain malondialdehyde (MDA) level by 31% and acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities by 40% and 30%, respectively, relative to the SC-impaired group. The results showed that 4b acted as an antioxidant agent and brain protector, making it promising for further experimental research in the field of neurodegenerative diseases.

Effect of chlorogenic acid plus donepezil on critical neurocortical enzyme activities, inflammatory markers, and synaptophysin immunoreactivity in scopolamine-assaulted rats, supported by multiple ligand simultaneous docking

The effect of chlorogenic acid (a natural phenolic acid ubiquitous in plant foods) on selected therapeutic properties of donepezil (DON) in a scopolamine (SCOP)-induced rat model of amnesia was the focus of this study. Adult albino (Wister strain) rats were allocated into five groups (n = 11) consisting of control, SCOP, SCOP + chlorogenic acid (CGA), SCOP + DON, and SCOP + CGA + DON for 7 days. Post-treatment, the rat brain cerebral cortex homogenate was assayed for cholinesterase and monoamine oxidase activities. Also, the reactive oxygen species, total thiol and nitric oxide contents, alongside catalase, and superoxide dismutase activities were determined. Routine histology for neuronal and glial cells as well as synaptophysin immunoreactivity was also carried out on the cerebral cortex. Thereafter, multiple ligand simultaneous docking was carried out for DON and CGA at the active sites of AChE and BChE. The results revealed that the biochemical parameters, glial cells, and synaptophysin immunoreactivity were significantly impaired in the cerebral cortex of scopolamine-treated rats. However, impaired butyrylcholinesterase and monoamine oxidase activity, together with antioxidant, glial cells, and synaptophysin levels were significantly ameliorated in scopolamine-treated rats administered DON + CGA compared to donepezil alone. The docking of both DON and CGA at the active sites of AChE or BChE showed higher binding energy to both enzymes compared to individual interactions of either DON or CGA. Hence, this study has been able to show that CGA could improve some of the therapeutic effects of DON, which could broaden the therapeutic spectrum of this drug. PRACTICAL APPLICATIONS: This study showed that chlorogenic acid (a major phenolic acid found in plant foods such as coffee) modulated some of the therapeutic properties of donepezil (an anticholinesterase drug used in the treatment of mild-to-moderate Alzheimer's disease). The combinations elicited better anti-butyrylcholinesterase, antimonoamine oxidase, and antioxidant properties, thus presenting this food-drug interaction as potentially able to offer better therapeutic properties.

Protection against Morphine-Induced Inhibitory Avoidance Memory Impairment in Rat by Curcumin: Possible Role of Nitric Oxide/ cAMP-Response Element Binding Protein Pathway

BACKGROUND

Although a substantial body of research suggests curcumin (CUR) has the preventive potential in memory impairment, the mechanism by which CUR prevents memory loss is still being investigated. This study employs an inhibitory avoidance (IA) model to investigate whether CUR can prevent morphine (Mor)-induced memory impairment as well as the possible role of cAMP-response element binding (CREB) protein, and nitric oxide (NO) signaling in this mechanism.

METHODS

This experimental study was conducted at the Animal Lab of the Physiology Research Center, Kashan University of Medical Sciences (Kashan, Iran) in 2018. Forty rats were randomly divided into four groups: control, CUR (pretreatment gavage of CUR [10 mg/Kg] for 35 days), Mor (7.5 mg/Kg, i.p.), and CUR+Mor (n=10 per group). Following the evaluation of the IA memory and locomotor activity of the animals, the CREB protein expression in the hippocampus and NO metabolites (NOx) level in the brain tissue were also investigated. The data were analyzed using Sigmaplot software (version 14.0) by using the ANOVA, Kruskal-Wallis, Holm-Sidak, and Dunn's post hoc tests. P<0.05 was considered to be statistically significant.

RESULTS

In the Mor group, the IA memory of the rats was significantly impaired (P=0.001). CUR prevented the Mor-induced IA memory impairment (P=0.075). While the Mor treatment decreased the phosphorylated CREB (p-CREB) expression, the CUR+Mor cotreatment increased p-CREB expression (P=0.010). Nevertheless, the Mor treatment increased the total CREB expression (P=0.010). The NOx concentration in the brain tissue was decreased following the Mor treatment (P=0.500) but increased after the CUR+Mor cotreatment (P=0.001).

CONCLUSION

The present findings suggest that CUR prevents the memory impairment of rats, possibly through NO and its downstream CREB signaling.

Parquetina nigrescens and Spondias mombin protects against neurochemical alterations in the scopolamine model of cognitive dysfunction

