Curcumin improves spatial memory and decreases oxidative damage in aged female rats

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.

Long-term behavioral and neurochemical paradoxical alterations elicited following intranasal application of a chlorpyrifos formulation in mice

The intranasal (IN) administration route represents a pathway for xenobiotics to reach the brain. The present study aimed to address the long-term consequences of IN administration of a chlorpyrifos (CPF) commercial formulation (fCPF) in mice. For this purpose, adult male CF-1 mice were intranasally administered with fCPF (10 mg/kg/day) three days a week, for 2 and 4 weeks, respectively. Behavioral and biochemical analyses were conducted 3-7, and 7.5 months after the last IN fCPF administration, respectively. Following a 6-month fCPF-free washout period, fur appearance and body injuries scores improved in the fCPF-treated groups. Notably, spatial learning and memory enhancement was observed 4 and 7 months after the last IN fCPF administration. Changes in oxidative stress markers and the activities of enzymes involved in cholinergic and glutamatergic pathways were observed in different brain areas from fCPF-treated mice, still after 7.5 months from fCPF application. Altogether, these neurochemical disturbances could be responsible for the described behavioral observations.

Curcumin displays a potent caloric restriction mimetic effect in an accelerated senescent model of rat

Curcumin, a strong natural compound with numerous health benefits, is extracted from the Curcuma longa. According to recent research findings, it also acts as a calorie restriction mimetic. We examined established aging biomarkers in erythrocytes and plasma and tested a persistent oral dietary dose of curcumin in young and D-galactose-induced accelerated rat aging models. For four weeks, D-gal (300 mg/kg b.w. subcutaneously) and curcumin (200 mg/kg b.w. oral) were administered simultaneously to test the protective effects of curcumin against D-galactose-induced accelerated aging and oxidative stress. In the accelerated senescent rat model, we discovered a significant rise in protein carbonyl, malonaldehyde (MDA), and advanced oxidation protein products. Increased levels of catalase, superoxide dismutase, ferric-reducing antioxidant potential, and reduced glutathione (GSH) were observed. Our findings reveal that curcumin has characteristics resembling a calorie restriction mimic and can successfully maintain redox equilibrium throughout the aging process in rat erythrocytes and plasma.

Ageing, Metabolic Dysfunction, and the Therapeutic Role of Antioxidants

The gradual ageing of the world population has been accompanied by a dramatic increase in the prevalence of obesity and metabolic diseases, especially type 2 diabetes. The adipose tissue dysfunction associated with ageing and obesity shares many common physiological features, including increased oxidative stress and inflammation. Understanding the mechanisms responsible for adipose tissue dysfunction in obesity may help elucidate the processes that contribute to the metabolic disturbances that occur with ageing. This, in turn, may help identify therapeutic targets for the treatment of obesity and age-related metabolic disorders. Because oxidative stress plays a critical role in these pathological processes, antioxidant dietary interventions could be of therapeutic value for the prevention and/or treatment of age-related diseases and obesity and their complications. In this chapter, we review the molecular and cellular mechanisms by which obesity predisposes individuals to accelerated ageing. Additionally, we critically review the potential of antioxidant dietary interventions to counteract obesity and ageing.

Molecular and functional characterization of an evolutionarily conserved CREB-binding protein in the Lymnaea CNS

In eukaryotes, CREB-binding protein (CBP), a coactivator of CREB, functions both as a platform for recruiting other components of the transcriptional machinery and as a histone acetyltransferase (HAT) that alters chromatin structure. We previously showed that the transcriptional activity of cAMP-responsive element binding protein (CREB) plays a crucial role in neuronal plasticity in the pond snail Lymnaea stagnalis. However, there is no information on the molecular structure and HAT activity of CBP in the Lymnaea central nervous system (CNS), hindering an investigation of its postulated role in long-term memory (LTM). Here, we characterize the Lymnaea CBP (LymCBP) gene and identify a conserved domain of LymCBP as a functional HAT. Like CBPs of other species, LymCBP possesses functional domains, such as the KIX domain, which is essential for interaction with CREB and was shown to regulate LTM. In-situ hybridization showed that the staining patterns of LymCBP mRNA in CNS are very similar to those of Lymnaea CREB1. A particularly strong LymCBP mRNA signal was observed in the cerebral giant cell (CGC), an identified extrinsic modulatory interneuron of the feeding circuit, the key to both appetitive and aversive LTM for taste. Biochemical experiments using the recombinant protein of the LymCBP HAT domain showed that its enzymatic activity was blocked by classical HAT inhibitors. Preincubation of the CNS with such inhibitors blocked cAMP-induced synaptic facilitation between the CGC and an identified follower motoneuron of the feeding system. Taken together, our findings suggest a role for the HAT activity of LymCBP in synaptic plasticity in the feeding circuitry.

