Neuroprotective Properties of Asiatic Acid against 5-Fluorouracil Chemotherapy in the Hippocampus in an Adult Rat Model

Nasal Delivery of Asiatic Acid Ameliorates Scopolamine-Induced Memory Dysfunction in Mice

Asiatic acid (AA) has previously shown its neuroprotective effects, but low oral bioavailability limits its penetration into the brain. This study aimed to investigate the effect of intranasal AA administration in mice with memory dysfunction induced by scopolamine. Mice received either intranasal AA (INAA), oral AA (POAA3 or POAA30), or donepezil, followed by scopolamine for 10 days. Morris water maze (MWM) was performed on days 0-5, 30 min after treatment. Locomotor activity was conducted on day 6 followed by brain collection. In MWM, INAA treatment had significantly reduced escape latency on days 2-4, while POAA3 decreased escape latency on day 3 and POAA30 and donepezil decreased escape latency on day 4. INAA inhibited acetylcholinesterase activity, increased catalase protein expression, and decreased malondialdehyde levels in the brain tissue. Therefore, intranasal administration of AA produced a rapid onset in the protection of learning and memory deficits induced by scopolamine through acetylcholinesterase inhibition and antioxidant effect.

Medicinal herbal remedies in neurodegenerative diseases: an update on antioxidant potential

It has been widely documented that medicinal herbal remedies are effective, have fewer side effects than conventional medicine, and have a synergistic effect on health collaborations in the fight against complicated diseases. Traditional treatments for neurological problems in ancient times sometimes involved the use of herbal remedies and conventional methods from East Asian countries including India, Japan, China, and Korea. We collected and reviewed studies on plant-derived neuroprotective drugs and tested them in neurotoxic models. Basic research, preclinical and clinical transgene research can benefit from in silico, in vitro, and in vivo investigations. Research, summaries of the extracts, fractions, and herbal ingredients were compiled from popular scientific databases, which were then examined according to origin and bioactivity. Given the complex and varied causes of neurodegeneration, it may be beneficial to focus on multiple mechanisms of action and a neuroprotection approach. This approach aims to prevent cell death and restore function to damaged neurons, offering promising strategies for preventing and treating neurodegenerative diseases. Neurodegenerative illnesses can potentially be treated with natural compounds that have been identified as neuroprotective agents. To gain deeper insights into the neuropharmacological mechanisms underlying the neuroprotective and therapeutic properties of naturally occurring antioxidant phytochemical compounds in diverse neurodegenerative diseases, this study aims to comprehensively review such compounds, focusing on their modulation of apoptotic markers such as caspase, Bax, Bcl-2, and proinflammatory markers. In addition, we delve into a range of efficacies of antioxidant phytochemical compounds as neuroprotective agents in animal models. They reduce the oxidative stress of the brain and have been shown to have anti-apoptotic effects. Many researches have demonstrated that plant extracts or bioactive compounds can fight neurodegenerative disorders. Herbal medications may offer neurodegenerative disease patients' new treatments. This may be a cheaper and more culturally appropriate alternative to standard drugs for millions of people with age-related NDDs.

Ganoderma lucidum Polysaccharide Peptide Alleviates Cyclophosphamide-Induced Male Reproductive Injury by Reducing Oxidative Stress and Apoptosis

Chemotherapy is an important factor leading to male infertility. It is crucial to discover safe and effective treatments to prevent male reproductive injury caused by chemotherapy. The Ganoderma lucidum polysaccharide peptide (GLPP) has multiple pharmacological activities. The purpose of this study was to determine whether GLPP could protect the male sperm production from chemotherapeutic injury using a mouse model, with testicular damage induced by cyclophosphamide (CP). CP (50 mg/kg/day) was injected intraperitoneally into male ICR mice gavaged with different doses of GLPP at certain spermatogenic stages. The experimental results showed that GLPP alleviated the CP-induced reduction in reproductive organ coefficients and sperm parameters and reduced the morphological damage of testicular tissues in a dose-dependent manner. GLPP significantly improved the reproductive index, sperm-related parameters, sex hormone levels, and histological testis architecture at different spermatogenic stages. Furthermore, GLPP significantly increased superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), Nrf2, and HO-1, and decreased malondialdehyde (MDA) and Keap-1 in the testicular tissue, indicating reduced oxidative stress. In addition, GLPP limited CP-induced apoptosis via a reduction in Bax expression and increase in Bcl-2 expression. This study suggests that GLPP plays a protective role in spermatogenesis by reducing chemotherapeutic injury and might be developed into drug for male patients receiving chemotherapy.

