Protective effect of curcumin against intracerebral streptozotocin induced impairment in memory and cerebral blood flow

Application of curcuminoids in inflammatory, neurodegenerative and aging conditions - Pharmacological potential and bioengineering approaches to improve efficiency

Curcumin, a natural compound found in turmeric, has shown promise in treating brain-related diseases and conditions associated with aging. Curcumin has shown multiple anti-inflammatory and brain-protective effects, but its clinical use is limited by challenges like poor absorption, specificity and delivery to the right tissues. A range of contemporary approaches at the intersection with bioengineering and systems biology are being explored to address these challenges. Data from preclinical and human studies highlight various neuroprotective actions of curcumin, including the inhibition of neuroinflammation, modulation of critical cellular signaling pathways, promotion of neurogenesis, and regulation of dopamine levels. However, curcumin's multifaceted effects - such as its impact on microRNAs and senescence markers - suggest novel therapeutic targets in neurodegeneration. Tetrahydrocurcumin, a primary metabolite of curcumin, also shows potential due to its presence in circulation and its anti-inflammatory properties, although further research is needed to elucidate its neuroprotective mechanisms. Recent advancements in delivery systems, particularly brain-targeting nanocarriers like polymersomes, micelles, and liposomes, have shown promise in enhancing curcumin's bioavailability and therapeutic efficacy in animal models. Furthermore, the exploration of drug-laden scaffolds and dermal delivery may extend the pharmacological applications of curcumin. Studies reviewed here indicate that engineered dermal formulations and devices could serve as viable alternatives for neuroprotective treatments and to manage skin or musculoskeletal inflammation. This work highlights the need for carefully designed, long-term studies to better understand how curcumin and its bioactive metabolites work, their safety, and their effectiveness.

Tangeretin offers neuroprotection against colchicine-induced memory impairment in Wistar rats by modulating the antioxidant milieu, inflammatory mediators and oxidative stress in the brain tissue

BACKGROUND

Tangeretin, a flavone compound (O-polymethoxylated) naturally present in tangerine and other citrus peels has demonstrated effectiveness as an anti-inflammatory and neuroprotective agent in several disease model. This study evaluated the impact of tangeretin in mitigating cognitive dysfunction and oxidative stress induced by colchicine in rats, comparing its efficacy with donepezil hydrochloride.

METHODS

Cognitive dysfunction was induced by administering colchicine (15 µg/rat) intracerebroventricularly (ICV) via a stereotaxic apparatus in male Wistar rats. Colchicine resulted in poor memory retention in acquiring and retaining a spatial navigation task, passive avoidance apparatus, and Morris water maze paradigms. Chronic treatment with tangeretin (at doses of 50, 100, and 200 mg/kg, p.o. once daily) and donepezil hydrochloride (at a dose of 10 mg/kg, p.o. daily) for 28 days, starting seven days before colchicine injection, significantly ameliorated colchicine-induced cognitive impairment.

RESULTS

The biochemical analysis showed that chronic administration of tangeretin effectively reversed the colchicine-induced increase in the level/activity of lipid peroxidation, hydrogen peroxide (H2O2), myeloperoxidase (MPO), nitrite, reactive oxygen species (ROS), tumour necrosis factor-α (TNF-α), nuclear factor kappa B (NF-κB), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), serotonin, dopamine, glutamate, amyloid beta (Aβ) peptide, and caspase-3. Tangeretin also reversed the colchicine-induced reduction in the level/activity of brain-derived neurotrophic factor (BDNF), amma-aminobutyric acid (GABA), acetylcholinesterase (AChE), glutathione S-Transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), and total thiol (T-SH) in rat brains. However, donepezil hydrochloride did not prevent oxidative stress.

CONCLUSIONS

These findings suggest that chronic administration of tangeretin at 50, 100, and 200 mg/kg, p.o. once daily, was protective in mitigating colchicine-induced cognitive impairment and associated oxidative stress. At the same time, donepezil hydrochloride did not demonstrate similar effects.

Therapeutic potential of curcumin on the cognitive decline in animal models of Alzheimer's disease: a systematic review and meta-analysis

Curcumin, a polyphenol derived from the herb turmeric, has emerged as a prospective potential therapy in the treatment of Alzheimer's disease (AD). However, the efficacy of curcumin treatment in improving cognitive decline caused controversy recently. We aimed to systematically review the effect of curcumin on cognitive impairment in an animal model of AD. We conducted an exhaustive database search of related studies. Two investigators identified studies and independently extracted data. Stratified meta-analyses and meta-regression analyses were carried out to explore the sources of heterogeneity. Publication bias was assessed using funnel plots and Egger's test. Our systematic review included 33 articles. A meta-analysis of 29 publications showed that curcumin exerts significant positive effects on cognitive performance. For acquisition, the global estimated effect of curcumin was - 2.027 (95% CI - 2.435 to - 1.619, p < 0.001); for retention, the global estimated effect of curcumin was 1.606 (95% CI 1.101 to 2.111, p < 0.001). The stratified meta-analysis demonstrated that an increased effect size depended on diverse study characteristics. Additionally, publication bias was detected. We conclude that curcumin may reduce cognitive deficits in experimental AD. Furthermore, we emphasize that additional well-designed and well-reported animal studies are needed to inform further clinical studies.

Curcumin Lowers the Accelerated Speed of Epileptogenesis by Traumatic Brain Injury

Background

Traumatic brain injury or TBI can underlie epilepsy. Prevention of PTE has been of great interest to scientists. Given the antiepileptic, antioxidant and anti-inflammatory activities of curcumin, we examined whether this compound can affect epileptogenesis in rats after TBI.

Methods

Curcumin was injected once a day for two weeks. TBI was induced in the temporal cortex of anesthetized rats using a controlled cortical impact device. One day after TBI, pentylenetetrazole (PTZ), 35 mg/kg, was injected i.p. every other day until manifestation of generalized seizures. The number of PTZ injections was then recorded. Moreover, the extent of cortical and hippocampal IL-1β and glial fibrillary acidic protein (GFAP) expression in the epileptic rats were measured by Western blot analysis.

Results

Curcumin 50 and 150 mg/kg prevented the development of kindling, whereas TBI accelerated the rate of kindling. Curcumin 20 mg/kg prohibited kindling facilitation by TBI, and reduced the expression of IL-1β and GFAP induced by TBI.

Conclusion

Curcumin can stop the acceleration of epileptogenesis after TBI in rats. Inhibiting hippocampal and cortical overexpression of IL-1β and GFAP seems to be involved in this activity.

Monitoring Alzheimer's disease via ultraweak photon emission

In an innovative experiment, we detected ultraweak photon emission (UPE) from the hippocampus of male rat brains and found significant correlations between Alzheimer's disease (AD), memory decline, oxidative stress, and UPE intensity. These findings may open up novel methods for screening, detecting, diagnosing, and classifying neurodegenerative diseases, particularly AD. The study suggests that UPE from the brain's neural tissue can serve as a valuable indicator. It also proposes the development of a minimally invasive brain-computer interface (BCI) photonic chip for monitoring and diagnosing AD, offering high spatiotemporal resolution of brain activity. The study used a rodent model of sporadic AD, demonstrating that STZ-induced sAD resulted in increased hippocampal UPE, which was associated with oxidative stress. Treatment with donepezil reduced UPE and improved oxidative stress. These findings support the potential utility of UPE as a screening and diagnostic tool for AD and other neurodegenerative diseases.