Natural plants which are effective in Alzheimer's disease (AD) management are of pharmacological importance, though there is little or no scientific proof for most of their claims. This study sought to evaluate the effect of Hog plum (Spondias mombin) and Ogbo (Parquetina nigrescens) leaves extracts on antioxidant levels and activities of key enzymes linked to cognitive function in scopolamine-induced cognitive dysfunctioned rats. Rats were pretreated with S. mombin (SM) and P. nigrescens (PN) leaves extracts (50 and 100 mg/kg), donepezil (5 mg/kg) for 2 weeks via oral administration before induction of memory impairment via single i.p. administration of scopolamine (3 mg/kg body weight). Experimental rats were subjected to behavioral tests to check for cognitive performance before experiment termination. The activities of hippocampal key enzymes linked to cognitive function were determined. Results showed that pretreatment with SM and PN prevented the cognitive impairment induced by scopolamine. Furthermore, increased cholinesterases, adenosine deaminase (ADA), ATP hydrolysis, monoamine oxidase (MAO), and arginase activities induced by scopolamine were significantly reduced in rats treated with SM and PN leaves extract. Additionally, elevated malondialdehyde (MDA) and reactive oxygen species (ROS) levels observed in scopolamine-induced rats were reduced significantly in SM- and PN- pretreated rats. Decreased AMP hydrolysis, and nitric oxide and antioxidant level induced by scopolamine were prevented in pretreated rats. This study concluded that SM and PN leave extract effectiveness in cognitive management may be due to their high antioxidant activities and neuromodulatory effects on key enzymes linked to AD. PRACTICAL APPLICATIONS: The use of natural products in the treatment and management of neurodegenerative diseases in Africa is becoming pertinent as the continent is blessed with medicinal plants while the price of synthetic drugs has been observed to be an economic burden on the continent. Parquetina nigrescens and Spondias mombin are examples of such medicinal plants that have been explored in folklore for the management of neurodegenerative diseases but there is a dearth of scientific validation for their use while there is no present data to evaluate possible mechanisms of action employed by these medicinal plants to mediate the therapeutic potential observed in folklore. Therefore, the present study seeks to validate the therapeutic use of P. nigrescens and S. mombin as observed in folklore as well as explore the possible mechanism of actions the plants may employ in mediating the proposed therapeutic potentials in neurodegenerative disease conditions while considering its toxicological effects in experimental animals.

Effect of ivabradine on cognitive functions of rats with scopolamine-induced dementia

Alzheimer's disease is among the challenging diseases to social and healthcare systems because no treatment has been achieved yet. Although the ambiguous pathological mechanism underlying this disorder, ion channel dysfunction is one of the recently accepted possible mechanism. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play important roles in cellular excitability and synaptic transmission. Ivabradine (Iva), an HCN blocker, is acting on HCN channels, and is clinically used for angina and arrhythmia. The current study aimed to investigate the therapeutic effects of Iva against scopolamine (Sco) induced dementia. To test our hypothesis, Sco and Iva injected rats were tested for behavioural changes, followed by ELISA and histopathological analysis of the hippocampus. Induced dementia was confirmed by behavioural tests, inflammatory cytokines and oxidative stress tests and histopathological signs of neurodegeneration, multifocal deposition of congo red stained amyloid beta plaques and the decreased optical density of HCN1 immunoreactivity. Iva ameliorated the scopolamine-induced dysfunction, the hippocampus restored its normal healthy neurons, the amyloid plaques disappeared and the optical density of HCN1 immunoreactivity increased in hippocampal cells. The results suggested that blockage of HCN1 channels might underly the Iva therapeutic effect. Therefore, Iva might have beneficial effects on neurological disorders linked to HCN channelopathies.

New 1,2,3-Triazole-genipin Analogues and Their Anti-Alzheimer's Activity

A novel series of 1,2,3-triazole-genipin analogues were designed, synthesized, and evaluated for neuroprotective activity, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) inhibitory activity. The genipin analogues bearing bromoethyl- and diphenylhydroxy-triazole showed in vitro neuroprotective properties against H₂O₂ toxicity along with potent inhibitory activity on BuChE with IC₅₀ values of 31.77 and 54.33 μM, respectively, compared with galantamine (IC₅₀ = 34.05 μM). The molecular docking studies of these genipin analogues showed good binding energy and interact well with the key amino acids of BuChE via hydrogen-bonding and hydrophobic interactions. Triazole genipins might be promising lead compounds as anti-Alzheimer's agents.

Influence of Moringa (Moringa oleifera) enriched ice creams on rats’ brain: Exploring the redox and cholinergic systems

The broad application of Moringa oleifera leaves in the treatment of numerous diseases is prevalent globally where it extends to the management of diabetes, hypertension, inflammation, hypercholesterolemia and neurodegenerative diseases. This study provides findings on the role of Moringa oleifera leaves (MO) [MO leaves] formulated ice creams on brain cholinergic enzymes [acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)], antioxidant enzymes, glycemic index and blood lipid profile of rats. Thirty (30) adult male rats acclimatized for 2 weeks were divided into five groups: Group 1 rats received commercial ice cream, Group 2 rats were received plain ice-cream, Group 3, 4 and 5 received 0.5 g, 1.0 g and 2.0 g of MO-formulated ice creams. Rats were fed on normal pellets and exposed to ice creams produced from whipping cream, skimmed milk and Moringa oleifera leaves for 30 consecutive days. Following administration, results from this study revealed that rats that received Moringa formulated ice-creams had reduced brain butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) enzymes activities, glycemic index (GI), total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels and significantly increased high-density lipoprotein-cholesterol (HDL-C) level in the plasma while revealing elevated brain antioxidant status (Superoxide dismutase (SOD) and Catalase (CAT)) when compared against rats consuming commercial ice creams. Therefore, results from this study attests to the intake of ice creams made from blends of Moringa leaves in the reduction of rats’ body weight, glycemic index and lipid profile (TC, TG, LDL-C), inhibition of brain cholinergic enzymes (AChE and BChE) while increasing brain antioxidant enzymes activities (SOD and CAT).