Can Asiatic Acid from Centella asiatica Be a Potential Remedy in Cancer Therapy?-A Review

Centella asiatica has been recognized for centuries in Eastern medicine for its pharmacological properties. Due to the increasing prevalence of oncological diseases worldwide, natural substances that could qualify as anticancer therapeutics are becoming increasingly important subjects of research. This review aims to find an innovative use for asiatic acid (AA) in the treatment or support of cancer therapy. It has been demonstrated that AA takes part in inhibiting phosphorylation, inducing cell death, and reducing tumor growth and metastasis by influencing important signaling pathways, such as PI3K, Akt, mTOR, p70S6K, and STAT3, in cancer cells. It is also worth mentioning the high importance of asiatic acid in reducing the expression of markers such as N-cadherin, β-catenin, claudin-1, and vimentin. Some studies have indicated the potential of asiatic acid to induce autophagy in cancer cells through changes in the levels of specific proteins such as LC3 and p62. It can also act as an anti-tumor immunotherapeutic agent, thanks to its inductive effect on Smad7 in combination with naringenin (an Smad3 inhibitor). It seems that asiatic acid may be a potential anticancer drug or form of adjunctive therapy. Further studies should take into account safety and toxicity issues, as well as limitations related to the pharmacokinetics of AA and its low oral bioavailability.

Natural products for the treatment of chemotherapy-related cognitive impairment and prospects of nose-to-brain drug delivery

Chemotherapy-related cognitive deficits (CRCI) as one of the common adverse drug reactions during chemotherapy that manifest as memory, attention, and executive function impairments. However, there are still no effective pharmacological therapies for the treatment of CRCI. Natural compounds have always inspired drug development and numerous natural products have shown potential therapeutic effects on CRCI. Nevertheless, improving the brain targeting of natural compounds in the treatment of CRCI is still a problem to be overcome at present and in the future. Accumulated evidence shows that nose-to-brain drug delivery may be an excellent carrier for natural compounds. Therefore, we reviewed natural products with potential anti-CRCI, focusing on the signaling pathway of these drugs' anti-CRCI effects, as well as the possibility and prospect of treating CRCI with natural compounds based on nose-to-brain drug delivery in the future. In conclusion, this review provides new insights to further explore natural products in the treatment of CRCI.

Asiatic acid protects against pressure overload-induced heart failure in mice by inhibiting mitochondria-dependent apoptosis

BACKGROUND

Mitochondrial dysfunction and subsequent cardiomyocyte apoptosis significantly contribute to pressure overload-induced heart failure (HF). A highly oxidative environment leads to mitochondrial damage, further exacerbating this condition. Asiatic acid (AA), a proven antioxidant and anti-hypertrophic agent, might provide a solution, but its role and mechanisms in chronic pressure overload-induced HF remain largely unexplored.

METHODS

We induced pressure overload in mice using transverse aortic constriction (TAC) and treated them with AA (100 mg/kg/day) or vehicle daily by oral gavage for 8 weeks. The effects of AA on mitochondrial dysfunction, oxidative stress-associated signaling pathways, and overall survival were evaluated. Additionally, an in vitro model using hydrogen peroxide-exposed neonatal rat cardiomyocytes was established to further investigate the role of AA in oxidative stress-induced mitochondrial apoptosis.

RESULTS

AA treatment significantly improved survival and alleviated cardiac dysfunction in TAC-induced HF mice. It preserved mitochondrial structure, reduced the LVW/BW ratio by 20.24%, mitigated TAC-induced mitochondrial-dependent apoptosis by significantly lowering the Bax/Bcl-2 ratio and cleaved caspase-9/3 levels, and attenuated oxidative stress. AA treatment protected cardiomyocytes from hydrogen peroxide-induced apoptosis, with concurrent modulation of mitochondrial-dependent apoptosis pathway-related proteins and the JNK pathway.

CONCLUSIONS

Our findings suggest that AA effectively combats chronic TAC-induced and hydrogen peroxide-induced cardiomyocyte apoptosis through a mitochondria-dependent mechanism. AA reduces cellular levels of oxidative stress and inhibits the activation of the JNK pathway, highlighting its potential therapeutic value in the treatment of HF.

Disorders of the central nervous system: Insights from Notch and Nrf2 signaling

The functional complexity of the central nervous system (CNS) is unparalleled in living organisms. It arises from neural crest-derived cells that migrate by the exact route, leading to the formation of a complex network of neurons and glial cells. Recent studies have shown that novel crosstalk exists between the Notch1 and Nrf2 pathways and is associated with many neurological diseases. The Notch1-Nrf2 axis may act on nervous system development, and the molecular mechanism has recently been reported. In this review, we summarize the essential structure and function of the CNS. The significance of interactions between signaling pathways and between developmental processes like proliferation, apoptosis and migration in ensuring the correct development of the CNS is also presented. We primarily focus on research concerning possible mechanism of interaction between Notch1 and Nrf2 and the functions of Notch1-Nrf2 in neurons. There may be a direct interaction between Notch1 and NRF2, which is closely related to the crosstalk that occurs between them. The significance and potential applications of the Notch1-Nrf2 axis in abnormal development of the nervous system are been highlighten. We also discuss the molecular mechanisms by which the Notch1-Nrf2 axis controls the apoptosis, antioxidant pathway and differentiation of neurons to modulate the development of the nervous system. This information will lead to a better understanding of Notch1-Nrf2 axis signaling pathways in the nervous system and may facilitate the development of new therapeutic strategies.