Targeted therapies of curcumin focus on its therapeutic benefits in cancers and human health: Molecular signaling pathway-based approaches and future perspectives

The curry powder spices turmeric (Curcuma longa L.), which contains curcumin (diferuloylmethane), an orange-yellow chemical. Polyphenols are the most commonly used sources of curcumin. It combats oxidative stress and inflammation in diseases, such as hyperlipidemia, metabolic syndrome, arthritis, and depression. Most of these benefits are due to their anti-inflammatory and antioxidant properties. Curcumin consumption leads to decreased bioavailability, resulting in limited absorption, quick metabolism, and quick excretion, which hinders health improvement. Numerous factors can increase its bioavailability. Piperine enhances bioavailability when combined with curcumin in a complex. When combined with other enhancing agents, curcumin has a wide spectrum of health benefits. This review evaluates the therapeutic potential of curcumin with a specific emphasis on its approach based on molecular signaling pathways. This study investigated its influence on the progression of cancer, inflammation, and many health-related mechanisms, such as cell proliferation, apoptosis, and metastasis. Curcumin has a significant potential for the prevention and treatment of various diseases. Curcumin modulates several biochemical pathways and targets involved in cancer growth. Despite its limited tissue accumulation and bioavailability when administered orally, curcumin has proven useful. This review provides an in-depth analysis of curcumin's therapeutic applications, its molecular signaling pathway-based approach, and its potential for precision medicine in cancer and human health.

Alzheimer's disease: Molecular aspects and treatment opportunities using herbal drugs

Alzheimer's disease (AD), also called senile dementia, is the most common neurological disorder. Around 50 million people, mostly of advanced age, are suffering from dementia worldwide and this is expected to reach 100-130 million between 2040 and 2050. AD is characterized by impaired glutamatergic and cholinergic neurotransmission, which is associated with clinical and pathological symptoms. AD is characterized clinically by loss of cognition and memory impairment and pathologically by senile plaques formed by Amyloid β deposits or neurofibrillary tangles (NFT) consisting of aggregated tau proteins. Amyloid β deposits are responsible for glutamatergic dysfunction that develops NMDA dependent Ca2+ influx into postsynaptic neurons generating slow excitotoxicity process leading to oxidative stress and finally impaired cognition and neuronal loss. Amyloid decreases acetylcholine release, synthesis and neuronal transport. The decreased levels of neurotransmitter acetylcholine, neuronal loss, tau aggregation, amyloid β plaques, increased oxidative stress, neuroinflammation, bio-metal dyshomeostasis, autophagy, cell cycle dysregulation, mitochondrial dysfunction, and endoplasmic reticulum dysfunction are the factors responsible for the pathogenesis of AD. Acetylcholinesterase, NMDA, Glutamate, BACE1, 5HT6, and RAGE (Receptors for Advanced Glycation End products) are receptors targeted in treatment of AD. The FDA approved acetylcholinesterase inhibitors Donepezil, Galantamine and Rivastigmine and N-methyl-D-aspartate antagonist Memantine provide symptomatic relief. Different therapies such as amyloid β therapies, tau-based therapies, neurotransmitter-based therapies, autophagy-based therapies, multi-target therapeutic strategies, and gene therapy modify the natural course of the disease. Herbal and food intake is also important as preventive strategy and recently focus has also been placed on herbal drugs for treatment. This review focuses on the molecular aspects, pathogenesis and recent studies that signifies the potential of medicinal plants and their extracts or chemical constituents for the treatment of degenerative symptoms related to AD.

Curcumin protects against the age-related hearing loss by attenuating apoptosis and senescence via activating Nrf2 signaling in cochlear hair cells

Age-related hearing loss (ARHL) is a most widespread neurodegenerative disease affecting the elderly population, but effective pharmacological treatments remain limited. Curcumin is a bioactive compound of Curcuma longa with antioxidant properties. Herein, we looked into the effects of curcumin on the H₂O₂-induced oxidative stress in cochlear hair cells and hearing function in an ARHL animal model (C57BL/6J mice). We found that pretreatment of curcumin could attenuate H₂O₂-induced apoptosis and cell senescence in auditory hair cells and prevent mitochondrial function dysfunction. More specifically, Western blot and luciferase activity assay showed that curcumin activated the nuclear translocation of Nrf2, which in turn triggered the activation of its downstream target gene Heme Oxygenase1 (HO-1). The enhanced Nrf2 and HO-1 activity by curcumin was blocked by the AKT inhibitor LY294002, indicating the protective effect of curcumin was mainly achieved by activating Nrf2/HO-1 through the AKT pathway. Furthermore, the knockdown of Nrf2 with siRNA diminished the protective effects of Nrf2 against apoptosis and senescence, consolidating the pivotal role of Nrf2 in the protective effect of curcumin on auditory hair cells. More importantly, curcumin (10 mg/kg/d) could attenuate progressive hearing loss in C57BL/6J mice, as evident from the reduced threshold of auditory nerve brainstem response. Administration of curcumin also elevated the expression of Nrf2 and reduced the expression of cleaved-caspase-3, p21, and γ-H2AX in cochlear. This study is the first to demonstrate that curcumin can prevent oxidative stress-induced auditory hair cell degeneration through Nrf2 activation, highlighting its potential therapeutic value in preventing ARHL.

Formulation and Development of Curcumin-Piperine-Loaded S-SNEDDS for the Treatment of Alzheimer's Disease

Curcumin (CUR) and piperine (PIP) are very well-known phytochemicals that claimed to have many health benefits and have been widely used in foods and traditional medicines. This study investigated the therapeutic efficacy of these compounds to treat Alzheimer's disease (AD). However, poor oral bioavailability and permeability of curcumin are a major challenge for formulation scientists. In this research study, the researcher tried to enhance the bioavailability and permeability of curcumin by a nanotechnological approach. In this research study, we developed a CUR-PIP-loaded SNEDDS in various oils. Optimised formulation NF3 was subjected to evaluate its therapeutic effectiveness on AD animal model in comparison with untreated AD model and treated group (by market formulation donepezil). On the basis of characterisation results, it is confirmed that NF3 formulation is the best formulation. The optimised formulation shows a significant dose-dependent manner therapeutic effect on AD-induced model. Novel formulation CUR-PIP solid-SNEDDS was successfully developed and optimised. It is expected that the developed S-SNEDDS can be a potential, safe and effective carrier for the oral delivery of curcumin to the brain. To date, this article is the only study of CUR-PIP-loaded S-SNEDDS for the treatment of AD.