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Ice creams enriched with Moringa leaves reduces rats' body weight gain and GI.

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Also, rats' brain antioxidant and cholinergic enzymes activities was modulated.

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This study shows the influence of Moringa ice creams on brain enzymes activities.

Effects of New Galantamine Derivatives in a Scopolamine Model of Dementia in Mice

Alzheimer's disease (AD), a progressive neurodegenerative disorder characterized by memory loss and cognitive functions decline, is a leading cause for dementia and currently ranked as the sixth foremost cause of death. As of present, treatment of AD is symptomatic without convincing therapeutic benefits and new, effective, therapeutic agents are pursued. Due to massive loss of cholinergic neurons and decreased acetylcholine levels, cholinesterase inhibitors like galantamine, remain the backbone of pharmacological treatment of the disease. In the present study, using behavioral and biochemical methods, four newly synthesized galantamine derivatives, Gal 34, Gal 43, Gal 44, and Gal 46, were evaluated for a beneficial effect in a scopolamine model of dementia in mice. They were designed to have all the advantages of galantamine and additionally to inhibit β-secretase and exert favorable effects on plasma lipids. Behavioral tests included step-through inhibitory avoidance, T-maze, and the hole-board test, whereas biochemical evaluations involved assessment of acetylcholinesterase activity, brain monoamines levels, lipid peroxidation, catalase, glutathione peroxidase, and superoxide dismutase activities along with measurement of total glutathione. Results show that Gal 43, Gal 44, and, in particular, Gal 46 are especially effective in improving both short- and long-term memory and in the case of Gal 46 having a significant effect on exploratory activity as well. Although Gal 34 did not show behavioral effects as convincing as those of the other three galantamine derivatives, it demonstrated persuasive antioxidant and restorative capacities, making all four galantamine derivatives promising AD treatment agents and prompting further research, especially that in many of our studies they performed better than galantamine.

Action Mechanisms of Curcumin in Alzheimer's Disease and Its Brain Targeted Delivery

AD is a chronic neurodegenerative disease. Many different signaling pathways, such as Wnt/β-catenin, Notch, ROS/JNK, and PI3K/Akt/mTOR are involved in Alzheimer’s disease and crosstalk between themselves. A promising treatment involves the uses of flavonoids, and one of the most promising is curcumin; however, because it has difficulty permeating the blood–brain barrier (BBB), it must be encapsulated by a drug carrier. Some of the most frequently studied are lipid nanocarriers, liposomes, micelles and PLGA. These carriers are further conjugated with brain-targeting agents such as lactoferrin and transferrin. In this review paper, curcumin and its therapeutic effects, which have been examined in vivo, are analyzed and then the delivery systems to the brain are addressed. Overall, the analysis of the literature revealed great potential for curcumin in treating AD and indicated the challenges that require further research.

Antioxidant activities and glycemic indices of ice creams enriched with orange (Citrus sinensis) and shaddock (Citrus maxima) peels and effects on rat lipid profiles

This study evaluated the effects of ice creams produced from blends of orange (Citrus sinensis) and shaddock (Citrus maxima) peels on the blood lipid profile, glycemic index, and antioxidant indices in the liver and heart of rats. Formulated ice cream was produced at a different proportion of citrus (orange and shaddock) blends and fed to rats for 28 days. The result showed that the formulated ice cream enriched with citrus peels blends caused a significant increase in high-density lipoprotein-cholesterol level in the plasma and antioxidant status in the liver and heart homogenates, decreased the glycemic index, concentration of total cholesterol, triglycerides, and low-density lipoprotein in the plasma as against rats fed on plain and commercial ice creams. To conclude, the use of ice creams from blends of orange and shaddock peels could serve as a functional food for weight reduction, glycemic index, management of lipid-related diseases, and prevention of oxidative stress-related complications in the liver and heart. PRACTICAL APPLICATIONS: The consumption of ice creams has increased in many parts of the world. However, there have been limited efforts aimed at improving the medicinal properties of frozen dairy products. Hence, these ice creams could be produced on a large scale under regulated condition since they have improved medicinal properties which would be a good option for preventing/combating degenerative conditions and their related complications.

Enhancing Therapeutic Efficacy of Donepezil by Combined Therapy: A Comprehensive Review

Combination therapy involving different therapeutic strategies mostly provides more rapid and effective results as compared to monotherapy in diverse areas of clinical practice. The most worldwide famous acetylcholinesterase inhibitor (AChEIs) donepezil for its dominant role in Alzheimer's disease (AD) has also attracted the attention of many pharmaceuticals due to its promising pharmacological potencies such as neuroprotective, muscle relaxant, and sleep inducer. Recently, a combination of donepezil with other agents has displayed better desirable results in managing several disorders, including the most common Alzheimer's disease (AD). This study involves all the data regarding the therapeutic effect of donepezil in its combination with other agents and explains its therapeutic targets and mode of action. Furthermore, this review also puts light on the current status of donepezil with other agents in clinical trials. The combination therapy of donepezil with symptomatic relief drugs and disease-modifying agents opens a new road for treating multiple pathological disorders. To the best of our knowledge, this is the first report encircling all the pharmacologic effects of donepezil in its combination therapy with other agents and their current status in clinical trials.

