Prophylactic neuroprotective property of Centella asiatica against 3-nitropropionic acid induced oxidative stress and mitochondrial dysfunctions in brain regions of prepubertal mice

A clinical study and future prospects for bioactive compounds and semi-synthetic molecules in the therapies for Huntington's disease

A neurodegenerative disorder (ND) refers to Huntington's disease (HD) which affects memory loss, weight loss, and movement dysfunctions such as chorea and dystonia. In the striatum and brain, HD most typically impacts medium-spiny neurons. Molecular genetics, excitotoxicity, oxidative stress (OS), mitochondrial, and metabolic dysfunction are a few of the theories advanced to explicit the pathophysiology of neuronal damage and cell death. Numerous in-depth studies of the literature have supported the therapeutic advantages of natural products in HD experimental models and other treatment approaches. This article briefly discusses the neuroprotective impacts of natural compounds against HD models. The ability of the discovered natural compounds to suppress HD was tested using either in vitro or in vivo models. Many bioactive compounds considerably lessened the memory loss and motor coordination brought on by 3-nitropropionic acid (3-NP). Reduced lipid peroxidation, increased endogenous enzymatic antioxidants, reduced acetylcholinesterase activity, and enhanced mitochondrial energy generation have profoundly decreased the biochemical change. It is significant since histology showed that therapy with particular natural compounds lessened damage to the striatum caused by 3-NP. Moreover, natural products displayed varying degrees of neuroprotection in preclinical HD studies because of their antioxidant and anti-inflammatory properties, maintenance of mitochondrial function, activation of autophagy, and inhibition of apoptosis. This study highlighted about the importance of bioactive compounds and their semi-synthetic molecules in the treatment and prevention of HD.

The neuroprotective effect of traditional Chinese medicinal plants-A critical review

Neurodegenerative and neuropsychiatric diseases are increasingly affecting individuals' quality of life, thus increasing their cost to social and health systems. These diseases have overlapping mechanisms, such as oxidative stress, protein aggregation, neuroinflammation, neurotransmission impairment, mitochondrial dysfunction, and excitotoxicity. Currently, there is no cure for neurodegenerative diseases, and the available therapies have adverse effects and low efficacy. For neuropsychiatric disorders, such as depression, the current therapies are not adequate to one-third of the patients, the so-called treatment-resistant patients. So, searching for new treatments is fundamental. Medicinal plants appear as a strong alternative and complement towards new treatment protocols, as they have been used for health purposes for thousands of years. Thus, the main goal of this review is to revisit the neuroprotective potential of some of the most predominant medicinal plants (and one fungus) used in traditional Chinese medicine (TCM), focusing on their proven mechanisms of action and their chemical compositions, to give clues on how they can be useful against neurodegeneration progression.

Regulation of mitochondrial dysfunction induced cell apoptosis is a potential therapeutic strategy for herbal medicine to treat neurodegenerative diseases

Neurodegenerative disease is a progressive neurodegeneration caused by genetic and environmental factors. Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD) are the three most common neurodegenerative diseases clinically. Unfortunately, the incidence of neurodegenerative diseases is increasing year by year. However, the current available drugs have poor efficacy and large side effects, which brings a great burden to the patients and the society. Increasing evidence suggests that occurrence and development of the neurodegenerative diseases is closely related to the mitochondrial dysfunction, which can affect mitochondrial biogenesis, mitochondrial dynamics, as well as mitochondrial mitophagy. Through the disruption of mitochondrial homeostasis, nerve cells undergo varying degrees of apoptosis. Interestingly, it has been shown in recent years that the natural agents derived from herbal medicines are beneficial for prevention/treatment of neurodegenerative diseases via regulation of mitochondrial dysfunction. Therefore, in this review, we will focus on the potential therapeutic agents from herbal medicines for treating neurodegenerative diseases via suppressing apoptosis through regulation of mitochondrial dysfunction, in order to provide a foundation for the development of more candidate drugs for neurodegenerative diseases from herbal medicine.

Incorporation of a Biocompatible Nanozyme in Cellular Antioxidant Enzyme Cascade Reverses Huntington's Like Disorder in Preclinical Model

The potentiality of nano-enzymes in therapeutic use has directed contemporary research to develop a substitute for natural enzymes, which are suffering from several disadvantages including low stability, high cost, and difficulty in storage. However, inherent toxicity, inefficiency in the physiological milieu, and incompatibility to function in cellular enzyme networks limit the therapeutic use of nanozymes in living systems. Here, it is shown that citrate functionalized manganese-based biocompatible nanoscale material (C-Mn₃ O₄ NP) efficiently mimics glutathione peroxidase (GPx) enzyme in the physiological milieu and easily incorporates into the cellular multienzyme cascade for H₂ O₂ scavenging. A detailed computational study reveals the mechanism of the nanozyme action. The in vivo therapeutic efficacy of C-Mn₃ O₄ nanozyme is further established in a preclinical animal model of Huntington's disease (HD), a prevalent progressive neurodegenerative disorder, which has no effective medication to date. Management of HD in preclinical animal trial using a biocompatible (non-toxic) nanozyme as a part of the metabolic network may uncover a new paradigm in nanozyme based therapeutic strategy.

Loss of NRF2 accelerates cognitive decline, exacerbates mitochondrial dysfunction, and is required for the cognitive enhancing effects of Centella asiatica during aging

The water extract of Centella asiatica (CAW) improves cognitive and mitochondrial function and activates the nuclear factor erythroid 2-related factor 2 (NRF2) regulated antioxidant response pathway in aged mice. Here we investigate whether NRF2 activation is required for the cognitive and mitochondrial effects of prolonged CAW exposure during aging. Five-month-old NRF2 knockout (NRF2KO) and wild-type mice were treated with CAW for 1, 7, or 13 months. Each cohort underwent cognitive testing and hippocampal mitochondrial analyses. Age-related cognitive decline was accelerated in NRF2KO mice and while CAW treatment improved cognitive performance in wild-type mice, it had no effect on NRF2KO animals. Hippocampal mitochondrial function also declined further with age in NRF2KO mice and greater hippocampal mitochondrial dysfunction was associated with poorer cognitive performance in both genotypes. Long-term CAW treatment did not affect mitochondrial endpoints in animals of either genotype. These data indicate that loss of NRF2 results in accelerated age-related cognitive decline and worsened mitochondrial deficits. NRF2 also appears to be required for the cognitive enhancing effects of CAW during aging.