Neuroprotective Effects of Agri-Food By-Products Rich in Phenolic Compounds

Neurodegenerative diseases are known for their wide range of harmful conditions related to progressive cell damage, nervous system connections and neuronal death. These pathologies promote the loss of essential motor and cognitive functions, such as mobility, learning and sensation. Neurodegeneration affects millions of people worldwide, and no integral cure has been created yet. Here, bioactive compounds have been proven to exert numerous beneficial effects due to their remarkable bioactivity, so they could be considered as great options for the development of new neuroprotective strategies. Phenolic bioactives have been reported to be found in edible part of plants; however, over the last years, a large amount of research has focused on the phenolic richness that plant by-products possess, which sometimes even exceeds the content in the pulp. Thus, their possible application as an emergent neuroprotective technique could also be considered as an optimal strategy to revalorize these agricultural residues (those originated from plant processing). This review aims to summarize main triggers of neurodegeneration, revise the state of the art in plant extracts and their role in avoiding neurodegeneration and discuss how their main phenolic compounds could exert their neuroprotective effects. For this purpose, a diverse search of studies has been conducted, gathering a large number of papers where by-products were used as strong sources of phenolic compounds for their neuroprotective properties. Finally, although a lack of investigation is quite remarkable and greatly limits the use of these compounds, phenolics remain attractive for research into new multifactorial anti-neurodegenerative nutraceuticals.

The effect of curcumin on blood pressure and cognitive impairment in spontaneously hypertensive rats

BACKGROUND/OBJECTIVES

It is known that the renin-angiotensin system (RAS) in the brain could regulate cognitive functions as well as blood pressure. Inhibition of RAS for the improvement of cognitive function may be a new strategy, but studies so far have mostly reported on the effects of RAS inhibition by drugs, and there is no research on cognitive improvement through RAS inhibition of food ingredients. Therefore, this study investigated the effect of curcumin on blood pressure and cognitive function and its related mechanism in spontaneously hypertensive rat/Izm (SHR/Izm).

MATERIALS/METHODS

Six-week-old SHR/Izm rats were divided into 5 groups: control group (CON), scopolamine group (SCO, drug for inducing cognitive deficits), positive control (SCO and tacrine [TAC]), curcumin 100 group (CUR100, SCO + Cur 100 mg/kg), and curcumin 200 group (CUR200, SCO + Cur 200 mg/kg). Changes in blood pressure, RAS, cholinergic system, and cognitive function were compared before and after cognitive impairment.

RESULTS

The SCO group showed increased blood pressure and significantly reduced cognitive function based on the y-maze and passive avoidance test. Curcumin treatments significantly improved blood pressure and cognitive function compared with the SCO group. In both the CUR100 and CUR200 groups, the mRNA expressions of angiotensin-converting enzyme (ACE) and angiotensin II receptor type1 (AT1), as well as the concentrations of angiotensin II (Ang II) in brain tissue were significantly decreased. The mRNA expression of the muscarinic acetylcholine receptors (mAChRs) and acetylcholine (ACh) content was significantly increased, compared with the SCO group.

CONCLUSIONS

The administration of curcumin improved blood pressure and cognitive function in SCO-induced hypertensive mice, indicating that the cholinergic system was improved by suppressing RAS and AT1 receptor expression and increasing the mAChR expression.

Protective effects of curcumin on ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a term used to describe phenomena connected to the dysfunction of various tissue damage due to reperfusion after ischemic injury. While I/R may result in systemic inflammatory response syndrome or multiple organ dysfunction syndrome, there is still a long way to improve therapeutic outcomes. A number of cellular metabolic and ultrastructural alterations occur by prolonged ischemia. Ischemia increases the expression of proinflammatory gene products and bioactive substances within the endothelium, such as cytokines, leukocytes, and adhesion molecules, even as suppressing the expression of other "protective" gene products and substances, such as thrombomodulin and constitutive nitric oxide synthase (e.g., prostacyclin, nitric oxide [NO]). Curcumin is the primary phenolic pigment derived from turmeric, the powdered rhizome of Curcuma longa. Numerous studies have shown that curcumin has strong antiinflammatory and antioxidant characteristics. It also prevents lipid peroxidation and scavenges free radicals like superoxide anion, singlet oxygen, NO, and hydroxyl. In our study, we highlight the mechanisms of protective effects of curcumin against I/R injury in various organs.

A New Perspective on the Treatment of Alzheimer's Disease and Sleep Deprivation-Related Consequences: Can Curcumin Help?

Sleep disturbances, as well as sleep-wake rhythm disorders, are characteristic symptoms of Alzheimer's disease (AD) that may head the other clinical signs of this neurodegenerative disease. Age-related structural and physiological changes in the brain lead to changes in sleep patterns. Conditions such as AD affect the cerebral cortex, basal forebrain, locus coeruleus, and the hypothalamus, thus changing the sleep-wake cycle. Sleep disorders likewise adversely affect the course of the disease. Since the sleep quality is important for the proper functioning of the memory, impaired sleep is associated with problems in the related areas of the brain that play a key role in learning and memory functions. In addition to synthetic drugs, utilization of medicinal plants has become popular in the treatment of neurological diseases. Curcuminoids, which are in a diarylheptanoid structure, are the main components of turmeric. Amongst them, curcumin has multiple applications in treatment regimens of various diseases such as cardiovascular diseases, obesity, cancer, inflammatory diseases, and aging. Besides, curcumin has been reported to be effective in different types of neurodegenerative diseases. Scientific studies exclusively showed that curcumin leads significant improvements in the pathological process of AD. Yet, its low solubility hence low bioavailability is the main therapeutic limitation of curcumin. Although previous studies have focused different types of advanced nanoformulations of curcumin, new approaches are needed to solve the solubility problem. This review summarizes the available scientific data, as reported by the most recent studies describing the utilization of curcumin in the treatment of AD and sleep deprivation-related consequences.

Medicinal herbs and nutritional supplements for dementia therapy: potential therapeutic targets and clinical evidence

Spices and herbs have been used for medicinal purposes for centuries. Also, in the last decades, the use of different nutritional supplements has been implemented to treat all kinds of diseases, including those that present an alteration in cognitive functioning. Dementia is a clinical syndrome in which a person's mental and cognitive capacities gradually decline. As the disease progresses, the person's autonomy diminishes. As there is not an effective treatment to prevent progressive deterioration in many of these pathologies, nutritional interventions have been, and still are, one of the most widely explored therapeutic possibilities. In this review, we have discussed a great number of potentially interesting plants, nutritional derivatives and probiotics for the treatment of dementia around the world. Their action mechanisms generally involve neuroprotective effects via anti-inflammatory, antioxidant, anti-apoptotic, b-amyloid and tau anti-aggregate actions; brain blood flow improvement, and effects on synaptic cholinergic and dopaminergic neurotransmission, which may optimize cognitive performance in patients with cognitive impairment. As for their efficacy in patients with cognitive impairment and/or dementias, evidence is still scarce and/or their outcomes are controversial. We consider that many of these substances have promising therapeutic properties. Therefore, the scientific community has to continue with a more complete research focused on both identifying possible action mechanisms and carrying out clinical trials, preferably randomized double-blind ones, with a greater number of patients, a long-term follow-up, dose standardization and the use of current diagnosis criteria.

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.