Role of natural plant products against Alzheimer's disease

Alzheimer's disease (AD) is one of the major neurodegenerative disorder. Deposition of amyloid fibrils and tau protein are associated with various pathological symptoms. Currently limited medication is available for AD treatment. Most of the drugs are basically cholinesterase inhibitors and associated with various side effects. Natural plant products have shown potential as a therapeutic agent for the treatment of AD symptoms. Variety of secondary metabolites like flavonoids, tannins, terpenoids, alkaloids and phenols are used to reduce the progression of the disease. Plant products have less or no side effect and are easily available. The present review gives a detailed account of the potential of natural plant products against the AD symptoms.

Evaluation of different almond (Terminalia catappa) extracts against oxidative stress induced by cyclosporine in brain and liver of rats

OBJECTIVES

This study was designed to evaluate the ameliorative effect of almond (Terminalia catappa) leaf (ALE) and stem bark (ABE) extracts on the enzyme activities and oxidative stress markers in the brain and liver tissues of cyclosporine-A (CsA) stressed male albino rats.

METHODS

Eighty-eight adult male rats weighing between 200 and 220 g were randomly distributed to into 11 groups (n=8) and different doses (100 and 200 mg/kg bwt.) of ALE and ABE were administered through oral gavages to the normal rats and 50 mg/kg/bwt/day CsA-stressed, while normal control rats was given a saline solution (p.o), and the treatment lasted for 14 days. Blood plasma, liver and brain tissues were prepared for biochemical analysis.

RESULTS

Neuronal [acetylcholinesterase (AChE) and butrylcholinesterase (BChE) and arginase] enzyme activities and thiobarbituric acid reactive species (TBARS) level, plasma aspartate transferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities, liver non-protein thiol (NPSH) level were analyzed. The results revealed that, the administration of CsA induced a significant increase in neuronal AChE, BChE, arginase, TBARS level, but decreased nitric oxide (NO) level. CsA also increased ALT, AST, and ALP activities in the blood plasma of CsA stress rats compared to normal control, but were significantly reversed respectively (p<0.001) upon treatment with the ALE and ABE dose-dependently.

CONCLUSIONS

The study revealed that ALE and ABE could prevent neuronal dysfunction and liver toxicity induced by CsA administration, however, higher dose (200 mg/kg) of the studied extracts appears to be more potent.

Comparative effects of berberine and piperine on the neuroprotective potential of neostigmine

OBJECTIVES

This study examined effect of berberine and piperine on neuroprotective potential of neostigmine in the management of neurological disorders.

METHODS

Berberine and neostigmine were weighed (30 g), dissolved in distilled water (30 mL) separately, while, 30 mg piperine was dissolved in ethanol (0.45 mL), made up to 30 mL with distilled water. Antioxidant activities in 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH), 2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonate) radical (ABTS), Fe-chelation, ferric reducing properties (FRAP), nitric oxide (NO) and hydroxyl (OH) radical scavenging abilities and Fe²⁺, cisplatin and sodium nitroprusside (SNP) induced lipid peroxidation (LPO), and acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and monoamine oxidase (MAO) activities were assessed in vitro.

RESULTS

The result revealed that tested compounds inhibited enzymes activities dose-dependently. However, berberine (IC₅₀=0.17 mg/mL) had slight higher AChE inhibitory effect than piperine and neostigmine (p<0.05). Also, berberine had the highest BChE inhibitory effect (IC₅₀=0.16 mg/mL) while piperine exhibited the highest MAO inhibitory effect (IC₅₀=0.21 mg/mL). Berberine, piperine and neostigmine exhibited high antioxidant properties and inhibited Fe²⁺, cisplatin and SNP induced LPO.

CONCLUSIONS

Both alkaloids demonstrated antiradical scavenging ability comparable to neostigmine action against Alzheimer's disease (AD). The modulatory and antioxidant berberine and piperine properties on these enzymes (AChE, BChE and MAO) could be possible underlying mechanisms in employing these compounds as a complementary therapy in neurodegenerative diseases (NDDs) management.

Indian Medicinal Herbs and Formulations for Alzheimer's Disease, from Traditional Knowledge to Scientific Assessment

Cognitive impairment, associated with ageing, stress, hypertension and various neurodegenerative disorders including Parkinson's disease and epilepsy, is a major health issue. The present review focuses on Alzheimer's disease (AD), since it is the most important cause of cognitive impairment. It is characterized by progressive memory loss, language deficits, depression, agitation, mood disturbances and psychosis. Although the hallmarks of AD are cholinergic dysfunction, β-amyloid plaques and neurofibrillary tangle formation, it is also associated with derangement of other neurotransmitters, elevated levels of advanced glycation end products, oxidative damage, neuroinflammation, genetic and environmental factors. On one hand, this complex etiopathology makes a response to commonly used drugs such as donepezil, rivastigmine, galantamine and memantine less predictable and often unsatisfactory. On the other hand, it supports the use of herbal medicines due to their nonspecific antioxidant and anti-inflammatory activity and specific cholinesterase inhibitory activity. The popularity of herbal medicines is also increasing due to their perceived effectiveness, safety and affordability. In the present article, the experimental and clinical evidence have been reviewed for various Indian herbal medicines such as Centella asiatica, Bacopa monnieri, Curcuma longa, Clitoria ternatea, Withania somnifera, Celastrus paniculatus, Evolvulus alsinoides, Desmodium gangeticum, Eclipta alba, Moringa oleifera and Convolvulus pluricaulis, which have shown potential in cognitive impairment. Some commonly available herbal formulations for memory impairment in India have also been reviewed.