Hesperidin ameliorates impairment in hippocampal neural stem cells related to apoptosis induced by methotrexate in adult rats

Neurogenesis is a process of generating neural stem cells (NSCs) as functional neurons can be decreased after chemotherapy treatments. Methotrexate (MTX) is a folate antagonist that is used for cancer treatment but has negative effects, including oxidative stress, neuronal apoptosis and cognitive impairments. Hesperidin (Hsd), a flavonoid found in citrus fruits, has antioxidant and neuroprotection properties. This study investigated whether Hsd could attenuate impairments of hippocampal neural stem cells related to apoptosis induced by MTX. Spraque-Dawley rats (n = 24) were divided into 4 groups: (1) Vehicle group received propylene glycol (21 days) and 0.9% normal saline (day 8 and 15), (2) Hsd group received 100 mg/kg (21 days), (3) MTX group received 75 mg/kg (days 8 and 15) and (4) MTX+Hsd group received MTX, 75 mg/kg (day 8 and 15) and Hsd 100 mg/kg (21 days). Our results showed that MTX decreased hippocampal neural stem cells including SRY (sex determining region Y)-box 2 (SOX2) and nestin. MTX diminished vascular related (VR) Ki-67 positive cells in the hippocampus but not non-vascular related (NVR) Ki-67. Additionally, MTX reduced SOX2, nestin, postsynaptic density protein 95 (PSD-95) and B-cell lymphoma-2 family of proteins (Bcl-2), whereas Bax and caspase-3 were enhanced in the hippocampal tissues. Interestingly, co-treatment with Hsd and MTX revealed upregulation of SOX2, nestin and VR Ki-67 positive cells as well as elevated SOX2, nestin, PSD-95 and Bcl-2 proteins. Moreover, receiving both Hsd and MTX significantly suppressed increased Bax and caspase-3. These results confirm that Hsd can ameliorate MTX-induced impairments of hippocampal NSC proliferation and neuronal apoptosis.

Potential anxiolytic and antidepressant-like effects of luteolin in a chronic constriction injury rat model of neuropathic pain: Role of oxidative stress, neurotrophins, and inflammatory factors

This study aimed to examine the effects of luteolin (LUT) on chronic neuropathic pain (NP)-induced mood disorders (i.e., anxiety and depression) by regulating oxidative stress, neurotrophic factors (NFs), and neuroinflammation. Chronic constrictive injury (CCI) was used to induce NP in the animals. Animals in the treatment groups received LUT in three doses of 10, 25, and 50 mg/kg for 21 days. The severity of pain and mood disorders were examined. Finally, animals were sacrificed, and their brain tissue was used for molecular and histopathological studies. CCI led to cold allodynia and thermal hyperalgesia. Mood alterations were proven in the CCI group, according to the behavioral tests. Levels of glial cell-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), B-cell lymphoma-2 (Bcl2), superoxide dismutase (SOD), catalase (CAT), and nuclear factor erythroid-2-related factor 2 (Nrf2) were reduced in the hippocampus (HPC) and prefrontal cortex (PFC). Furthermore, the levels of MDA, Bcl-2-associated X protein (Bax), and inflammatory markers, including nuclear factor kappa B (NF-κB), NLR family pyrin domain containing 3 (NLRP3), interleukin-1β (IL-1β), IL-18, IL-6, and tumor necrosis factor-α (TNF-α) significantly increased in the HPC and PFC following CCI induction. LUT treatment reversed the behavioral alterations via regulation of oxidative stress, neurotrophines, and inflammatory mediators in the HPC and PFC. Findings confirmed the potency of LUT in the improvement of chronic pain-induced anxiety- and depressive-like symptoms, probably through antioxidant, anti-inflammatory, and neuroprotective properties in the HPC and PFC.

Protective effect of metformin on methotrexate induced reduction of rat hippocampal neural stem cells and neurogenesis

Adult neurogenesis is a process in which the adult neural stem cells produce newborn neurons that are implicated in terms of learning and memory. Methotrexate (MTX) is a chemotherapeutic drug, which has a negative effect on memory and hippocampal neurogenesis in animal models. Metformin is an antidiabetic drug with strong antioxidant capacities. We found that metformin ameliorates MTX induced deteriorations of memory and hippocampal neurogenesis in adult rats. In this study, we focus to investigate neural stem cells, biomarkers of apoptosis, and the protein for synaptogenesis, which involves in the transcription factors of the hippocampus in rats that received metformin and MTX. Male Sprague-Dawley rats were composed of control, MTX, metformin, and MTX+metformin groups. MTX (75 mg/kg, i.v.) was given on days 7 and 14, whereas metformin (200 mg/kg, i.p.) was given for 14 days. Hippocampal neural stem cells in the subgranular zone (SGZ) were quantified using immunofluorescence staining of Sox2 and nestin. Protein expression including PSD95, Casepase-3, Bax, Bcl-2, CREB, and pCREB were determined using Western blotting. MTX-treated rats displayed decreases in Sox2 and nestin-positive cells in the SGZ. Increases in Caspase-3 and Bax levels and decreases in PSD95, Bcl-2, CREB, and pCREB protein expressions in the hippocampus were also detected. However, these negative impacts of MTX were ameliorated by co-treatment with metformin. These consequences postulate that metformin has a potential to increase neural stem cells, synaptic plasticity, decreased apoptotic activities, and transcription factors, resulting in upregulation of hippocampal neurogenesis in MTX-treated rats.