Interaction between Gut Microbiota and Curcumin: A New Key of Understanding for the Health Effects of Curcumin

Curcumin, a lipophilic polyphenol contained in the rhizome of Curcuma longa (turmeric), has been used for centuries in traditional Asian medicine, and nowadays it is widely used in food as dietary spice worldwide. It has received considerable attention for its pharmacological activities, which appear to act primarily through anti-inflammatory and antioxidant mechanisms. For this reason, it has been proposed as a tool for the management of many diseases, among which are gastrointestinal and neurological diseases, diabetes, and several types of cancer. However, the pharmacology of curcumin remains to be elucidated; indeed, a discrepancy exists between the well-documented in vitro and in vivo activities of curcumin and its poor bioavailability and chemical instability that should limit any therapeutic effect. Recently, it has been hypothesized that curcumin could exert direct regulative effects primarily in the gastrointestinal tract, where high concentrations of this polyphenol have been detected after oral administration. Consequently, it might be hypothesized that curcumin directly exerts its regulatory effects on the gut microbiota, thus explaining the paradox between its low systemic bioavailability and its wide pharmacological activities. It is well known that the microbiota has several important roles in human physiology, and its composition can be influenced by a multitude of environmental and lifestyle factors. Accordingly, any perturbations in gut microbiome profile or dysbiosis can have a key role in human disease progression. Interestingly, curcumin and its metabolites have been shown to influence the microbiota. It is worth noting that from the interaction between curcumin and microbiota two different phenomena arise: the regulation of intestinal microflora by curcumin and the biotransformation of curcumin by gut microbiota, both of them potentially crucial for curcumin activity. This review summarizes the most recent studies on this topic, highlighting the strong connection between curcumin and gut microbiota, with the final aim of adding new insight into the potential mechanisms by which curcumin exerts its effects.

Bioactive Polyphenols and Neuromodulation: Molecular Mechanisms in Neurodegeneration

The interest in dietary polyphenols in recent years has greatly increased due to their antioxidant bioactivity with preventive properties against chronic diseases. Polyphenols, by modulating different cellular functions, play an important role in neuroprotection and are able to neutralize the effects of oxidative stress, inflammation, and apoptosis. Interestingly, all these mechanisms are involved in neurodegeneration. Although polyphenols display differences in their effectiveness due to interindividual variability, recent studies indicated that bioactive polyphenols in food and beverages promote health and prevent age-related cognitive decline. Polyphenols have a poor bioavailability and their digestion by gut microbiota produces active metabolites. In fact, dietary bioactive polyphenols need to be modified by microbiota present in the intestine before being absorbed, and to exert health preventive effects by interacting with cellular signalling pathways. This literature review includes an evaluation of the literature in English up to December 2019 in PubMed and Web of Science databases. A total of 307 studies, consisting of research reports, review articles and articles were examined and 146 were included. The review highlights the role of bioactive polyphenols in neurodegeneration, with a particular emphasis on the cellular and molecular mechanisms that are modulated by polyphenols involved in protection from oxidative stress and apoptosis prevention.

Protection of cholinergic and antioxidant system contributes to the effect of Vitamin D3 ameliorating memory dysfunction in sporadic dementia of Alzheimer's type

OBJECTIVE

Investigate Vitamin D3 (VD3) effect on the Acetylcholinesterase (AChE), oxidative damage and behavioral tests in animals subjected to Intracerebroventicular injection of Streptozotocin (ICV-STZ) simulating a Sporadic Dementia of Alzheimer's Type (SDAT) and treated with VD3 (21 days).

METHODS

Animals were divided into eight groups: Vehicle, VD12.5 μg/kg, VD42 μg/kg, VD125 μg/kg, STZ, STZ+VD12.5 μg/kg, STZ+VD42 μg/kg, STZ+VD125 μg/kg.

RESULTS

VD3 prevented the increase in AChE in groups of VD42 µg/kg and VD125 µg/kg; in AChE of synaptossomes and TBARS levels prevented the increase in group VD125 µg/kg; in ROS levels there was not a significant difference; for the Carbonyl Content all doses prevented the increase. Total Thiols prevent the decrease in VD42 µg/kg and VD125 µg/kg, and Reduced Glutathione prevented the decrease in VD125 µg/kg, Oxidized Glutathione prevented the increase in VD125 µg/kg. In relation to behavioral tests, the VD3 prevented the increase in time to find (days 2 and 3), in the time to find the platform (day 3) and in time spent in the quadrant (day 2). However, in relation to crossings there was not difference in groups. These results indicated the therapeutic effect of the VD3 in model of STZ in rats.

The effect of curcumin on cognition in Alzheimer's disease and healthy aging: A systematic review of pre-clinical and clinical studies

Alzheimer's disease constitutes a growing cause of cognitive impairment in aging population. Given that current treatments do not produce the desired therapeutic effects, the need for finding alternative biological and pharmacological approaches is critical. Accumulating evidence suggests inflammatory and oxidative stress responses as potential causal factors of cognitive impairments in Alzheimer's disease and healthy aging. Curcumin has received increased interest due to its unique molecular structure that targets inflammatory and antioxidant pathways as well as (directly) amyloid aggregation; one of the major hallmarks of Alzheimer's disease. Therefore, this review summarizes preclinical and clinical findings on curcumin as a potential cognitive enhancer in Alzheimer's disease and normal aging. Databases used for literature searches include PubMed, EMBASE and Web of Science; in addition, clinicaltrials.gov was used to search for clinical studies. Overall, animal research has shown very promising results in potentiating cognition, both physiologically and behaviourally. However, human studies are limited and results are less consistent, complicating their interpretation. These inconsistencies may be related to differences in methodology and the included population. Taking into account measurements of important inflammatory and antioxidant biomarkers, optimal dosages of curcumin, food interactions, and duration of treatment would increase our understanding on curcumin's promising effects on cognition. In addition, increasing curcumin's bioavailability could benefit future research.

Arbutin reduces cognitive deficit and oxidative stress in animal model of Alzheimer's disease

Objectives: Recent evidences have shown the beneficial effects of natural products for treating of Alzheimer's disease (AD). Arbutin is derived from Pyrus biossieriana and exerts a wide range of pharmacological activities including anti-inflammatory and anti-oxidant effects. The present study was designed to examine the protective effects of arbutin on streptozotocin (STZ)-induced neurotoxicity in rats. Materials and methods: The spatial memory impairment was induced by intracerebroventricular (i.c.v) microinjection of STZ (3 mg/kg, 10 μL). Animals received the pretreatment of arbutin (50 mg/kg) for 21 days before STZ injection. The Morris Water maze (MWM) task was used to study the spatial learning and memory. The levels of oxidative stress markers including malondialdehyde (MDA), nitrite and carbonyl were measured in serum and hippocampus samples. In addition, antioxidant level was assessed by ferric reducing antioxidant power (FRAP) test. Results: The obtained result indicated that administration of STZ is led to memory impairment and increases the levels of oxidative stress markers in the hippocampus tissues. Conversely, arbutin improves spatial memory and reduces oxidative and nitrosative stress, as evidenced by a significant decrease in the amount of MDA and nitrite in the serum and hippocampus. In addition, an increase in FRAP levels of hippocampus was observed in arbutin receiving animals. The protein carbonyl content was not reduced in arbutin receiving animals. Conclusion: It could be concluded that arbutin protects the brain against STZ-induced memory impairment and oxidative damage in the hippocampus. The neuroprotective effect of arbutin might be mediated through its antioxidant and free radical scavenging effects.

Protective Effects of Curcumin Against Ischemia-Reperfusion Injury in the Nervous System

Ischemia-reperfusion injury (I/R injury) is a common feature of ischemic stroke which occurs when blood supply is restored after a period of ischemia. Although stroke is an important cause of death in the world, effective therapeutic strategies aiming at improving neurological outcomes in this disease are lacking. Various studies have suggested the involvement of different mechanisms in the pathogenesis of I/R injury in the nervous system. These mechanisms include oxidative stress, platelet adhesion and aggregation, leukocyte infiltration, complement activation, blood-brain barrier (BBB) disruption, and mitochondria-mediated mechanisms. Curcumin, an active ingredient of turmeric, can affect all these pathways and exert neuroprotective activity culminating in the amelioration of I/R injury in the nervous system. In this review, we discuss the protective effects of curcumin against I/R injury in the nervous system and highlight the studies that have linked biological functions of curcumin and I/R injury improvement.