Differential effects of voluntary and forced exercise trainings on spatial learning ability and hippocampal biomarkers in aged female rats

This study aimed to compare the effects of voluntary and forced exercise trainings on cognitive functions and to evaluate their relationship with hippocampal synaptic proteins, neurotrophic factors and markers of oxidative damage in aged female rats. Aged female rats were randomly assigned to control, voluntary exercise training and forced exercise training groups. Voluntary or forced exercise trainings were performed for 12 weeks. At the end of the training period, cognitive functions of the animals were assessed with Morris water maze (MWM) test. After the behavioral test, hippocampus tissues were taken for the analysis of synaptophysin, acetylcholinesterase (AChE), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), malondialdehyde (MDA), protein carbonyl (PC), glutathione (GSH) and superoxide dismutase (SOD). During the MWM test, the number of platform crossings was higher in the voluntary exercise group than in the control group (P < 0.05). In the hippocampus tissue, levels of the synaptophysin, BDNF, NGF and SOD were higher, but MDA levels were lower in the voluntary exercise group than in the control group (P < 0.05). Additionally, hippocampal AChE concentration was higher, but PC levels were lower in the both voluntary and forced exercise groups than in the control group (P < 0.05). In conclusion, voluntary exercise was more effective intervention to improve spatial learning ability in aging process. Increased neurotrophic factors, synaptic proteins, and improved oxidative damage may play a role in these positive effects.

Effects of Curcumin on Aging: Molecular Mechanisms and Experimental Evidence

Aging is characterized by a progressive inability to maintain homeostasis, self-repair, renewal, performance, and fitness of different tissues throughout the lifespan. Senescence is occurring following enormous intracellular or extracellular stress stimuli. Cellular senescence serves as an antiproliferative process that causes permanent cell cycle arrest and restricts the lifespan. Senescent cells are characterized by terminal cell cycle arrest, enlarged lysosome, and DNA double-strand breaks as well as lipofuscin granularity, senescence-associated heterochromatin foci, and activation of DNA damage response. Curcumin, a hydrophobic polyphenol, is a bioactive chemical constituent of the rhizomes of Curcuma longa Linn (turmeric), which has been extensively used for the alleviation of various human disorders. In addition to its pleiotropic effects, curcumin has been suggested to have antiaging features. In this review, we summarized the therapeutic potential of curcumin in the prevention and delaying of the aging process.

Epigenetic enzymes: A role in aging and prospects for pharmacological targeting

The development of interventions aimed at improving healthspan is one of the priority tasks for the academic and public health authorities. It is also the main objective of a novel branch in biogerontological research, geroscience. According to the geroscience concept, targeting aging is an effective way to combat age-related disorders. Since aging is an exceptionally complex process, system-oriented integrated approaches seem most appropriate for such an interventional strategy. Given the high plasticity and adaptability of the epigenome, epigenome-targeted interventions appear highly promising in geroscience research. Pharmaceuticals targeted at mechanisms involved in epigenetic control of gene activity are actively developed and implemented to prevent and treat various aging-related conditions such as cardiometabolic, neurodegenerative, inflammatory disorders, and cancer. In this review, we describe the roles of epigenetic mechanisms in aging; characterize enzymes contributing to the regulation of epigenetic processes; particularly focus on epigenetic drugs, such as inhibitors of DNA methyltransferases and histone deacetylases that may potentially affect aging-associated diseases and longevity; and discuss possible caveats associated with the use of epigenetic drugs.

Pharmacological and Molecular Evidence of Neuroprotective Curcumin Effects Against Biochemical and Behavioral Sequels Caused by Methamphetamine: Possible Function of CREB-BDNF Signaling Pathway

INTRODUCTION

The neuroprotective impact of curcumin and the role of CREB (Cyclic AMP Response Element Binding protein)-BDNF (Brain-Derived Neurotrophic Factor) signaling pathway was evaluated in Methamphetamine (METH)-induced neurodegeneration in rats.

METHODS

Sixty adult male rats were randomly divided into 6 groups. While normal saline and 10 mg/kg METH were administered intraperitoneally in groups 1 and 2, groups 3, 4, 5, and 6 received METH (10 mg/kg) and curcumin (10, 20, 40, and 80 mg/kg, respectively) simultaneously. Morris water maze test was administered, and oxidative hippocampal, antioxidant, inflammatory, apoptotic, and CREB and BDNF were assessed.

RESULTS

We found that METH disturbs learning and memory. Concurrent curcumin therapy (40 and 80 mg/kg) decreased cognitive disturbance caused by METH. Multiple parameters, such as lipid peroxidation, the oxidized form of glutathione, interleukin 1 beta, tumor necrosis factor-alpha, and Bax were increased by METH therapy, while the reduced type of glutathione, Bcl-2, P-CREB, and BDNF concentrations in the hippocampus were decreased.

CONCLUSION

Different doses of curcumin adversely attenuated METH-induced apoptosis, oxidative stress, and inflammation but enhanced the concentrations of P-CREB and BDNF. The neuroprotection caused by curcumin against METH-induced neurodegeneration is mediated through P-CREB-BDNF signaling pathway activation.