Mitochondrial and Redox-Based Therapeutic Strategies in Huntington's Disease

Significance: The molecular processes that determine Huntington's disease (HD) pathogenesis are not yet fully understood, and until now no effective neuroprotective therapeutic strategies have been developed. Mitochondria are one of most important organelles required for neuronal homeostasis, by providing metabolic pathways relevant for energy production, regulating calcium homeostasis, or controlling free radical generation and cell death. Because augmented reactive oxygen species (ROS) accompanied by mitochondrial dysfunction are relevant early HD mechanisms, targeting these cellular mechanisms may constitute relevant therapeutic approaches. Recent Advances: Previous findings point toward a close relationship between mitochondrial dysfunction and redox changes in HD. Mutant huntingtin (mHTT) can directly interact with mitochondrial proteins, as translocase of the inner membrane 23 (TIM23), disrupting mitochondrial proteostasis and favoring ROS production and HD progression. Furthermore, abnormal brain and muscle redox signaling contributes to altered proteostasis and motor impairment in HD, which can be improved with the mitochondria-targeted antioxidant mitoquinone or resveratrol, an SIRT1 activator that ameliorates mitochondrial biogenesis and function. Critical Issues: Various antioxidants and metabolic enhancers have been studied in HD; however, the real outcome of these molecules is still debatable. New compounds have proven to ameliorate mitochondrial and redox-based signaling pathways in early stages of HD, potentially precluding selective neurodegeneration. Future Directions: Unraveling the molecular etiology of deregulated mitochondrial function and dynamics, and oxidative stress opens new prospects for HD therapeutics. In this review, we explore the role of redox unbalance and mitochondrial dysfunction in HD progression, and further describe advances on clinical trials in HD based on mitochondrial and redox-based therapeutic strategies.

A Multimodal Hair-Loss Treatment Strategy Using a New Topical Phytoactive Formulation: A Report of Five Cases

Introduction. Current approved medications for hair loss, such as topical minoxidil and oral finasteride, may have suboptimal efficacy or side effects precluding continued use in some patients. Thus, we report an evaluation of the efficacy, safety, and tolerability of a new topical botanical formulation -GASHEE containing over 12 phytoactive ingredients that affect multiple targets in the cascade of pathophysiologic events that cause hair loss. Five patients with various hair-loss conditions, including cases of previous treatment failures, are presented. Case Presentation. This is a case series of four women and one man with hair loss due to various causes, four of whom had failed minoxidil treatment for over a year. All patients used the topical treatment as a sole therapy for at least 3 months before the documentation of outcomes, which involved interval changes noted through each patient's account, direct observation, and photography. Discussion. In all patients, we observed significant improvements in hair regrowth in the nape, crown, vertex, and temple areas after 3-15 months of treatment. All patients were highly satisfied with their results and reported no adverse events. Although the use of botanicals in the treatment of hair loss is in an infant stage, the new formulation used in this study demonstrated a good efficacy related to hair growth, warranting further evaluation.

Role of medicinal plants against neurodegenerative diseases

Diseases with a significant loss of neurons, structurally and functionally are termed as neurodegenerative diseases. Due to the present therapeutic interventions and progressive nature of diseases, a variety of side effects have risen up, thus leading the patients to go for an alternative medication. The role of medicinal plants in such cases has been beneficial because of their exhibition via different cellular and molecular mechanisms. Alleviation in inflammatory responses, suppression of the functionary aspect of pro-inflammatory cytokines like a tumor, improvement in antioxidative properties is among few neuroprotective mechanisms of traditional plants. Variation in transcription and transduction pathways play a vital role in the preventive measures of plants in such diseases. Neurodegenerative diseases are generally caused by depletion of proteins, oxidative and inflammatory stress, environmental changes and so on, with aging being the most important cause. Natural compounds can be used in order to treat neurodegenerative diseases Medicinal plants such as Ginseng, Withania somnifera, Bacopa monnieri, Ginkgo biloba, etc. are some of the medicinal plants for prevention of neurological symptoms. This review deals with the use of different medicinal plants for the prevention of neurodegenerative diseases.

Protective Effect of Natural Products against Huntington's Disease: An Overview of Scientific Evidence and Understanding Their Mechanism of Action

Huntington's disease (HD), a neurodegenerative disease, normally starts in the prime of adult life, followed by a gradual occurrence of characteristic psychiatric disturbances and cognitive and motor dysfunction. To the best of our knowledge, there is no treatment available to completely mitigate the progression of HD. Among various therapeutic approaches, exhaustive literature reports have confirmed the medicinal benefits of natural products in HD experimental models. Building on this information, this review presents a brief overview of the neuroprotective mechanism(s) of natural products against in vitro/in vivo models of HD. Relevant studies were identified from several scientific databases, including PubMed, ScienceDirect, Scopus, and Google Scholar. After screening through literature from 2005 to the present, a total of 14 medicinal plant species and 30 naturally isolated compounds investigated against HD based on either in vitro or in vivo models were included in the present review. Behavioral outcomes in the HD in vivo model showed that natural compounds significantly attenuated 3-nitropropionic acid (3-NP) induced memory loss and motor incoordination. The biochemical alteration has been markedly alleviated with reduced lipid peroxidation, increased endogenous enzymatic antioxidants, reduced acetylcholinesterase activity, and increased mitochondrial energy production. Interestingly, following treatment with certain natural products, 3-NP-induced damage in the striatum was ameliorated, as seen histologically. Overall, natural products afforded varying degrees of neuroprotection in preclinical studies of HD via antioxidant and anti-inflammatory properties, preservation of mitochondrial function, inhibition of apoptosis, and induction of autophagy.

NRF2 as a Therapeutic Target in Neurodegenerative Diseases

Increased reactive oxygen species production and oxidative stress have been implicated in the pathogenesis of numerous neurodegenerative conditions including among others Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, Friedrich’s ataxia, multiple sclerosis, and stroke. The endogenous antioxidant response pathway protects cells from oxidative stress by increasing the expression of cytoprotective enzymes and is regulated by the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2). In addition to regulating the expression of antioxidant genes, NRF2 has also been shown to exert anti-inflammatory effects and modulate both mitochondrial function and biogenesis. This is because mitochondrial dysfunction and neuroinflammation are features of many neurodegenerative diseases as well NRF2 has emerged as a promising therapeutic target. Here, we review evidence for a beneficial role of NRF2 in neurodegenerative conditions and the potential of specific NRF2 activators as therapeutic agents.

Effect of Edible Bird's Nest Extract on Lipopolysaccharide-Induced Impairment of Learning and Memory in Wistar Rats

Cognitive disability is a common feature associated with a variety of neurological conditions including Alzheimer's Disease (AD), Parkinson's Disease (PD), brain injury, and stroke. Emerging evidence has demonstrated that neuroinflammation plays an important role in the development of cognitive impairment. Current available therapies are relatively ineffective in treating or preventing cognitive disabilities, thus representing an important, unfulfilled medical need. Hence, developing potential treatment is one of the major areas of research interest. Edible bird's nests (EBN) are nests formed by swiftlet's saliva containing sialic acid, which is believed to improve brain function. This present study was embarked upon to evaluate the learning and memory enhancing potential effect of EBN by using Morris water maze test in a Wistar rat model of LPS-induced neuroinflammation. LPS elicited cognitive impairment in the rats by significantly increasing the escape latency while decreasing the number of entries in the probe trial, which are coupled with increased production of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and oxidative markers (ROS and TBARS) in the hippocampus. Treatment with EBN (125 mg/kg, 250 mg/kg, and 500 mg/kg; p.o.) effectively reversed the effect of LPS on escape latency and probe trial and, in addition, inhibited the LPS-induced upregulation of proinflammatory cytokines and oxidative markers. These findings are suggestive that there is existence of neuroprotective effect contained inside the edible bird's nest.

