Prophylactic neuroprotective efficiency of co-administration of Ginkgo biloba and Trifolium pretense against sodium arsenite-induced neurotoxicity and dementia in different regions of brain and spinal cord of rats

Unveiling the neuroprotective properties of isoflavones: current evidence, molecular mechanisms and future perspectives

Neurodegenerative diseases encompass a wide range of debilitating and incurable brain disorders characterized by the progressive deterioration of the nervous system's structure and function. Isoflavones, which are naturally occurring polyphenolic phytochemicals, have been found to regulate various cellular signaling pathways associated with the nervous system. The main objective of this comprehensive review is to explore the neuroprotective effects of isoflavones, elucidate the underlying mechanisms, and assess their potential for treating neurodegenerative disorders. Relevant data regarding isoflavones and their impact on neurodegenerative diseases were gathered from multiple library databases and electronic sources, including PubMed, Google Scholar, Web of Science, and Science Direct. Numerous isoflavones, including genistein, daidzein, biochanin A, and formononetin, have exhibited potent neuroprotective properties against various neurodegenerative diseases. These compounds have been found to modulate neurotransmitters, which in turn contributes to their ability to protect against neurodegeneration. Both in vitro and in vivo experimental studies have provided evidence of their neuroprotection mechanisms, which involve interactions with estrogenic receptors, antioxidant effects, anti-inflammatory properties, anti-apoptotic activity, and modulation of neural plasticity. This review aims to provide current insights into the neuroprotective characteristics of isoflavones and shed light on their potential therapeutic applications in future clinical scenarios.

Memantine versus Ginkgo biloba Extract: A Comparative Study on Cognitive Dysfunction Treatment in a Novel Rat Model

Extracellular senile plaques and intraneuronal neurofibrillary tangles are two devastating brain proteinopathies that are indicative of Alzheimer's disease, the most prevalent type of dementia. Currently, no effective medications are available to stop or reverse Alzheimer's disease. Ginkgo biloba extract, commonly referred to as EGb 761, is a natural product made from the leaves of the G. biloba tree. It has long been demonstrated to have therapeutic benefits in Alzheimer's disease. The current study assessed the beneficial effects of EGb 761 against Alzheimer's disease in comparison with memantine, a standard treatment for Alzheimer's disease. The scopolamine-heavy metals mixture rat Alzheimer's disease model is a newly created model to study the effects of EGb 761 oral therapy on cognitive performance and other Alzheimer's disease-like changes over a 28-day experimental period. This new Alzheimer's disease model provides better criteria for Alzheimer's disease hallmarks than the conventional scopolamine model. The EGb 761 reversed memory and learning deficits induced by the scopolamine-heavy metals mixture. These outcomes were linked to a more pronounced inhibitory effect on acetylcholinesterase, caspase-3, hippocampal amyloid-beta protein (Aβ1 - 42), phosphorylated tau protein counts, and proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β) compared to the memantine-treated group. Furthermore, EGb 761 treatment considerably reduced lipid peroxidation (malondialdehyde) and improved reduced glutathione levels compared to memantine. Our results suggest EGb 761's potential in treating central nervous system disorders. It's a promising candidate for future Alzheimer's disease therapeutic exploration. This study also highlights the need for future research to focus on the positive benefits of herbal medicines.

The protective effect of natural or chemical compounds against arsenic-induced neurotoxicity: Cellular and molecular mechanisms

Arsenic is a notorious metalloid that exists in the earth's crust and is considered toxic for humans and the environment. Both cancerous and non-cancerous complications are possible after arsenic exposure. Target organs include the liver, lungs, kidney, heart, and brain. Arsenic-induced neurotoxicity, the main focus of our study, can occur in central and peripheral nervous systems. Symptoms can develop in a few hours, weeks, or years depending on the quantity of arsenic and the duration of exposure. In this review, we aimed to gather all the compounds, natural and chemical, that have been studied as protective agents in cellular, animal, and human reports. Oxidative stress, apoptosis, and inflammation are frequently described as destructive mechanisms in heavy metal toxicity. Moreover, reduced activity of acetylcholinesterase, the altered release of monoamine neurotransmitters, down-regulation of N-methyl-D-aspartate receptors, and decreased brain-derived neurotrophic factor are important underlying mechanisms of arsenic-induced neurotoxicity. As for neuroprotection, though some compounds have yet limited data, there are others, such as curcumin, resveratrol, taurine, or melatonin which have been studied more deeply and might be closer to a reliable protective agent. We collected the available information on all protective agents and the mechanisms by which they fight against arsenic-induced neurotoxicity.