Thymus vulgaris Essential Oil Protects Zebrafish against Cognitive Dysfunction by Regulating Cholinergic and Antioxidants Systems

Thymus vulgaris L. is an aromatic herb used for medicinal purposes such as antimicrobial, spasmolytic, antioxidant, anti-inflammatory, antinociceptive, antitumor, and may have beneficial effects in the treatment of Alzheimer’s disease. The present study aimed to investigate whether Thymus vulgaris L. essential oil enhances cognitive function via the action on cholinergic neurons using scopolamine (Sco)-induced zebrafish (Danio rerio) model of memory impairments. Thymus vulgaris L. essential oil (TEO, 25, 150, and 300 µL/L) was administered by immersion to zebrafish once daily for 13 days, whereas memory impairment was induced by Sco (100 μM), a muscarinic receptor antagonist, delivered 30 min before behavioral tests. Spatial memory was assessed using the Y-maze test and novel object recognition test (NOR). Anxiety and depression were measured in the novel tank diving test (NTT). Gas Chromatograph-Mass Spectrometry (GC-MS) analysis was used to study the phytochemical composition of TEO. Acetylcholinesterase (AChE) activity and oxidative stress response in the brain of zebrafish were determined. TEO ameliorated Sco-induced increasing of AChE activity, amnesia, anxiety, and reduced the brain antioxidant capacity. These results suggest that TEO may have preventive and/or therapeutic potentials in the management of memory deficits and brain oxidative stress in zebrafish with amnesia.

Editan (Lasianthera africana) leaf-inclusive diets modulate some neuronal enzyme activities and antioxidant status of cyclophosphamide-treated Wistar rats

The effect of Editan (Lasianthera africana) leaf inclusive diet (ELD) on neuronal cholinesterases (ChE), ecto-5'-nucleotidase, and endogenous antioxidant indices [superoxide dismutase (SOD), catalase (CAT), glutathione (GSH)] in cyclophosphamide (CYP)-administered albino rats were investigated. Thirty male albino Wistar rats were dissevered appropriately (n = 6). Group I-normal control rats (NC), II-untreated CYP-administered rats, III-CYP-administered rats pre-treated with donepezil (DON), group IV-CYP-administered rats fed ELD, and V-normal rats fed with ELD for 21 days. Results obtained revealed that CYP-administered rats significantly (p < .05) had elevated activities of ChE, ecto-5'-nucleotidase and thiobarbituric acid reactive species (TBARS), and concomitantly decreased in the antioxidant indices. However, pre-treatment with either DON or ELD reversed these effects, thereby eliciting a therapeutic effect which could be linked to the rich polyphenol and alkaloid constituents in the studied leaf, and could be responsible for the potential ethnopharmacological actions of the ELD in the management neurodegeneration. PRACTICAL APPLICATIONS: Currently, the use of plant-food to control diseased conditions due to their phytochemicals has been explored, most especially, the indigenous edible vegetables from the Southwestern part of Nigeria. "Editan" leafy vegetable scientifically known as Lasianthera africana is commonly used in soups preparation and in folklore for the management of some human ailments. Editan leaf is a rich source of alkaloid and phenolic compounds, which could be used to treat and or manage neurological diseases. This study, therefore, unravels the fact that the studied leafy vegetable possesses therapeutic potentials toward the management of neurological disorders.

Hypoglycemic effect of biscuits produced from flour blends of three medicinal foods on high-fat diet-streptozotocin-induced diabetic rats

The study evaluated the hypoglycemic effect of biscuits produced from flour blends of three medicinal foods (Unripe plantain fruits, Moringa seed, and pigeon pea) on high-fat diet (HFD)/streptozotocin (STZ)-induced (HFD/STZ) diabetic rats. The formulated biscuits were produced at different proportion of the flour blends and fed to HFD-STZ-induced diabetic rats for 14 days. The result showed that the formulated biscuits caused a significant increase in pancreas, liver, and kidney antioxidant molecules, decreased the production of thiobarbituric reactive acid species (TBARS) in pancreas, liver, and kidney homogenates, and reduced pancreatic α-amylase and intestinal α-glucosidase activities as against untreated diabetic rats. In conclusion, the use of formulated biscuits from the blends of flours from unripe plantain, Moringa seed, and pigeon pea could serve as functional food toward the treatment/management of diabetes and its possible complications such as diabetes-induced liver and kidney damage. PRACTICAL APPLICATIONS: The drug use in the management of diabetes such as acarbose have been reported to have side effects, while diet therapy is gaining much interest in the management of diabetes. Hence, there is a need for diets base therapy that will not only cure diabetes, but also combat its complications. In sight of this, unripe plantain, Moringa seed, and pigeon pea flours were blended and used to produce functional biscuits for diabetic rats. The biscuit could be produced on the large scale under hygienic and regulated condition.