Centella asiatica increases hippocampal synaptic density and improves memory and executive function in aged mice

INTRODUCTION

Centella asiatica is a plant used for centuries to enhance memory. We have previously shown that a water extract of Centella asiatica (CAW) attenuates age-related spatial memory deficits in mice and improves neuronal health. Yet the effect of CAW on other cognitive domains remains unexplored as does its mechanism of improving age-related cognitive impairment. This study investigates the effects of CAW on a variety of cognitive tasks as well as on synaptic density and mitochondrial and antioxidant pathways.

METHODS

Twenty-month-old CB6F1 mice were treated with CAW (2 mg/ml) in their drinking water for 2 weeks prior to behavioral testing. Learning, memory, and executive function were assessed using the novel object recognition task (NORT), object location memory task (OLM), and odor discrimination reversal learning (ODRL) test. Tissue was collected for Golgi analysis of spine density as well as assessment of mitochondrial, antioxidant, and synaptic proteins.

RESULTS

CAW improved performance in all behavioral tests suggesting effects on hippocampal and cortical dependent memory as well as on prefrontal cortex mediated executive function. There was also an increase in synaptic density in the treated animals, which was accompanied by increased expression of the antioxidant response gene NRF2 as well as the mitochondrial marker porin.

CONCLUSIONS

These data show that CAW can increase synaptic density as well as antioxidant and mitochondrial proteins and improve multiple facets of age-related cognitive impairment. Because mitochondrial dysfunction and oxidative stress also accompany cognitive impairment in many pathological conditions this suggests a broad therapeutic utility of CAW.

Comparison of three different extracts of Centella asiatica for anti-amnesic, antioxidant and anticholinergic activities: in vitro and in vivo study

Centella asiatica (CA) has been used by Ayurvedic medical practitioners in India for almost 3000 years. The neuropharmacological properties of CA and its constituents have been studied extensively. Anti-oxidant, free radical scavenging and cholinergic modulatory activities are the reported mechanisms of action for its efficacy in memory disorders. Its medicinal values are mainly attributed to the presence of several triterpenes, namely asiatic acid, madecassic acid, asiaticoside, and madecassoside. The present study was aimed to investigate the role of these triterpenes content in CA extract on the antioxidant, cholinesterase modulation and anti-amnesic properties. The fractions of CA extract enriched for (CAE-EF) and depleted/freed of (CAE-FF) triterpenes contents were compared with methanolic extract (CAE). Both in vitro and in vivo methods for evaluation of antioxidant and anticholinergic activities were used. In vitro, free radical scavenging assays (ABTS, DPPH, NO, NORAC, and ORAC) and cholinesterase (AChE and BuChE) inhibition assays were used. For evaluation of anti-amnesic effect, scopolamine induced amnesia in rats, as the acute model of memory loss was used. Following behavioural assessments (MWM, PA, EPM), biomarkers of oxidative stress (reduced GSH, MDA and SOD activity) and cholinesterase (AChE and BuChE) status were also estimated in cerebral cortex and hippocampus of rat brain. The methanolic extract (CAE) was found to perform best among all three fractions for in vitro free radical scavenging, cholinesterase inhibition, improvement of scopolamine-induced amnesia and also in vivo antioxidant effect and cholinesterase inhibitory activities. Interestingly triterpenes free fraction (CAE-FF) showed better antioxidant activity than triterpenes enriched fraction (CAE-EF) along with comparable anti-amnesic effect. This indicates that triterpenes are not solely responsible for antioxidant activity, cholinesterase inhibitory and anti-amnesic effect of CA.

Ayurvedic Medicine for the Treatment of Dementia: Mechanistic Aspects

Ayurvedic medicine is a personalized system of traditional medicine native to India and the Indian subcontinent. It is based on a holistic view of treatment which promotes and supports equilibrium in different aspects of human life: the body, mind, and soul. Popular Ayurvedic medicinal plants and formulations that are used to slow down brain aging and enhance memory include Ashwagandha (Withania somnifera), Turmeric (Curcuma longa), Brahmi (Bacopa monnieri), Shankhpushpi (Convolvulus pluricaulis, Evolvulus alsinoides, and other species), gotu kola (Centella asiatica), and guggulu (Commiphora mukul and related species) and a formulation known as Brāhmī Ghṛita, containing Brahmi, Vacā (Acorus calamus), Kuṣṭha (Saussurea lappa), Shankhpushpi, and Purāṇa Ghṛita (old clarified butter/old ghee). The rationale for the utilization of Ayurvedic medicinal plants has depended mostly on traditional usage, with little scientific data on signal transduction processes, efficacy, and safety. However, in recent years, pharmacological and toxicological studies have begun to be published and receive attention from scientists for verification of their claimed pharmacological and therapeutic effects. The purpose of this review is to outline the molecular mechanisms, signal transduction processes, and sites of action of some Ayurvedic medicinal plants. It is hoped that this description can be further explored with modern scientific methods, to reveal new therapeutic leads and jump-start more studies on the use of Ayurvedic medicine for prevention and treatment of dementia.

Centella asiatica - Phytochemistry and mechanisms of neuroprotection and cognitive enhancement

This review describes in detail the phytochemistry and neurological effects of the medicinal herb Centella asiatica (L.) Urban. C. asiatica is a small perennial plant that grows in moist, tropical and sub-tropical regions throughout the world. Phytochemicals identified from C. asiatica to date include isoprenoids (sesquiterpenes, plant sterols, pentacyclic triterpenoids and saponins) and phenylpropanoid derivatives (eugenol derivatives, caffeoylquinic acids, and flavonoids). Contemporary methods for fingerprinting and characterization of compounds in C. asiatica extracts include liquid chromatography and/or ion mobility spectrometry in conjunction with high-resolution mass spectrometry. Multiple studies in rodent models, and a limited number of human studies support C. asiatica's traditional reputation as a cognitive enhancer, as well as its anxiolytic and anticonvulsant effects. Neuroprotective effects of C.asiatica are seen in several in vitro models, for example against beta amyloid toxicity, and appear to be associated with increased mitochondrial activity, improved antioxidant status, and/or inhibition of the pro-inflammatory enzyme, phospholipase A2. Neurotropic effects of C. asiatica include increased dendritic arborization and synaptogenesis, and may be due to modulations of signal transduction pathways such as ERK1/2 and Akt. Many of these neurotropic and neuroprotective properties of C.asiatica have been associated with the triterpene compounds asiatic acid, asiaticoside and madecassoside. More recently, caffeoylquinic acids are emerging as a second important group of active compounds in C. asiatica, with the potential of enhancing the Nrf2-antioxidant response pathway. The absorption, distribution, metabolism and excretion of the triterpenes, caffeoylquinic acids and flavonoids found in C. asiatica have been studied in humans and animal models, and the compounds or their metabolites found in the brain. This review highlights the remarkable potential for C. asiatica extracts and derivatives to be used in the treatment of neurological conditions, and considers the further research needed to actualize this possibility.