Spice-Derived Bioactive Ingredients: Potential Agents or Food Adjuvant in the Management of Diabetes Mellitus

Spices possess tremendous therapeutic potential including hypoglycemic action, attributed to their bioactive ingredients. However, there is no study that critically reviewed the hypoglycemic potency, safety and the bioavailability of the spice-derived bioactive ingredients (SDBI). Therefore, the aim of the study was to comprehensively review all published studies regarding the hypoglycemic action of SDBI with the purpose to assess whether the ingredients are potential hypoglycemic agents or adjuvant. Factors considered were concentration/dosages used, the extent of blood glucose reduction, the IC50 values, and the safety concern of the SDBI. From the results, cinnamaldehyde, curcumin, diosgenin, thymoquinone (TQ), and trigonelline were showed the most promising effects and hold future potential as hypoglycemic agents. Conclusively, future studies should focus on improving the tissue and cellular bioavailability of the promising SDBI to achieve greater potency. Additionally, clinical trials and toxicity studies are with these SDBI are warranted.

Abd El-Aziz G, N. Mustafa H, El-Fark M, Mansour Tashkandi J, Hassan Alzahrani A, Mal A, AboRass M, Halim Deifalla A. Beneficial Effects of Curcumin in Maternal and Fetal Oxidative Stress and Brain Damage Induced by Gestational Lead Administration

This study was planned to explore the protective role of curcumin (Cur) against maternal and fetal oxidative stress and cerebral damage induced by lead (Pb) during pregnancy. Positively pregnant female rats were divided into seven groups: control group, Cur group (300 mg/kg of Cur/b.wt.), DMSO group (50% DMSO), two Pb-treated groups (exposed to 160 and 320 mg/kg b.wt./day of Pb acetate, respectively), and two groups treated with both Pb and Cur (exposed to Pb as previous groups together with 300 mg/kg b.wt./day of Cur). Treatments through oral gavage once a day started from gestation day 1 (GD1) till day 20 (GD20), where the mother rats of different experimental groups were sacrificed to obtain the fetuses. Different chemical parameters were assessed. Brain specimens of mother and fetal groups were processed with examination. The results displayed that Pb administration to pregnant rats resulted in a dose-dependent toxicity for both mothers and fetuses. Also, there was a significant rise in lipid peroxidation and decreased antioxidant enzyme activities in the brains of the different Pb-treated groups. The histological examination of the brain of treated dams and fetuses showed marked alterations. Co-treatment of Cur along with Pb caused a significant decrease in Pb levels as compared with those treated with Pb alone, improving the oxidative condition with amelioration of the brain’s histopathological changes. Co-administration of Cur could have ameliorative effect against Pb-induced neurotoxicity through the reduction of oxidative stress and reversal of histopathological changes.

5-HT6 receptor agonist and antagonist modulates ICV-STZ-induced memory impairment in rats

RATIONALE AND OBJECTIVES

5-HT6 receptors are mainly expressed in brain areas associated with learning and memory. Several studies have reported procognitive effects of both 5-HT6 agonist and antagonists. However, the exact mechanism 5-HT6 receptor modulation has not been properly studied especially in the context of cholinergic functions, cerebral blood flow (CBF), brain-derived neural factor (BDNF), oxidative stress, and behavioral changes.

METHODS

In the present study, memory impairment was induced in albino Wistar rats by two doses of intracerebroventricular (ICV) injection of streptozotocin (STZ, 3 mg/kg) on first and third day. These rats were evaluated in a battery of behavioral tasks after 14 days from the first day of ICV-STZ.

RESULTS

Significant memory impairment was seen when ICV-STZ induced rats are assessed by Morris water maze, novel object recognition, social recognition, and passive avoidance tests. There was a significant reduction in CBF, increased oxidative stress (MDA, GSH, and ROS), acetylcholinesterase (AChE) activity, and a decrease in BDNF. Treatment with selective 5-HT6 agonist EMD-386088 (5 mg/kg) and antagonist SB-399885 (10 mg/kg) prevented ICV-STZ-induced memory impairment when assessed by behavioral tests. Treatment with 5-HT6 ligands significantly prevented the change in CBF and BDNF. Further, protected from MDA and ROS and decreasing GSH in the brain compared to ICV-STZ rats. The rice in brain AChE activity was normalized by both ligands. The changes in locomotor activity by EMD-386088 and SB-399885 treatment were negligible.

CONCLUSION

The findings in this study support the therapeutic potential of 5-HT6 receptor ligands in the treatment of cognitive dysfunction.

Effects of curcumin on short-term spatial and recognition memory, adult neurogenesis and neuroinflammation in a streptozotocin-induced rat model of dementia of Alzheimer's type

Curcumin is a natural polyphenol with evidence of antioxidant, anti-inflammatory and neuroprotective properties. Recent evidence also suggests that curcumin increases cognitive performance in animal models of dementia, and this effect would be related to its capacity to enhance adult neurogenesis. The aim of this study was to test the hypothesis that curcumin treatment would be able to preserve cognition by increasing neurogenesis and decreasing neuroinflammation in the model of dementia of Alzheimer's type induced by an intracerebroventricular injection of streptozotocin (ICV-STZ) in Wistar rats. The animals were injected with ICV-STZ or vehicle and curcumin treatments (25, 50 and 100mg/kg, gavage) were performed for 30days. Four weeks after surgery, STZ-lesioned animals exhibited impairments in short-term spatial memory (Object Location Test (OLT) and Y maze) and short-term recognition memory (Object Recognition Test - ORT), decreased cell proliferation and immature neurons (Ki-67- and doublecortin-positive cells, respectively) in the subventricular zone (SVZ) and dentate gyrus (DG) of hippocampus, and increased immunoreactivity for the glial markers GFAP and Iba-1 (neuroinflammation). Curcumin treatment in the doses of 50 and 100mg/kg prevented the deficits in recognition memory in the ORT, but not in spatial memory in the OLT and Y maze. Curcumin treatment exerted only slight improvements in neuroinflammation, resulting in no improvements in hippocampal and subventricular neurogenesis. These results suggest a positive effect of curcumin in object recognition memory which was not related to hippocampal neurogenesis.

TLR2 knockout protects against diabetes-mediated changes in cerebral perfusion and cognitive deficits

The risk of cognitive decline in diabetes (Type 1 and Type 2) is significantly greater compared with normoglycemic patients, and the risk of developing dementia in diabetic patients is doubled. The etiology for this is likely multifactorial, but one mechanism that has gained increasing attention is decreased cerebral perfusion as a result of cerebrovascular dysfunction. The innate immune system has been shown to play a role in diabetic vascular complications, notably through the Toll-like receptor (TLR)-stimulated release of proinflammatory cytokines and chemokines that lead to vascular damage. TLR2 has been implicated in playing a crucial role in the development of diabetic microvascular complications, such as nephropathy, and thus, we hypothesized that TLR2-mediated cerebrovascular dysfunction leads to decreased cerebral blood flow (CBF) and cognitive impairment in diabetes. Knockout of TLR2 conferred protection from impaired CBF in early-stage diabetes and from hyperperfusion in long-term diabetes, prevented the development of endothelium-dependent vascular dysfunction in diabetes, created a hyperactive and anxiolytic phenotype, and protected against diabetes-induced impairment of long-term hippocampal and prefrontal cortex-mediated fear learning. In conclusion, these findings support the involvement of TLR2 in the pathogenesis of diabetic vascular disease and cognitive impairment.