Melatonin Attenuates Methotrexate-Induced Reduction of Antioxidant Activity Related to Decreases of Neurogenesis in Adult Rat Hippocampus and Prefrontal Cortex

Previous studies have revealed that the side effects of anticancer drugs induce a decrease of neurogenesis. Methotrexate (MTX), one of anticancer drugs, can induce lipid peroxidation as an indicator of oxidative stress in the brain. Melatonin has been presented as an antioxidant that can prevent oxidative stress-induced neuronal damage via the activation of antioxidant enzymes associated with the increase of neurogenesis. The aims of the present study are to examine the neuroprotective effect of melatonin on the neurotoxicity of MTX on neurogenesis and the changes of protein expression and antioxidant enzyme levels in adult rat hippocampus and prefrontal cortex (PFC). Male Sprague-Dawley rats were assigned into four groups: vehicle, MTX, melatonin, and melatonin+MTX groups. The vehicle group received saline solution and 10% ethanol solution, whereas the experimental groups received MTX (75 mg/kg, i.v.) and melatonin (8 mg/kg, i.p.) treatments. After the animal examination, the brains were removed for p21 immunofluorescence staining. The hippocampus and PFC were harvested for Western blot analysis and biochemical assessments of malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GPX), and superoxide dismutase (SOD). The immunofluorescence result showed that coadministration with melatonin diminished p21-positive cells in the hippocampal dentate gyrus, indicating a decrease of cell cycle arrest. Melatonin reduced the levels of MDA and prevented the decline of antioxidant enzyme activities in rats receiving MTX. In the melatonin+MTX group, the protein expression results showed that melatonin treatment significantly upregulated synaptic plasticity and an immature neuron marker through enhancing brain derived neurotrophic factor (BDNF) and doublecortin (DCX), respectively. Moreover, melatonin ameliorated the antioxidant defense system by improving the nuclear factor erythroid 2-related factor 2 (Nrf2) in rats receiving MTX. These findings suggested that the effects of melatonin can ameliorate MTX toxicity by several mechanisms, including an increase of endogenous antioxidants and neurogenesis in adult rat hippocampus and PFC.

Recent Advances Regarding the Molecular Mechanisms of Triterpenic Acids: A Review (Part I)

Triterpenic acids are phytocompounds with a widespread range of biological activities that have been the subject of numerous in vitro and in vivo studies. However, their underlying mechanisms of action in various pathologies are not completely elucidated. The current review aims to summarize the most recent literature, published in the last five years, regarding the mechanism of action of three triterpenic acids (asiatic acid, oleanolic acid, and ursolic acid), corelated with different biological activities such as anticancer, anti-inflammatory, antidiabetic, cardioprotective, neuroprotective, hepatoprotective, and antimicrobial. All three discussed compounds share several mechanisms of action, such as the targeted modulation of the PI3K/AKT, Nrf2, NF-kB, EMT, and JAK/STAT3 signaling pathways, while other mechanisms that proved to only be specific for a part of the triterpenic acids discussed, such as the modulation of Notch, Hippo, and MALAT1/miR-206/PTGS1 signaling pathway, were highlighted as well. This paper stands as the first part in our literature study on the topic, which will be followed by a second part focusing on other triterpenic acids of therapeutic value.

Medha Plus - A novel polyherbal formulation ameliorates cognitive behaviors and disease pathology in models of Alzheimer's disease

Alzheimer's disease (AD) is a multi-faceted neurodegenerative disorder that leads to drastic cognitive impairments culminating in death. Pathologically, it is characterized by amyloid-β (Aβ) plaques, neurofibrillary tangles and neurodegeneration in brain. Complete cure of AD remains elusive to date. Available synthetic drugs only provide symptomatic reliefs targeting single molecule, hence, are unable to address the multi-factorial aspects in AD pathogenesis. It is imperative to develop combinatorial drugs that address the multiple molecular targets in AD. We show a unique polyherbal formulation of Brahmi, Mandukaparni, Shankhpushpi, Yastimadhu, Kokilaksha and Shunthi called 'Medha Plus' (MP), conventionally used for improving memory and reducing anxiety, was able to ameliorate cognitive deficits and associated pathological hallmarks of AD. Viability assays revealed that MP prevented Aβ-induced loss of neurites as well as neuronal apoptosis in cellular models. An array of behavioral studies showed that MP was able to recover AD-associated memory deficits in both Aβ-injected rats and 5XFAD mice. Immunohistochemical studies further revealed that MP treatment reduced Aβ depositshpi and decreased apoptotic cell death in the hippocampus. Enzymatic assays demonstrated anti-oxidative and anti-acetyl cholinesterase properties of MP especially in hippocampus of Aβ-injected rats. An underlying improvement in synaptic plasticity was observed with MP treatment in 5XFAD mice along with an increased expression of phospho-Akt at serine 473 indicating a role of PI3K/Akt signaling in correcting these synaptic deficits. Thus, our strong experiment-driven approach shows that MP is an incredible combinatorial drug that targets multiple molecular targets with exemplary neuroprotective properties and is proposed for clinical trial.