Complete Comparison Display (CCD) evaluation of ethanol extracts of Centella asiatica and Withania somnifera shows that they can non-synergistically ameliorate biochemical and behavioural damages in MPTP induced Parkinson's model of mice

Parkinson's disease remains as one of the most common debilitating neurodegenerative disorders. With the hopes of finding agents that can cure or reduce the pace of progression of the disease, we studied two traditional medicinal plants: Centella asiatica and Withania somnifera that have been explored in some recent studies. In agreement with the previous work on ethanol extracts of these two plants in mice model, we saw an improvement in oxidative stress profile as well as behavioral performance in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced Parkinson-like symptoms in Balb/c mice. Given the known potential of both the herbal extracts in improving Parkinson-like symptoms, we expected the combination of the two to show better results than either of the two but surprisingly there was no additivity in either oxidative stress or behavioural recovery. In fact, in some assays, the combination performed worse than either of the two individual constituents. This effect of mixtures highlights the need of testing mixtures in supplements market using enthomedicine. The necessity of comparing multiple groups in this study to get most information from the experiments motivated us to design a ladder-like visualization to show comparison with different groups that we call complete comparison display (CCD). In summary, we show the potential of Centella asiatica and Withania somnifera to ameliorate Parkinson's disorder.

The Role of Reactive Oxygen Species in the Pathogenesis of Alzheimer's Disease, Parkinson's Disease, and Huntington's Disease: A Mini Review

Neurodegenerative diseases affect not only the life quality of aging populations, but also their life spans. All forms of neurodegenerative diseases have a massive impact on the elderly. The major threat of these brain diseases includes progressive loss of memory, Alzheimer's disease (AD), impairments in the movement, Parkinson's disease (PD), and the inability to walk, talk, and think, Huntington's disease (HD). Oxidative stress and mitochondrial dysfunction are highlighted as a central feature of brain degenerative diseases. Oxidative stress, a condition that occurs due to imbalance in oxidant and antioxidant status, has been known to play a vital role in the pathophysiology of neurodegenerative diseases including AD, PD, and HD. A large number of studies have utilized oxidative stress biomarkers to investigate the severity of these neurodegenerative diseases and medications are available, but these only treat the symptoms. In traditional medicine, a large number of medicinal plants have been used to treat the symptoms of these neurodegenerative diseases. Extensive studies scientifically validated the beneficial effect of natural products against neurodegenerative diseases using suitable animal models. This short review focuses the role of oxidative stress in the pathogenesis of AD, PD, and HD and the protective efficacy of natural products against these diseases.

Characterization of age-dependent changes in the striatum: Response to the mitochondrial toxin 3-nitropropionic acid

Neurodegenerative phenomena are associated with mitochondrial dysfunction and this could be exacerbated by aging. Age-dependence of mitochondrial response to toxins could help understand these mechanisms and evolve novel therapeutics. 3-Nitropropionic acid (3-NPA) is a mitochondrial toxin that induces neurotoxicity in the striatum via inhibition of complex II. We investigated the age-related events that contribute to 3-NPA toxicity. 3-NPA induced neuronal death, oxidative stress and altered mitochondrial structure in neuronal cells. 3-NPA injection in vivo caused motor impairment, mitochondrial dysfunction and oxidative damage with different trend in young and adult mice. To understand the age-dependent mechanisms, we carried out proteomic analysis of the striatal protein extract from young mice (control: YC vs. 3-NPA treated: YT) and adult mice (control: AC vs. 3-NPA treated: AT). Among the 3752 identified proteins, 33 differentially expressed proteins (mitochondrial, synaptic and microsomal proteins) were unique either to YT or AT. Interestingly, comparison of the proteomic profile in AC and YC indicated that 161 proteins (linked with cytoskeletal structure, neuronal development, axogenesis, protein transport, cell adhesion and synaptic function) were down-regulated in AC compared to YC. We surmise that aging contributes to the cellular and molecular architecture in the mouse striatum with implications for neurodegeneration.

Centella asiatica Attenuates Amyloid-β-Induced Oxidative Stress and Mitochondrial Dysfunction

BACKGROUND

We previously showed that a water extract of the medicinal plant Centella asiatica (CAW) attenuates amyloid-β (Aβ)-induced cognitive deficits in vivo, and prevents Aβ-induced cytotoxicity in vitro. Yet the neuroprotective mechanism of CAW is unknown.

OBJECTIVE

The goal of this study was to identify biochemical pathways altered by CAW using in vitro models of Aβ toxicity.

METHODS

The effects of CAW on aberrations in antioxidant response, calcium homeostasis, and mitochondrial function induced by Aβ were evaluated in MC65 and SH-SY5Y neuroblastoma cells.

RESULTS

CAW decreased intracellular reactive oxygen species and calcium levels elevated in response to Aβ, and induced the expression of antioxidant response genes in both cell lines. In SH-SY5Y cells, CAW increased basal and maximal oxygen consumption without altering spare capacity, and attenuated Aβ-induced decreases in mitochondrial respiration. CAW also prevented Aβ-induced decreases in ATP and induced the expression of mitochondrial genes and proteins in both cell types. Caffeoylquinic acids from CAW were shown to have a similar effect on antioxidant and mitochondrial gene expression in neuroblastoma cells. Primary rat hippocampal neurons treated with CAW also showed an increase in mitochondrial and antioxidant gene expression.

CONCLUSIONS

These data suggest an effect of CAW on mitochondrial biogenesis, which in conjunction with activation of antioxidant response genes and normalizing calcium homeostasis, likely contributes to its neuroprotective action against Aβ toxicity.

Curcumin ameliorates dopaminergic neuronal oxidative damage via activation of the Akt/Nrf2 pathway

Parkinson's disease (PD) is an age-related complex neurodegenerative disease that affects ≤ 80% of dopaminergic neurons in the substantia nigra pars compacta (SNpc). It has previously been suggested that mitochondrial dysfunction, oxidative stress and oxidative damage underlie the pathogenesis of PD. Curcumin, which is a major active polyphenol component extracted from the rhizomes of Curcuma longa (Zingiberaceae), has been reported to exert neuroprotective effects on an experimental model of PD. The present study conducted a series of in vivo experiments, in order to investigate the effects of curcumin on behavioral deficits, oxidative damage and related mechanisms. The results demonstrated that curcumin was able to significantly alleviate motor dysfunction and increase suppressed tyrosine hydroxylase (TH) activity in the SNpc of rotenone (ROT)-injured rats. Biochemical measurements indicated that rats pretreated with curcumin exhibited increased glutathione (GSH) levels, and reduced reactive oxygen species activity and malondialdehyde content. Mechanistic studies demonstrated that curcumin significantly restored the expression levels of heme oxygenase-1 and

NAD(P)H

quinone oxidoreductase 1, thus ameliorating ROT-induced damage in vivo, via the phosphorylation of Akt and nuclear factor erythroid 2-related factor 2 (Nrf2). Further studies indicated that the Akt/Nrf2 signaling pathway was associated with the protective role of curcumin in ROT-treated rats. Inhibiting the Akt/Nrf2 pathway using a lentiviral vector containing Nrf2-specific short hairpin RNA, or the phosphoinositide 3-kinase inhibitor LY294002, markedly reduced the expression levels of TH and GSH, ultimately attenuating the neuroprotective effects of curcumin against oxidative damage. These results indicated that curcumin was able to significantly ameliorate ROT-induced dopaminergic neuronal oxidative damage in the SNpc of rats via activation of the Akt/Nrf2 signaling pathway.