Curcumin Administration Mitigates Cyclophosphamide-Induced Oxidative Damage and Restores Alteration of Enzymes Associated with Cognitive Function in Rats' Brain

The use of chemotherapeutic drugs is associated with oxidative damage, cognitive dysfunction, and brain damage. This study sought to investigate the neuroprotective effect of curcumin against cognitive problems associated with treatment with cyclophosphamide via assessment of biomolecules associated with cognitive function in rats' brain homogenates. Rats were divided in to five groups: Control (vehicle), CUR (curcumin [20 mg/kg]), CPA (cyclophosphamide [150 mg/kg]), CUR1 + CPA (curcumin [20 mg/kg] and cyclophosphamide [150 mg/kg]), and CPA + CUR2 (cyclophosphamide [150 mg/kg] and curcumin [20 mg/kg]). After the treatment, cognitive behavior was assessed and enzymes [cholinesterases, purinergic enzymes, arginase, and angiotensin I-converting enzyme] associated with cognitive function were examined. Oxidative stress parameters [total thiol, non-protein thiol, malondialdehyde, and nitric oxide] including the expression of caspase-3 were also assessed in rats' brain. Our results showed that curcumin improved cognitive behavior, attenuated cholinergic deficit as revealed by the inhibition of cholinesterases, and improved purinergic signaling in cyclophosphamide-treated rats. Furthermore, curcumin reduced angiotensin-I-converting enzyme and arginase activities before and after treatment with cyclophosphamide. Curcumin also improved redox balance and showed protection against cyclophosphamide-induced oxidative damage to rats' brain via an increase in protein and non-protein thiols and nitric oxide levels as well as a significant reduction in malondialdehyde levels. Curcumin also prevented neuronal degeneration in different brain regions and reduced caspase-3 expression. Hence this study suggests that pre and post-treatment with curcumin improved neurobehavior, modulates some biomarkers associated with cognitive function and exhibit neuroprotection against cyclophosphamide-induced neurotoxicity in rats.

Curcumin-Loaded BSA Nanoparticles Protect More Efficiently Than Natural Curcumin Against Scopolamine-Induced Memory Retrieval Deficit

Introduction:

There is evidence indicating that the rate of AD is lower in curry consuming populations. Then, there is an effort to elucidate if curcumin -as the main ingredient of turmeric-might affect the process of AD. However, in clinical trials of AD, a six-month curcumin treatment failed to show any progress, which might be attributable to its low bioavailability. In this line, a recent human study revealed that a more bioavailable solid lipid curcumin enhances cognition in aged adults. By the application of Bovine Serum Albumin (BSA), the current study aimed at converting curcumin to nano sizes and assessing its protective effects against scopolamine-induced passive avoidance memory retrieval deficit.

Methods:

Nanocurcumin was prepared via dissolution method. Male NMRI mice (20–25 g body weight) were used. The effective doses of nanocurcumin were selected according to the initial pilot test. The mice were treated with nanocurcumin 15 or 20 mg/kg/p.o or distilled water for 10 days. The animals were habituated and trained in passive avoidance apparatus on the day 10. The retention test was performed 24 hours later. Scopolamine (1 mg/kg/i.p.) or saline was injected 30 minutes before memory retention trial.

Results:

The findings indicated that nanocurcumin in doses 15 or 20 mg/kg/p.o prevented the retrieval deficit induced by scopolamine while natural curcumin in its equivalent doses did not have such an effect. Furthermore, nanocurcumin by itself improved memory retention comparing with the control group.

Conclusion:

These findings implied that the potential anti-amnesic effects of curcumin might be observed by producing and using its nanoformulation form.

Cellular and molecular mechanisms of curcumin in prevention and treatment of disease

Curcumin is a naturally occurring polyphenolic compound present in rhizome of Curcuma longa belonging to the family zingiberaceae. Growing experimental evidence revealed that curcumin exhibit multitarget biological implications signifying its crucial role in health and disease. The current review highlights the recent progress and mechanisms underlying the wide range of pharmacological effects of curcumin against numerous diseases like neuronal, cardiovascular, metabolic, kidney, endocrine, skin, respiratory, infectious, gastrointestinal diseases and cancer. The ability of curcumin to modulate the functions of multiple signal transductions are linked with attenuation of acute and chronic diseases. Numerous preclinical and clinical studies have revealed that curcumin modulates several molecules in cell signal transduction pathway including PI3K, Akt, mTOR, ERK5, AP-1, TGF-β, Wnt, β-catenin, Shh, PAK1, Rac1, STAT3, PPARγ, EBPα, NLRP3 inflammasome, p38MAPK, Nrf2, Notch-1, AMPK, TLR-4 and MyD-88. Curcumin has a potential to prevent and/or manage various diseases due to its anti-inflammatory, anti-oxidant and anti-apoptotic properties with an excellent safety profile. In contrast, the anti-cancer effects of curcumin are reflected due to induction of growth arrest and apoptosis in various premalignant and malignant cells. This review also carefully emphasized the pharmacokinetics of curcumin and its interaction with other drugs. Clinical studies have shown that curcumin is safe at the doses of 12 g/day but exhibits poor systemic bioavailability. The use of adjuvant like piperine, liposomal curcumin, curcumin nanoparticles and curcumin phospholipid complex has shown enhanced bioavailability and therapeutic potential. Further studies are warranted to prove the potential of curcumin against various ailments.