Anxiolytic, antioxidant, and neuroprotective effects of goji berry polysaccharides in ovariectomized rats: experimental evidence from behavioral, biochemical, and immunohistochemical analyses

Recent studies have indicated that polysaccharides, the main component of the Lycium barbarum L. fruit, have beneficial effects (e.g., anxiolytic, antioxidant, and neuroprotective) on humans and rodents. However, the effects of different dosages of such polysaccharides on ovariectomized rats and their underlying mechanisms in the brain have not been evaluated in the literature. Here, we aimed to evaluate the effects of the high and low doses of polysaccharides obtained from Lycium barbarum fruits (HD-LBP and LD-LBP, respectively) on anxious behaviors via behavioral (using the OFT and EPM), biochemical (using ELISA), and immunohistochemical (using immunohistochemical staining) measures in detail. Two weeks after ovariectomy, the rats were randomly assigned to either the treatment conditions [control (DW, 3 mL/kg, p.o., per day), LD-LBP (20 mg/kg, 3 mL/kg, p.o., per day), HD-LBP (200 mg/kg, 3 mL/kg, p.o., per day), 17 β-ES (1 mg/kg, 3 mL/kg, p.o., per day), DZ(1 mg/kg, 3 mL/kg, p.o., per day)] or operation type [SHAM (pseudo-ovariectomized) and OVX (ovariectomized)]. The treatments were applied for 30 consecutive days, and then serum and brain tissue samples of all rats were collected. Biochemical (SOD, CAT, GPX, MDA, and 17 β-ES) and immunohistochemical (BDNF, SER, and apoptosis) analyses of the samples were performed as well. The rats administered HD-LBP and LD-LBP were less anxious than the control groups. The HD-LBP-treated rats had high levels of SOD and low levels of MDA in their serum samples. Moreover, HD-LBP and drug-treated groups had a high number of SER receptors and BDNF-positive cells and a low number of TUNEL-positive cells in their hippocampal brain tissues. The HD-LBP treatments decrease anxious behavior by increasing antioxidant enzyme activities, hippocampal SER and BDNF neurotransmitter levels and decreasing the TUNEL-positive cell count of ovariectomized rats. Given these findings, we suggest that menopause-induced symptoms of anxiety can be reduced by polysaccharides obtained from goji berry fruits, and that these findings will be beneficial for the production studies of natural herbal-origin antianxiety (anxiolytic) drugs in the future.

Nanotechnology for Medical and Surgical Glaucoma Therapy-A Review

Glaucoma is the second leading cause of blindness worldwide. Even though significant advances have been made in its management, currently available antiglaucoma therapies suffer from considerable drawbacks. Typically, the success and efficacy of glaucoma medications are undermined by their limited bioavailability to target tissues and the inadequate adherence demonstrated by patients with glaucoma. The latter is due to a gradual decrease in tolerability of lifelong topical therapies and the significant burden to patients of prescribed stepwise antiglaucoma regimens with frequent dosing which impact quality of life. On the other hand, glaucoma surgery is restricted by the inability of antifibrotic agents to efficiently control the wound healing process without causing severe collateral damage and long-term complications. Evolution of the treatment paradigm for patients with glaucoma will ideally include prevention of retinal ganglion cell degeneration by the successful delivery of neurotrophic factors, anti-inflammatory drugs, and gene therapies. Nanotechnology-based treatments may surpass the limitations of currently available glaucoma therapies through optimized targeted drug delivery, increased bioavailability, and controlled release. This review addresses the recent advances in glaucoma treatment strategies employing nanotechnology, including medical and surgical management, neuroregeneration, and neuroprotection.

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.

Effect of curcumin on hippocampus dentate gyrus injury induced by nicotine in rats

Introduction: Nicotine is the most important alkaloid compound in tobacco and is a major risk factor in the development of functional disorder of several organ systems. Some plants produce Curcumin, which has antioxidant and neuroprotective properties. This study was designed to evaluate the therapeutic effects of curcumin against nicotine injury on the hippocampus CA1 region of rats. Methods: In this study, 48 male Wistar rats were randomly assigned to eight groups: Normal control (saline) group, Nicotine control group (0.5 mg/kg); Curcumin groups (10, 30, and 60 mg/kg) and Nicotine + Curcumin groups (10, 30, and 60 mg/kg). Treatments were administered intraperitoneally daily for 28 days. Golgi staining technique investigated the number of dendritic spines. Cresyl violet staining method was used to determine the number of neurons in hippocampal region CA1. Griess technique was assessed to determine serum nitrite oxide level. Also, the Ferric reducing/antioxidant power (FRAP) method was applied to determine the total antioxidant capacity. Results: Nicotine administration significantly increased nitrite oxide level and decreased total antioxidant capacity as well as the number of neuronal dendritic spines and neurons compared to the normal control group (P < 0.01). In all Curcumin and Nicotine + Curcumin groups, the number of neurons, neuronal dendritic spines, and total antioxidant capacity increased significantly compared to the nicotine control group, while nitrite oxide level decreased significantly compared to the nicotine control group (P < 0.01). Conclusion: Curcumin administration can improve hippocampal CA1 region injury induced by nicotine.