Asiatic acid induces endoplasmic reticulum stress and apoptotic death in glioblastoma multiforme cells both in vitro and in vivo

Glioblastoma multiforme (GBM) is an untreatable malignancy. Existing therapeutic options are insufficient, and adversely affect functional and non-cancerous cells in the brain impairing different functions of the body. Therefore, there is an urgent need for additional preventive and therapeutic non-toxic drugs against GBM. Asiatic acid (AsA; 2,3,23-trihydroxy-12-ursen-28-oic acid, C30 H48 O5 ) is a natural small molecule widely used to treat various neurological disorders, and the present research investigates AsA's efficacy against GBM both in vitro and in vivo. Results showed that AsA treatment (10-100 µM) decreased the human GBM cell (LN18, U87MG, and U118MG) viability, with better efficacy than temozolomide at equimolar doses. Orally administered AsA (30 mg/kg/d) strongly decreased tumor volume in mice when administered immediately after ectopic U87MG xenograft implantation (54% decrease, P ≤ 0.05) or in mice with established xenografts (48% decrease, P ≤ 0.05) without any apparent toxicity. Importantly, AsA feeding (30 mg/kg/twice a day) also decreased the orthotopic U87MG xenografts growth in nude mice as measured by magnetic resonance imaging. Using LC/MS-MS methods, AsA was detected in mice plasma and brain tissue, confirming that AsA crosses blood-brain barrier. Mechanistic studies showed that AsA induces apoptotic death by modulating the protein expression of several apoptosis regulators (caspases, Bcl2 family members, and survivin) in GBM cells. Furthermore, AsA induced ER stress (increased GRP78 and Calpain, and decreased Calnexin and IRE1α expression), enhanced free intra-cellular calcium, and damaged cellular organization in GBM cells. These experimental results demonstrate that AsA is effective against GBM, and advocate further pre-clinical and clinical evaluations of AsA against GBM.

Plants and phytochemicals for Huntington's disease

Huntington's disease (HD) is a neurodegenerative disorder characterized by progressive motor dysfunction, including chorea and dystonia, emotional disturbances, memory, and weight loss. The medium spiny neurons of striatum and cortex are mainly effected in HD. Various hypotheses, including molecular genetics, oxidative stress, excitotoxicity, metabolic dysfunction, and mitochondrial impairment have been proposed to explain the pathogenesis of neuronal dysfunction and cell death. Despite no treatment is available to fully stop the progression of the disease, there are treatments available to help control the chorea. The present review deals with brief pathophysiology of the disease, plants and phytochemicals that have shown beneficial effects against HD like symptoms. The literature for the current review was collected using various databases such as Science direct, Pubmed, Scopus, Sci-finder, Google Scholar, and Cochrane database with a defined search strategy.

Neuroprotective efficacy of a combination of fish oil and ferulic acid against 3-nitropropionic acid-induced oxidative stress and neurotoxicity in rats: behavioural and biochemical evidence

The beneficial effects of fish oil (FO) supplements on the central nervous system have been adequately demonstrated. However, FO supplementation at higher doses for longer duration is likely to cause oxidative stress in vivo. To overcome this, attempts have been made to enrich FO with known antioxidants/phytochemicals. In the present study, we examined the hypothesis that a combination of FO with ferulic acid (FA), a naturally occurring phenolic compound, is likely to provide higher degree of neuroprotection. This was examined by employing 3-nitropropionic acid (NPA), a well-known neurotoxin used to mimic behavioural and neurochemical features of Huntington’s disease. Growing male rats administered with NPA (25 mg/kg of body weight (bw) for 4 days) were provided with either FO (2 mL/kg bw), FA (50 mg/kg bw) or FO+FA for 2 weeks. Interestingly, FO+FA not only offered significant protection against NPA-induced behavioural impairments, but also markedly attenuated oxidative stress in brain regions (striatum/cerebellum) as evidenced by the reduction in reactive species, malondialdehyde, hydroperoxides and nitric oxide (NO) levels. Further, FO+FA combination restored the activities of various antioxidant enzymes and the levels of cytosolic calcium. In striatum, activity levels of acetylcholinesterase enzyme and dopamine levels were markedly restored among FO+FA rats. Interestingly, NPA-induced mitochondrial dysfunctions were also attenuated among FO+FA rats. Collectively, our findings suggest the advantage of co-treatment of FO with known antioxidants to achieve a higher therapeutic benefit in the treatment of oxidative stress-mediated neurodegenerative conditions.

Standardized extract of Withania somnifera (Ashwagandha) markedly offsets rotenone-induced locomotor deficits, oxidative impairments and neurotoxicity in Drosophila melanogaster

Withania somnifera (Ashwagandha, WS) or Indian ginseng possesses multiple pharmacological properties which are mainly attributed to the active constituents, withanolides. Despite its extensive usage as a memory enhancer and a nerve tonic, few attempts have been made to ascertain its usage in the management of Parkinson's disease. In the present study, we investigated the neuroameliorative effects of WS in a rotenone (ROT) model of Drosophila melanogaster (Oregon-K). Initially, we ascertained the ability of WS-enriched diet (0-0.05 %) to protect against ROT induced lethality and locomotor phenotype in adult male flies. Further, employing a co-exposure paradigm, we investigated the propensity of WS to offset ROT-induced oxidative stress, mitochondrial dysfunctions and neurotoxicity. WS conferred significant protection against ROT-induced lethality, while the survivor flies exhibited improved locomotor phenotype. Biochemical investigations revealed that ROT-induced oxidative stress was significantly diminished by WS enrichment. WS caused significant elevation in the levels of reduced GSH/non-protein thiols. Furthermore, the altered activity levels of succinate dehydrogenase, MTT, membrane bound enzymes viz., NADH-cytochrome-c reductase and succinate-cytochrome-c reductase were markedly restored to normalcy. Interestingly, ROT-induced perturbations in cholinergic function and depletion in dopamine levels were normalized by WS. Taken together these data suggests that the neuromodulatory effect of WS against ROT- induced neurotoxicity is probably mediated via suppression of oxidative stress and its potential to attenuate mitochondrial dysfunctions. Our further studies aim to understand the underlying neuroprotective mechanisms of WS and withanolides employing neuronal cell models.