Pterostilbene ameliorates intracerebroventricular streptozotocin induced memory decline in rats

There is strong evidence that mitochondrial dysfunction mediated oxidative stress results in aging and energy metabolism deficits thus playing a prime role in pathogenesis of Alzheimer's disease, neuronal death and cognitive dysfunction. Evidences accrued in empirical studies suggest the antioxidant, anticancer and anti-inflammatory activities of the phytochemical pterostilbene (PTS). PTS also exhibits favourable pharmacokinetic attributes compared to other stilbenes. Hence, in the present study, we explored the neuroprotective role of PTS in ameliorating the intracerebroventricular administered streptozotocin (STZ) induced memory decline in rats. PTS at doses of 10, 30 and 50 mg/kg, was administered orally to STZ administered Sprague-Dawley (SD) rats. The learning and memory tests, Morris water maze test and novel object recognition test were performed which revealed improved cognition on PTS treatment. Further, there was an overall improvement in brain antioxidant parameters like elevated catalase and superoxide dismutase activities, GSH levels, lowered levels of nitrites, lipid peroxides and carbonylated proteins. There was improved cholinergic transmission as evident by decreased acetylcholinesterase activities. The action of ATPases (Na+ K+, Ca2+ and Mg2+) indicating the maintenance of cell membrane potential was also augmented. mRNA expression of battery of genes involved in cellular mitochondrial biogenesis and inflammation showed variations which extrapolate to hike in mitochondrial biogenesis and abated inflammation. The histological findings corroborated the effective role of PTS in countering STZ induced structural aberrations in brain.

Streptozotocin Intracerebroventricular-Induced Neurotoxicity and Brain Insulin Resistance: a Therapeutic Intervention for Treatment of Sporadic Alzheimer's Disease (sAD)-Like Pathology

Alzheimer's disease (AD) is a neurodegenerative disorder that is remarkably characterized by pathological hallmarks which include amyloid plaques, neurofibrillary tangles, neuronal loss, and progressive cognitive loss. Several well-known genetic mutations which are being used for the development of a transgenic model of AD lead to an early onset familial AD (fAD)-like condition. However, these settings are only reasons for a small percentage of the total AD cases. The large majorities of AD cases are considered as a sporadic in origin and are less influenced by a single mutation of a gene. The etiology of sporadic Alzheimer's disease (sAD) remains unclear, but numerous risk factors have been identified that increase the chance of developing AD. Among these risk factors are insulin desensitization/resistance state, oxidative stress, neuroinflammation, synapse dysfunction, tau hyperphosphorylation, and deposition of Aβ in the brain. Subsequently, these risk factors lead to development of sAD. However, the underlying molecular mechanism is not so clear. Streptozotocin (STZ) produces similar characteristic pathology of sAD such as altered glucose metabolism, insulin signaling, synaptic dysfunction, protein kinases such as protein kinase B/C, glycogen synthase-3β (GSK-3β) activation, tau hyperphosphorylation, Aβ deposition, and neuronal apoptosis. Further, STZ also leads to inhibition of Akt/PKB, insulin receptor (IR) signaling molecule, and insulin resistance in brain. These alterations mediated by STZ can be used to explore the underlying molecular and pathophysiological mechanism of AD (especially sAD) and their therapeutic intervention for drug development against AD pathology.

The mechanisms of action of flavonoids in the brain: Direct versus indirect effects

The projected increase in the incidence of dementia in the population highlights the urgent need for a more comprehensive understanding of how different aspects of lifestyle, in particular exercise and diet, may affect neural function and consequent cognitive performance throughout the life course. In this regard, flavonoids, found in a variety of fruits, vegetables and derived beverages, have been identified as a group of promising bioactive compounds capable of influencing different aspects of brain function, including cerebrovascular blood flow and synaptic plasticity, both resulting in improvements in learning and memory in mammalian species. However, the precise mechanisms by which flavonoids exert these actions are yet to be fully established, although accumulating data indicate an ability to interact with neuronal receptors and kinase signaling pathways which are key to neuronal activation and communication and synaptic strengthening. Alternatively or concurrently, there is also compelling evidence derived from human clinical studies suggesting that flavonoids can positively affect peripheral and cerebrovascular blood flow, which may be an indirect effective mechanism by which dietary flavonoids can impact on brain health and cognition. The current review examines the beneficial effects of flavonoids on both human and animal brain function and attempts to address and link direct and indirect actions of flavonoids and their derivatives within the central nervous system (CNS).

Curcumin alleviates cisplatin-induced learning and memory impairments

The present study has been designed to investigate the role of curcumin on cisplatin-inducedcognitive impairment and to reveal mechanisms of cisplatin's detrimental actions on cognition in rats. Animals were treated with cisplatin (5mg/kg/week) and/or curcumin (300mg/kg/day) for 5weeks. Morris water maze test was used to assess spatial learning and memory. Enzymatic activities of acetylcholinesterase (AChE) and superoxide dismutase (SOD) were evaluated from hippocampus and plasma samples, and malondialdehyde (MDA), which is the end-product of lipid peroxidation, was determined by a colorimetric method. Our results showed that cisplatin (5mg/kg/week, 5weeks) caused learning and memory deficits, elevated MDA content, decreased SOD activity in the hippocampus and plasma, and AChE activity in the hippocampus. Curcumin improved learning and memory in rats with administration of cisplatin. In addition, curcumin significantly reduced the level of MDA and increased the activities of SOD and AChE. Taken together, our findings indicate that curcumin ameliorates cisplatin-induced spatial learning and memory impairment, possibly through restored cholinergic function and enhanced oxidative status.

Effect of homeopathic Lycopodium clavatum on memory functions and cerebral blood flow in memory-impaired rats

BACKGROUND

Lycopodium clavatum (Lyc) is a widely used homeopathic medicine for the liver, urinary and digestive disorders. Recently, acetyl cholinesterase (AchE) inhibitory activity has been found in Lyc alkaloid extract, which could be beneficial in dementia disorder. However, the effect of Lyc has not yet been explored in animal model of memory impairment and on cerebral blood flow.

AIM

The present study was planned to explore the effect of Lyc on learning and memory function and cerebral blood flow (CBF) in intracerebroventricularly (ICV) administered streptozotocin (STZ) induced memory impairment in rats.

MATERIALS AND METHODS

Memory deficit was induced by ICV administration of STZ (3 mg/kg) in rats on 1st and 3rd day. Male SD rats were treated with Lyc Mother Tincture (MT) 30, 200 and 1000 for 17 days. Learning and memory was evaluated by Morris water maze test on 14th, 15th and 16th day. CBF was measured by Laser Doppler flow meter on 17th day.