Targeting Inflammatory Pathways in Alzheimer's Disease: A Focus on Natural Products and Phytomedicines

Studies of the brains of Alzheimer's disease (AD) patients have revealed key neuropathological features, such as the deposition of aggregates of insoluble amyloid-β (Aβ) peptides and neurofibrillary tangles (NFTs). These pathological protein deposits, including Aβ peptides (which form senile plaques) and hyperphosphorylated tau (which aggregates into NFTs), have been assumed to be 'the cause of AD'. Aβ has been extensively targeted to develop an effective disease-modifying therapy, but with limited clinical success. Emerging therapies are also now targeting further pathological processes in AD, including neuroinflammation. This review focuses on the inflammatory and oxidative stress-related changes that occur in AD, and discusses some emerging anti-inflammatory natural products and phytomedicines. Many of the promising compounds are cytokine-suppressive anti-inflammatory drugs (CSAIDs), which target the proinflammatory AP1 and nuclear factor-κB signalling pathways and inhibit the expression of many proinflammatory cytokines, such as interleukin (IL)-1, IL-6, tumour necrosis factor-α, or nitric oxide produced by inducible nitric oxide synthase. However, many of these phytomedicines have not been tested in rigorous clinical trials in AD patients. It is not yet clear if the active compounds reach an effective concentration in the brain (due to limited bioavailability) or if they can slow down AD progression in long-term trials. The authors suggest that it is crucial for both the pharmacological and complementary medicine industries to conduct and fund those studies to significantly advance the field.

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.

Curcumin, Cardiometabolic Health and Dementia

Current research indicates curcumin [diferuloylmethane; a polyphenolic compound isolated from the rhizomes of the dietary spice turmeric (Curcuma longa)] exerts a beneficial effect on health which may be partly attributable to its anti-oxidative and anti-inflammatory properties. The aim of this review is to examine potential mechanisms of the actions of curcumin in both animal and human studies. Curcumin modulates relevant molecular target pathways to improve glucose and lipid metabolism, suppress inflammation, stimulate antioxidant enzymes, facilitate insulin signalling and reduce gut permeability. Curcumin also inhibits Aβ and tau accumulation in animal models and enhances mitochondria and synaptic function. In conclusion, in high-dose animal studies and in vitro, curcumin exerts a potential beneficial effect on cardiometabolic disease. However, human studies are relatively unconvincing. More intervention studies should be conducted with the new curcumin formulation with improved oral bioavailability.

Systemic Administration of Curcumin Affect Anxiety-Related Behaviors in a Rat Model of Posttraumatic Stress Disorder via Activation of Serotonergic Systems

Posttraumatic stress disorder (PTSD) is a trauma-induced psychiatric disease characterized by impaired hyperarousal, fear extermination, depression, anxiety, and amnesic symptoms that may include the release of monoamines in the dread circuit. Curcumin (CUR), a major diarylheptanoid and polyphenolic component of Curcuma longa, reportedly possesses several pharmacological features, including antidiabetic, antiatherosclerotic, anticancer, and neuropsychiatric actions. But the anxiolytic-like effects of CUR and its mechanism of action in PTSD are unclear. The current research measured some anxiety-related behavioral responses to examine the effects of CUR on symptoms of anxiety in rats after single prolonged stress (SPS) exposure by reversing the serotonin (5-HT) dysfunction. Rats received CUR (20, 50, or 100 mg/kg, i.p., once daily) for 14 days after SPS exposure. Administration of CUR significantly increased the number of central zone crossings in the open field test and reduced grooming behavior in the elevated plus maze (EPM) test and increased the number of open-arm visits on the EPM test. CUR administration significantly reduced freezing response to contextual fear conditioning. CUR recovered neurochemical abnormalities and SPS-induced decreased 5-HT tissue levels in the hippocampus, amygdala, and striatum. These results suggested that CUR has anxiolytic-like effects on biochemical and behavioral symptoms associated with anxiety. Thus, CUR may be a useful agent to alleviate or treat psychiatric disorders similar to those observed in patients with PTSD.

Curcumin supplementation and motor-cognitive function in healthy middle-aged and older adults

BACKGROUND

Recent studies suggest curcumin is a promising nutraceutical for improving important clinical and physiological markers of healthy aging, including motor and cognitive function.

OBJECTIVE

To determine if curcumin supplementation improves motor and cognitive function in healthy middle-aged and older adults.

METHODS

39 healthy men and postmenopausal women (45-74 yrs) were randomized to 12 weeks of placebo (n = 19) or curcumin supplementation (2000 mg/day Longvida®; n = 20) with motor and cognitive function assessed at week 0 and 12.

RESULTS

Using measures of the NIH Toolbox and other standardized tests, there were no changes in muscle strength and rate of torque development, dexterity, fatigability, mobility, endurance, and balance between the placebo and curcumin groups after 12 weeks (all P > 0.05). Additionally, there were no changes after 12 weeks of placebo and curcumin supplementation in measures of fluid cognitive ability, a cognitive domain that declines with age, including processing speed, executive function, working memory, and episodic memory (all P > 0.3). There were marginal changes in language, a measure of crystallized cognitive ability that is stable with age, following the intervention, wherein reading decoding increased 3% in the curcumin group (post: 2428±35 vs. pre: 2357±34, P = 0.003), but was unchanged in the placebo group (post: 2334±39 vs. pre: 2364±40, P = 0.07).