Effect of metformin treatment on memory and hippocampal neurogenesis decline correlated with oxidative stress induced by methotrexate in rats

Metformin is currently used as a first-line drug to treat patients with type 2 diabetes. Previous studies have demonstrated that metformin has antioxidant properties and reduces neuroinflammation and hippocampal neuronal cell loss, which eventually improves memory. Methotrexate (MTX) is an antimetabolite chemotherapeutic agent reported to activate cognitive impairment found in many patients. Moreover, MTX negatively affects the spatial working memory, related to neurogenesis reduction in animal models. Therefore, the present study aimed to investigate the antioxidant effect of metformin on the reduction of memory and neurogenesis caused by MTX. Male Sprague-Dawley rats were divided into four groups: control, MTX, metformin, and MTX+metformin. MTX (75 mg/kg, i.v.) was administered on days 7 and 14. Rats were administered metformin (200 mg/kg, i.p.) for 14 days. Memory was determined using novel object location (NOL) and novel object recognition (NOR) tests. Furthermore, cell cycle arrest was quantified by p21 immunostaining. Levels of neuronal protein expression, scavenging enzymes activity, and malondialdehyde (MDA) level changes in the hippocampus and prefrontal cortex were investigated. Rats receiving only MTX showed memory impairment. Decreases in scavenging enzyme activity and BDNF, DCX, and Nrf2 protein expressions levels were detected in the MTX-treated rats. In addition, MTX significantly increased p21-positive cell numbers and MDA levels. However, these adverse MTX effects were counteracted by co-administration with metformin. These results demonstrate that metformin can improve memory impairments, increase BDNF, DCX and Nrf2 protein expressions and antioxidant capacities, and decrease MDA levels in MTX-treated rats.

Chemotherapy-Induced Cognitive Impairment and Hippocampal Neurogenesis: A Review of Physiological Mechanisms and Interventions

A wide range of cognitive deficits, including memory loss associated with hippocampal dysfunction, have been widely reported in cancer survivors who received chemotherapy. Changes in both white matter and gray matter volume have been observed following chemotherapy treatment, with reduced volume in the medial temporal lobe thought to be due in part to reductions in hippocampal neurogenesis. Pre-clinical rodent models confirm that common chemotherapeutic agents used to treat various forms of non-CNS cancers reduce rates of hippocampal neurogenesis and impair performance on hippocampally-mediated learning and memory tasks. We review the pre-clinical rodent literature to identify how various chemotherapeutic drugs affect hippocampal neurogenesis and induce cognitive impairment. We also review factors such as physical exercise and environmental stimulation that may protect against chemotherapy-induced neurogenic suppression and hippocampal neurotoxicity. Finally, we review pharmacological interventions that target the hippocampus and are designed to prevent or reduce the cognitive and neurotoxic side effects of chemotherapy.

Melatonin Ameliorates Valproic Acid-Induced Neurogenesis Impairment: The Role of Oxidative Stress in Adult Rats

Background

Valproic acid (anticonvulsant medication) has been found to inhibit histone deacetylase activity and suppress hippocampal neurogenesis, which causes memory impairment in both humans and rodents. The neurohormone melatonin, which regulates mammalian seasonal and circadian physiology, has recently been shown to have neuroprotective properties, counteracting memory impairment associated with VPA-caused hippocampal neurogenesis reduction. This study is aimed at investigating the molecular mechanisms of melatonin associated with VPA-induced hippocampal neurogenesis and memory impairment.

Methods

Male Spraque-Dawley rats received VPA (300 mg/kg) twice daily or melatonin (8 mg/kg/day) or some rats were given melatonin for 14 days during VPA administration.

Results

The VPA-treated rats showed a significant increase in malondialdehyde (MDA) levels in the hippocampus and p21-positive cells in the subgranular zone (SGZ) of the dentate gyrus (DG) but decreased superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) activities. Moreover, VPA significantly decreased levels of nestin, Notchl, nuclear factor erythroid 2-related factor 2 (Nrf2), doublecortin (DCX), sex determining region Y-box 2 (SOX2), and brain-derived neurotrophic factor (BDNF).

Conclusions

We found that melatonin was able to counteract these neurotoxic effects, acting as a neuroprotectant in VPA-induced memory hippocampal neurogenesis impairment by preventing intracellular oxidative stress and increasing antioxidant activity.