RESULTS

STZ (ICV) treated rats showed impairment in learning and memory along with reduced CBF. Lyc MT and 200 showed improvement in learning and memory. There was increased CBF in STZ (ICV) treated rats at all the potencies of Lyc studied.

CONCLUSION

The above study suggests that Lyc may be used as a drug of choice in condition of memory impairment due to its beneficial effect on CBF.

Molecular mechanisms of curcumin on diabetes-induced endothelial dysfunctions: Txnip, ICAM-1, and NOX2 expressions

We aim to investigate the effects of curcumin on preventing diabetes-induced vascular inflammation in association with its actions on Txnip, ICAM-1, and NOX2 enzyme expressions. Male Wistar rats were divided into four groups: control (CON), diabetic (DM; streptozotocin (STZ), i.v. 55 mg/kg BW), control-treated with curcumin (CONCUR; 300 mg/kg BW), and diabetes treated with curcumin (DMCUR; 300 mg/kg BW). 12th week after STZ injection, iris blood perfusion, leukocyte adhesion, Txnip, p47phox, and malondialdehyde (MDA) levels were determined by using laser Doppler, intravital fluorescent confocal microscopy, Western Blot analysis, and TBAR assay, respectively. The iris blood perfusion of DM and DMCUR was decreased significantly compared to CON and CONCUR (P < 0.001). Plasma glucose and HbA1c of DM and DMCUR were increased significantly compared to CON and CONCUR (P < 0.001). Leukocyte adhesion, ICAM-1, p47phox expression, and MDA levels in DM were increased significantly compared to CON, CONCUR, and DMCUR (P < 0.05). Txnip expression in DM and DMCUR was significantly higher than CON and CONCUR (P < 0.05). From Pearson's analysis, the correlation between the plasma MDA level and the endothelial functions was significant. It suggested that curcumin could ameliorate diabetic vascular inflammation by decreasing ROS overproduction, reducing leukocyte-endothelium interaction, and inhibiting ICAM-1 and NOX2 expression.

Clitoria ternatea ameliorated the intracerebroventricularly injected streptozotocin induced cognitive impairment in rats: behavioral and biochemical evidence

RATIONALE

Clitoria ternatea, commonly known as Aparajita, is used as Medhya rasayana in Ayurveda. The role of C. ternatea in experimental models of cognitive impairment is yet to be explored.

OBJECTIVES

The present study was designed to study the effect of aqueous and hydroalcoholic extracts of C. ternatea on biochemical and behavioral parameters related to cognitive impairment in in vitro and in vivo studies.

METHODS

In vitro free radical scavenging and enzyme-inhibitory (cholinesterase, glycogen synthase kinase-3-β, rho kinase, prolyl endopeptidase, catechol-O-methyl transferase, and lipoxygenase) activities of aqueous and hydroalcoholic extracts of C. ternatea plant were evaluated. Based on in vitro results, hydroalcoholic extract of C. ternatea (100, 300, and 500 mg/kg, p.o.) was selected for evaluation in intracerebroventricularly injected streptozotocin (STZ)-induced cognitive impairment in male Wistar rats. Behavioral assessment was performed at baseline and on the 14th, 21st, and 28th days after STZ injection using elevated plus maze, passive avoidance, Morris water maze, and photoactometer. Oxidative stress parameters (malondialdehyde, reduced glutathione, nitric oxide levels, and superoxide dismutase activity), cholinesterase activity, and rho kinase (ROCK II) expression were studied in cerebral cortex and hippocampus of rats' brain at the end of the study.

RESULTS

The hydroalcoholic extract possessed significantly more in vitro antioxidant and enzyme-inhibitory activities as compared to aqueous extract. The hydroalcoholic extract of C. ternatea prevented STZ-induced cognitive impairment dose dependently by reducing oxidative stress, cholinesterase activity, and ROCK II expression.

CONCLUSION

In vitro and in vivo results suggest the potential of hydroalcoholic extract of C. ternatea for treatment of cognitive deficit in neurological disorders.

Ameliorative effect of Noni fruit extract on streptozotocin-induced memory impairment in mice

This study evaluated the effects of a standardized ethyl acetate extract of Morinda citrifolia L. (Noni) fruit on impairment of memory, brain energy metabolism, and cholinergic function in intracerebral streptozotocin (STZ)-treated mice. STZ (0.5 mg/kg) was administered twice at an interval of 48 h. Noni (50 and 100 mg/kg, postoperatively) was administered for 21 days following STZ administration. Memory function was evaluated using Morris Water Maze and passive avoidance tests, and brain levels of cholinergic function, oxidative stress, energy metabolism, and brain-derived neurotrophic factor (BDNF) were estimated. STZ caused memory impairment in Morris Water Maze and passive avoidance tests along with reduced brain levels of ATP, BDNF, and acetylcholine and increased acetylcholinesterase activity and oxidative stress. Treatment with Noni extract (100 mg/kg) prevented the STZ-induced memory impairment in both behavioral tests along with reduced oxidative stress and acetylcholinesterase activity, and increased brain levels of BDNF, acetylcholine, and ATP level. The study shows the beneficial effects of Noni fruit against STZ-induced memory impairment, which may be attributed to improved brain energy metabolism, cholinergic neurotransmission, BDNF, and antioxidative action.

Curcumin and its derivatives: their application in neuropharmacology and neuroscience in the 21st century

Curcumin (diferuloylmethane), a polyphenol extracted from the plant Curcuma longa, is widely used in Southeast Asia, China and India in food preparation and for medicinal purposes. Since the second half of the last century, this traditional medicine has attracted the attention of scientists from multiple disciplines to elucidate its pharmacological properties. Of significant interest is curcumin's role to treat neurodegenerative diseases including Alzheimer's disease (AD), and Parkinson's disease (PD) and malignancy. These diseases all share an inflammatory basis, involving increased cellular reactive oxygen species (ROS) accumulation and oxidative damage to lipids, nucleic acids and proteins. The therapeutic benefits of curcumin for these neurodegenerative diseases appear multifactorial via regulation of transcription factors, cytokines and enzymes associated with (Nuclear factor kappa beta) NFκB activity. This review describes the historical use of curcumin in medicine, its chemistry, stability and biological activities, including curcumin's anti-cancer, anti-microbial, anti-oxidant, and anti-inflammatory properties. The review further discusses the pharmacology of curcumin and provides new perspectives on its therapeutic potential and limitations. Especially, the review focuses in detail on the effectiveness of curcumin and its mechanism of actions in treating neurodegenerative diseases such as Alzheimer's and Parkinson's diseases and brain malignancies.

Protective effect of Cnestis ferruginea and its active constituent on scopolamine-induced memory impairment in mice: a behavioral and biochemical study

CONTEXT

Cnestis ferruginea Vahl ex DC (Connaraceae) (CF) is used in traditional African medicine in the management of CNS disorders. The degeneration and dysfunction of cholinergic neurons is closely associated with the cognitive deficits of Alzheimer's disease (AD) and oxidative stress has been implicated in its pathogenesis. However, the influence of C. ferruginea on the cholinergic system and oxidative stress parameters has not been explored.

OBJECTIVE

The present study investigates the effect of methanol root extract of C. ferruginea and its active constituent amentoflavone (CF-2) on memory, oxidative stress and acetylcholinesterase (AChE) activity in scopolamine-induced amnesia.