CONCLUSIONS

Overall, 12 weeks of curcumin supplementation does not improve motor and cognitive functions in healthy middle-aged and older adults. It is possible that curcumin may enhance these functions in groups with greater baseline impairments than those studied here, including adults greater than 75 years of age and/or patients with clinical disorders.

Efficacy of curcumin for age-associated cognitive decline: a narrative review of preclinical and clinical studies

Processes such as aberrant redox signaling and chronic low-grade systemic inflammation have been reported to modulate age-associated pathologies such as cognitive impairment. Curcumin, the primary therapeutic component of the Indian spice, Turmeric (Curcuma longa), has long been known for its strong anti-inflammatory and antioxidant activity attributable to its unique molecular structure. Recently, an interest in this polyphenol as a cognitive therapeutic for the elderly has emerged. The purpose of this paper is to critically review preclinical and clinical studies that have evaluated the efficacy of curcumin in ameliorating and preventing age-associated cognitive decline and address the translational progress of preclinical to clinical efficacy. PubMed, semantic scholar, and Google scholar searches were used for preclinical studies; and clinicaltrials.gov , the Australian and New Zealand clinical trials registry, and PubMed search were used to select relevant completed clinical studies. Results from preclinical studies consistently demonstrate curcumin and its analogues to be efficacious for various aspects of cognitive impairment and processes that contribute to age-associated cognitive impairment. Results of published clinical studies, while mixed, continue to show promise for curcumin's use as a therapeutic for cognitive decline but overall remain inconclusive at this time. Both in vitro and in vivo studies have found that curcumin can significantly decrease oxidative stress, systemic inflammation, and obstruct pathways that activate transcription factors that augment these processes. Future clinical studies would benefit from including evaluation of peripheral and cerebrospinal fluid biomarkers of dementia and behavioral markers of cognitive decline, as well as targeting the appropriate population.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Cytokine alterations and cognitive impairment in major depressive disorder: From putative mechanisms to novel treatment targets

Overwhelming evidence indicates the involvement of immune-inflammatory processes in the pathophysiology of major depressive disorder (MDD). Peripheral cytokine alterations serve as one of most consistently reported indices of subthreshold inflammatory state observed in MDD. Although cytokines cannot pass directly through the blood-brain barrier, a number of transport mechanisms have been reported. In addition, peripheral cytokines may impact central nervous system via downstream effectors of their biological activity. Animal model studies have provided evidence that cytokines might impact cognitive performance through direct and indirect effects on long-term potentiation, neurogenesis and synaptic plasticity. Therefore, it has been hypothesized that cytokine alterations might contribute to cognitive impairment that is widely observed in MDD and persists beyond episodes of acute relapse in the majority of patients. Although several studies have provided that peripheral cytokine alterations might be related to cognitive deficits in patients with MDD, the quality of evidence still leaves much to be desired due to methodological heterogeneity and limitations. In this article, we provide an overview of studies investigating the association between peripheral cytokine alterations and cognitive performance in MDD, discuss underlying mechanisms and neural substrates. Finally, we propose possible treatment targets related to cytokine alterations taking into account existing evidence for antidepressant efficacy of anti-inflammatory pharmacological treatment modalities.

Use of curcumin in diagnosis, prevention, and treatment of Alzheimer's disease

This review summarizes and describes the use of curcumin in diagnosis, prevention, and treatment of Alzheimer's disease. For diagnosis of Alzheimer's disease, amyloid-β and highly phosphorylated tau protein are the major biomarkers. Curcumin was developed as an early diagnostic probe based on its natural fluorescence and high binding affinity to amyloid-β. Because of its multi-target effects, curcumin has protective and preventive effects on many chronic diseases such as cerebrovascular disease, hypertension, and hyperlipidemia. For prevention and treatment of Alzheimer's disease, curcumin has been shown to effectively maintain the normal structure and function of cerebral vessels, mitochondria, and synapses, reduce risk factors for a variety of chronic diseases, and decrease the risk of Alzheimer's disease. The effect of curcumin on Alzheimer's disease involves multiple signaling pathways: anti-amyloid and metal iron chelating properties, antioxidation and anti-inflammatory activities. Indeed, there is a scientific basis for the rational application of curcumin in prevention and treatment of Alzheimer's disease.

Curcuma longa L. extract improves the cortical neural connectivity during the aging process

Turmeric or Curcuma is a natural product that has anti-inflammatory, antioxidant and anti-apoptotic pharmacological properties. It can be used in the control of the aging process that involves oxidative stress, inflammation, and apoptosis. Aging is a physiological process that affects higher cortical and cognitive functions with a reduction in learning and memory, limited judgment and deficits in emotional control and social behavior. Moreover, aging is a major risk factor for the appearance of several disorders such as cerebrovascular disease, diabetes mellitus, and hypertension. At the brain level, the aging process alters the synaptic intercommunication by a reduction in the dendritic arbor as well as the number of the dendritic spine in the pyramidal neurons of the prefrontal cortex, hippocampus and basolateral amygdala, consequently reducing the size of these regions. The present review discusses the synaptic changes caused by the aging process and the neuroprotective role the Curcuma has through its anti-inflammatory, antioxidant and anti-apoptotic actions