Natural Phytochemicals as Novel Therapeutic Strategies to Prevent and Treat Parkinson's Disease: Current Knowledge and Future Perspectives

Parkinson's disease (PD) is the second-most common neurodegenerative chronic disease affecting both cognitive performance and motor functions in aged people. Yet despite the prevalence of this disease, the current therapeutic options for the management of PD can only alleviate motor symptoms. Research has explored novel substances for naturally derived antioxidant phytochemicals with potential therapeutic benefits for PD patients through their neuroprotective mechanism, targeting oxidative stress, neuroinflammation, abnormal protein accumulation, mitochondrial dysfunction, endoplasmic reticulum stress, neurotrophic factor deficit, and apoptosis. The aim of the present study is to perform a comprehensive evaluation of naturally derived antioxidant phytochemicals with neuroprotective or therapeutic activities in PD, focusing on their neuropharmacological mechanisms, including modulation of antioxidant and anti-inflammatory activity, growth factor induction, neurotransmitter activity, direct regulation of mitochondrial apoptotic machinery, prevention of protein aggregation via modulation of protein folding, modification of cell signaling pathways, enhanced systemic immunity, autophagy, and proteasome activity. In addition, we provide data showing the relationship between nuclear factor E2-related factor 2 (Nrf2) and PD is supported by studies demonstrating that antiparkinsonian phytochemicals can activate the Nrf2/antioxidant response element (ARE) signaling pathway and Nrf2-dependent protein expression, preventing cellular oxidative damage and PD. Furthermore, we explore several experimental models that evaluated the potential neuroprotective efficacy of antioxidant phytochemical derivatives for their inhibitory effects on oxidative stress and neuroinflammation in the brain. Finally, we highlight recent developments in the nanodelivery of antioxidant phytochemicals and its neuroprotective application against pathological conditions associated with oxidative stress. In conclusion, naturally derived antioxidant phytochemicals can be considered as future pharmaceutical drug candidates to potentially alleviate symptoms or slow the progression of PD. However, further well-designed clinical studies are required to evaluate the protective and therapeutic benefits of phytochemicals as promising drugs in the management of PD.

Melatonin Protects against the Side-Effects of 5-Fluorouracil on Hippocampal Neurogenesis and Ameliorates Antioxidant Activity in an Adult Rat Hippocampus and Prefrontal Cortex

Melatonin is an endogenous hormone that exhibits antioxidant functions and neuroprotective effects. The hippocampus and the prefrontal cortex (PFC) play an important role linked to working memory. 5-fluorouracil (5-FU) can induce oxidative stress and reduce neurogenesis in the subgranular zone (SGZ) of the dentate gyrus in a rat hippocampus and these alterations are related to working memory deficits. This study aimed to determine the effect of melatonin on 5-FU-induced oxidative stress that interferes with the antioxidant enzymes and protein expression levels in a rat hippocampus and PFC. A total of 68 male Sprague Dawley rats were divided into four groups: vehicle, 5-FU, melatonin and melatonin+5-FU groups. Rats were administered 5-FU (25 mg/kg, i.v.) on days 9, 12, 15, 18 and 21 and received melatonin (8 mg/kg, i.p.) at 19:00 from day 1 to day 21 of the experiment. Lipid peroxidation was assessed by measuring malondialdehyde (MDA) levels. Antioxidant enzyme levels including glutathione peroxidase (GPX), catalase (CAT) and superoxide dismutase (SOD) were determined. p21 immunofluorescence staining and Western blotting were used to detect the cell cycle arrest and protein expression of the nuclear factor erythroid 2-related factor 2 (Nrf2), doublecortin (DCX) and brain derived neurotrophic factor (BDNF), respectively. The results showed that melatonin reduced the number of p21-positive cells in the SGZ of the dentate gyrus and increased Nrf2, DCX and BDNF protein expression in rats treated with 5-FU. Moreover, melatonin restored antioxidant enzyme levels and reduced oxidative stress in the hippocampus and PFC caused by 5-FU. These findings reveal a mechanism of the neuroprotective properties of melatonin against 5-FU in a rat hippocampus and PFC.

Anti-Cancer Effects of Asiatic Acid, a Triterpene from Centilla asiatica L: A Review

BACKGROUND

Centilla asiatica L is a medicinal herb that has been widely used in folk medicine to treat various diseases. Asiatic Acid (AA), a triterpene and a known component of this herb, has been shown to display important biological activities, including anti-inflammatory, antibacterial, antidiabetic and antihyperlipidemic, neuroprotective, anxiolytic and antidepressant, hepatoprotective, pancreas protective, and cardio- protective.

OBJECTIVE

This review focuses on AA's anti-cancer effects on the basis of published literature found in a number of databases such as PubMed and Science Direct. Emphasis has been given to the mechanisms of action of its anti-cancer effect.

METHODS

A literature survey was conducted using known databases such as PubMed and Science Direct using the keywords 'Asiatic acid', pairing with 'cancer', 'tumor', 'anti-cancer effect', 'cytotoxic effect', 'anti-tumor activity', 'cell line', 'animal cancer', and 'human cancer'.

RESULTS

Findings suggest that AA exerts anti-cancer effects in several test systems through various pathways, including oxidative/antioxidant, anti-inflammatory, cytotoxicity, apoptotic cell death, necrosis, anti-angiogenesis, inhibition of proliferation and cell migration, and chemoprevention.

CONCLUSION

AA may be an effective plant-based cancer chemotherapeutic agent and a promising lead for the development of potent anticancer drugs.