MATERIALS AND METHODS

Mice were orally treated with CF (25-200 mg/kg), CF-2 (6.25-25 mg/kg) for three days and memory impairment was induced by intraperitoneal injection of scopolamine (3 mg/kg). Memory function was evaluated by passive avoidance and Morris water maze tests. Biochemical parameters of oxidative stress and cholinergic function were estimated in brain after the completion of behavioral studies.

RESULTS

Scopolamine caused memory impairment along with increased AChE activity and oxidative stress in mice brain. Oral administration of CF and CF-2 significantly prevented scopolamine-induced memory impairment, inhibited AChE and enhanced antioxidant enzyme activity in the brain following scopolamine injection as compared to vehicle administration in scopolamine (i.p.)-treated mice that were comparable to the effect of tacrine.

DISCUSSION AND CONCLUSION

The study demonstrated that C. ferruginea and its constituent have significant protective effect against scopolamine-induced memory deficits in mice that can be attributed to their antioxidant and antiAChE activity.

Effects of turmeric on Alzheimer's disease with behavioral and psychological symptoms of dementia

We describe here three patients with the Alzheimer's Disease (AD) whose behavioral symptoms were improved remarkably as a result of the turmeric treatment, which is the traditional Indian medicine. Their cognitive decline and Behavioral and Psychological Symptoms of Dementia (BPSD) were very severe. All three patients exhibited irritability, agitation, anxiety, and apathy, two patients suffer from urinary incontinence and wonderings. They were prescribed turmeric powder capsules and started recovering from these symptoms without any adverse reaction in the clinical symptom and laboratory data. After 12 weeks of the treatment, total score of the Neuro-Psychiatric Inventory-brief questionnaire decreased significantly in both acuity of symptoms and burden of caregivers. In one case, the Mini-Mental State Examination (MMSE) score was up five points, from 12/30 to 17/30. In the other two cases, no significant change was seen in the MMSE; however, they came to recognize their family within 1 year treatment. All cases have been taking turmeric for more than 1 year, re-exacerbation of BPSD was not seen. The present cases suggest a significant improvement of the behavioral symptoms in the AD with the turmeric treatment, leading to probable benefit of the use of turmeric in individuals with the AD with BPSD.

Effect of angiotensin II on spatial memory, cerebral blood flow, cholinergic neurotransmission, and brain derived neurotrophic factor in rats

RATIONAL

Studies have shown the involvement of angiotensin II (Ang II) in neurobehavioral aspects, but the exact role of Ang II in memory is still ambiguous.

OBJECTIVE

This study explored the effect of central Ang II on spatial memory along with cholinergic neurotransmission, brain energy metabolism, cerebral blood flow (CBF), and brain-derived neurotrophic factor (BDNF) in rats.

METHODS

Spatial memory was evaluated by Morris water maze (MWM) after Ang II (ICV) administration in male Sprague-Dawley rats. CBF was measured by laser Doppler flowmetry. Oxidative stress adenosine triphosphate (ATP), BDNF, acetylcholinesterase (AChE), and acetylcholine (ACh) were estimated in the cortex and hippocampus at 1, 24, and 48 h after Ang II administration. The effect of AT1 and AT2 receptor blocker (candesartan and PD123,319, respectively), AChE inhibitor (donepezil), and antioxidant melatonin was studied on memory, CBF, and biochemical parameters.

RESULTS

Ang II caused spatial memory impairment by affecting acquisition, consolidation, and recall in the MWM test along with a significant reduction in CBF. Ang II significantly reduced ACh level and caused oxidative stress in the rat brain 1 h post-injection. No significant change was observed in BDNF, AChE, and ATP level. Candesartan and donepezil prevented Ang II-induced memory impairment, reduction in CBF and ACh level. However, PD123,319 and melatonin failed to prevent Ang II-induced memory impairment but improved CBF partially.

CONCLUSION

This study suggests that Ang II, via the AT1 receptor, affects spatial memory formation, CBF, and ACh level while AT2 receptor has no significant role.

Cognition-enhancing and neuroprotective activities of the standardized extract of Betula platyphylla bark and its major diarylheptanoids

Diarylheptanoids have been the center of the intensive research efforts for Alzheimer's disease and other neurodegenerative diseases. The present study aimed to determine the effect of the standardized extract of B. platyphylla bark and its major diarylheptanoids in scopolamine-induced amnesic mice through cyclic AMP response element-binding protein (CREB) activation. Oral administration of the standardized extract of B. platyphylla bark (100mg/kg body weight), aceroside VIII (1mg/kg body weight) and platyphylloside (1 or 2mg/kg body weight) significantly ameliorated scopolamine-induced amnesia in passive avoidance test. CREB phosphorylation and brain-derived neurotrophic factor (BDNF) expression in the cortex and hippocampus of the scopolamine-treated mice were markedly increased by the treatment of the standardized extract of B. platyphylla bark and platyphylloside. The standardized extract of B. platyphylla bark and its major diarylheptanoids also significantly protected HT22 cells against neurotoxicity induced by glutamate insult. The standardized extract of B. platyphylla bark and platyphylloside may ameliorate memory deficits by activating the CREB-BDNF pathway and prevent a neurodegeneration by inhibiting neuronal cell death.

Promising therapeutics with natural bioactive compounds for improving learning and memory--a review of randomized trials

Cognitive disorders can be associated with brain trauma, neurodegenerative disease or as a part of physiological aging. Aging in humans is generally associated with deterioration of cognitive performance and, in particular, learning and memory. Different therapeutic approaches are available to treat cognitive impairment during physiological aging and neurodegenerative or psychiatric disorders. Traditional herbal medicine and numerous plants, either directly as supplements or indirectly in the form of food, improve brain functions including memory and attention. More than a hundred herbal medicinal plants have been traditionally used for learning and memory improvement, but only a few have been tested in randomized clinical trials. Here, we will enumerate those medicinal plants that show positive effects on various cognitive functions in learning and memory clinical trials. Moreover, besides natural products that show promising effects in clinical trials, we briefly discuss medicinal plants that have promising experimental data or initial clinical data and might have potential to reach a clinical trial in the near future.

Can healthy lifestyle modify risk factors for dementia? Findings from a pilot community-based survey in Chennai (India) and Newcastle (UK)

BACKGROUND

Currently there are no effective treatments available for dementia. Attention has turned to defining preventive strategies and identifying modifying effects of lifestyle, including physical activity, diet, alcohol intake and smoking, in reducing cognitive decline and overt memory problems in the elderly.

METHODS

In this study, we addressed the modifying aspects of various components of lifestyle in two ageing samples and explored the possible effects that exercise, diet and spiritual and religious beliefs have upon physical and mental health. A total of 251 subjects (128 in Chennai, India, and 123 in Newcastle, UK) filled in a questionnaire regarding their lifestyle habits. Data were analysed with χ² analysis.

RESULTS

Our findings highlight that spiritual and religious beliefs promoted good physical and mental health and were negatively associated with risk factors for dementia, such as high blood pressure, high cholesterol level and diabetes. Lifelong diet and physical activity also contributed to better overall well-being in both samples.

CONCLUSIONS

Our study suggests substantial lifestyle variations between two urban populations in Chennai, India, and Newcastle-upon-Tyne, UK. Further detailed work is required to identify the lifestyle components that have the greatest impact on modifying the known risk factors for dementia.