Polysorbate-80-coated, polymeric curcumin nanoparticles for in vivo anti-depressant activity across BBB and envisaged biomolecular mechanism of action through a proposed pharmacophore model

Depression is a modern world epidemic. Its main causative factor is oxidative stress, as reported in study subjects. Natural products are yet to show significant therapeutic effects in comparison with synthetic drugs. Current study deals with the preparation of brain-targeted polysorbate-80-coated curcumin PLGA nanoparticles (PS-80-CUR-NP), and their characterisation via Spectral and optical methods. PS-80-CUR-NP were evaluated against the oxidative stress-mediated depressant (OSMD) activity via Force despair, Tail suspension tests and stress biomarker assay (SOD and catalase activity). A significant reduction in immobility (p < 0.01) in force despair and tail suspension test and a significant increase (p < 0.001 and p < 0.01) in SOD and catalase activity was found and compared with stress control, which confirmed the OSMD activity of PS-80-CUR-NP at 5 mg equivalent dose. Further, AUC_(0.5-15 h) curve of brain homogenates estimated the curcumin concentration of 1.73 ng/g C_max at T_max 3 h via HPLC technique.

Single cell amperometry reveals curcuminoids modulate the release of neurotransmitters during exocytosis from PC12 cells

We used single cell amperometry to examine whether curcumin and bisdemethoxycurcumin (BDMC), substances that are suggested to affect learning and memory, can modulate monoamine release from PC12 cells. Our results indicate both curcumin and BDMC need long-term treatment (72 h in this study) to influence exocytosis effectively. By analyzing the parameters calculated from single exocytosis events, it can be concluded that curcumin and BDMC affect exocytosis through different mechanisms. Curcumin accelerates the event dynamics with no significant change of the monoamine amount released from single exocytotic events, whereas BDMC attenuates the amount from single exocytotic event with no significant change of the event dynamics. This comparison of the effect of curcumin and BDMC on exocytosis at the single cell level brings insight into their different mechanisms, which might lead to different biological actions. The effect of curcumin and BDMC on the opening and closing of the exocytotic fusion pore were also investigated. These results might be helpful for understanding the improvement of learning and memory and the anti-depression properties of curcuminoids.

Effects of exercise training on hepatic oxidative stress and antioxidant status in aged rats

This study investigated the effects of exercise training on oxidative stress, and antioxidant defense markers in the liver tissues of young and aged rats. Two age groups of 4-(young) and 20-months-(aged) old male Wistar rats were performed exercise training program consisted of swimming exercise for 8 weeks. The biomarkers of pro/antioxidant status malondialdehyde (MDA), protein carbonyl (PC), 8-hydroxy-2'-deoxyguanosine (8-OHdG), total glutathione (GSH) and superoxide dismutase (SOD) were assessed by commercially available kits. PC levels were higher in the untrained aged rats compared to the young groups and exercise training decreased PC levels (p < 0.05). 8-OHdG levels were higher in the aged groups (p < 0.05). MDA and GSH levels and SOD activity did not differ significantly between the groups (p > 0.05). The present findings indicate that exercise training prevents aging-induced hepatic oxidative damage especially in the proteins.

Curcumin and Resveratrol in the Management of Cognitive Disorders: What is the Clinical Evidence?

A growing body of in vitro and in vivo evidences shows a possible role of polyphenols in counteracting neurodegeneration: curcumin and resveratrol are attractive substances in this regard. In fact, epidemiological studies highlight a neuroprotective effect of turmeric (rhizome of Curcuma longa L.), the main source of curcumin. Moreover, the consumption of red wine, the main source of resveratrol, has been related to a lower risk of developing dementia. In this review, we analyzed the published clinical trials investigating curcumin and resveratrol in the prevention or treatment of cognitive disorders. The ongoing studies were also described, in order to give an overview of the current search on this topic. The results of published trials (five for curcumin, six for resveratrol) are disappointing and do not allow to draw conclusions about the therapeutic or neuroprotective potential of curcumin and resveratrol. These compounds, being capable of interfering with several processes implicated in the early stages of dementia, could be useful in preventing or in slowing down the pathology. To this aim, an early diagnosis using peripheral biomarkers becomes necessary. Furthermore, the potential preventive activity of curcumin and resveratrol should be evaluated in long-term exposure clinical trials, using preparations with high bioavailability and that are well standardized.