Centelloside accumulation in leaves of Centella asiatica is determined by resource partitioning between primary and secondary metabolism while influenced by supply levels of either nitrogen, phosphorus or potassium

In the present study we aimed to investigate the relevance of either N, P or K supply for herb and leaf yield and for centelloside concentrations in Centella asiatica L. Urban leaves. In this regard, we elucidated the causal relationship between assimilation rate, leaf N, P and K concentrations, herb and leaf production, and centelloside accumulation. The experiments were conducted consecutively in a greenhouse where C. asiatica was grown in hydroponic culture and fertigated with nutrient solutions at either 0, 30, 60, 100 or 150% of the N, P or K amount in a standard Hoagland solution. In general, the increase in N, P or K supply enhanced assimilation rate and herb and leaf yield. However, exceeding specific thresholds, the high availability of one single nutrient caused lower leaf N concentrations and a decline in assimilation rate and plant growth. Irrespective of N, P and K supply, the leaf centelloside concentrations were negatively associated with herb and leaf yield, which is in accordance with the assumptions of the carbon/nutrient balance and the growth differentiation balance hypotheses. Moreover, we found strong negative correlations between saponins and leaf N concentrations, while the respective sapogenins were negatively correlated with K concentrations. Using C. asiatica as model system, our experiments reveal for the first time that the accumulation of saponins and sapogenins is affected by resource allocation between primary and secondary metabolism and that besides carbon, also nutrient availability is relevant for the regulation of the centelloside synthesis. Finally, our results highlight the huge potential of optimized and carefully controlled mineral nutrition of medicinal plants for steering the bio-production of high-quality natural products.

Enhanced neuroprotective effect of fish oil in combination with quercetin against 3-nitropropionic acid induced oxidative stress in rat brain

While the beneficial effects of fish oil (FO) supplements on the central nervous system function are well established, few findings have led to the hypothesis that long term n-3 polyunsaturated fatty acid (n-3 PUFA) supplements at higher doses render the membranes more susceptible to lipid peroxidation. Hence recent studies suggest the use of dietary antioxidants as adjuncts with n-3 fatty acids to effectively improve the clinical outcome in neurological disorders. In the present investigation, we examined the hypothesis, if enrichment of FO with quercetin (a natural flavonoid) can provide a higher degree of neuroprotection and tested the same in a 3-nitropropionic acid (NPA) rat model. Growing male rats administered with NPA (25 mg/kg bw/d, i.p. 4 days) were provided either with FO (2 mL/kg bw), or Q (25mg/kg bw) or FO+Q for 14 days. NPA elicited marked oxidative stress in brain (striatum and cerebellum) as evidenced by significantly enhanced ROS, malondialdehyde, protein carbonyls and nitric oxide levels. Although varying degree of protection was evident among FO or Q groups, complete normalization of oxidative markers ensued only among FO+Q rats. Further, FO+Q combination completely normalized the elevated acetylcholinesterase activity and protected against NPA-induced mitochondrial dysfunctions. NPA induced depletion of dopamine levels was restored among all groups. Interestingly, NPA induced motor deficits were significantly improved among FO+Q rats. However, further studies are necessary to understand the mechanism/s by which FO enrichment with Q provides higher degree of protection. Nevertheless, our findings clearly suggest that the use of natural phytochemicals with moderate doses of FO may provide better neuroprotection and higher therapeutic advantage in the prevention or treatment of neurodegenerative diseases like Huntington's disease.

Naringin modulates oxidative stress and inflammation in 3-nitropropionic acid-induced neurodegeneration through the activation of nuclear factor-erythroid 2-related factor-2 signalling pathway

Nuclear factor-erythroid 2-related factor-2 (Nrf2) mediated regulation of cellular antioxidant production and the anti-inflammatory mechanism play an important role in neuroprotection against neurodegenerative diseases. Naringin a citrus flavonone, has been reported to possess neuroprotective effect against Huntington's disease, and other neurodegenerative disorders, however the mechanisms underlying its beneficial effects on 3-nitropropionic acid (3-NP)-induced neurodegeneration are poorly defined. The objective of the present study was to investigate the neuroprotective role of naringin and delineate the mechanism of action on 3-NP-induced neurodegeneration. Rats were injected with 3-NP (10mg/kg body weight/day, i.p.) for 2 weeks to develop neurodegeneration, while naringin (80 mg/kg body weight/day, orally) was administered throughout the experimental period, 1h prior to 3-NP exposure. Thereafter rats were euthanized for biochemical, histological, and molecular studies. Treatment with naringin ameliorated the reduced glutathione/oxidized glutathione ratio with concomitant decrease in the levels of hydroxyl radical, hydroperoxide and nitrite in 3-NP-induced rats. Nissl staining and transmission electron microscopic studies showed that naringin modulated 3-NP-induced histological changes. Naringin induces NAD(P)H:quinone oxidoreductase-1, heme oxygenase-1, glutathione S-transferase P1 and gamma-glutamylcysteine ligase mRNA expressions through the activation of Nrf2 and decreased the expressions of pro-inflammatory mediators like tumour necrosis factor-alpha, cyclooxygenase-2 and inducible nitric oxide synthase. These results indicate that naringin might be beneficial in mitigating 3-NP-induced neurodegeneration through the enhancement of phase II and antioxidant gene expressions via Nrf2 activation; thereby modulating the oxidative stress and inflammatory responses.

Mitoprotective effect of Centella asiatica against aluminum-induced neurotoxicity in rats: possible relevance to its anti-oxidant and anti-apoptosis mechanism

Role of mitochondrial dysfunction and oxidative stress has been well documented in various cognitive-related disorders such as Alzheimer's disease. Aluminum is a neurotoxic metal that may be involved in the progression of neurodegenerative processes. The antioxidant and memory enhancing effects of Centella asiatica (CA) are well known in the last few decades. Therefore, the present study has been designed to explore the neuroprotective effect of CA on chronic aluminum exposure induced mitochondrial enzyme alteration, oxidative stress, apoptosis and cognitive dysfunction in rat. Aluminum (100 mg/kg) and CA (150 and 300 mg/kg) were administered daily for a period of 6 weeks in male Wistar rats. Various behavioral, biochemical and cellular estimations and aluminum concentration were assessed. Chronic aluminum administration resulted in memory impairment and caused marked oxidative damage associated with mitochondria impairment. It also caused a significant increase in caspase-3 activity, acetylcholine esterase activity and aluminum concentration in hippocampus and cerebral cortex of rat brain. Chronic administration of CA significantly improved memory performance, oxidative defense decreased aluminum concentration, caspase-3, acetylcholinestrease activity and reversal of mitochondrial enzyme activity as compared to aluminum-treated animals. Results of the study demonstrate neuroprotective potential of CA against aluminum-induced cognitive dysfunction and mito- oxidative damage.