Ethnobotany, Phytochemistry and Pharmacological Features of Centella asiatica: A Comprehensive Review

Centella asiatica (CA) or Gotu cola is an herbal plant from the Apiaceae family with a long history of usage in different traditional medicines. It has long been used for the treatment of various ailments such as central nervous system (CNS), skin and gastrointestinal disorders especially in the Southeast Asia. This chapter focused on the phytochemical constituent and pharmacological activities of CA based on preclinical and clinical studies. Additionally, botanical description and distribution, traditional uses, interactions, and safety issues are reviewed. Electronic databases of Google Scholar, Scopus, PubMed, and Web of Science were searched to obtain relevant studies on the pharmacological activities of CA. Approximately, 124 chemical compounds including triterpenoids, polyphenolic compounds, and essential oils have been isolated and identified from CA. Ethnomedicinal applications of CA mostly include treatment of gastrointestinal diseases, wounds, nervous system disorders, circulatory diseases, skin problems, respiratory ailments, diabetes and sleep disorders in various ethnobotanical practices. Pharmacological studies revealed a wide range of beneficial effects of CA on CNS, cardiovascular, lung, liver, kidney, gastrointestinal, skin, and endocrine system. Among them, neuroprotective activity, wound healing and treatment of venous insufficiency, as well as antidiabetic activity seem to be more frequently reported. At the moment, considering various health benefits of CA, it is marketed as an oral supplement as well as a topical ingredient in some cosmetic products. Additional preclinical studies and particularly randomized controlled trials are needed to clarify the therapeutic roles of CA.

Prolonged Treatment with Centella asiatica Improves Memory, Reduces Amyloid-β Pathology, and Activates NRF2-Regulated Antioxidant Response Pathway in 5xFAD Mice

BACKGROUND

The medicinal herb Centella asiatica has been long been used for its neuroprotective and cognitive enhancing effects. We have previously shown that two weeks of treatment with a water extract of Centella asiatica (CAW) improves cognition and activates the endogenous antioxidant response pathway without altering amyloid-β (Aβ) plaque burden.

OBJECTIVE

Here, we assess the effect of long-term treatment of CAW in the 5xFAD mouse model of Aβ accumulation.

METHODS

Four-month-old 5xFAD mice were treated with CAW in their drinking water (2 g/L) for three months at which point they underwent cognitive testing as well as analysis of Aβ plaque levels and antioxidant and synaptic gene expression. In order to confirm the involvement of the antioxidant regulatory transcription factor NRF2 on the effects of CAW on synaptic plasticity, neurons isolated from 5xFAD mice were also treated with CAW and the targeted inhibitor ML385.

RESULTS

Three months of treatment with CAW improved spatial and contextual memory as well as executive function in 5xFAD mice. This improvement was accompanied by increased antioxidant gene expression and a decrease in Aβ plaque burden relative to untreated 5xFAD animals. In isolated neurons, treatment with ML385 blocked the effects of CAW on dendritic arborization and synaptic gene expression.

CONCLUSION

These results suggest that prolonged CAW exposure could be beneficial in Alzheimer's disease and that these effects likely involve NRF2 activation. Moreover, these findings suggest that targeting NRF2 itself may be a relevant therapeutic strategy for improving synaptic plasticity and cognitive function in Alzheimer's disease.

Therapeutic Potential of Centella asiatica and Its Triterpenes: A Review

Centella asiatica (also known as Centella asiatica (L.) Urb. or Gotu kola) is a traditional Chinese medicine with extensive medicinal value, which is commonly used in Southeast Asian countries. This study aimed to summarize the effects of C. asiatica and its main components on neurological diseases, endocrine diseases, skin diseases, cardiovascular diseases, gastrointestinal diseases, immune diseases, and gynecological diseases, as well as potential molecular mechanisms, to study the pathological mechanism of these diseases based on the changes at the molecular level. The results showed that C. asiatica and its triterpenoids had extensive beneficial effects on neurological and skin diseases, which were confirmed through clinical studies. They exhibited anti-inflammatory, anti-oxidative stress, anti-apoptotic effects, and improvement in mitochondrial function. However, further clinical studies are urgently required due to the low level of evidence and lack of patients.

Neurotoxicity of antineoplastic drugs: Mechanisms, susceptibility, and neuroprotective strategies

This review summarizes the adverse effects on the central and/or peripheral nervous systems that may occur in response to antineoplastic drugs. In particular, we describe the neurotoxic side effects of the most commonly used drugs, such as platinum compounds, doxorubicin, ifosfamide, 5-fluorouracil, vinca alkaloids, taxanes, methotrexate, bortezomib and thalidomide. Neurotoxicity may result from direct action of compounds on the nervous system or from metabolic alterations produced indirectly by these drugs, and either the central nervous system or the peripheral nervous system, or both, may be affected. The incidence and severity of neurotoxicity are principally related to the dose, to the duration of treatment, and to the dose intensity, though other factors, such as age, concurrent pathologies, and genetic predisposition may enhance the occurrence of side effects. To avoid or reduce the onset and severity of these neurotoxic effects, the use of neuroprotective compounds and/or strategies may be helpful, thereby enhancing the therapeutic effectiveness of antineoplastic drug.