Oral administration of d-galactose induces cognitive impairments and oxidative damage in rats

d-Galactose (d-gal) is a reducing sugar that can be used to mimic the characteristics of aging in rodents; however, the effects of d-gal administration by oral route are not clear. Therefore, the aim of this study was to elucidate if the oral administration of d-gal induces cognitive impairments, neuronal loss, and oxidative damage, mimicking an animal model of aging. Male adult Wistar rats (4 months old) received d-gal (100mg/kg) via the oral route for a period of 1, 2, 4, 6 or 8 weeks. The results showed cognitive impairments in the open-field test in the 4th and 6th weeks after d-gal administration, as well as an impairment in spatial memory in the radial maze test after the 6th week of d-gal administration. The results indicated increase of levels of thiobarbituric acid reactive species-TBARS-and carbonyl group content in the prefrontal cortex from the 4th week, and in all weeks of d-gal administration, respectively. An increase in the levels of TBARS and carbonyl group content was observed in the hippocampus over the entire period of d-gal treatment. In the 8th week of d-gal administration, we also observed reductions in synaptophysin and TAU protein levels in the prefrontal cortex. Thus, d-gal given by oral route caused cognitive impairments which were accompanied by oxidative damage. Therefore, these results indicate that orally administered d-gal can induce the behavioral and neurochemical alterations that are observed in the natural aging process. However, oral d-gal effect in rats deserve further studies to be better described.

Examining the potential clinical value of curcumin in the prevention and diagnosis of Alzheimer’s disease

Curcumin derived from turmeric is well documented for its anti-carcinogenic, antioxidant and anti-inflammatory properties. Recent studies show that curcumin also possesses neuroprotective and cognitive-enhancing properties that may help delay or prevent neurodegenerative diseases, including Alzheimer’s disease (AD). Currently, clinical diagnosis of AD is onerous, and it is primarily based on the exclusion of other causes of dementia. In addition, phase III clinical trials of potential treatments have mostly failed, leaving disease-modifying interventions elusive. AD can be characterised neuropathologically by the deposition of extracellular β amyloid (Aβ) plaques and intracellular accumulation of tau-containing neurofibrillary tangles. Disruptions in Aβ metabolism/clearance contribute to AD pathogenesis. In vitro studies have shown that Aβ metabolism is altered by curcumin, and animal studies report that curcumin may influence brain function and the development of dementia, because of its antioxidant and anti-inflammatory properties, as well as its ability to influence Aβ metabolism. However, clinical studies of curcumin have revealed limited effects to date, most likely because of curcumin’s relatively low solubility and bioavailability, and because of selection of cohorts with diagnosed AD, in whom there is already major neuropathology. However, the fresh approach of targeting early AD pathology (by treating healthy, pre-clinical and mild cognitive impairment-stage cohorts) combined with new curcumin formulations that increase bioavailability is renewing optimism concerning curcumin-based therapy. The aim of this paper is to review the current evidence supporting an association between curcumin and modulation of AD pathology, including in vitro and in vivo studies. We also review the use of curcumin in emerging retinal imaging technology, as a fluorochrome for AD diagnostics.

Association of Neuroprotective Effect of Di-O-Demethylcurcumin on Aβ25-35-Induced Neurotoxicity with Suppression of NF-κB and Activation of Nrf2

Amyloid-β peptides (Aβ), a major component of senile plaques, play an important role in the development and progression of Alzheimer's disease. Several lines of evidence have demonstrated that Aβ-induced neuronal death is mediated by oxidative stress. The present study aimed to evaluate the potential involvement of di-O-demethylcurcumin, an analog of curcuminoid, on Aβ-induced neurotoxicity in culture neuroblastoma cells (SK-N-SH cells) through the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and the suppression of nuclear factor-κB (NF-κB) signaling pathway and their downstream targets. The results showed that pretreatment with di-O-demethylcurcumin elevated cell viability and decreased the level of reactive oxygen species. Moreover, treatment with di-O-demethylcurcumin promoted the translocation of Nrf2 protein from the cytoplasm to the nucleus, increased the expression of Nrf2-ARE pathway-related downstream proteins including heme oxygenase (HO-1), NAD(P)H:quinone oxidoreductase 1 and glutamate-cysteine ligase catalytic subunit, and increased the activity of superoxide dismutase enzymes. On the other hand, di-O-demethylcurcumin suppressed the degradation of IκBα, translocation of the p65 subunit of NF-κB from cytoplasm to nucleus and thereby, attenuated the expression of inducible nitric oxide synthase protein and nitric oxide production. Taken together, these results suggest that neuroinflammatory effect of di-O-demethylcurcumin might potentially be due to inhibit NF-κB and activate Nrf2 signaling pathways induced by Aβ25-35.

The effects of Ginkgo biloba extract on cognitive functions in aged female rats: the role of oxidative stress and brain-derived neurotrophic factor

The aim of this study was to investigate the effects of Ginkgo biloba extract (GBE) on cognitive functions as well as oxidative stress and brain-derived neurotrophic factor (BDNF) levels in aged female rats. Rats were divided into 4 groups according to age (young vs. aged) and treatment (GBE vs. vehicle). GBE or vehicle was given for 30 d, and a series of behavioral tests were performed. Following behavioral testing, blood samples and brain tissues were obtained for analysis of BDNF, malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and glutathione levels, and superoxide dismutase activity. Locomotor activity and anxiety levels were lower in the aged rats. Based on Morris water maze probe trial findings, GBE supplementation increased the number of platform crossings in the aged rats. MDA and 8-OHdG levels were lower in the brain tissue, and BDNF levels were higher in plasma in the rates treated with GBE. Based on these findings, we concluded that GBE supplementation improved cognitive functions by decreasing oxidative damage and increasing the BDNF level in aged female rats.