Neuroprotective efficacy of eugenol and isoeugenol in acrylamide-induced neuropathy in rats: behavioral and biochemical evidence

The primary objective of this investigation was to assess the neuroprotective efficacy of spice active principles namely Eugenol (Eug) and isoeugenol (IE) in an acrylamide (ACR) neuropathy model in rats. In the present study, ACR administration (50 mg/kg bw, i.p. 3 times/week) for 5 weeks to growing rats caused typical symptoms of neuropathy. We found that treatment of ACR rats with spice active principles (10 mg/kg bw, for 5 weeks) caused marked improvement in gait score and responses in a battery of behavioral tests. Terminally, both spice active principles markedly attenuated ACR-induced markers of oxidative stress viz., reactive oxygen species (ROS), malondialdehyde (MDA) and nitric oxide (NO) in sciatic nerve (SN) as well as brain regions (cortex Ct, cerebellum Cb). Treatment with Eug restored the reduced glutathione levels in SN and brain regions. Interestingly, both spice active principles effectively diminished ACR-induced elevation in cytosolic calcium levels and acetylcholinesterase activity in SN and Ct. Further, the diminished activity of ATPase among ACR rats was enhanced in SN and restored in brain regions. Furthermore, Eug treatment significantly offset ACR-induced depletion in dopamine levels in brain regions. Collectively our findings suggest the propensity of these spice active principles to attenuate ACR-induced neuropathy. Further studies are necessary to understand the precise molecular mechanism/s by which these spice active principles attenuate neuropathy. Nevertheless, our data clearly demonstrate the beneficial effects of spice active principles in ACR-induced neuropathy in rats and suggest their possible therapeutic usage as an adjuvant in the management of other forms of neuropathy in humans.

Microwave blanching and drying characteristics of Centella asiatica (L.) urban leaves using tray and heat pump-assisted dehumidified drying

The appropriate stage of maturity of Centella asiatica (L.) Urban leaves was investigated. Mature leaves with large diameter contained high total phenolics and % inhibition. Microwave blanching for 30 s retained the highest total phenolics and the microwave blanching for 30 s and 45 s retained the highest % inhibition. Modified Henderson and Modified Chung-Pfost models showed the best fit to both fresh and blanched leaves for equilibrium moisture content, Xe = f(RHe, T) and equilibrium relative humidity, RHe = f(Xe, T), respectively. The Modified Page model was the most effective model in describing the leaf drying. All drying was in the falling rate period. The drying constant was related to drying air temperature using the Arrhenius model. Effective moisture diffusivities increased with increasing temperature and blanching treatments as well as dehumidification by heat pump-assisted dehumidified dryer. The heat pump-assited dehumidified drying incorporated by the microwave blanching could reduce the drying time at 40 °C by 31.2 % and increase % inhibition by 6.1 %. Quality evaluation by total phenolics, % inhibition and rehydration ratio showed the best quality for C. asiatica leaves pretreated by microwave blanching and dried at 40 °C in heat pump-assisted dehumidified dryer.

Critical evaluation of ayurvedic plants for stimulating intrinsic antioxidant response

Oxidative damage caused by free radicals plays an important role in the causation and progression of many diseases, including aging. Free-radical damage is countered by many mechanisms, including both active antioxidant enzymatic activity in our body and passive antioxidants. Antioxidant response of our body can accommodate increased oxidative damage in diseased states to a level but beyond that level, additional antioxidants are required to combat the increased stress. Apart from the regular dietary sources of antioxidants, many traditional herbal medicines demonstrate a potential to boost antioxidant activity. Rasayana chikitsa that deals with rejuvenation and revitalization is a branch of the Indian traditional medical system of ayurveda. We review some select herbs described in rasayana chikitsa that have been assessed by modern means for stimulating intrinsic antioxidant responses in humans. A critical evaluation of rasayana chikitsa will likely provide urgently needed, actual stimulants of our physiological antioxidant responses and not just more passive antioxidants to add to an already large catalog.

Evidence of acrylamide induced oxidative stress and neurotoxicity in Drosophila melanogaster - its amelioration with spice active enrichment: relevance to neuropathy

Acrylamide (ACR) intoxication in its monomeric form leads to neuronal damage in both experimental animals and humans. Oxidative stress is one of the principle mechanisms related to the neurotoxicity of ACR exposure. Hence, the present study aimed to recapitulate the potential of ACR to cause oxidative stress and neurotoxic effects in Drosophila melanogaster. Exposure of adult male flies (Oregon K strain) to ACR (1-10 mM, 7 d) in the diet resulted in a concentration and time dependent mortality, while the survivors exhibited significant locomotor deficits. Further, ACR exposure (1-5 mM, 3 d) caused robust oxidative stress as evidenced by markedly elevated levels of reactive oxygen species and hypdroperoxides in head/body regions. Enhanced lipid peroxidation, perturbations in the activities of antioxidant enzymes accompanied with depletion of reduced glutathione levels in head region at high concentrations suggested induction of oxidative stress. Further, marked diminution in the activities of complexes I-III, Succinic dehydrogenase, with concomitant reduction in MTT suggested the propensity of ACR to impair mitochondrial function. Furthermore, ACR-induced neurotoxic effects were discernible in terms of diminished ATPase activity, enhanced activity of acetylcholinesterase and dopamine depletion. In a satellite study, employing a co-exposure paradigm, we tested the propensity of spice actives namely eugenol (EU) and isoeugenol (IE) to ameliorate ACR-induced neurotoxicity. EU/IE enriched diet offered marked protection against ACR-induced mortality, locomotor dysfunctions and oxidative stress. Furthermore, the spice actives prevented the depletion of reduced GSH levels, maintained the activity of AChE enzyme and dopamine levels in head region. Collectively, these findings clearly demonstrate that ACR induced neurotoxicity in Drosophila may be mediated through oxidative stress mechanisms and the potential of spice actives to abrogate the condition. These data suggest that Drosophila may serve as a suitable model to understand the possible mechanism/s associated with ACR associated neuropathy.

Pretreatment with Bacopa monnieri extract offsets 3-nitropropionic acid induced mitochondrial oxidative stress and dysfunctions in the striatum of prepubertal mouse brain

The present investigation was designed to determine the efficacy of Bacopa monnieri (Brahmi; BM) to offset 3-nitropropionic acid (3-NPA) induced oxidative stress and mitochondrial dysfunction in dopaminergic (N27) cells and prepubertal mouse brain. Pretreatment of N27 cells with BM ethanolic extract (BME) significantly attenuated 3-NPA-induced cytotoxicity. Further, we determined the degree of oxidative stress induction, redox status, enzymic antioxidants, and protein oxidation in the striatal mitochondria of mice given BME prophylaxis followed by 3-NPA challenge. While 3-NPA-induced marked oxidative stress in the mitochondria of the striatum, BME prophylaxis markedly prevented 3-NPA-induced oxidative dysfunctions and depletion of reduced glutathione and thiol levels. The activities of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, glutathione reductase, thioredoxin reductase), Na(+),K(+)-ATPase, and citric acid cycle enzymes in the striatum discernible among 3-NPA mice were significantly restored with BME prophylaxis. Interestingly, BME offered protection against 3-NPA-induced mitochondrial dysfunctions as evidenced by the restoration of the activities of ETC enzymes (NADH:ubiquinone oxidoreductase, NADH:cytochrome c reductase, succinate-ubiquinone oxidoreductase, and cytochrome c oxidase) and mitochondrial viability. We hypothesize that the neuroprotective effects of BME may be wholly or in part related to its propensity to scavenge free radicals, maintain redox status, and upregulate antioxidant machinery in striatal mitochondria.