Anti-kindling effect of Ginkgo biloba leaf extract and L-carnitine in the pentylenetetrazol model of epilepsy

Epilepsy is one of the most common serious brain disorders, affecting about 1% of the population all over the world. Ginkgo biloba extract (GbE) and L-carnitine (LC) reportedly possess the antioxidative activity and neuroprotective potential. In this report, we investigated the possible protective and therapeutic effects of GbE and LC against pentylenetetrazol (PTZ)-induced epileptic seizures in rat hippocampus and hypothalamus. Adult male albino rats were equally divided into eight groups: control, GbE (100 mg/kg), LC (300 mg/kg), PTZ (40 mg/kg), protective groups (GbE + PTZ and LC + PTZ), and therapeutic groups (PTZ + GbE and PTZ + LC). The oxidative stress, antioxidant, and neurochemical parameters, viz., malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), acetylcholine esterase (AchE), dopamine (DA), norepinephrine (NE), and serotonin (5-HT), in the hippocampal and hypothalamic regions have been evaluated. PTZ injection leads to an increase in the seizure score, the levels of MDA and NO, and to a decrease in the activity of GSH, SOD, CAT, and GPx. Besides, monoamine neurotransmitters, DA, NE, and 5-HT, were depleted in PTZ-kindled rats. Furthermore, PTZ administration caused a significant elevation in the activity of AchE. Hippocampal and hypothalamic sections from PTZ-treated animals were characterized by severe histopathological alterations and, intensely, increased the ezrin immunolabeled astrocytes. Pre- and post-treatment of PTZ rats with GbE and LC suppressed the kindling acquisition process and remarkably alleviated all the aforementioned PTZ-induced effects. GbE and LC have potent protective and therapeutic effects against PTZ-induced kindling seizures via the amelioration of oxidative/antioxidative imbalance, neuromodulatory, and antiepileptic actions.

Oral Supplements of <i>Ginkgo biloba</i> Extract Alleviate Neuroinflammation, Oxidative Impairments and Neurotoxicity in Rotenone-Induced Parkinsonian Rats

BACKGROUND

Ginkgo biloba extract (GbE) is known to contain several bioactive compounds and exhibits free radical scavenging activity. Parkinson's Disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons and is associated with oxidative stress, neuroinflammation and apoptosis.

OBJECTIVE

The current study aimed to investigate the neuroprotective effect of GbE in a rat model of PD induced by rotenone (ROT; a neurotoxin).

METHODS

Twenty-four male albino rats were randomly divided into four groups of six rats each: normal control, GbE treated, toxin control (ROT treated) and GbE+ROT group.

RESULTS

Oral administration of ROT (2.5 mg/kg b.w.) for 50 days caused an increased generation of lipid peroxidation products and significant depletion of reduced glutathione, total thiol content and activities of enzymatic antioxidants, i.e., superoxide dismutase and glutathione peroxidase in the brains of treated rats. Furthermore, ROT caused an elevation in acetylcholinesterase, interleukin-1β, interleukin- 6 and tumor necrosis factor-α and a significant reduction in dopamine in the stratum and substantia nigra. Immunohistochemical results illustrated that ROT treatment reduced the expression of tyrosine hydroxylase (TH). GbE treatment (150 mg/kg b.w./day) significantly reduced the elevated oxidative stress markers and proinflammatory cytokines and restored the reduced antioxidant enzyme activities, DA level and TH expression. These results were confirmed by histological observations that clearly indicated a neuroprotective effect of GbE against ROT-induced PD.

CONCLUSION

GbE mitigated ROT-induced PD via the inhibition of free-radical production, scavenging of ROS, and antioxidant enhancement.

Arsenic induces autophagy in developmental mouse cerebral cortex and hippocampus by inhibiting PI3K/Akt/mTOR signaling pathway: involvement of blood-brain barrier's tight junction proteins

For the past decade, there has been an increased concern about the health risks from arsenic (As) exposure, because of its neurotoxic effects on the developing brain. The exact mechanism underlying As-induced neurotoxicity during sensitive periods of brain development remains unclear, especially the role of blood-brain barrier's (BBB) tight junction (TJ) proteins during As-induced neurotoxicity. Here, we highlight the involvement of TJ proteins in As-induced autophagy in cerebral cortex and hippocampus during developmental periods [postnatal day (PND) 21, 28, 35 and 42]. Here, the administration of arsenic trioxide (As₂O₃) at doses of 0.15 mg or 1.5 mg or 15 mg As₂O₃/L in drinking water from gestational to lactational and continued to the pups till PND42 resulted in a significant decrease in the mRNA expression levels of TJ proteins (Occludin, Claudin, ZO-1 and ZO-2) and Occludin protein expression level. In addition, As exposure significantly decreased PI3K, Akt, mTOR, and p62 with a concomitant increase in Beclin1, LC3I, LC3II, Atg5 and Atg12. Moreover, As exposure also significantly downregulated the protein expression levels of mTOR with a concomitant upregulation of Beclin 1, LC3 and Atg12 in all the developmental age points. However, no significant alterations were observed in low and medium dose-exposed groups of PND42. Histopathological analysis in As-exposed mice revealed decreased number of pyramidal neurons in hippocampus; and neurons with degenerating axons, shrinkage of cells, remarkable vacuolar degeneration in cytoplasm, karyolysis and pyknosis in cerebral cortex. Ultrastructural analysis by transmission electron microscopy revealed the occurrence of autophagosomes and vacuolated axons in the cerebral cortex and hippocampus of the mice exposed to high dose As at PND21 and 42. The severities of changes were found to more persist in the cerebral cortex than in the hippocampus of As-exposed mice. Finally, we conclude that the leaky BBB in cerebral cortex and hippocampus may facilitate the transfer of As and induces autophagy by inhibiting PI3K/Akt/mTOR signaling pathway in an age-dependent manner, i.e., among the four different developmental age points, PND21 animals were found to be more vulnerable to the As-induced neurotoxicity than the other three age points.

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

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