Neuroprotective effects of hesperidin against methotrexate-induced changes in neurogenesis and oxidative stress in the adult rat

Methotrexate (MTX) induces the formation of reactive oxygen species (ROS) and leads to neurotoxicity. The drug also negatively impacts neurogenesis and memory. Hesperidin (Hsd) is a major flavanoid with multiple beneficial pharmacological effects such as anti-oxidation, anti-inflammation, and neuroprotective effects. The aim of our study was to investigate the neuroprotective effects of Hsd against MTX-induced alterations in oxidative stress and neurogenesis. Sprague Dawley rats were divided into four groups: 1) a vehicle group, which received saline and propylene glycol, 2) an Hsd group, which was orally administered with Hsd (100 mg/kg) for 21 days, 3) an MTX group, which received MTX (75 mg/kg) by intravenous injection on days 8 and 15, and 4) an MTX + Hsd group, which received both MTX and Hsd. After treatment with MTX, p21-positive cells had increased significantly and doublecortin (DCX) expression in the hippocampus had decreased significantly. Treatment with MTX also increased malondialdehyde (MDA) in both the hippocampus and prefrontal cortex and decreased levels of brain-derived neurotropic factor (BDNF) and nuclear factor erythroid 2-related factor 2 (Nrf2) in the hippocampus and prefrontal cortex. Additionally, there were significant decreases in superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) in the hippocampus and prefrontal cortex in the MTX group. However, co-treatment with Hsd ameliorated the negative effects of MTX on neurogenesis, oxidative stress, and antioxidant enzymes. These findings suggest that Hsd may be able to prevent neurotoxic effects of MTX by reducing oxidative stress and enhancing hippocampal neurogenesis.

Melatonin attenuates 5-fluorouracil-induced spatial memory and hippocampal neurogenesis impairment in adult rats

AIMS

Treatment with 5-fluorouracil (5-FU) can cause impairment to adult hippocampal neurogenesis, resulting in cognitive deficits. As melatonin has been shown to enhance memory and hippocampal neurogenesis in animal models, this research investigated the neuroprotective effects of melatonin against spatial memory and hippocampal neurogenesis impairment in 5-fluorouracil (5-FU)-treated rats.

MATERIALS AND METHODS

Four-Five weeks old male Spraque-Dawley rats weighing between 180 and 200 g were used. Animals were maintained under standard laboratory conditions with 25 °C and 12 h light/dark cycle. Animal were administered intravenous (i.v.) injections of 5-FU (25 mg/kg) 5 times every 3 days starting on day 9 of the experiment. The rats were divided into preventive, recovery, and throughout groups and co-treated with melatonin (8 mg/kg, i.p.) once daily (at 7.00 pm) for 21 days prior to, after, and throughout 5-FU treatment, respectively. Spatial memory was assessed using a novel object location (NOL) test. Hippocampal neurogenesis was then examined using Ki67, bromodeoxyuridine (BrdU), and doublecortin (DCX) immunohistochemistry staining.

KEY FINDINGS

Melatonin administration was able to both protect the subjects from and reverse spatial memory deficits. 5-FU was also found to reduce the generation of hippocampal newborn neurons. However, co-treatment with melatonin ameliorated the reductions in neurogenesis caused by 5-FU.

SIGNIFICANCE

These findings suggest that melatonin administration was able to ameliorate the 5-FU-induced spatial memory deficits associated with neurogenesis. The present work will be valuable for patients who suffer memory deficits from 5-FU chemotherapy.

Centella Asiatica Improves Memory and Promotes Antioxidative Signaling in 5XFAD Mice

Centella asiatica (CA) herb is a traditional medicine, long reputed to provide cognitive benefits. We have reported that CA water extract (CAW) treatment improves cognitive function of aged Alzheimer’s disease (AD) model Tg2576 and wild-type (WT) mice, and induces an NRF2-regulated antioxidant response in aged WT mice. Here, CAW was administered to AD model 5XFAD female and male mice and WT littermates (age: 7.6 +/− 0.6 months), and object recall and contextual fear memory were tested after three weeks treatment. CAW’s impact on amyloid-β plaque burden, and markers of neuronal oxidative stress and synaptic density, was assessed after five weeks treatment. CAW antioxidant activity was evaluated via nuclear transcription factor (erythroid-derived 2)-like 2 (NRF2) and NRF2-regulated antioxidant response element gene expression. Memory improvement in both genders and genotypes was associated with dose-dependent CAW treatment without affecting plaque burden, and marginally increased synaptic density markers in the hippocampus and prefrontal cortex. CAW treatment increased Nrf2 in hippocampus and other NRF2 targets (heme oxygenase-1, NAD(P)H quinone dehydrogenase 1, glutamate-cysteine ligase catalytic subunit). Reduced plaque-associated SOD1, an indicator of oxidative stress, was observed in the hippocampi and cortices of CAW-treated 5XFAD mice. We postulate that CAW treatment leads to reduced oxidative stress, contributing to improved neuronal health and cognition.