Effect of curcumin on memory impairment: A systematic review

BACKGROUND

Memory impairment (MI) is one of the most common complaints of people referred to physicians for proper diagnosis. In addition, the prevalence of neurodegenerative lesions like Alzheimer is generally on the increase. Thus far, numerous laboratory studies have been conducted to evaluate the effect of curcumin on the improvement of MI.

PURPOSE

The aim of this study was to review the efficacy of curcumin on MI in animal studies.

METHODS

Keywords related to memory and curcumin were searched in PubMed, Web of Science, and Scopus databases based on MeSH; and articles published until July 2017 were later extracted. Then the articles (full text or abstract) were examined based on the inclusion and exclusion criteria. The present study evaluated articles that did not include specific pathologies such as Alzheimer.

RESULTS

A total of 90 articles met the inclusion criteria but only 25 articles underwent final review. The minimum and maximum dosages of curcumin were 5 and 480  mg/kg respectively. Curcumin was administered over the period of 1-84 days. The results of 24 articles showed that curcumin moderates short-term and long-term MI in various laboratory models such as aging, acute and chronic stress, anxiety, smoking, benzodiazepine and anticonvulsant consumption, and other conditions associated with increased oxidative stress.

CONCLUSION

The findings of this study revealed that curcumin moderated or reversed MI in rodents and did not have a placebo effect. Accordingly, curcumin can play a preventive and therapeutic role in MI.

Effect of Alkaloid Extract from African Jointfir (Gnetum africanum) Leaves on Manganese-Induced Toxicity in Drosophila melanogaster

Metal-induced toxicity in fruit fly (Drosophila melanogaster) is one of the established models for studying neurotoxicity and neurodegenerative diseases. Phytochemicals, especially alkaloids, have been reported to exhibit neuroprotection. Here, we assessed the protective effect of alkaloid extract from African Jointfir (Gnetum africanum) leaf on manganese- (Mn-) induced toxicity in wild type fruit fly. Flies were exposed to 10 mM Mn, the alkaloid extract and cotreatment of Mn plus extract, respectively. The survival rate and locomotor performance of the flies were assessed 5 days posttreatment, at which point the flies were homogenized and assayed for acetylcholinesterase (AChE) activity, nitric oxide (NO), and reactive oxygen species (ROS) levels. Results showed that the extract significantly reverted Mn-induced reduction in the survival rate and locomotor performance of the flies. Furthermore, the extract counteracted the Mn-induced elevation in AChE activity, NO, and ROS levels. The alkaloid extract of the African Jointfir leaf may hence be a source of useful phytochemicals for the development of novel therapies for the management of neurodegeneration.

Curcumin ameliorates scopolamine-induced mice memory retrieval deficit and restores hippocampal p-Akt and p-GSK-3β

The loss of cholinergic neurons has been a major issue in researches on Alzheimer's disease (AD) for about 40 years. Therefore, the scopolamine model of amnesia has been widely used in AD researches. Recently, it was reported that the early stage amnesia of AD is related to memory retrieval deficit. Curcumin, as the main ingredient of turmeric, has been suggested to decrease the prevalence of AD in human population. This study was conducted to assess if curcumin prevents retrieval deficit induced by scopolamine in passive avoidance task. Moreover, according to the proposed link between cholinergic system and Akt/GSK-3β (Glycogen synthase kinase 3 beta) signaling, the hippocampal contents of these proteins were determined. Male NMRI mice (20-25 g body weight) were treated with 50 or 100 mg/kg/po curcumin or its vehicle for 10 days. On day 10, the animals were trained in passive avoidance apparatus. The retention trial was performed 24 h later. Scopolamine (1 mg/kg/i.p.) or its vehicle was administered 30 min before retention test. At the completion of behavioral studies, the hippocampi were removed and western blot analysis was performed to determine hippocampal phosphorylated and total Akt and GSK-3β and beta actin contents. The results showed that curcumin treatment at 50 and 100 mg/kg doses prevented scopolamine-induced memory retrieval deficit and restored Akt and GSK dephosphorylation caused by scopolamine. Overall, these findings showed that pre-test scopolamine administration disrupts memory retrieval along with the diminished Akt and GSK-3β phosphorylation in hippocampus while curcumin administration prevented those changes.

Green leafy vegetables from two Solanum spp. (Solanum nigrum L and Solanum macrocarpon L) ameliorate scopolamine-induced cognitive and neurochemical impairments in rats

This study examined the modulatory effect of Black nightshade (Solanum nigrum L) and African eggplant (Solanum macrocarpon L) leaves on cognitive function, antioxidant status, and activities of critical enzymes of monoaminergic and cholinergic systems of neurotransmission in scopolamine-administered rats. Cognitive impairment was induced in albino rats pretreated with dietary inclusions of Black nightshade (BN) and African eggplant (AE) leaves by single administration (i.p.) of scopolamine (2 mg/kg body weight). Prior to termination of the experiment, the rats were subjected to spontaneous alternation (Y-maze) test to assess their spatial working memory. Thereafter, activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), monoamine oxidase (MAO), arginase, and antioxidant enzymes (catalase, SOD, and GST) of rat brain homogenate were determined. Also, the malondialdehyde (MDA), nitrite, and GSH contents of the homogenate were determined. The results showed that pretreatment with dietary inclusions of AE and BN significantly reversed the impairment in the rats' spatial working memory induced by scopolamine. Similarly, elevations in activities of AChE, BChE, and MAO induced by scopolamine were significantly reversed in rats pretreated with dietary inclusions of AE and BN. In addition, impaired antioxidant status induced by scopolamine was reversed by pretreatment with dietary inclusions of AE and BN. This study has shown that dietary inclusions of AE and BN could protect against cognitive and neurochemical impairments induced by scopolamine, and hence, these vegetables could be used as a source of functional foods and nutraceuticals for the prevention and management of cognitive impairments associated diseases such as Alzheimer's disease.