Di-O-demethylcurcumin protects SK-N-SH cells against mitochondrial and endoplasmic reticulum-mediated apoptotic cell death induced by Aβ25-35

Alzheimer's disease (AD) is a neurodegenerative and progressive disorder. The hallmark of pathological AD is amyloid plaque which is the accumulation of amyloid β (Aβ) in extracellular neuronal cells and neurofibrillary tangles (NFT) in neuronal cells, which lead to neurotoxicity via reactive oxygen species (ROS) generation related apoptosis. Loss of synapses and synaptic damage are the best correlates of cognitive decline in AD. Neuronal cell death is the main cause of brain dysfunction and cognitive impairment. Aβ activates neuronal death via endoplasmic reticulum (ER) stress and mitochondria apoptosis pathway. This study investigated the underlying mechanisms and effects of di-O-demethylcurcumin in preventing Aβ-induced apoptosis. Pretreatment with di-O-demethylcurcumin for 2 h, which was followed by Aβ25-35 (10 µM) in human neuroblastoma SK-N-SH cells improved cell viability by using MTS assay and decreased neuronal cell apoptosis. Pretreatment with di-O-demethylcurcumin attenuated the number of nuclear condensations and number of apoptotic cells in Aβ25-35-induced group in a concentration-dependent manner by using transmission electron microscope (TEM) and flow cytometry, respectively. Di-O-demethylcurcumin also increased the ratio of Bcl-XL/Bax protein, and reduced intracellular ROS level, cytochrome c protein expression, cleaved caspase-9 protein expression, and cleaved caspase-3 protein expression. Additionally, di-O-demethylcurcumin treatment also reduced the expression of ER stress protein markers, including protein kinase RNA like endoplasmic reticulum kinase (PERK) phosphorylation, eukaryotic translation initiation factor 2 alpha (eIF2α) phosphorylation, inositol-requiring enzyme 1 (IRE1) phosphorylation, X-box-binding protein-1 (XBP-1), activating transcription factor (ATF6), C/EBP homologous protein (CHOP), and cleaved caspase-12 protein. CHOP and cleaved caspase-12 protein are the key mediators of apoptosis. Our data suggest that di-O-demethylcurcumin is a candidate protectant against neuronal death through its suppression of the apoptosis mediated by mitochondrial death and ER stress pathway.

Curcumin prevents the structural changes induced in the rats' deep cerebellar nuclei by sodium metabisulfite, a preservative agent

OBJECTIVE

To evaluate the the possible neurotoxic effects of sulfite and the protective potential of curcumin on the deep cerebellar nuclei using stereological methods.

METHODS

The rats were randomly divided into five experimental groups (n=6): Group I: distilled water, Group II: Olive oil, Group III: Curcumin (100 mg/kg/day), Group IV: Sodium metabisulfite (25 mg/kg/day), and Group V: Sodium metabisulfite+curcumin. At the end of 56 d, the right cerebellar hemispheres were removed and assigned to stereological studies. The total volume and total neuron number of deep cerebellar nuclei were assessed using Cavalieri and optical disector methods, respectively.

RESULTS

The data showed ∼20% and ∼16% decrease was respectively observed in the total volume and the total neuron number of the deep cerebellar nuclei of the sulfite-treated rats in comparison to the distilled water group (P<0.04). However, no significant change was observed in the total volume and neuronal number of the deep cerebellar nuclei in sulfite+curcumin-treated rats and curcumin played a protective role against sulfite. Curcumin or its vehicle (olive oil) did not induce any significant changes.

CONCLUSIONS

Curcumin, the main part of the turmeric, could prevent the structural changes induced in the deep cerebellar nuclei by sodium metabisulfite, a preservative agent, in rats.

Protective effect of curcuminoids on age-related mitochondrial impairment in female Wistar rat brain

The present study demonstrated the neuroprotective effect of curcuminoids, the active polyphenols of Curcuma longa (L.) rhizomes on mitochondrial dysfunctioning in middle aged and aged female Wistar rat brain. Rats were orally treated with curcuminoids (100 mg/kg) for 3 months and their brain was collected for evaluation of mitochondrial enzymes and complexes activity, ultra structural changes in mitochondria, neuronal nitric oxide synthase (nNOS) protein expression, adenosine triphosphate (ATP) and lipofuscin content. Significant alterations were observed in all the tested parameters in highly aged rat brain when compared with young control. Long term curcuminoids administration prevented this age associated loss of mitochondrial enzymes and complexes activity in middle aged rat brain except for malate dehydrogenase, Complex II and IV activity when compared with young control. Among aged rats, curcuminoids treatment specifically elevated isocitrate and NADH dehydrogenase, cytochrome c oxidase, Complex I and total ATP content. A significant down-regulation of nNOS protein expression along with reduced lipofuscin content was also observed in curucminoids treated middle aged and aged rats. Thus, it was suggested that curcuminoids may act as a putative drug candidate for the prevention of deleterious effects of ageing and age associated neurodegenerative disorders through amelioration of aberrant mitochondrial functioning.