Neuromodulatory propensity of Bacopa monnieri leaf extract against 3-nitropropionic acid-induced oxidative stress: in vitro and in vivo evidences

We previously reported the propensity of Bacopa monnieri (BM) leaf powder to modulate endogenous levels of oxidative stress markers in the brain of prepubertal mice. In this study, we tested the hypothesis that pretreatment with an alcoholic extract of BM (BME) could provide neuroprotection against 3-nitropropionic acid (3-NPA)-induced oxidative stress under in vitro and in vivo conditions. In chemical systems, BME exhibited multiple free radical scavenging ability. Further, BME pretreatment completely abolished 3-NPA-induced oxidative stress response in brain (striatum, St) mitochondria in vitro. Likewise, pretreatment of dopaminergic (N27 cell lines) cells with BME not only abrogated the generation of reactive oxygen species (ROS) levels, but also offered marked protection against 3-NPA-mediated cytotoxicity. These findings were further validated employing a 3-NPA mice model in vivo. We determined the degree of oxidative stress induction, redox status, enzymic antioxidants, protein oxidation, and cholinergic function in various brain regions of male mice provided with BME for 10 days (prophylaxis) followed by 3-NPA challenge (75 mg/kg bw/day, i.p.). BME prophylaxis completely prevented 3-NPA-induced oxidative dysfunctions in St and other brain regions. 3-NPA-induced robust elevation of oxidative markers (malondialdehyde levels, ROS generation, hydroperoxide levels and protein carbonyls) in cytosol of brain regions was predominantly abolished among mice given BME prophylaxis. Interestingly, BME prophylaxis also prevented the depletion of reduced glutathione, thiol levels, and perturbations in antioxidant enzymes caused by 3-NPA. Collectively these findings provide evidence on the significant prophylactic neuroprotective efficacy of BME in prepubertal mice brain. Based on these data, it is hypothesized that BME can serve as a useful adjuvant in protecting brain against oxidative-mediated neurodegenerative disorders involving oxidative stress conditions.

Bacopa monnieri extract offsets rotenone-induced cytotoxicity in dopaminergic cells and oxidative impairments in mice brain

Bacopa monnieri (BM), an ayurvedic medicinal herb is widely known for its memory enhancing ability and improvement of brain function. In this study, we tested the hypothesis that BM extract (BME) could offset neurotoxicant-induced oxidative dysfunctions in developing brain in a rotenone (ROT) mouse model. Pretreatment of dopaminergic (N27 cell lines) cells with BME exhibited significant cytoprotective effect as evidenced by the attenuation of ROT-induced oxidative stress and cell death. Further, the neuroprotective efficacy of BME was assessed in prepubertal mice administered ROT (i.p. 1.0 mg/kg b.w./day) for 7 days. BME treatment significantly offset ROT-induced oxidative damage in striatum (St) and other brain regions as evident by the normalized levels of oxidative markers (malondialdehyde, ROS levels, and hydroperoxides) and restoration of depleted GSH levels. Further, BME effectively normalized the protein carbonyl content in all brain regions suggesting its ability to prevent protein oxidation. Furthermore, BME treatment restored the activity levels of cytosolic antioxidant enzymes, neurotransmitter function, and dopamine levels in St. Based on our findings, we hypothesize that the neuroprotective effects of BM extract may be at least in part related to its ability to enhance reduced glutathione and antioxidant defenses in brain regions. It is suggested that BM may be effectively exploited as a prophylactic/therapeutic adjuvant for neurodegenerative disorders involving oxidative stress.

Neuroprotective effect of naringin, a dietary flavonoid against 3-nitropropionic acid-induced neuronal apoptosis

The aim of this study was to investigate the protective effect of naringin, a flavonoid on 3-Nitropropionic acid (3-NP)-induced neurodegeneration through the modulation of intrinsic apoptotic cascade in Wistar rats. 3-NP is an irreversible inhibitor of complex II in the mitochondria. 3-NP-induced neurodegeneration has been widely used as an animal model of Huntington's disease (HD). Increased oxidative stress is one of the major deleterious events in 3-NP-induced neuronal apoptosis. Rats administered with 3-NP showed increase in the levels of lipid peroxidation and protein carbonyl, which was significantly decreased upon naringin treatment (80 mg/kg body weight). 3-NP-induced rats showed decrease in the activities of enzymic antioxidants and reduced levels of non-enzymic antioxidants. Naringin treatment ameliorated the antioxidant status by increasing the activities of enzymic antioxidants and the levels of non-enzymatic antioxidants. 3-NP-induced rats showed decrease in the activities of ATPases in striatum, which was restored to normal level upon naringin treatment. Histopathological observation of the striatal tissue showed protective role of naringin in 3-NP-induced rats. Naringin also reduced the 3-NP-induced apoptosis via decrease in the cytochrome c release from mitochondria and caspase 3 activation as revealed by Western blot. Naringin treatment also decreased the expressions of pro-apoptotic markers like Bad and Bax. Further, naringin antagonized 3-NP-induced decrease in Bcl-2 mRNA expression. The results of this study show evidence on the neuroprotective effect of naringin against 3-NP-induced neuronal apoptosis through its antioxidant and anti-apoptotic effects.

Asiatic acid inhibits pro-angiogenic effects of VEGF and human gliomas in endothelial cell culture models

Malignant gliomas are one of the most devastating and incurable tumors. Sustained excessive angiogenesis by glioma cells is the major reason for their uncontrolled growth and resistance toward conventional therapies resulting in high mortality. Therefore, targeting angiogenesis should be a logical strategy to prevent or control glioma cell growth. Earlier studies have shown that Asiatic Acid (AsA), a pentacyclic triterpenoid, is effective against glioma and other cancer cells; however, its efficacy against angiogenesis remains unknown. In the present study, we examined the anti-angiogenic efficacy of AsA using human umbilical vein endothelial cells (HUVEC) and human brain microvascular endothelial cells (HBMEC). Our results showed that AsA (5–20 µM) inhibits HUVEC growth and induces apoptotic cell death by activating caspases (3 and 9) and modulating the expression of apoptosis regulators Bad, survivin and pAkt-ser473. Further, AsA showed a dose-dependent inhibition of HUVEC migration, invasion and capillary tube formation, and disintegrated preformed capillary network. AsA also inhibited the VEGF-stimulated growth and capillary tube formation by HUVEC and HBMEC. Next, we analyzed the angiogenic potential of conditioned media collected from human glioma LN18 and U87-MG cells treated with either DMSO (control conditioned media, CCM) or AsA 20 µM (AsA20 conditioned media, AsA20CM). CCM from glioma cells significantly enhanced the capillary tube formation in both HUVEC and HBMEC, while capillary tube formation in both endothelial cell lines was greatly compromised in the presence of AsA20CM. Consistent with these results, VEGF expression was lesser in AsA20CM compared to CCM, and indeed AsA strongly inhibited VEGF level (both cellular and secreted) in glioma cells. AsA also showed dose-dependent anti-angiogenic efficacy in Matrigel plug assay, and inhibited the glioma cells potential to attract HUVEC/HBMEC. Overall, the present study clearly showed the strong anti-angiogenic potential of AsA and suggests its usefulness against malignant gliomas.