Moringa oleifera supplemented diet modulates nootropic-related biomolecules in the brain of STZ-induced diabetic rats treated with acarbose

There are strong correlations between diabetes mellitus and cognitive dysfunction. This study sought to investigate the modulatory effects of Moringa oleifera leaf (ML) and seed (MS) inclusive diets on biomolecules [acetylcholinesterase (AChE), butyrylcholinesterase (BChE)] angiotensin-I converting enzyme (ACE), arginase, catalase, glutathione transferase (GST) and glutathione peroxidase (GSH-Px) activities, glutathione (GSH) and nitric oxide (NO) levels] associated with cognitive function in the brain of streptozotocin (STZ)-induced diabetic rats treated with acarbose (ACA). The rats were made diabetic by intraperitoneal administration of 0.1 M sodium-citrate buffer (pH 4.5) containing STZ [60 mg/kg b.w (BW)] and fed with diets containing 2 and 4% ML/MS. Acarbose (25 mg/kg BW) was administered by gavage daily for 14 days. The animals were distributed in eleven groups of eight animals as follows: control, STZ-induced, STZ + ACA, STZ + 2% ML, STZ + ACA + 2% ML, STZ + 4% ML, STZ + ACA + 4% ML, STZ + 2% MS, STZ + ACA + 2% MS, STZ + 4% MS, STZ + ACA + 4% MS. There were marked increase in AChE, BChE, arginase, ACE and concomitant decrease in catalase, GST, GSH-Px, activities and NO levels in STZ-diabetic group compared with the control. However, there was a decrease in AChE, BChE and ACE activities and concomitant increase in the antioxidant molecules in the groups fed with supplemented diets treated with/without ACA compared with the STZ-diabetic group. These findings suggest that ML/MS supplemented diet could prevent cognitive dysfunction-induced by chronic hyperglycemia.

Ethnopharmacological Approaches for Dementia Therapy and Significance of Natural Products and Herbal Drugs

Dementia is a clinical syndrome wherein gradual decline of mental and cognitive capabilities of an afflicted person takes place. Dementia is associated with various risk factors and conditions such as insufficient cerebral blood supply, toxin exposure, mitochondrial dysfunction, oxidative damage, and often coexisting with some neurodegenerative disorders such as Alzheimer's disease (AD), Huntington's disease (HD), and Parkinson's disease (PD). Although there are well-established (semi-)synthetic drugs currently used for the management of AD and AD-associated dementia, most of them have several adverse effects. Thus, traditional medicine provides various plant-derived lead molecules that may be useful for further medical research. Herein we review the worldwide use of ethnomedicinal plants in dementia treatment. We have explored a number of recognized databases by using keywords and phrases such as “dementia”, “Alzheimer's,” “traditional medicine,” “ethnopharmacology,” “ethnobotany,” “herbs,” “medicinal plants” or other relevant terms, and summarized 90 medicinal plants that are traditionally used to treat dementia. Moreover, we highlight five medicinal plants or plant genera of prime importance and discuss the physiological effects, as well as the mechanism of action of their major bioactive compounds. Furthermore, the link between mitochondrial dysfunction and dementia is also discussed. We conclude that several drugs of plant origin may serve as promising therapeutics for the treatment of dementia, however, pivotal evidence for their therapeutic efficacy in advanced clinical studies is still lacking.

Diverse Effects of an Acetylcholinesterase Inhibitor, Donepezil, on Hippocampal Neuronal Death after Pilocarpine-Induced Seizure

Epileptic seizures are short episodes of abnormal brain electrical activity. Many survivors of severe epilepsy display delayed neuronal death and permanent cognitive impairment. Donepezil is an acetylcholinesterase inhibitor and is an effective treatment agent for Alzheimer’s disease. However, the role of donepezil in seizure-induced hippocampal injury remains untested. Temporal lobe epilepsy (TLE) was induced by intraperitoneal injection of pilocarpine (25 mg/kg). Donepezil (2.5 mg/kg/day) was administered by gavage in three different settings: (1) pretreatment for three days before the seizure; (2) for one week immediately after the seizure; and (3) for three weeks from three weeks after the seizure. We found that donepezil showed mixed effects on seizure-induced brain injury, which were dependent on the treatment schedule. Pretreatment with donepezil aggravated neuronal death, oxidative injury, and microglia activation. Early treatment with donepezil for one week showed neither adverse nor beneficial effects; however, a treatment duration of three weeks starting three weeks after the seizure showed a significant reduction in neuronal death, oxidative injury, and microglia activation. In conclusion, donepezil has therapeutic effects when injected for three weeks after seizure activity subsides. Therefore, the present study suggests that the therapeutic use of donepezil for epilepsy patients requires a well-conceived strategy for administration.